HK1056071A

HK1056071A - Multicast transmission system comprising a bandwidth scaler

Info

Publication number: HK1056071A
Application number: HK03108294.3A
Authority: HK
Inventors: Arye Ram
Original assignee: 竹媒介分配股份有限公司
Priority date: 2000-06-27
Filing date: 2001-05-31
Publication date: 2004-01-30

Description

Multicast transmission system including bandwidth measurement device

Technical Field

The present invention relates to signal processing, and more particularly, to a multicast transmission system for transmitting multimedia data.

Background

In a video on demand system (VOD system) for wireless transmission of real-time multimedia information in the prior art, a typical VOD system includes at least one video content source, a content exchange, and at least one video receiving terminal. Each VOD terminal contains a dedicated channel that wirelessly sends requests for desired video content to the video content source via the content switch. When a set of multimedia data (e.g., a set of video files) is transmitted from a content source to a single user over a dedicated channel, the data rate may be adaptively adjusted according to the reception conditions of the particular user terminal. The better the reception of a particular user terminal, the higher the bit rate at which the data set can transmit data to the user terminal.

However, prior art single-drop VOD systems suffer from certain disadvantages. In fact, for a unicast (unicast) transmission system in operation, each user requires two dedicated channels, one for reception and one for continuous return of the video reception status to the content provider. A given video content must be transmitted on twice the number of channels as the users. Thus, the number of users is limited by the number of time slots (or channels) that can be supported by the radio cell. Since each wireless cell can only support 5-50 video channels (i.e. 5-50 video users at most), or 20-200 audio channels, or 2-20 data channels, it enters into saturation state very quickly.

There is therefore a need for a multimedia wireless system (e.g., a video system) that does not have the above limitations. In particular, there is a need for a multicast transmission system that can transmit data on the same channel for a plurality of intelligent (smart) terminals, wherein each intelligent terminal can independently and locally adjust the quality of the received multimedia data without sending feedback information to the content provider.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides a multicast transmission system and a multicast transmission method for receiving multimedia information. Before a group of data is transmitted through a channel, it is finely measured (scaled) and grouped into sub-streams (sub-streams) that are processed by the intelligent terminal. Each intelligent terminal determines the substream used individually according to the reception quality and when to switch to another substream according to a change in the reception status. In order to optimize multimedia reception by minimizing data loss and smoothing the transition between the used sub-streams, each intelligent terminal also determines when and how to synchronize the switching operation between the sub-streams.

One aspect of the present invention is directed to a multicast system comprising a content switch coupled to a multimedia content source and at least one multimedia intelligent terminal. The multimedia content source comprises N multimedia contents, wherein each multimedia content is supported by a basic bit rate multimedia stream transmitted on a basic dedicated channel, the dedicated channel comprising a basic bandwidth. N is an integer.

In one embodiment of the invention, the content switch further comprises a bandwidth meter configured to meter each elementary multimedia stream with K secondary multimedia sub-streams, each elementary multimedia stream being transmitted at a substantially high bit rate on a substantially dedicated channel having a basic bandwidth, where K is an integer. In one embodiment, the K secondary multimedia sub-streams are substantially synchronized. In an alternative embodiment, the K multimedia sub-streams are not synchronized.

In one embodiment, each multimedia intelligent terminal is configured to receive each multimedia content from the content switch over the network as K secondary multimedia sub-streams transmitted on a secondary channel having a secondary bandwidth.

In one embodiment, each multimedia intelligent terminal further comprises an intelligent terminal sub-stream switch configured to switch between the K secondary multimedia sub-streams to select a substantially optimized secondary multimedia sub-stream, the selected sub-stream having a substantially optimized low bit rate. The intelligent terminal substream switch further comprises means for continuously determining the current bit error rate for the currently used optimized secondary multimedia substream containing the substantially optimized bit rate. The preferred secondary multimedia sub-stream includes an optimized relationship between the determined bit error rate level upon reception and the optimized multimedia content reception quality supported by the secondary multimedia sub-stream.

In one embodiment, the intelligent terminal sub-stream switch further comprises a synchronous intelligent terminal sub-stream switch when the K secondary multimedia sub-streams are substantially synchronized. In this embodiment, the synchronized intelligent terminal substream switch is configured to switch between the K secondary multimedia substreams to select an optimized secondary multimedia substream having an optimized low bit rate.

In one embodiment, the synchronized intelligent terminal substream switch further comprises a dynamically loaded database comprising a look-up table comprising N multimedia content entries, wherein the look-up table further comprises K secondary multimedia substreams for each content entry N. For each secondary multimedia sub-stream, the look-up table further includes a lower bit error rate threshold, an upper bit error rate threshold, and a set of synchronization data. Here, N is an integer less than or equal to N, and K is an integer less than or equal to K.

In one embodiment, the synchronized intelligent terminal substream switch further comprises a switching intelligent terminal substream device for switching between the k available secondary multimedia substreams to select a substantially optimized secondary multimedia substream for each multimedia content according to a look-up table.

If the selected optimized secondary multimedia sub-stream has a determined bit error rate above a preset higher bit error rate threshold, the intelligent end switch switches content from the substantially optimized secondary multimedia sub-stream to a lower secondary multimedia sub-stream containing a lower low bit rate, wherein the lower low bit rate is lower than the substantially optimized low bit rate. On the other hand, if the substantially optimized secondary multimedia sub-stream has a determined bit error rate below a preset lower bit error rate threshold, the intelligent end switch switches content from the substantially optimized secondary multimedia sub-stream to a higher secondary multimedia sub-stream containing a higher low bit rate, wherein the higher low bit rate is lower than the substantially optimized low bit rate.

In one embodiment, the intelligent terminal switch further comprises means for continuously determining the error rate of the previously optimized secondary multimedia sub-stream. The determined error rate indicates a direction of switching from a previously optimized secondary multimedia sub-stream to a subsequently optimized multimedia sub-stream. The switching direction may comprise from top to bottom if the subsequent optimized secondary multimedia sub-stream comprises a lower bitrate than the previous optimized bitrate. The switching direction may comprise from bottom to top if the subsequent optimized secondary multimedia sub-stream comprises a higher bitrate than the previous optimized bitrate. The switch with the top-down direction contains the top-down switch, and the switch with the bottom-up direction contains the bottom-up switch. In one embodiment, the decision to make or delay making the current handover is dependent on the direction of the current handover as indicated by the detection means, a history of existing handovers including at least one existing top-down or at least one existing bottom-up handover, and a time series data set for each existing top-down or bottom-up handover.

In one embodiment, the synchronized intelligent terminal substream switch further comprises a synchronized intelligent terminal substream means for substantially synchronizing the timing of transitions between a previously optimized secondary multimedia substream and a subsequently optimized secondary multimedia substream with the timing of a set of synchronized data groups provided by the look-up table, thereby minimizing data loss during the transitions.

In one embodiment, the timing of the transition between the previously optimized secondary multimedia sub-stream and the subsequently optimized secondary multimedia sub-stream is substantially synchronized with the timing of a set of synchronized data sets transmitted by the secondary multimedia stream, thereby minimizing data loss during the transition. In another embodiment, the synchronization data set further comprises a plurality of flags indicating at least one optimization occasion when a switch should be made from a previously optimized secondary multimedia sub-stream to a subsequently optimized secondary multimedia sub-stream.

In one embodiment, the synchronized intelligent terminal sub-stream switch further comprises a receiving multimedia synchronized intelligent terminal sub-stream switch further comprising only one receiving device configured to receive the N multimedia content from the content switch over the network. In an alternative embodiment, the synchronized intelligent terminal sub-stream switch further comprises a transceiver multimedia intelligent terminal further comprising transceiver means configured to receive the N multimedia content from the content switch over the network and to send each received multimedia content reception status to the content switch.

Another aspect of the present invention is directed to a video multicast system that receives video information. In one embodiment, a system comprises: a content switch coupled to a video content source; and at least one video intelligent terminal. The video content source includes a plurality of video content. And each video content is supported by a primary video stream transmitted on a primary dedicated channel having a primary bandwidth. Each content intelligent terminal is configured to receive each video content from the content exchange via the network as a secondary video stream transmitted via a secondary channel having a secondary bandwidth.

In one embodiment, the video content switch further comprises a bandwidth meter configured to meter each primary video stream with a plurality of substantially synchronized secondary video sub-streams.

In one embodiment, a video intelligent terminal sub-stream switch is configured to switch between a plurality of secondary video sub-streams to select a substantially optimized secondary video sub-stream having a substantially optimized secondary video sub-stream; wherein substantially optimizing the secondary video sub-stream includes substantially optimizing a relationship between a determined bit error rate level upon reception and a multimedia content reception quality supported by the optimized secondary multimedia sub-stream.

In one embodiment, the video intelligent terminal sub-stream switch further comprises a synchronized video intelligent terminal sub-stream switch configured to switch between the plurality of secondary video sub-streams to select a substantially optimized secondary video sub-stream having a substantially optimized low bit rate. The synchronized intelligent terminal sub-stream switch is further configured to substantially synchronize timing of transitions between a previously optimized secondary video sub-stream and a subsequently optimized secondary video sub-stream with timing of a set of synchronized data sets conveyed by the secondary video streams, thereby minimizing data loss during the transitions.

In a preferred embodiment of the present invention, the base video stream comprises a compressed video stream further comprising a plurality of independent frames and a plurality of non-independent frames. The plurality of independent frames further comprises a plurality of snapshots. The plurality of non-independent frames further comprises a plurality of motion vectors. The vector-based image comprises a set of computed dependent frames. Each calculated non-independent frame is calculated using a set of motion vectors within the non-independent frame and a previous independent frame. Each secondary sub-stream further contains a plurality of independent frames and a plurality of non-independent frames. The plurality of independent frames within each substream contain a plurality of synchronization data. In this embodiment, the synchronized intelligent terminal video sub-stream switch further comprises video means for substantially synchronizing the timing of the transition between the previously optimized secondary video sub-stream and the subsequently optimized secondary video sub-stream with the timing of a set of synchronized data sets conveyed by the secondary video stream to minimize data loss during the transition.

Another aspect of the present invention is directed to a method of receiving multimedia information in a multicast mode. In one embodiment, the method comprises the steps of: (1) receiving, with a content switch coupled to a multimedia content source, N multimedia contents provided by the multimedia content source, wherein each multimedia content is received as a primary multimedia stream transmitted via a primary dedicated channel having a primary bandwidth and at a primary bitrate, where N is an integer; (2) transmitting each multimedia content over the network by utilizing a content switch, wherein each multimedia content is transmitted as a multimedia stream over a secondary channel having a secondary bandwidth; and (3) at least one multimedia intelligent terminal receives the multimedia content over the network as a multimedia stream transmitted on a secondary channel having a secondary bandwidth.

In a preferred embodiment of the present invention, the content switch further comprises a bandwidth measure; the method of the present invention further comprises the steps of: (4) each primary multimedia stream transmitted at a primary high bit rate on a primary dedicated channel having a primary bandwidth is measured in a plurality of secondary multimedia substreams.

In one embodiment, the step (3) of at least one multimedia intelligent terminal receiving the multimedia content as a multimedia stream transmitted on a secondary channel having a secondary bandwidth via the network further comprises the sub-steps of: (3A) switching between the plurality of secondary multimedia sub-streams to select a substantially optimized secondary multimedia sub-stream having a substantially optimized low bit rate; and (3B) substantially synchronizing the timing of step (3A) with the timing of the set of synchronization data.

Drawings

The above and other advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments of the present invention when taken in conjunction with the accompanying drawings.

Fig. 1 shows a multicast system for multimedia information transmission and reception according to the present invention.

Fig. 2 shows a prior art compression/decompression system.

Fig. 3 illustrates a multimedia intelligent terminal including a content switch configured to select one multimedia content among N offered contents and an intelligent terminal substream switch configured to select an optimized substream for the selected content.

Fig. 4 shows a synchronized database containing N multimedia content entries and N corresponding look-up table entries.

Fig. 5 shows a flow chart describing the logical flow of the switch, which corresponds to the method of multicast reception of multimedia information according to the invention.

Detailed Description

Preferred embodiments of the present invention are described in detail below with the aid of the accompanying drawings. While the invention will be described in conjunction with the preferred embodiments, it will be understood that they are not intended to limit the invention to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims. Furthermore, in the following detailed description of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that the present invention may be practiced without reference to these specific details. In other instances, well-known methods, procedures, components and circuits have not been described in detail so as not to obscure the present invention.

Fig. 1 illustrates a multicast system 10 for multimedia information reception that is representative of the subject matter of the present invention. In the preferred embodiment, the system 10 includes a content switch 20 coupled to the multimedia content source 12. The multimedia content source 12 includes N multimedia content 14, 16 … … 18, N being an integer. For example, content source 12 comprises a video server having several channels including, but not limited to CNN, BBC, ABC, etc. A Real-time Player (Real Player) as a standard for internet-related applications may contain these servers for the wired application of the present invention. For wireless applications of the present invention, a satellite television server may be employed as the multimedia content source 12 of FIG. 1.

In a wireless embodiment of the present invention, each multimedia content 14, 16 … … 18 is supported by a compressed elementary bit rate multimedia stream transmitted on an elementary dedicated channel having an elementary bandwidth. In one embodiment, each multimedia content 14, 16 … … 18 comprises a compressed video stream transmitted over a substantially dedicated channel having a substantially bandwidth. The video compression techniques used in this application conform to the international Organization for Standardization (OSI)/International Electrotechnical Commission (IEC) Moving Picture Experts Group (MPEG) specifications.

Video compression may be provided within a video processing system to reduce video transmission time in a communication link, or to transmit broadband signals over a narrowband communication channel. And video compression may be employed to increase the amount of video data that can be stored in a given space or to decrease the space required to store a given amount of video data.

The MPEG standard defines compression and decompression algorithms for moving picture video services. One example of such a service is a Video On Demand (VOD) system, in which a user interacts with a remote video store to request that a particular movie or video program be played on the user's television set top box. Due to video compression, pictures of moving images can be transmitted over a communication channel using only a portion of a common television channel. Thus, more video channels can be carried on a given communication medium (e.g., a cable television medium). And a normal telephone link can carry broadband television signals.

In the MPEG algorithm, each moving image frame is defined either independently or as a change from a displayed image before and/or after. A video scene may be described by a single frame (an I-frame is an intra-frame that generates an I-picture) that represents the entire scene as it first appears, followed by a long series of changing frames like P-frames (the "predicted" frames that generate P-pictures) and/or B-frames (the "interpolated" frames that give B-pictures) that describe the changes to the scene. The MPEG video compression technique thus eliminates redundant transmission of scene-invariant units.

As shown in fig. 2, an MPEG video compression/decompression system 40 contains an image source 42 (e.g., a video camera) or video service memory that stores moving image video. MPEG encoder 44 compresses the image data of image source 42 in accordance with an MPEG compression algorithm. The compressed image data set is sent to a video service medium 46, such as a television cable or telephone system, for transmission to a remote user. Alternatively, the compressed image data may be loaded into a local video memory for further retrieval by a local or remote user. The MPEG decoder 48 decompresses the compressed image data according to the MPEG decompression algorithm and supplies to the video terminal 50 which displays the received image.

The MPEG algorithm is defined in the following specifications: ISO/IEC11172(MEPG1) published in 11 months in 1991 and ISO/IEC 13818(MPEG2) published in 3 months in 1995. MPEG-1 processes a complete image to be displayed as defined by a frame. The size of the frame is set equal to 22 macroblocks in the horizontal direction x 16 macroblocks in the vertical direction, where 1 macroblock consists of 6 blocks of picture, where 4 blocks represent luminance and 2 blocks represent chrominance. Each block of images contains 8 x 8 image elements (pixels).

The moving picture is provided at a speed of 30 frames/sec to form a continuous moving picture. Since each image is composed of thousands of pixels, the storage capacity required to store even a short motion sequence is enormous. As the resolution requirements increase, the number of pixels per image also increases. Fortunately, lossy compression techniques developed using the special properties of the human eye achieve very high data compression without perceptible loss of image quality. (lossy compression techniques achieve the target image quality by discarding non-essential information). There is no doubt that the compression processor is required to reconstruct each pixel of the stored motion sequence in real time.

The "MPEG standard" enables compatibility between compression and decompression devices. The standard specifies an encoded digital representation of a video signal on a storage medium and a decoding method. This representation method supports playback and other play modes of color moving images at normal speed, and supports generation of still images. The standard covers the common 525 and 625 line television, personal computer and workstation display formats. The MPEG standard is directed to devices that support continuous transmission rates of up to 1.5 Mb/sec, such as compact discs, digital audio tapes, or magnetic hard disks. The MPEG standard is used to support image frames consisting of 288 x 352 pixels at rates between 24Hz and 30 Hz.

Under the MPEG standard, an image frame is divided into a series of "macroblock slices" (MBS), each MBS containing a certain number of image areas (called "macroblocks"), each macroblock area being 16 × 16 pixels. Each image area is represented by one or more 8 x 8 matrices, the elements of which are spatial luminance and chrominance values. In one representation (4: 2: 2 macroblocks, providing one luminance value (Y-type) for each pixel within a 16 × 16 pixel image area (4 8 × 8 "Y" matrices), U and V being chrominance values, i.e. blue chrominance and red chrominance), each macroblock covering the same 16 × 16 image area is provided within two 8 × 8 "U" matrices and two 8 × 8 "V" matrices, respectively. That is, each 8 × 8U or 8 × 8V covers an area of 8 × 16 pixels. In another representation (4: 2: 0 macroblocks), a luminance value is provided for each pixel within a 16 x 16 pixel image area, and an 8 x 8 matrix is provided for each of the U and V shapes to represent chrominance values of the 16 x 16 pixel image area. The 4 contiguous groups of pixels in a2 x 2 structure are referred to as "quadtixels"; a macroblock can also be considered to consist of 64 tetraploid pixels in an 8 x 8 structure.

Thus, as described above, in the prior art, to reduce the bit rate of a video stream, a content source stream can be directly decompressed and compressed. But to maintain a high quality target video stream, extended computational power is required to accomplish this.

This application claims priority to provisional patent application 60/214,550, filed on 27/6/2000 and entitled "method for bandwidth measurement of compressed video streams".

The provisional patent application 60/214,550 discloses a method for bandwidth measurement of a compressed video stream using a bandwidth meter 21, which is the basis of the present invention. The novel method of bandwidth measurement of compressed video streams according to provisional patent application 60/214,550 utilizes motion vectors to represent small differences between frames including, but not limited to, the MPEG-1, MPEG-2, MPEG-4, MPEG-7, H-261, H-263 standards.

The new method of bandwidth measurement of compressed video streams according to provisional patent application 60/214,550 does not employ the normal methods of decompressing and compressing the source streams. Instead, the new method of bandwidth measurement of compressed video streams according to provisional patent application 60/214,550 utilizes the initial motion vectors of the source stream. This approach significantly reduces the computational power required to complete the bandwidth measurement operation. The bandwidth measurement may be done using a dedicated computer chip or a general purpose specially programmed computer.

Still referring to fig. 1, the content exchange 20 further comprises a bandwidth measurer 21 configured to measure each elementary primary bit-rate multimedia stream (not shown) transmitted at an elementary high bit-rate on an elementary dedicated channel (not shown) with K secondary bit-rate multimedia sub-streams 22, 24 … … 26(K being an integer). The first secondary bit rate secondary multimedia sub-stream 22 has a first low bit rate, the second secondary bit rate secondary multimedia sub-stream 24 has a second low bit rate, and the kth secondary bit rate secondary multimedia sub-stream 26 has a kth low bit rate.

In one embodiment, the K secondary bit rate secondary multimedia sub-streams 22, 24 … … 26 of each elementary stream (not shown) are substantially synchronized.

Still referring to fig. 1, the system 10 for multicast delivery of multimedia information further includes at least one multimedia intelligent terminal 36 configured to receive each multimedia content 14, 16 … … 18 from the content exchange 20 via a network (not shown) as K secondary bitrate secondary multimedia sub-streams 22, 24 … … 26 transmitted on secondary channels, wherein each sub-stream occupies a respective bandwidth according to its bitrate.

In a preferred embodiment, as shown in FIG. 3, the multimedia intelligent terminal 36 further includes a content switch 62 configured to select multimedia content among the N offerings. The N provided contents depend on the type of content and the nature of the network 74. The network 74 that the multimedia intelligent terminal 36 uses to receive multimedia information from the content exchange 20 may comprise a wireless network that supports specific multimedia information. For example, for video information, the network 74 comprises a wireless video network having a number of channels in the range of 5 to 50. Thus, the maximum number of allowed channels that a particular user can receive is 50, depending on where the user is located within the radio cell during reception. If the multimedia information contains only audio data, the number of channels ranges from 20 to 200. For a set of sensitive data, the number of channels ranges from 2 to 20.

As described above, each item of content selected by the intelligent terminal 36 is supported by K secondary bitrate secondary multimedia sub-streams 68, 70 … … 72. The intelligent terminal 36 further includes an intelligent terminal substream switch 64 configured to switch between the K secondary multimedia substreams 68, 70 … … 72. Before selecting an optimized substream from the plurality of substreams, which has a basic optimized relationship between the bit error rate level determined at reception and the bit rate or the multimedia content reception quality, the intelligent terminal quality switch must continuously check the error rate for each received quality using the error rate determining means 75. The intelligent terminal content exchange 62, the sub-stream exchange 64 and the error rate determination means 75 may be implemented using a dedicated computer or chip or a specially programmed general purpose computer.

After continuously checking the error rates, the sub-stream switch determines which sub-stream with the highest bit rate (called optimized sub-stream) can support the multimedia information with an acceptable error rate, and switches the intelligent terminal to the specific optimized sub-stream.

Bandwidth measurement of the compressed video stream by the bandwidth measurer 21 results in multiple sub-streams for each received multimedia stream. For receiving intelligent terminals 36 at different locations, the optimized substreams for receiving the same multimedia content may differ according to the local bit error rate levels at different receiving sites for the same selected content. The following description focuses on an intelligent terminal that determines whether to switch from a previously optimized sub-stream to a subsequently optimized sub-stream, wherein the previously optimized sub-stream is a pre-transition optimized sub-stream and the subsequently optimized sub-stream is a post-transition optimized sub-stream.

The receiving intelligent terminal 36 selects the optimized substream with the highest bit rate for each content provided by the multimedia content source 12 based on the acceptable error rate (subject to a reception quality that is not outside the expected degradation range). If the sub-stream with the highest possible bit rate to support the selected content starts to have an unacceptable reception quality due to an increased error rate, the intelligent terminal 36 may switch or hop to another sub-stream with a lower bit rate and an acceptable error rate level, as described below.

In prior art systems for multimedia multicasting over wireless networks, the data reception capabilities of wireless devices change dynamically according to their physical state (e.g., the reception capabilities of the wireless devices decrease if entering a shadow area and/or switching from static to dynamic (moving) and/or changing speed). The prior art bandwidth quantifier receives a high bit rate primary multimedia stream and scales with a secondary multimedia stream having a lower bit rate than the base stream. The measured secondary multimedia stream is returned to the receiver. The receiver decodes the received multimedia stream, checks the bit error rate, and continuously sends a feedback signal to the prior art bandwidth meter via a common loop according to the bit error rate level, thereby increasing or decreasing the bit rate of the multimedia stream.

In another aspect, the present invention employs a novel approach to bandwidth measurement of compressed multimedia streams in multicast delivery of multimedia information. In the preferred embodiment, the data reception capabilities of the wireless smart terminal device 36 also dynamically change based on the reception conditions. For example, if a mobile intelligent terminal enters a shielded area, the movement state is changed from direct to dynamic (motion) and/or the speed is also changed. In all of these events, the receiving capability of the wireless smart terminal device 36 decreases.

In the present invention, the bandwidth meter (21 in fig. 1) also receives a high bit rate elementary multimedia stream. The elementary multimedia stream is measured with a lower bit rate stream at a plurality of bit rates, using a known protocol such as SDP. It is preferable that the plurality of secondary substreams are synchronized and identical in structure. The intelligent terminal 36 is able to switch between these sub-streams according to the bit error rate level. It is preferable that the switching is done at the closest I-frame type, as described below, to avoid video distortion. Thus, in the present invention, the receiving intelligent terminal 36 does not feedback to the content exchange 36.

In one embodiment of the invention, the transition in timing between the previously optimized secondary bitrate secondary multimedia sub-stream and the subsequently optimized secondary bitrate secondary multimedia sub-stream is not synchronized.

In a preferred embodiment of the present invention, the intelligent terminal substream switch 64 of fig. 3 further comprises a synchronous intelligent terminal substream switch configured to substantially synchronize the timing of transitions between a previously optimized secondary bitrate secondary multimedia substream and a subsequently optimized secondary bitrate secondary multimedia substream with the timing of a set of synchronized data sets transmitted by the secondary multimedia stream to minimize data loss during the transitions.

In one embodiment, the synchronized intelligent terminal substream switch 64 further comprises a dynamic loading database 76 containing a look-up table 78 to synchronize the timing of transitions between a previously optimized secondary bitrate secondary multimedia substream and a subsequently optimized secondary bitrate secondary multimedia substream.

In one embodiment, FIG. 4 illustrates a synchronization database 76 containing N multimedia content entries 82, 84 … … 86 and N corresponding look-up table entries 92, 94 … … 96.

The lookup table #178 shown in FIG. 4 further contains a number of additional entries: k secondary bit rate secondary multimedia sub-streams 100, 102 … … 104. The lookup table also contains, for each secondary bit rate secondary multimedia sub-stream, a lower bit error rate threshold 106, 108 … … 110, an upper bit error rate threshold 112, 114 … … 116, and a set of synchronization data 118, 120 … … 122.

In one embodiment, the synchronized intelligent terminal substream switch 64 further comprises a synchronized intelligent terminal substream means for substantially synchronizing the timing of transitions between previously optimized and subsequently optimized secondary multimedia substreams with the timing of the set of synchronized data groups 118, 120 … … 122.

In one embodiment, fig. 5 shows a flow chart depicting a switch logic flow 140, which also corresponds to the multimedia information multicast reception method of the present invention. After receiving the N multimedia content provided by the multimedia content source using the intelligent terminal content switch 62 (step 142), the intelligent terminal substream switch 64 initially selects a substream with an optimized bitrate by switching between K secondary multimedia substreams (step 144).

In a next step (step 146), the current bit error rate of the currently employed optimized secondary multimedia sub-stream (including the substantially optimized bit rate) is continuously determined. If the selected secondary multimedia sub-stream has a determined bit error rate above the preset higher bit rate threshold (logic state 148 is logic value Yes) and if the switching timing is synchronized, then switching to the lower bit rate sub-stream (step 156). On the other hand, if the selected secondary multimedia sub-stream has a determined bit error rate below the preset higher bit error rate threshold (logic state 148 is logic value No), or if the switching sequence is not synchronized (timing state 152 is logic value No), then No switching is made to the lower bit rate sub-stream.

The next logic state is checked. If the selected multimedia sub-stream has a determined bit error rate below a preset lower bit rate threshold (logic state 150 is logic value Yes) and if the switching timing is synchronized (timing state 154 is logic value Yes), then switch to the higher bit rate sub-stream (step 158). On the other hand, if the selected secondary multimedia sub-stream has a determined bit error rate above the preset higher bit error rate threshold (logic state 150 is logic value No), or if the switching sequence is not synchronized (timing state 154 is logic value No), then No switching to the higher bit rate sub-stream occurs.

In one embodiment, the synchronization data set further comprises a plurality of flags indicating at least one optimization instance of when to switch from a previously optimized secondary multimedia sub-stream to a subsequently optimized secondary multimedia sub-stream. In one embodiment, the at least one flag contains the precise time instant at which an I-frame occurs within the selected substream.

In one embodiment, the substream switch 64 further includes a substream switch history block 66. The substream switch history block 66 includes decision logic for deciding whether to make a current switch or a delayed switch depending on several factors. One factor is the optimized switching direction to switch from a previously optimized secondary multimedia sub-stream to a subsequently optimized secondary multimedia sub-stream. The switching direction includes a direction from top to bottom or from bottom to top. The direction is from top to bottom if the subsequent optimized secondary multimedia sub-stream has a lower bitrate than the previous optimized bitrate. If this is the case, switches containing the top-down direction contain top-down switches. The direction is from bottom to top if the subsequent optimized secondary multimedia sub-stream has a higher bitrate than the previous optimized bitrate. If this is the case, the switches comprising the bottom-up direction comprise bottom-up switches. Another factor is the set of timing data for each existing top-down or top-down switch.

In one embodiment, the substream switch history block 66 may delay the current switch if the current switch fails to determine the quality of reception of the multimedia information (e.g., there are too many switches in the same direction within a very short time interval compared to the time of viewing the multimedia content). In another embodiment, the quality handover history block 66 may delay the current handover if the number of handovers already over a preset time interval exceeds a preset threshold.

Example I

The equation for quality switching is:

switching time: time remaining for current handover (real number)

Switching time is not (d1 (exclusive or) dd) × (tmin- (tt-t 1));

if the switching time is less than 0, the switching action can be completed;

wherein: t1 is the time (real number) of the last handover;

tmin is the minimum time to switch again (real number);

tt is the current time (real number);

d1 is the direction of the last handover: (0) to the lower bit rate, (-1) to the higher bit rate (boolean);

dd is the direction required by the current handover: (0) for lower bit rates, (-1) for higher bit rates (boolean values).

In a preferred embodiment, the present invention includes a wireless video multicast system for receiving video information. The system 10 of fig. 1 may be used to illustrate this embodiment, where the multimedia content source 12 comprises a video content source, the content exchange 20 comprises a video content exchange, and the multimedia intelligent terminal 36 comprises a wireless video intelligent terminal. In this embodiment, the video content exchange 20 further comprises a video bandwidth measurer 21 configured to measure each elementary video stream transmitted at a substantially high bit rate on a substantially dedicated channel with K secondary video substreams, where K is an integer. In one embodiment, the K secondary bit rate secondary video sub-streams are not synchronized. In the preferred embodiment, the K secondary bit rate secondary video substreams are substantially synchronized.

In one embodiment, the video intelligent terminal 36 includes a video intelligent terminal sub-stream switch 64 configured to switch between the K secondary video sub-streams to select a substantially optimized secondary video sub-stream having a substantially optimized low bit rate. The substantially optimized secondary video substream contains the highest possible bit rate at which the selected video content can be received at an acceptable error rate.

In a preferred embodiment, the video intelligent terminal sub-stream switch 64 further comprises a synchronized video intelligent terminal sub-stream switch configured to substantially synchronize the timing of transitions between a previously optimized secondary bitrate secondary multimedia sub-stream and a subsequently optimized secondary bitrate secondary multimedia sub-stream with the timing of a set of synchronized data sets transmitted by the secondary multimedia stream to minimize data loss during the transitions.

In one embodiment, the synchronized video intelligent terminal substream switch 64 further comprises a dynamically loaded database 76 comprising a look-up table 78, the look-up table 78 comprising N video content entries comprising: one entry for multiple secondary video sub-streams 100, 102 … … 104, one entry for the lower bit error rate threshold 106, 108 … … 110, one entry for the higher bit error rate threshold 112, 114 … … 116, and one entry for a set of synchronization data 118, 120 … … 122.

In a preferred embodiment of the present invention, the base video stream comprises a compressed video stream, which is intended to comprise a plurality of I independent frames and a plurality of dependent frames. The plurality of independent frames contain a plurality of scenes. The plurality of dependent frames includes a plurality of motion vectors.

In one embodiment, each video image comprises a set of dependent frames calculated using a set of motion vectors in the dependent frame and in existing independent frames. In this embodiment, each secondary sub-stream further contains a plurality of independent frames and a plurality of dependent frames, and the plurality of independent frames within each sub-stream can be used as the plurality of synchronization data. In this embodiment, the synchronized smart terminal sub-stream further comprises a video device for substantially synchronizing timing of transitions between a previously optimized secondary video sub-stream and a subsequently optimized secondary video sub-stream with timing of occurrence of a plurality of dependent frames within the subsequently optimized secondary video sub-stream, thereby minimizing data loss during the transitions.

The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description only. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and many modifications and variations are possible in light of the above teaching. The embodiment was chosen and described in order to explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims

1. A multicast system for receiving multimedia information, the system comprising:

a content switch coupled to a multimedia content source, said multimedia content source comprising N multimedia content, each of said multimedia content being supported by a basic bit rate multimedia stream transmitted on a basic dedicated channel, said dedicated channel comprising a basic bandwidth, N being an integer, said content switch further comprising:

a bandwidth quantifier configured to measure at K secondary bitrate secondary multimedia sub-streams each transmitting said elementary bitrate multimedia stream at an elementary high bitrate on an elementary dedicated channel having an elementary bandwidth, K being an integer, wherein a first secondary bitrate secondary multimedia sub-stream has a first low bitrate, a second secondary bitrate secondary multimedia sub-stream has a second low bitrate, and the kth secondary bitrate secondary multimedia sub-stream has a kth low bitrate; and

at least one multimedia intelligent terminal, each said multimedia intelligent terminal configured to receive each multimedia content from the content switch over the network, each multimedia content as a secondary multimedia stream transmitted over a secondary channel having a secondary bandwidth.

2. The system of claim 1, wherein at least one of the multimedia intelligent terminals further comprises:

an intelligent terminal sub-stream switch configured to switch between the K secondary bitrate secondary multimedia sub-streams to select a substantially optimized secondary bitrate secondary multimedia sub-stream, the selected sub-stream having a substantially optimized low bitrate; wherein the substantially optimized secondary bitrate secondary multimedia sub-stream comprises an optimized relationship between a determined bit error rate level at the time of receiving the substantially optimized secondary bitrate secondary multimedia sub-stream and a multimedia content reception quality supported by the substantially optimized secondary bitrate secondary multimedia sub-stream.

3. The system of claim 2, wherein the K secondary bit rate secondary video sub-streams are substantially synchronized, and wherein the intelligent terminal sub-stream switch further comprises:

synchronizing the intelligent terminal sub-flow switch;

wherein the synchronous intelligent terminal sub-stream switch is configured to switch between the K secondary bitrate secondary multimedia sub-streams to select a substantially optimized secondary bitrate secondary multimedia sub-stream having a substantially optimized low bitrate; and

wherein the synchronized intelligent terminal sub-stream switch is configured to substantially synchronize timing of transitions between a previously optimized secondary bitrate secondary multimedia sub-stream and a subsequently optimized secondary bitrate secondary multimedia sub-stream with timing of a set of synchronized data sets transmitted by the secondary multimedia streams to minimize data loss during the transitions.

4. The system of claim 3, wherein the synchronous intelligent terminal subflow switch further comprises:

a dynamically loaded database comprising a lookup table containing N of said multimedia content entries, N being an integer less than or equal to N, said lookup table further comprising K secondary bitrate secondary multimedia sub-streams; k is an integer less than or equal to K; and for each of said secondary bit rate secondary multimedia sub-streams, the look-up table further comprises a lower bit error rate threshold, an upper bit error rate threshold and a set of synchronization data.

5. The system of claim 4, wherein the synchronous intelligent terminal subflow switch further comprises:

a switching intelligent terminal substream device for switching among k available secondary multimedia substreams at a secondary bitrate to select a substantially optimized secondary bitrate secondary multimedia substream for each of said multimedia contents according to said look-up table; and

a synchronized intelligent terminal sub-stream configuration for substantially synchronizing timing of transitions between a previously optimized secondary bitrate secondary multimedia sub-stream and a subsequently optimized secondary bitrate secondary multimedia sub-stream with timing of a set of synchronized data sets provided by said look-up table, thereby minimizing data loss during transitions.

6. The system of claim 5, wherein the switching intelligent terminal sub-flow means further comprises:

means for continuously determining a current bit error rate for a currently used optimized secondary multimedia sub-stream containing a substantially optimized bit rate;

a higher threshold switching means; wherein if the selected optimized secondary multimedia sub-stream has a determined bit error rate above a preset higher bit error rate threshold, said higher threshold switching means switches said content from said substantially optimized secondary bit rate secondary multimedia sub-stream to a lower such secondary multimedia sub-stream comprising a lower low bit rate, wherein said lower low bit rate is lower than said substantially optimized low bit rate; and

lower threshold switching means, wherein if said substantially optimized secondary multimedia sub-stream has a determined bit error rate below a preset lower bit error rate threshold, the lower threshold switching means switches said content from said substantially optimized secondary bit rate secondary multimedia sub-stream to a higher secondary bit rate secondary multimedia sub-stream comprising a higher low bit rate, wherein the higher low bit rate is lower than the substantially optimized low bit rate.

7. The system of claim 6, wherein the synchronized data set further comprises a plurality of flags, the system further comprising:

-flag means for continuously determining said plurality of flags indicating at least one optimization instant for switching from said previously optimized secondary bitrate secondary multimedia sub-stream to a subsequent secondary bitrate secondary multimedia sub-stream.

8. The system of claim 5, wherein the switching intelligent terminal sub-flow means further comprises:

means for continuously determining the error rate of the previously optimized secondary multimedia sub-stream; wherein the determined bit error rate indicates a direction of switching from a previously optimized secondary bitrate secondary multimedia sub-stream to a subsequently optimized secondary bitrate secondary multimedia sub-stream; wherein the switching direction may comprise a top-down direction if the subsequent optimized secondary bitrate secondary multimedia sub-stream comprises a lower bitrate than the previous optimized bitrate; the switching direction may comprise a bottom-up direction if the subsequent optimized secondary bitrate secondary multimedia sub-stream comprises a higher bitrate than the previous optimized bitrate;

existing history switching means for determining an existing switching history including at least one existing top-down or at least one bottom-up switching; and tracking and collecting a set of timing data for each top-down or bottom-up handover; and

and the judging device is used for judging whether to carry out or delay the current switching according to the direction of the current switching indicated by the detecting device, the existing switching history comprising at least one existing switching from top to bottom or at least one switching from bottom to top and the time sequence data group of each switching from top to bottom or from bottom to top.

9. The system of claim 8, wherein said means for determining further comprises:

a device for calculating the existing switching times in a preset time interval; if the existing switching times in the preset time interval are larger than a preset threshold value, the judgment of the current switching is delayed until the existing switching times in the preset time interval are smaller than the preset threshold value.

10. The system of claim 4, wherein the synchronous intelligent terminal subflow switch further comprises:

a received multimedia synchronous intelligent terminal sub-flow switch, further comprising:

a receiving device configured to receive N multimedia contents from said content exchange via a network and to receive a look-up table containing entries of said N multimedia contents; wherein for each of said content entries N, N being an integer less than or equal to N, said look-up table further contains k secondary bit-rate secondary multimedia sub-streams;

wherein K is an integer less than or equal to K;

and for each said secondary bit rate secondary multimedia sub-stream, said look-up table further contains a lower bit error rate threshold, a higher bit error rate threshold and a set of synchronization data; and

an intelligent terminal content switch configured to switch between the N available multimedia content according to the look-up table.

11. The system of claim 4, wherein at least one of the multimedia intelligent terminals further comprises:

a transceiver multimedia smart terminal, further comprising:

a transceiver device; and

an intelligent terminal content switch;

wherein the receiving/transmitting device is configured to receive N multimedia contents from the content exchange via a network; and is

The intelligent terminal content switch is configured to receive a look-up table containing the N multimedia content entries;

wherein for each of said content entries N, N being an integer less than or equal to N, said look-up table further contains k secondary bit-rate secondary multimedia sub-streams;

wherein K is an integer less than or equal to K;

and for each said secondary bit rate secondary multimedia sub-stream, said look-up table further contains a lower bit error rate threshold, a higher bit error rate threshold and a set of synchronization data; and is

The receiving/transmitting means is configured to transmit the reception status of each of the received multimedia contents to the content exchange.

12. The system of claim 1, wherein at least one of the multimedia intelligent terminals further comprises:

a transceiver multimedia smart terminal, further comprising:

a receiving/transmitting means configured to initially receive from the content exchange via a network N1 multimedia content; n1 is an integer less than N and is configured to communicate with the content exchange via the network to expand the initially available N1 multimedia content into subsequently available N2 multimedia content; n2 is an integer greater than N1 but less than N; and

a smart terminal content switch configured to switch between the first N1 available multimedia content to select multimedia content and configured to switch between the subsequent N2 available multimedia content to select multimedia content.

13. A multicast transmission system, wherein a multimedia content source comprises N multimedia contents, N being an integer, and the content switch receives the multimedia content as a primary multimedia stream transmitted at a substantially high bit rate on a primary dedicated channel having a primary bandwidth, said content switch further comprising a bandwidth measure configured to measure each of said received elementary bit-rate multimedia streams into K secondary bit-rate secondary multimedia sub-streams, K being an integer, wherein the first secondary bitrate secondary multimedia sub-stream has a first low bitrate, the second secondary bitrate secondary multimedia sub-stream has a second low bitrate, and the kth secondary multimedia sub-stream has a kth low bit-rate and each of said secondary bit-rate secondary multimedia sub-streams is substantially synchronized with one of said elementary bit-rate multimedia streams; the multimedia intelligent terminal is configured to receive at least one multimedia content from the content switch over a network as a multimedia stream transmitted on a secondary channel having a secondary bandwidth, the multimedia intelligent terminal further comprising:

an intelligent terminal substream switch configured to switch among the K secondary bitrate secondary multimedia substreams to select a substantially optimized secondary bitrate secondary multimedia substream, the substantially optimized secondary bitrate secondary multimedia substream comprising an optimized relationship between a determined error rate level at reception of the substantially optimized secondary bitrate secondary multimedia substream and a multimedia content reception quality supported by the substantially optimized secondary bitrate secondary multimedia substream.

14. The multicast delivery system of claim 13, wherein the intelligent terminal sub-flow switch further comprises:

synchronizing the intelligent terminal sub-flow switch;

wherein the intelligent terminal sub-stream switch is configured to switch between the K secondary bitrate secondary multimedia sub-streams to select a substantially optimized secondary bitrate secondary multimedia sub-stream having a substantially optimized low bitrate; and

the synchronized intelligent terminal sub-stream switch is configured to substantially synchronize timing of transitions between a previously optimized secondary bitrate secondary multimedia sub-stream and a subsequently optimized secondary bitrate secondary multimedia sub-stream with timing of a set of synchronized data sets provided by the look-up table, thereby minimizing data loss during transitions.

15. The multicast delivery system of claim 14, wherein the intelligent terminal subflow switch further comprises:

a dynamically loaded database comprising a look-up table containing N multimedia content entries, wherein for each content entry N is an integer less than or equal to N, the look-up table further comprising K secondary bitrate secondary multimedia sub-streams, K being an integer less than or equal to K; and for each secondary bit rate secondary multimedia sub-stream, the look-up table further comprises a lower bit error rate threshold, an upper bit error rate threshold, and a set of synchronization data.

16. The multicast delivery system of claim 15, wherein the intelligent terminal sub-flow switch further comprises:

17. A multicast delivery system, wherein a multimedia content source comprises N multimedia contents, N being an integer;

a content switch coupled to the multimedia content source;

wherein the content switch is configured to receive each of the multimedia content as a primary multimedia stream transmitted at a primary bit rate on a primary dedicated channel having a primary bandwidth; and is

The content switch is configured to transmit at least one multimedia content to at least one multimedia intelligent terminal over a network as a multimedia stream transmitted over a secondary channel having a secondary bandwidth; the content switch further comprises:

a bandwidth quantifier configured to scale each of said elementary high-bit-rate multimedia streams for transmission at an elementary high bit-rate on an elementary dedicated channel having an elementary bandwidth into K secondary multimedia sub-streams, K being an integer, wherein a first secondary bit-rate secondary multimedia sub-stream has a first low bit-rate, a second secondary bit-rate secondary multimedia sub-stream has a second low bit-rate, a kth secondary bit-rate secondary multimedia sub-stream has a kth low bit-rate, and each of said secondary bit-rate secondary multimedia sub-streams is substantially synchronized with said elementary high-bit-rate multimedia stream.

18. A video multicasting system for receiving video information, said system comprising:

a content switch coupled to a video content source; the video content source comprises N video contents, each video content being supported by a primary video stream transmitted on a primary dedicated channel having a primary bandwidth, N being an integer; the content exchange further comprises:

a bandwidth quantifier configured to measure at K secondary bitrate secondary multimedia sub-streams, K being an integer, each transmitting said elementary high bitrate multimedia stream on an elementary dedicated channel having an elementary bandwidth, wherein a first secondary bitrate secondary multimedia sub-stream has a first low bitrate, a second secondary bitrate secondary multimedia sub-stream has a second low bitrate, a Kth secondary bitrate secondary multimedia sub-stream has a Kth low bitrate, and said K secondary bitrate secondary video sub-streams are substantially synchronized; and

at least one video intelligent terminal, each said video intelligent terminal configured to receive each video content from the content exchange over the network, each video content as a secondary video stream transmitted over a secondary channel having a secondary bandwidth.

19. A video multicast delivery system, wherein a video content source comprises N video contents, N being an integer, wherein the content switch is coupled to the video content source and the content switch receives the video content as a primary video stream transmitted at a substantially high bit rate over a primary dedicated channel having a primary bandwidth, said content switch further comprising a bandwidth measure configured to measure each of said received elementary base bit rate video streams into K secondary bit rate secondary video substreams, K being an integer, wherein the first secondary bit rate secondary video sub-stream has a first low bit rate, the second secondary bit rate secondary video sub-stream has a second low bit rate, and the kth secondary bit rate video sub-stream has a kth low bit rate and each of said secondary bit rate secondary video sub-streams is substantially synchronized with one of said elementary bit rate video streams; the video intelligent terminal is configured to receive at least one video content from the content exchange via the network as a video stream transmitted on a secondary channel having a secondary bandwidth, the video intelligent terminal further comprising:

a video intelligent terminal sub-stream switch configured to switch between the K secondary bit rate secondary video sub-streams to select a substantially optimized secondary bit rate secondary video sub-stream containing an optimized relationship between a determined bit error rate level upon receipt of the substantially optimized secondary bit rate secondary video sub-stream and a video content reception quality supported by the substantially optimized secondary bit rate secondary video sub-stream.

20. The video multicast delivery system according to claim 19, wherein the video intelligent terminal sub-stream switch further comprises:

a synchronous video intelligent terminal sub-stream switch;

wherein the video intelligent terminal sub-stream switch is configured to switch between the K secondary bit rate secondary video sub-streams to select a substantially optimized secondary bit rate secondary video sub-stream having a substantially optimized low bit rate; and

the synchronized video intelligent terminal sub-stream switch is configured to substantially synchronize timing of transitions between a previously optimized secondary bit rate secondary video sub-stream and a subsequently optimized secondary bit rate secondary video sub-stream with timing of a set of synchronized data sets provided by the look-up table, thereby minimizing data loss during transitions.

21. The video multicast delivery system according to claim 20, wherein the video intelligent terminal sub-stream switch further comprises:

a dynamically loaded database containing a look-up table containing N video content entries, wherein for each content entry N is an integer less than or equal to N, the look-up table further comprising K secondary bitrate secondary video sub-streams, K being an integer less than or equal to K; and for each secondary bit rate secondary video sub-stream, the look-up table further comprises a lower bit error rate threshold, a higher bit error rate threshold, and a set of synchronization data.

22. The multicast delivery system of claim 20, wherein the video intelligent terminal substream switch further comprises:

a switching intelligent terminal sub-stream means for switching between k available secondary bit rate secondary video sub-streams to select a substantially optimized secondary bit rate secondary video sub-stream for each of said video content according to said look-up table; and

a synchronized video intelligent terminal sub-stream configuration for substantially synchronizing timing of transitions between a previously optimized secondary bit rate secondary video sub-stream and a subsequently optimized secondary bit rate secondary video sub-stream with timing of a set of synchronized data sets provided by said look-up table, thereby minimizing data loss during transitions.

23. The multicast transmission system according to claim 20, wherein the primary video stream comprises a compressed video stream further comprising a plurality of independent frames and a plurality of non-independent frames, the plurality of independent frames further comprising a plurality of snapshots, the plurality of non-independent frames further comprising a plurality of motion vectors, the video image comprising a set of calculated non-independent frames, wherein each calculated non-independent frame is calculated using the set of motion vectors in the non-independent frame and a previous independent frame, each of the secondary sub-streams further comprising a plurality of independent frames and a plurality of non-independent frames, the plurality of independent frames in each sub-stream comprising a plurality of synchronization data, and the synchronized intelligent terminal video sub-stream device further comprising:

video means for substantially synchronizing the timing of transitions between a previously optimized secondary video sub-stream and a subsequently optimized secondary video sub-stream with the timing of a set of synchronized data sets conveyed by the secondary video stream, thereby minimizing data loss during the transitions.

24. The multicast transmission system according to claim 20, wherein the primary video stream comprises a compressed video and data stream further comprising a plurality of independent frames and a plurality of non-independent frames, the plurality of independent frames further comprising a plurality of snapshots, the plurality of non-independent frames further comprising a plurality of motion vectors, the video image comprising a set of calculated non-independent frames, wherein each calculated non-independent frame is calculated using the set of motion vectors in the non-independent frame and a previous independent frame, each of the secondary sub-streams further comprising a plurality of independent frames and a plurality of non-independent frames, the plurality of independent frames in each sub-stream comprising a plurality of synchronized data, and the synchronized intelligent terminal video sub-stream means further comprising:

25. A multicast delivery system, wherein a video content source comprises N video contents, N being an integer:

a content switch coupled to the video content source;

wherein the content switch is configured to receive each of the video content as primary video streaming support transmitted over a primary dedicated channel having a primary bandwidth;

and the content switch is configured to transmit the at least one video content to the at least one video intelligent terminal via the network as a secondary video stream transmitted on a secondary channel having a secondary bandwidth; the content switch further comprises:

a bandwidth meter configured to meter each of said elementary high bit rate video streams for transmission at an elementary high bit rate on an elementary dedicated channel having an elementary bandwidth into K secondary bit rate secondary video sub-streams, K being an integer, wherein a first secondary bit rate secondary video sub-stream has a first low bit rate, a second secondary bit rate secondary video sub-stream has a second low bit rate, a kth secondary bit rate secondary video sub-stream has a kth low bit rate, and each of said secondary bit rate secondary video sub-streams is substantially synchronized with said elementary high bit rate video stream.

26. A video and audio multicasting system for receiving video and audio information, said system comprising:

a content switch coupled to the video and audio content sources; said video and audio content sources comprising N video and audio contents, each said audio source being substantially synchronized with one said video and audio content source; and said content switch receiving each of said video and audio content as elementary video and audio streams transmitted on an elementary dedicated channel having an elementary bandwidth; the content exchange further comprises:

a bandwidth quantifier configured to measure at K secondary bitrate secondary video and audio substreams each of which is transmitted at a substantially high bitrate over a substantially dedicated channel having a substantially bandwidth, K being an integer, wherein a first secondary bitrate secondary video and audio substream has a first low bitrate, a second secondary bitrate secondary video and audio substream has a second low bitrate, the Kth secondary bitrate secondary video and audio substream has a Kth low bitrate, and each of said secondary bitrate secondary video and audio substreams is substantially synchronized with said substantially primary bitrate video and audio streams; and

at least one video intelligent terminal, each said video intelligent terminal configured to receive each video content from a content switch over a network as a secondary video stream transmitted over a secondary video downlink channel having a secondary video downlink bandwidth; and

at least one audio intelligent terminal, each said audio intelligent terminal configured to receive from a content switch over a network each audio content substantially synchronized with said video content as a secondary audio stream transmitted over a secondary audio duplex channel having an audio downlink bandwidth and an audio uplink bandwidth.

27. A method for multicast receiving of multimedia information, the method comprising the steps of:

receiving, with a content switch coupled to a multimedia content source, N multimedia contents provided by the multimedia content source, each of said multimedia contents being received as a primary bit rate multimedia stream transmitted on a primary dedicated channel having a primary bandwidth, N being an integer;

transmitting each of the multimedia content over a network using the content switch; wherein each of the multimedia content is transmitted as a multimedia stream on a secondary channel having a secondary bandwidth; and

receiving, by at least one multimedia intelligent terminal over a network, the multimedia content as a multimedia stream transmitted on a secondary channel having a secondary bandwidth.

28. The method of claim 27, wherein the content switch further comprises a bandwidth meter, and the step of sending each of the multimedia content over the network further comprises:

transmitting said elementary bit-rate multimedia streams at an elementary high bit-rate each on an elementary dedicated channel having an elementary bandwidth measured in K secondary multimedia sub-streams, K being an integer, wherein a first secondary bit-rate secondary multimedia sub-stream has a first low bit-rate, a second secondary bit-rate secondary multimedia sub-stream has a second low bit-rate, and a kth secondary bit-rate secondary multimedia sub-stream has a kth low bit-rate.

29. The method of claim 28, wherein at least one multimedia intelligent terminal further comprises an intelligent terminal sub-flow switch; and the step of receiving each multimedia content over the network using the intelligent terminal sub-stream switch further comprises the steps of:

switching among the K secondary multimedia substreams to select a substantially optimized secondary bitrate secondary multimedia substream, the substantially optimized secondary bitrate secondary multimedia substream comprising an optimized relationship between a bit error rate level determined upon receiving the substantially optimized secondary bitrate secondary multimedia substream and a multimedia content reception quality supported by the substantially optimized secondary bitrate secondary multimedia substream.

30. The method of claim 28, wherein at least one of said multimedia intelligent terminals further comprises a synchronous intelligent terminal subflow switch; and said step of receiving each of said multimedia contents via said network comprises the steps of:

(A) switching among the K secondary bitrate secondary multimedia sub-streams to select a substantially optimized secondary bitrate secondary multimedia sub-stream having a substantially optimized low bitrate; and

(B) synchronizing the timing of said step (a) with a set of synchronized data sets of said secondary bitrate secondary multimedia streaming.

31. The method of claim 28, wherein at least one of said multimedia intelligent terminals further comprises a synchronous intelligent terminal substream switch, further comprising a dynamically loaded database comprising a look-up table containing N of said multimedia content entries, N being an integer less than or equal to N, said look-up table further comprising K secondary bitrate secondary multimedia substreams; k is an integer less than or equal to K; and for each of said secondary bit rate secondary multimedia sub-streams, the look-up table further comprises a lower bit error rate threshold, a higher bit error rate threshold and a set of synchronization data, and the step of receiving said multimedia content over the network comprises the steps of:

(A) switching between k available secondary multimedia sub-streams to select a substantially optimized secondary bit-rate secondary multimedia sub-stream for each of said multimedia content according to said look-up table; and

(B) substantially synchronizing the timing of transitions between a previously optimized secondary bitrate secondary multimedia sub-stream and a subsequently optimized secondary bitrate secondary multimedia sub-stream with the timing of a set of synchronized data sets provided by the look-up table to minimize data loss during transitions.

32. The method of claim 31, wherein step (a) further comprises the steps of:

(A2) continuously determining a current bit error rate for a currently used optimized secondary multimedia sub-stream containing a substantially optimized bit rate;

(A2) if the selected optimized secondary multimedia sub-stream has a determined bit error rate above a preset higher bit error rate threshold, said higher threshold switching means switching said content from said substantially optimized secondary bit rate secondary multimedia sub-stream to a lower such bit rate secondary multimedia sub-stream comprising a lower low bit rate, wherein said lower low bit rate is lower than said substantially optimized low bit rate; and

(A3) a lower threshold switching means switches the content from the substantially optimized secondary bit rate secondary multimedia sub-stream to a higher secondary bit rate secondary multimedia sub-stream containing a higher low bit rate, wherein the higher low bit rate is lower than the substantially optimized low bit rate, if the substantially optimized secondary multimedia sub-stream has a determined bit error rate lower than a preset lower bit error rate threshold.

33. The method of claim 31, wherein step (a) further comprises the steps of: (A4) switching the multimedia content from a first optimized secondary multimedia sub-stream containing a first optimized low bitrate to a second optimized secondary multimedia sub-stream having a second optimized low bitrate, wherein the relationship between the second optimized low bitrate and the first low bitrate is determined by the bitrate direction of the existing switch, i.e. the currently switched bitrate direction of the multimedia content from the first optimized secondary bitrate secondary multimedia sub-stream to the second optimized secondary bitrate secondary multimedia sub-stream.

34. The method of claim 27, wherein at least one of the multimedia intelligent terminals further comprises a transceiver multimedia intelligent terminal further comprising a receiving/transmitting means and an intelligent terminal content exchange; wherein the step of receiving the multimedia content over a network further comprises the steps of:

initially receiving N1 multimedia content over a network from the content exchange using a receiving/sending device;

switching between said N1 multimedia content pieces initially available with said intelligent terminal content switch to select multimedia content;

communicating with the content exchange to expand the initially available N1 multimedia content into subsequently available N2 multimedia content; n2 is an integer greater than N1 but less than N; and

switching between the subsequent N2 available multimedia content using the intelligent terminal content switch to select multimedia content.

35. In a multicast delivery system, a multimedia content source comprising N multimedia contents, N being an integer, a content switch coupled to said content source and said content switch receiving each of said multimedia contents as a primary bit rate multimedia stream transmitted on a primary dedicated channel having a primary bandwidth; the method of receiving at least one multimedia content from the content exchange over a network with a receiving multimedia smart terminal as a multimedia stream transmitted on a secondary channel having a secondary bandwidth further comprises a receiving device and a smart terminal content exchange; the method comprises the following steps:

receiving, with the receiving device, N multimedia contents from the content exchange via the network; and

switching between N available multimedia content using the intelligent terminal content switch.

36. The method of claim 35, wherein the content switch further comprises a bandwidth meter configured to meter each of the elementary primary bit rate multimedia streams for transmission at an elementary high bit rate on an elementary dedicated channel having an elementary bandwidth in K secondary multimedia sub-streams, K being an integer, wherein a first secondary bit rate secondary multimedia sub-stream has a first low bit rate, a second secondary bit rate secondary multimedia sub-stream has a second low bit rate, a kth secondary bit rate secondary multimedia sub-stream has a kth low bit rate, and each of the secondary bit rate secondary multimedia sub-streams is substantially synchronized with a set of synchronization data; the multimedia intelligent terminal further comprises an intelligent terminal sub-flow switch; the method further comprises the steps of:

switching between the K secondary bitrate secondary multimedia sub-streams to select a substantially optimized secondary bitrate secondary multimedia sub-stream having a substantially optimized low bitrate.

37. A multicast system for wireless reception of multimedia information, the system comprising:

a content switch coupled to a video content source; said video content source comprises N video content, N being an integer, said content switch receiving each of said multimedia content as a primary video stream transmitted over a primary dedicated channel having a primary bandwidth over a first wireless network; and

at least one multimedia intelligent terminal, each configured to receive each video content from the content exchange via the wireless network, each video content as a multimedia stream transmitted on a secondary channel having a secondary bandwidth; the content switch further comprises:

a bandwidth quantifier configured to measure at K secondary bitrate secondary multimedia sub-streams each transmitting said elementary bitrate multimedia stream at an elementary high bitrate on an elementary dedicated channel having an elementary bandwidth, K being an integer, wherein a first secondary bitrate secondary multimedia sub-stream has a first low bitrate, a second secondary bitrate secondary multimedia sub-stream has a second low bitrate, the kth secondary bitrate secondary multimedia sub-stream has a kth bitrate, and each of said secondary bitrate secondary multimedia sub-streams is substantially synchronized with one of said elementary bitrate multimedia streams; and

at least one of the multimedia intelligent terminals further comprises:

an intelligent terminal substream switch configured to switch between the K secondary bit rate secondary multimedia substreams to substantially minimize an error rate determined upon receipt of each of the secondary bit rate secondary multimedia substreams.

38. A multicasting system for real-time multimedia information reception, said system comprising:

a content switch coupled to a video content source; said video content source comprises N video contents, N being an integer, said content switch receiving each of said multimedia contents as a primary video stream transmitted on a primary dedicated channel having a primary bandwidth; and

at least one multimedia intelligent terminal, each configured to receive each video content from the content switch over the network, each video content as a multimedia stream transmitted on a secondary channel having a secondary bandwidth; the content switch further comprises:

at least one of the multimedia intelligent terminals further comprises:

39. A multicasting system for receiving multimedia information from a multimedia content source containing N multimedia content, N being an integer, the system comprising:

content switching means for receiving each of said multimedia content as a primary multimedia stream transmitted on a primary dedicated channel having a primary bandwidth; and

at least one multimedia intelligent device for receiving each multimedia content from the content exchange via the network, each multimedia content being a multimedia stream transmitted on a secondary channel having a secondary bandwidth; the content switching device further includes:

bandwidth dimensioning means configured to dimension each of said elementary bit-rate multimedia streams at an elementary high bit-rate on an elementary dedicated channel having an elementary bandwidth with K secondary multimedia sub-streams, K being an integer, wherein a first secondary bit-rate secondary multimedia sub-stream has a first low bit-rate, a second secondary bit-rate secondary multimedia sub-stream has a second low bit-rate, a kth secondary bit-rate secondary multimedia sub-stream has a kth low bit-rate, and said K secondary bit-rate secondary multimedia sub-streams are substantially synchronized.

40. The system of claim 39, wherein at least one of said multimedia intelligent terminal devices further comprises:

intelligent terminal sub-stream switching means for switching between said K secondary bit rate secondary multimedia sub-streams to select a substantially optimized secondary bit rate secondary multimedia sub-stream having a substantially optimized low bit rate; wherein the substantially optimized secondary bitrate secondary multimedia sub-stream comprises a substantially optimized relationship between a determined bit error rate level at the time of receiving the substantially optimized secondary bitrate secondary multimedia sub-stream and a multimedia content reception quality supported by the substantially optimized secondary bitrate secondary multimedia sub-stream.

41. The system of claim 40, wherein said intelligent terminal sub-stream switching apparatus further comprises:

a synchronous intelligent terminal sub-stream switching means for switching between the K secondary bit rate secondary multimedia sub-streams to select a substantially optimized secondary bit rate secondary multimedia sub-stream having a substantially optimized low bit rate; and for substantially synchronizing the timing of a transition between a previously optimized secondary bitrate secondary multimedia sub-stream and a subsequently optimized secondary bitrate secondary multimedia sub-stream with the timing of a set of synchronized data provided by said secondary bitrate secondary multimedia sub-stream, thereby minimizing data loss during the transition.