JP2002335500A - Encoded data multiplex transmission apparatus and method - Google Patents

Abstract

(57) [Problem] To provide an encoded data multiplex transmission apparatus and method capable of reproducing a signal at a receiving side without lowering transmission efficiency even when a failure occurs in a transmission path. SOLUTION: A controller 7 detects whether or not character data that changes every predetermined period has changed from previously input data. When it has changed, control is performed so that the switch 8 is turned on. Also, when the character data input every predetermined period does not change for a predetermined time, the control is performed so that the switch 8 is turned on. Otherwise, the controller 7
Controls the switch 8 to be turned off. The multiplexer 9 determines whether or not to perform multiplexing according to the input from the switch 8 and outputs the multiplexed data signal from the output unit 10 to the transmission line.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to coded data multiplex transmission for multiplexing and transmitting, for example, coded image signals and audio signals and signals obtained by data conversion of information signals such as characters and superimposed characters. The present invention relates to an apparatus and a method.

[0002]

2. Description of the Related Art At present, signals transmitted from broadcasting stations include:
The signal includes a signal obtained by multiplexing an image signal and an audio signal of a camera or the like and a signal obtained by data-converting an information signal such as a character signal. The character signal is transmitted by superimposing the character data generated by the character generator on the vertical blanking (vertical blanking period) of the image signal.

[0003] Broadcasting stations are connected via a national network centering on stations called key stations.
When broadcast on a nationwide network, a control information signal called a net cue is used to switch between commercials (CM) and the like. Such a net cue signal is also superimposed on the vertical blanking and transmitted from the key station.

Recently, as an international standard image coding technology,
Moving Picture Coding Exp (MPEG) that encodes image signals without blanking to reduce redundancy
ertsGroup) scheme has been proposed. Even if the character signal is superimposed on the vertical blanking and input to the encoder, it is not encoded and disappears on the transmission side.

Therefore, when an information signal such as a character signal is transmitted at the same time as an encoded image signal or audio signal, the information signal is converted and then multiplexed with the encoded image signal or audio signal before being transmitted. You.

[0006]

However, since information signals such as character signals and net cues have a significantly lower rate of change than image signals and audio signals, the same data is multiplexed for each frame of the image signal. Then, the transmission efficiency decreases. If the information signal is transmitted only when a change occurs, the signal may not be reproduced on the receiving side when a failure occurs in the transmission path.

After transmitting an information signal, the MPEG
-2 Even if a program or CM is switched as encoded data (bit stream) without decoding all image signals and audio signals such as TS, the information signal is quickly decoded on the receiving side immediately after switching. Preferably, it can be converted.

[0008] It is an object of the present invention to be able to reproduce a signal on the receiving side without deteriorating the transmission efficiency even if a failure occurs in a transmission path, and to replace or switch between programs and CMs after transmitting an information signal. It is an object of the present invention to provide a coded data multiplex transmission apparatus and method capable of promptly decoding an information signal immediately after switching on a receiving side.

[0009]

According to the present invention, there is provided a method for multiplexed transmission of encoded data, comprising the steps of:
Detecting means, encoding means for encoding the first signal, detecting a change in a second signal having a lower rate of change than the first signal, or keeping the second signal unchanged for a predetermined time Second detecting means for detecting that the first signal has detected a predetermined amount of change in the first signal, when the second detecting means has detected a change in the second signal, or And multiplexing means for multiplexing the first signal and the second signal when detecting that the second signal does not change for a predetermined time.

According to the present invention, the multiplexing of the first signal and the second signal is performed not only when a change in the second signal is detected but also when the second signal does not change for a predetermined time. Therefore, even when a failure occurs in the transmission path, the signal can be reproduced on the receiving side without lowering the transmission efficiency.

[0011] Replacement or switching of programs and CMs is performed at a position where a change in an image such as a scene change is large so as not to be unnatural. Therefore, the scene change occurrence position is a switching candidate position of the encoded data. According to the present invention, the multiplexing of the first signal and the second signal is performed even when the amount of change of the first signal exceeds a predetermined amount.
As a result, a scene change is detected, and if there is a possibility of switching, a second signal is output. Therefore, even when a program or CM is replaced or switched after transmitting the information signal, the receiving side immediately performs the switching. The information signal can be quickly decoded.

A first example of the second detection means includes a storage means for storing the data of the second signal for one cycle, and a current data of the second signal which is stored in the storage means one cycle before. Comparing means for comparing the data of the second signal; determining means for determining a change in the second signal in accordance with the result of the comparing means; and determining the second signal in accordance with the result of the comparing means. 2. The coded data multiplex transmission apparatus according to claim 1, further comprising a measuring unit that measures a period during which the signal does not change.

[0013] A second example of the second detecting means is a calculating means for calculating the data of the second signal, a storing means for storing a calculation result of the data of the second signal, and a data storing means for calculating the data of the second signal. Comparing means for comparing the current operation result with the operation result stored in the storage means; determining means for determining a change in the second signal in accordance with the result of the comparison means; Measuring means for measuring a period during which the second signal does not change in accordance with the result of (1). In this case, the operation is preferably a checksum or a cyclic redundancy check.

In the coded data multiplex transmission method according to the present invention, a step of detecting a change amount of a first signal, a step of coding the first signal, and a step of changing a rate of change as compared with the first signal. Detecting a low change in the second signal or detecting that the second signal does not change for a predetermined time; and detecting a change in the second signal when the change in the first signal exceeds a predetermined amount. Multiplexing the first signal and the second signal when a change is detected or when the second signal does not change for a predetermined period of time.

According to the present invention, the multiplexing of the first signal and the second signal is performed not only when a change in the second signal is detected but also when the second signal does not change for a predetermined time. Therefore, even when a failure occurs in the transmission path, the signal can be reproduced on the receiving side without lowering the transmission efficiency.

Preferably, the change of the second signal is detected by a checksum or a cyclic redundancy check.

[0017]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a coded data multiplex transmission apparatus and method according to the present invention; FIG. 1 is a diagram showing an embodiment of an encoded data multiplex transmission apparatus according to the present invention. The coded data multiplex transmission apparatus includes a scene change detector 2 to which an image signal as a first signal is input from an input unit 1, and an image encoder 3 to which an image signal is input from the scene change detector 2.
And an audio encoder 5 to which an audio signal is input from the input unit 4
And a data converter 7 and a controller (CPU) 8 to which a character data signal as a second signal is input from the input unit 6, a switch 9, a multiplexer 10, and an output unit 11.

The image encoder 3 outputs the encoded image signal to the multiplexer 10, and the audio encoder 5 outputs the encoded audio signal to the multiplexer 10. The character data signals input to the data converter 7 and the controller 8 are output signals from a character generator (not shown) such as a personal computer, for example.

The data converter 7 outputs the character data signal converted into a predetermined format to the multiplexer 10 through the switch 9. As the predetermined format, a format conforming to the format of the image encoder 3 and the audio encoder 5 is used.

The controller 8 detects whether or not the character data input every predetermined period has changed from the previously input data. When it has changed, control is performed so that the switch 9 is turned on. In addition, even when the character data inputted every predetermined period does not change for a predetermined time, the switch 9 is controlled to be turned on. Otherwise, the controller 8
Controls the switch 9 to be turned off. The multiplexer 10 determines whether or not to perform multiplexing in accordance with the input from the switch 9 and outputs the multiplexed data signal from the output unit 11 to the transmission path.

Here, the scene change detector 2 will be described. The scene change detector 2 determines whether the inter-frame difference of the image signal is larger than a predetermined value. If the difference is larger than the predetermined value, the scene change detection signal is sent to the image encoder and the controller 8 for the scene change. Outputs a detection signal. At this time, the image encoder 3 performs processing for suppressing image quality degradation by performing intra-frame encoding and the like.
The controller 8 controls to transmit character data.

FIG. 2 is a diagram showing a first example of the controller of FIG. The illustrated controller 8 includes an input unit 12 to which a character data signal is input, a memory 13 such as a RAM, a comparator 14, a timer 15, a determiner 16, and an input to which a scene change detection signal is input. It has a unit 17 and an output unit 18.

The character data signal is stored in the memory 13 and the comparator 1
4 and the memory 13 stores the character data for one cycle. The comparator 14 outputs the character data input from the input unit 12 and the output from the memory 13 (character data one cycle before).
Is subtracted one byte at a time, and the result is output to the decision unit 16. One cycle of the character data is, for example, about 200 bytes.

The determiner 16 determines, based on the output of the comparator 14, whether or not the character data has changed from the data one cycle before. If it has changed, a control signal for turning on the switch 9 (FIG. 1) is output to the switch 9 (FIG. 1) through the output unit 18 and the control signal is output to the timer 15 so that the timer 15 Do the set. If there is no change, the determiner 16 compares the count value of the timer 15 with a predetermined value. When the count value is equal to or more than a predetermined value, that is, when the character data does not change for a predetermined time, the determiner 16 outputs a control signal for turning on the switch 9 (FIG. 1) through the output unit 18 to the switch 9 ( Output to Fig. 1). On the other hand, when the count value is lower than the predetermined value, the determiner 16 does not output the control signal.

The timer 15 counts at predetermined time intervals according to a control signal from the judging unit 16, and outputs a signal to the judging unit 16 when the counted value exceeds a predetermined value.

The decision unit 16 outputs a control signal to turn on the switch 9 (FIG. 1) to the switch 9 (FIG. 1) through the output unit 18 even when the scene change detection signal is input. I do.

FIG. 3 is a diagram showing a second example of the controller of FIG. In this case, a register 20 is used instead of the memory 13 (FIG. 2), and the character data signal is input to the comparator 14 and the register 20 through the calculator 19.

The arithmetic unit 19 performs one of a checksum for performing addition over one period and a cyclic redundancy check (CRC) on the input character data. The calculation result of the calculator 19 is held in the register 20 and is input to the comparator 14.

The comparator 14 subtracts the character data input from the arithmetic unit 19 from the output from the register 20 (the operation result one cycle before) one byte at a time, and outputs the result to the decision unit 16. The operations of the timer 15 and the determiner 16 are as follows.
It is the same as FIG.

FIG. 4 is a flowchart for explaining the operation of the controller shown in FIG. This routine is repeatedly executed by reading a program stored in a memory (not shown, for example, a flash memory).

First, in step S1, it is detected whether or not the scene change detector 2 has output a scene change detection signal. If the output of the scene change detection signal is not detected, the character data is read in step S2. In this case, the controller 8 in FIG. 2 writes the read character data into the memory 12, and
The controller 8 shown in FIG. When the output of the scene change detection signal is detected, the transmission flag is set as described later.

Next, in step S3, it is detected whether or not the character data has changed. When a change in character data is detected, the timer 15 is set (step S4),
On the other hand, when the change of the character data is not detected, the timer 15 is checked (step S5).

In step S5, the setting (predetermined value) of the timer 15 is set at the time of power-on initialization or at the time of data transmission, and is decremented by one each time step S5 is executed once. Thereafter, it is determined whether or not the count value of the timer 15 is equal to or more than the set value (Step S
6).

If the count value of the timer 15 is equal to or greater than the set value, the timer 15 is set (step S4), whereas if the count value of the timer 15 is less than the set value, the transmission flag is reset (step S4). S7), this routine ends. In step S7, a time interval when the character data does not change is set.

After setting the timer 15 in step S4, the transmission flag is set (step S8), and this routine ends. The determiner 16 creates a control signal according to the result of the transmission flag. That is, when the transmission flag is set, a control signal for turning on the switch 9 is generated, and when the transmission flag is reset, a control signal for turning off the switch 9 is generated.

The present invention is not limited to the above embodiment, and many modifications and variations are possible. For example, in the above embodiment, while the image signal is used as the first signal and the character data signal is used as the second signal, other types of signals may be used as the first signal and the second signal. For example, an image signal is used as a first signal, and a net cue is used as a second signal.
Predetermined data signals such as captions and superimposed text can also be used. In the above embodiment, the scene change was detected because the first signal was an image signal. However, when the first signal was an audio signal, the silence time of the audio signal was detected and the silence was detected. Similar processing can be performed by determining whether the time exceeds a predetermined time.

In FIG. 1, the speech encoder 4 and the data converter 6 can be omitted.
When the arithmetic unit 17 is inserted between the input unit 11 and the connection point between the memory 12 and the comparator 13, the register 18 can be used instead of the memory 12, and the memory 18 can be used instead of the register 18 in FIG. 12 can also be used. In FIG. 1, the switch 8 is provided at the subsequent stage of the data converter 6 to control the on / off of the switch 8. However, the control signal is supplied to the data converter 6, and the transmission flag from the control signal is considered. Data conversion can also be performed. In this case, it is necessary to change the operation of the multiplexer 9. Further, the scene change detector 2 can be housed inside the image encoding unit.

In the above embodiment, an example in which the image signal and the audio signal are multiplexed has been described. However, the present invention is applied to a case where the change rates of not only the image signal and the audio signal but also a plurality of data are extremely different. Is particularly effective.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of an encoded data multiplex transmission apparatus according to the present invention.

FIG. 2 is a diagram illustrating a first example of the controller in FIG. 1;

FIG. 3 is a diagram illustrating a second example of the controller in FIG. 1;

FIG. 4 is a flowchart illustrating an operation of the controller of FIG. 1;

[Explanation of symbols]

 1, 4, 6, 12, 17 Input unit 2 Scene change detector 3 Image encoder 5 Audio encoder 7 Data converter 8 Controller 9 Switch 10 Multiplexer 11, 18 Output unit 13 Memory 14 Comparator 15 Timer 16 Judgment unit 19 Operation unit 20 Register

Claims (6)

[Claims] A first detecting means for detecting an amount of change in the first signal; an encoding means for encoding the first signal; and a second signal having a lower change rate than the first signal. A second detecting means for detecting a change in the signal or detecting that the second signal does not change for a predetermined time; and when the first detecting means detects the first signal having a predetermined change amount, the second detecting means Multiplexing means for multiplexing the first signal and the second signal when detecting means detects a change in the second signal or when detecting that the second signal does not change for a predetermined time; A coded data multiplex transmission device comprising: 2. The storage device according to claim 1, wherein the second detection unit stores one cycle of the data of the second signal, and stores the current data of the second signal in the first cycle before the cycle stored in the storage unit. Comparing means for comparing data of two signals; determining means for determining a change in the second signal according to the result of the comparing means; and determining the second signal according to the result of the comparing means. 2. The coded data multiplex transmission apparatus according to claim 1, further comprising a measuring unit for measuring a period during which the data does not change. 3. The second detecting means, calculating means for calculating the data of the second signal, storing means for storing the calculation result of the data of the second signal, and the current value of the data of the second signal. Comparing means for comparing the result of the operation with the result of the operation stored in the storage means; determining means for determining a change in the second signal in accordance with the result of the comparing means; 2. The coded data multiplex transmission apparatus according to claim 1, further comprising: a measuring unit that measures a period during which the second signal does not change in accordance with the above. 4. The coded data multiplex transmission apparatus according to claim 3, wherein said operation is a checksum or a cyclic redundancy check. 5. A step of detecting a change amount of a first signal, a step of encoding the first signal, and detecting a change of a second signal having a lower change rate than the first signal. Or detecting that the second signal does not change for a predetermined time; and when the amount of change in the first signal exceeds a predetermined amount, when detecting a change in the second signal, or when detecting a change in the second signal. Multiplexing the first signal and the second signal when the signal does not change for a predetermined period of time. 6. The method according to claim 5, wherein the change of the second signal is detected by a checksum or a cyclic redundancy check.