JP2002077787A - Video data recording / reproducing device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] In an apparatus that simultaneously records and reproduces video data, even if access to a storage device temporarily stops, the video data is recorded without interruption. In addition, it is possible to output reproduced images without interruption. SOLUTION: A part of a buffer memory area for reproduction is
By temporarily controlling it to be available for recording, the buffer memory capacity that was insufficient for recording is secured, and the playback data is thinned out by the shortage for playback. Although the quality is lower, by reducing the amount of buffer memory required for playback,
The playback video is configured to guarantee continuity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video data recording and reproducing apparatus for recording and reproducing video data, and more particularly to a video data recording and reproducing apparatus capable of simultaneously performing recording and reproduction.

[0002]

2. Description of the Related Art Conventionally, in an apparatus for simultaneously processing the recording and reproduction of video data, the processing of the recording system and the processing of the reproduction system of the video data have been completely separated and independently controlled. Also, the buffer memory for temporary storage required for the processing systems has a configuration in which each processing system has a memory having an independent capacity. In addition, the access for recording and reproduction to and from the mass storage device includes a recording process (a write operation from the buffer memory to the mass storage device) and a reproduction process (a read operation from the mass storage device to the buffer memory). This has been realized by processing alternately by division.

[0003] By expanding the bus bandwidth of the buffer memory, it is possible to combine two buffer memory blocks into one system and simultaneously process recording and reproduction. Since the reproduction processing systems are independent of each other, the memory capacity required for each is fixed.

[0004]

In the above-mentioned conventional video data recording / reproducing apparatus, some trouble occurs in the storage device (mass storage device) when the recording and reproduction of video data are simultaneously performed. However, in the event that access to the storage device is temporarily interrupted, the recording buffer memory area and the reproduction data become insufficient. When this occurs, the video being recorded is interrupted, and the video being reproduced is also interrupted. The reproduced video does not cause a fatal problem because the recorded data is not erased, but a fatal error occurs when the recorded video is interrupted.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a method for temporarily stopping access to a storage device. However, an object of the present invention is to provide a video data recording / reproducing apparatus capable of recording video data without interruption and outputting a reproduced image without interruption.

[0006]

In order to achieve the above object, in a video data recording / reproducing apparatus according to the present invention, a part of a buffer memory area for reproduction is made temporarily available for recording. By controlling the buffer memory capacity that was insufficient for recording, and by thinning out the playback data by the amount that was insufficient for playback, the quality of the playback video deteriorated, but the buffer required for playback was reduced. The configuration is such that the continuity of the reproduced video is guaranteed by reducing the memory usage.

That is, by using a part of the buffer memory area for reproduction for recording, the video input data is recorded in the storage device without interruption, and the reproduction buffer memory size of the reproduced video is reduced. The amount of data is reduced by thinning out the reproduced video data by an amount corresponding to that, so that the reproduced video can be output without interruption.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a video data recording / reproducing apparatus according to one embodiment of the present invention.

In FIG. 1, 1 is a video input device, 2 is a video input data control circuit, 3 is a buffer memory & memory control circuit, 4 is a storage device I / F control circuit, and 5 is a storage device (here, a storage device). Is a system using an HDD, but the storage device is not limited to this),
6 is a data thinning control circuit, 7 is a video output data control circuit, 8 is a video output device, 9 is a system controller, 1
0 is a system bus. Here, the video input device 1 and the video output device 8 are external devices connected to the video data recording / reproducing device, and the components 2, 3, 4, 5, 6, 7,
9 and 10 are included in the video data recording / reproducing apparatus.

First, a system in which a signal input from the video input device 1 is recorded in a storage device (here, an HDD) 5 will be described.

In the configuration shown in FIG.
Is sent to the video input data control circuit 2. When the input video data is an analog signal, the input video data is converted into a digital signal by an A / D conversion circuit provided in the video input data control circuit 2, and further, a DV system provided in the video input data control circuit 2.
A digital data size reduction process is performed as necessary by a circuit that performs compression according to the MPEG1 system or the MPEG2 system. If the video data from the video input device 1 is a digital signal, the digital data is handled as it is without the need for A / D conversion. , M
A compression process such as the PEG2 method is performed (the video data from the video input device 1 may be digital data that has already been compressed to MPEG2 or the like.
/ D conversion only). Digital data output from the video input data control circuit 2 is sent to the buffer memory & memory control circuit 3 via the system bus 10.

The buffer memory & memory control circuit 3 is necessary for absorbing the difference between the input / output rate (data transfer rate) and the access rate to the HDD 5 and performing efficient data transfer processing. Here, it is assumed that the data transfer rate of the HDD 5 is much higher than the video data transfer rate.

FIG. 2 is a diagram showing the concept of changing the memory area of the buffer memory in the buffer memory & memory control circuit 3 and data control. As shown in the conceptual diagram of FIG. 3, the buffer memory 3a Apparently, four ports 3a for input / output to / from the buffer memory area 3a-1
-2, 3a-3, 3a-4, and 3a-5 are controlled by the system controller 9 via a memory control circuit. Two of the four ports are a recording-system video data input port 3a-2 and a recording data output port 3a-3, and the other two ports are a reproduction-system reproduction data input port 3a-4 and a video data input port 3a-4. Output port 3a-5. The buffer memory 3a is controlled so as to be shared and used by the recording processing and the reproduction processing, and is controlled so that the recording processing and the reproduction processing can be executed simultaneously. Since recording and reproduction are simultaneously performed, the memory area 3a-1 of the buffer memory 3a is processed.
Are divided into an area for recording data and an area for reproduction data, and are managed by the system controller 9 via the memory control circuit. When the data transfer rate of the video data to be recorded is equal to the data transfer rate of the video to be reproduced, the two areas are assigned as areas obtained by dividing the memory area 3a-1 of the buffer memory 3a into two equal parts. When the data transfer rate differs between recording and reproduction, the data transfer rate can be allocated to each area in proportion to the rate.

The video data sent from the video input data control circuit 2 to the buffer memory & memory control circuit 3 via the system bus 10 is transmitted to the video data input port 3a-2.
And is written to the recording data area of the buffer memory 3a (buffer memory area 3a-1).
The recording data written in this area is output from the recording data output port 3a-3 to the storage device I / F control circuit 4 via the system bus 10. The data sent to the storage device I / F control circuit 4 is recorded in a storage device (HDD) 5.

Next, a system for reproducing video data recorded in the storage device (HDD) 5 will be described.

The data read from the storage device (HDD) 5 is output to the storage device I / F control circuit 4, and when there is no need to thin out the data, the storage device I / F control circuit 4 sends the data to the system bus 10. Then, the data is sent to the reproduction data input port 3a-4 of the buffer memory 3a of the buffer memory & memory control circuit 3 and is written to the reproduction data area of the buffer memory 3a (buffer memory area 3a-1). When it is necessary to thin out the reproduction data, the data read from the storage device (HDD) 5
The data is sent to the data thinning circuit 6 via the storage device I / F control circuit 4. The data thinning circuit 6 performs a data thinning process in accordance with an instruction from the system controller 9, and outputs the thinned data to a reproduction data input port of the buffer memory 3 a of the buffer memory & memory control circuit 3 via the system bus 10. The data is sent to the buffer memory 3a-4, and is written to the reproduction data area of the buffer memory 3a (buffer memory area 3a-1).

The reproduction data written in the reproduction data area of the buffer memory 3a is supplied to the video data output port 3
a-5 to the video output data control circuit 7 via the system bus 10. In the video output data control circuit 7, when the subsequent video output device 8 handles an analog signal, the D / A provided in the video output data control circuit 7 is used.
The analog signal converted by the conversion circuit is output to the video output device 8. In addition, DV system, MPEG1 system, MP
With respect to data that has been subjected to compression such as the EG2 method, the data after being subjected to expansion processing by a decoder circuit provided in the video output data control circuit 7 is output. The data sent to the video output device 8 is reproduced and displayed on the display means of the video output device 8.

In the present embodiment, since an HDD (hard disk drive) is used as the storage device 5, the operation of the HDD, which is a problem when recording and reproducing video data, will be briefly described below. I do.

If an error occurs during sector read / write, the HDD automatically executes a retry process to recover from the error. Such retry processing includes read / write errors and seek errors.

In the retry process at the time of read / write, in order to access the same sector again, the disc 1 waits until the same sector comes to the head after one revolution of the disc.
A waiting time for the rotation occurs. This waiting time is about 11.1 ms in the case of an HDD of 5400 rpm, for example. For this reason, if several retries are required to recover from the error, an extra waiting time corresponding to the number of retries times one rotation time of the disk (11.1 ms) occurs.

In a retry process for a seek error, when an access request to a specified sector occurs, the head performs a seek operation (movement) to a track in which a target sector is located, and as a result, some cause (vibration from the outside) occurs. This occurs when it is not possible to on-track to the target track due to the following problems. The details of the processing differ slightly depending on the HDD manufacturer, but in order to improve the positioning accuracy on the target track, the head is once moved to a reference track or area, and then the head is moved to the target track again. is there. The processing time required at this time is also HD
Although it depends on D, several hundred ms is required.

If the error can be recovered after the retry of the number specified in the HDD specifications, the HDD automatically executes the replacement process. The content of the replacement process differs between read and write. First, the operation at the time of reading is to automatically move the sector data recovered from the error after executing the retry process the specified number of times to another unused sector (a replacement dedicated area is provided). Next, when there is an access request to the same sector, control is performed so that access is performed to the sector relocated by the above processing. Also, when writing,
If the error does not recover after the specified number of retries have been performed, write data is written to another unused sector (having a dedicated replacement area) in the same way as for reading, and the same sector is accessed next. When a request is made, control is performed so that access is performed to the sector relocated by the above processing.

Further, it is executed to maintain the accuracy and reliability of data access with respect to a temperature change around the HDD.
There is a processing operation called thermal calibration processing. This process also has different operation specifications depending on the HDD of each company, but the process is automatically executed approximately once every tens of minutes, and the time required for the process is several hundred ms. While the thermal calibration process is being performed, the host cannot access the HDD.

In the HDD, the processing for maintaining the data reliability as described above is automatically executed. Although such processing is very important for a computer system, it causes unpredictable overhead in a device that records and reproduces video data.

When recording and reproduction of video data are simultaneously processed, the buffer memory 3a and the storage device (HDD) 5
In the data transfer between the HDD and the HDD, if an error frequently occurs for some reason at the time of access, and the automatic processing operation of the HDD overlaps, the access to the HDD is interrupted. Since data and video output data for reproduction are sequentially input and output in real time without interruption, the data area for recording in the buffer memory is insufficient, and the data for reproduction is also insufficient. Even if such an access delay is temporary, if the recording data area and the reproduction data area of the buffer memory managed by the system controller are fixed, the recording When the remaining capacity of the data area is exhausted, a fatal situation that video input data cannot be continuously recorded is caused (in contrast, in the case of reproduction, the video is temporarily interrupted, and H
This does not mean that the data recorded on the DD is lost, so it is not a fatal problem).

Therefore, in the present embodiment, when there is a risk of falling into the above situation, that is, when it is detected that the remaining capacity of the recording data area of the buffer memory has decreased below a prescribed value, for example, As shown in FIG. 2, the system controller 9 changes the setting so that half of the data area for reproduction in the memory area 3a-1 of the buffer memory 3a can be used as the data area for recording. By doing so, a data area for recording is secured (that is, three quarters of the total capacity of the memory area 3a-1 is secured as a data area for recording). By performing such control, it is possible to avoid a catastrophic situation of missing recording data. In this example, one half of the data area for reproduction is set as the data area for recording. However, the setting of the data area for recording and the data area for reproduction by the system controller 9 is arbitrary. Then, it is possible to control the setting.

In this way, the data area for recording is secured, but the data area for reproduction is reduced, so that the data at the time of reproduction will be insufficient and the reproduced video will be interrupted if left as it is. . Therefore, in the data thinning control circuit 6 shown in FIG. 1, the system controller 9 instructs the data thinning control circuit 6 in the memory area 3a-1 so as to prevent a situation in which the quality of the video at the time of reproduction is reduced but the video is interrupted and disappears. By thinning out data in accordance with the decrease in the data area for reproduction, the amount of data to be transferred to the data area for reproduction is reduced, and the capacity of the data for reproduction is reduced.

More specifically, as shown in FIG. 2, half of the data area for reproduction in the memory area 3a-1 of the buffer memory 3a is used by the system controller 9 as a data area for recording. When set, the data thinning control circuit 6 plays back video data (here, data in units of frames) sent from the storage device (HDD) 5 by thinning out one frame data every two frame data. The system controller 9 sets so as to compensate for the decrease in the data area for use. Here, for the sake of simplicity of description, frame data having a uniform data size is used. However, in the case of video data compressed by MPEG2, the data size of each of I, P, and B frames is not constant. When the data size ratio is I: P: B = 5: 2.5: 1, one GOP (Gr.
The ratio of the amount of data occupied by each frame per unit of “up of picture” is I: P: B = 1: 2: 2 (MPE
G2 parameters; N = 15, M = 3). This means that, for example, by thinning out the B frames, the data amount of 40% can be reduced, so that 40% of the data area for reproduction can be set as the data area for recording. Also, if both the P and B frames are thinned out, the data amount of 80% of the entire data can be reduced, and similarly, 80% of the data area for reproduction can be used for recording. However, in this case, only one I-frame image is reproduced per GOP (0.5 second), and the quality of the image is reduced, but the continuity of the reproduction is guaranteed. You.

As another method of thinning out data,
The same effect can be obtained by lowering the horizontal and vertical resolution of the reproduction data input and applying data compression.

Next, the memory area 3 of the buffer memory 3a
A method of performing the thinning-out processing on the reproduction data already written in the reproduction data area in a-1 will be described with reference to FIGS.

FIG. 3 shows the relationship between the reproduction data input and each area in the memory area 3a-1 of the buffer memory 3a in which the input data is written, when the reproduction data thinning rate is 50%. (It is assumed that the reproduced data at this time is fixed-length frame data). First,
As shown in FIG. 3A, when the input data for reproduction in units of frames is sequentially input as 0 → 1 → 2 → 3 → 4 → 5 → 6 →... The data area is divided into four areas such as the reproduction areas "0" to "3", and the reproduction area "0" → "1" → "2" in the memory area 3a-1 is sequentially obtained in frame units. → “3” → “0” →
Control is performed such that recording is performed in the order of “1” → “2” → “3” →. Here, the thinning rate is 50%
Can be realized by thinning out one frame of data for every two frames of data. For example, as shown in FIG. 3A, control is performed to reproduce even-numbered frames and thin out odd-numbered frames. I do. That is, when the system controller 9 sets 50% of the data area for reproduction to be usable for recording, the reproduction area for odd numbers is already set by setting the reproduction area for odd numbers to be usable for recording. That is, the reproduction data recorded in the recording area is automatically invalidated, that is, 50% of the reproduction data is thinned out.

Similarly, FIG. 4 shows the reproduction data input and the memory area 3a of the buffer memory 3a in which the input data is written when the reproduction data thinning rate is 75%.
-1 indicates the relationship with each area (reproduction data at this time is also fixed-length frame data). In this case, since the data thinning rate is 75%, three frames out of four frames are thinned out, and here, for example, areas “1” to “3” out of four reproduction areas “0” to “3” 3 "are set so that they can be used for recording. By doing so, the numbers “1” to
The reproduction data recorded in the reproduction area of "3" is automatically invalidated, and the written reproduction data is subtracted for 75%.

In the examples shown in FIGS. 3 and 4 described above, frame data having a uniform data size is used for simplicity of description. However, in the case of video data compressed by MPEG2, I, P, B Since the data size of each frame is not constant, as described above, when the ratio of the data size per frame is I: P: B = 5: 2.5: 1, 1
The ratio of the amount of data occupied by each frame per GOP (Group of Picture) unit is I: P: B = 1: 2: 2 (MPEG2 parameters; N = 15, M = 3). This is 40% when the B frame is thinned out, as described above.
The data amount of the data area for reproduction can be reduced.
This means that 0% can be set in the data area for recording, and if both P and B frames are thinned out, 8
Since the data amount of 0% can be reduced, similarly, it means that 80% of the data area for reproduction can be used for recording. Therefore, the data area for reproduction is divided into three areas of reproduction areas "0" to "2", and the size distribution of each area is set to 1: 2: 2. And
Control is performed so that the I frame data is recorded in the reproduction area “0”, the P frame data is recorded in the reproduction area “1”, and the B frame data is recorded in the reproduction area “2”. By allocating the reproduction area in this way, when it is desired to use the reproduction data area for recording in accordance with an instruction from the system controller 9, first, the setting is performed so that the B frame data is thinned out. , 40% of the data area for reproduction (reproduction area “2”) can be used for recording. Further, by additionally setting the P frame data to be thinned out, 80% of the data area for reproduction (reproduction areas “1” and “2”) can be used for recording.

It should be noted that interpolation data is generated using data before and after the data for reproduction thinned out by the method described above, and this interpolation data is inserted between the data before and after to reproduce and display. It is also possible to provide various means.

In the above-described embodiment, an example is described in which an HDD is used as the storage device 5, but the storage device is not limited to this, and a magneto-optical disk, an optical disk, or the like can be applied. Also, the numerical values and the like specifically shown above are not limited to these.

[0036]

As described above, according to the present invention, in a device for simultaneously recording and reproducing video data, even if access to the storage device is temporarily interrupted, Can be recorded without interruption, and the reproduced image can be output without interruption. In other words, the interruption of the recorded video data is fatal and cannot be recovered. In the present invention, the recording buffer memory capacity is secured by temporarily lowering the image quality of the reproduced image, and the video data is interrupted. It is possible to record without any trouble, and also in the display, the image quality is reduced, but it is possible to reproduce and output without interruption (note that since the reproduction data recorded in the storage device is not operated, the next It will be displayed normally during playback.)

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a video data recording / reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the concept of changing a memory area of a buffer memory and controlling data in a buffer memory & memory control circuit in FIG. 1;

FIG. 3 shows a case where a thinning rate of reproduction data is set to 50%.
FIG. 4 is an explanatory diagram showing a relationship between a reproduction data input and each area of a buffer memory to which the input data is written.

FIG. 4 shows a case where a thinning rate of reproduction data is set to 75%.
FIG. 4 is an explanatory diagram showing a relationship between a reproduction data input and each area of a buffer memory to which the input data is written.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 video input device 2 video input data control circuit 3 buffer memory & memory control circuit 3a buffer memory 4 storage device I / F control circuit 5 storage device (HDD) 6 data thinning control circuit 7 video output data control circuit 8 video output device 9 System controller 10 System bus

Claims (18)

[Claims] 1. A video data recording / reproducing device for inputting / outputting video data to / from an external video data input / output device, comprising: a large-capacity storage device for recording and reproducing video data;
A buffer memory for temporarily storing video data to be recorded and reproduced in the storage device; and a control unit for controlling at least data transfer between the storage device and the buffer memory. Video data recording and playback device. 2. The video data recording / reproducing apparatus according to claim 1, wherein the control unit processes recording and reproducing at the same time. 3. The video data recording / reproducing apparatus according to claim 2, wherein the buffer memory is shared for recording and reproduction. 4. The video data recording / reproducing apparatus according to claim 3, wherein the buffer memory can change a memory size used for recording and reproducing by setting from the control unit. 5. The buffer memory size for recording according to claim 4, wherein when the capacity of the buffer memory for recording and reproduction is insufficient for some reason, the memory size is changed to give priority to recording. A video data recording / reproducing apparatus, wherein the control is performed so that the image data is increased. 6. The reproduction buffer memory according to claim 5, wherein when the reproduction buffer memory size is set small in the change of the memory size, the reproduction buffer memory size is adjusted to the reduced reproduction buffer memory size. A video data recording / reproducing apparatus characterized in that the amount of data to be recorded is reduced by, for example, thinning out reproduction data to be recorded, so that a reduction in the reproduction time can be compensated even with a small reproduction buffer memory size. 7. The video data recording / reproducing apparatus according to claim 6, wherein the data amount of the thinned-out reproduction data can be set in accordance with a reduced ratio of the size of the reproduction buffer memory set small. 8. The video data recording / reproducing apparatus according to claim 6, wherein the data to be decimated is a frame unit of the reproduced video data. 9. The video data recording / reproducing apparatus according to claim 6, wherein when the reproduced video data is MPEG2 video data, the thinned data is in I, P, and B frame units. 10. The video data recording / reproducing apparatus according to claim 6, wherein the data amount of the reproduced data is reduced by lowering the resolution of the reproduced video data. 11. The video data recording / reproducing apparatus according to claim 10, wherein the resolution of the reproduced video data is reduced in accordance with the reduced ratio of the size of the buffer memory for reproduction. 12. The video data recording / reproducing apparatus according to claim 6, wherein a data amount of the reproduced data is reduced by increasing a compression rate of the reproduced video data. 13. The video data recording / reproducing apparatus according to claim 12, wherein the compression rate of the reproduced video data is increased in accordance with a reduced ratio of the size of the buffer memory for reproduction set to a small value. 14. The reproduction data area according to claim 5, wherein a reproduction data area of the buffer memory set for normal reproduction is divided into two or more areas, and the reproduction data is stored in one of the plurality of areas. Data that is not thinned out when performing the thinning process is stored in other areas of the plurality of areas.
When performing the process of decimating the playback data, the data to be decimated can be recorded separately.
When the recording buffer memory size is set to be large by giving priority to the recording as described above, at least one of the areas allocated to the data to be thinned out becomes a recording data area. A video data recording / reproducing apparatus characterized by controlling. 15. The video data recording / reproducing apparatus according to claim 14, wherein the size of each of the plurality of areas of the reproducing data area can be arbitrarily set in accordance with the thinning rate of the reproducing data. apparatus. 16. The video data recording / reproducing apparatus according to claim 14, wherein the number of the plurality of areas obtained by dividing the data area for reproduction is set in accordance with a thinning rate of reproduced data. . 17. The method of claim 6, 7, 8, 9, 14, 15,
16. The video data output device according to any one of items 16, wherein interpolation data interpolated from previous and subsequent reproduction data is inserted into reproduction data thinned out from the reproduction buffer memory and output, and output to the video data output device. Video data recording and reproducing apparatus. 18. The storage device according to claim 1, wherein the large-capacity storage device is a magnetic recording medium storage device such as a hard disk device, a magneto-optical disk device, or an optical disk device, or a magneto-optical recording medium storage device. A video data recording / reproducing device, which is a device, an optical recording medium storage device, or a semiconductor storage device.