JPH08102144A - Reproducing device for digital animation image and digital voice - Google Patents

Abstract

PURPOSE: To realize synchronized reproducing of a normal digital animation image and a digital voice by providing a control means which controls the reading of data against a reading means and setting the capacity values of the buffer memories for digital animation image data and digital voice data so as to satisfy a specific relationship. CONSTITUTION: A control means 110 detects the amount of the data of buffer memories 106 and 107, decides the data reading of a reading means 103 in accordance with the detection and a switching means 105 is switched in accordance with the data read. The capacities of the memories 106 and 107, which temporarily store the data read from a recording medium 101, are set so that they become larger than [amount of the data in the buffer memory indicating a full condition of digital voice data]÷[fixed bit rate of digital voice data]×[maximum bit rate of the digital animation image data]. Thus, a shortage condition or a full condition of the memory 106 is avoided and the transfer control of the data to the memory 106 is made possible by only detecting the amount of the storage of the memory 107.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital moving image and a digital moving image for reproducing a recording medium in which digital moving image data is encoded at a variable bit rate and digital audio data is recorded at a fixed bit rate. The present invention relates to a sound reproducing device.

[0002]

2. Description of the Related Art Conventionally, various methods have been provided as a method for efficiently compressing and encoding digital moving image data. In particular, a compression method called MPEG standardized by ISO and CCITT Recommendation H.264. In recent years, research and development has been actively conducted on a compression encoding method for digital moving images, which uses a combination of intra-image compression and inter-image compression called H.261.
A relatively high image quality is obtained with a high compression rate. But,
Since the basis of the bit rate of these compressed data is a constant bit rate, there are a portion in which the image quality is sacrificed and a portion in which a given code amount is excessive within one digital moving image sequence. There was a balance issue.

Various methods have also been devised as a method for efficiently compressing and encoding digital audio data. For example, even in MPEG, a compression / decoding algorithm for performing synchronous reproduction on the output of a digital moving image is standardized. In this standard, the bit rate is fixed, and even in other digital audio data compression methods, the coding standard is a fixed bit rate.

In a compression coding method of a digital moving image, which uses a mixture of intra-image compression and inter-image compression represented by MPEG, first, all image data is divided into small areas called macroblocks, The compression process is performed for each area. Here, the intra-image unit compression is a compression mode in which only the compressed data can be decoded, and the inter-image unit compression uses the correlation with other image data and compresses it using its motion and difference. Encoding is performed, and compression / decoding is performed using other image data when decoding.

In the intra-image compression, two-dimensional discrete cosine transform (DCT) is performed on all macroblocks in the image as they are, spatial frequency components are obtained, and matrix division called quantization is performed on the spatial frequency components. . That is, this is to divide the frequency component by a matrix with a predetermined value,
By multiplying this matrix and the quantized data by the decoder,
It becomes possible to obtain the frequency component. Then, it is possible to reduce the accuracy of the matrix value or less. Then, more codes are assigned to the low frequency side than to the high frequency side. Also,
In the compression between image units, for each macroblock,
The motion vector from the referenced image is determined and the region closest to that macroblock is detected. Then, the two-dimensional discrete cosine transform (DCT) is performed on the difference between the area and the corresponding macroblock data, the quantization is performed and the compression encoding is performed, and the difference data and the motion vector are encoded. .

In the compression coding method for digital moving images represented by MPEG, which is processed in this way, the number of generated bits differs depending on the complexity of the image, the size of the motion, and the like.

For this reason, in order to perform constant bit rate output, it is permitted to change a multiplier for a quantization matrix called a quantization width at the time of quantization. In a real digital moving image / digital audio decoding device, a process of observing the generated code amount and increasing the quantization width when it is larger than the schedule and decreasing the quantization width when it is smaller is performed. Has been done. However, as a matter of course, when the quantization width is increased, the quantization is coarsely performed, the encoding accuracy is lowered, and the image quality is deteriorated. On the contrary, when the quantization is performed with an extremely small quantization width, an unnecessary code amount is assigned, and the image of the scene becomes image data of which the image quality is unnecessarily higher than the average.

However, due to the improvement of the technology of the recording medium reading device, the limitation of constant bit rate is being solved in recent years. That is, this is because the provision of the buffer memory on the side of the reading device has enabled control without problems even in the case of a variable bit rate. In addition, JP-A-4
In the "recording / reproducing apparatus" described in Japanese Patent No. 326687, MPEG digital moving image compressed data is encoded at a variable bit rate, and the maximum bit rate is limited for the reason of limitation of a decoding apparatus and a reading apparatus. The technique of doing is disclosed.

Here, when the digital moving image coded data having a variable bit rate and the audio coded data having a fixed bit rate are recorded on the same recording medium, the control of the buffer memory in each decoding device is a big problem. Becomes

For example, when the digital moving image coded data and the digital audio coded data are recorded on the same recording medium, the appearance frequency of the digital audio coded data is adjusted according to the bit rate of the digital moving image to obtain the synchronization. Will be adjusted. Then, it is necessary to use a buffer memory for each decoding means to change the bit rate in a minute time, recover from a failure in reading, and alleviate the digital moving image data because it has a variable bit rate. . In addition, each will control the data in the memory so that it will not become empty and will not exceed it, but at variable bit rates the changes are diversified and not constant, so very complicated processing is required. Therefore, there has been a problem that the circuit configuration becomes complicated. Next, this will be described with reference to FIG.

FIG. 4 is a block diagram showing an example of a conventional digital moving image digital audio decoding apparatus.

In FIG. 4, reference numeral 401 is a recording medium on which moving image compressed data and digital audio compressed data are recorded, which will be described here as an optical disc. Reference numeral 402 is a reading means for reading data from the optical disc. A switching unit 405 switches between digital moving image data and digital audio data and outputs the data. A buffer memory 406 temporarily stores the compressed digital moving image data. A buffer memory 407 temporarily stores the compressed digital audio data. Reference numeral 408 is a digital moving image decoder for decoding moving image compressed data. Reference numeral 409 is a digital audio decoder for decoding the digital audio compressed data.

Next, the operation of the conventional digital moving image digital audio decoding apparatus will be described.

Data is read from the recording medium 401 by the reading means 402. Here, it is assumed that the reading means can intermittently read data from a predetermined point in response to a request from the buffer memories 406 and 407. This data is divided and recorded in a recording unit of an optical disc, which is usually called a sector, and discrimination information of digital moving image compressed data or digital audio compressed data is recorded for each header. By using this data, the switching unit 405 can separate the digital moving image compressed data and the digital audio compressed data. Then, it is temporarily stored in the buffer memories 406 and 407 for digital moving images and digital sounds, and is decoded by the moving image decoders 408 and audio decoders 409 for digital moving images and digital sounds to obtain digital moving images and digital sounds. The data is played.

[0015]

In the conventional digital moving image / digital audio decoding apparatus, if there is no regularity and compensation in each buffer memory 406 and buffer memory 407, the respective buffer memory 406 and buffer memory 407 are provided. Insufficient control and excess state control must be performed by
It becomes impossible to predict the required amount of data. When either one of the digital voice and the digital moving image becomes insufficient, the data on the other side may be full. At this time, it becomes difficult to reproduce the normal image and the digital audio synchronously.

In order to realize this kind of normal image and digital audio synchronous reproduction, the difference in characteristics between digital audio data and digital moving image data becomes important. For example, in the case of digital moving image data, since the original nature is a discrete set of still images, the buffer memory 4
When the data in 06 and 407 is insufficient for decoding, a relatively natural video can be given to the viewer even by taking measures such as thinning out images. However, in the case of digital audio data, since the original property is continuity,
It is difficult to avoid errors such as thinning. For this reason, it is desirable that the synchronous reproduction is configured based on the decoding of digital audio data.

However, according to such a method, in a reproducing apparatus which encodes a digital moving image at a variable bit rate and decodes data obtained by encoding digital audio data at a fixed bit rate, regularity and compensation of the buffer memory are not achieved. Since it is not prepared, it is difficult to control the reading, and it may be difficult to synchronously reproduce a normal image and digital audio.

Therefore, according to the present invention, when reproducing the recording medium on which the compressed digital moving image data of the variable bit rate and the digital audio data of the fixed bit rate are reproduced, it is possible to realize the normal synchronous reproduction of the digital moving image and the digital audio. An object of the present invention is to provide a reproducing apparatus for digital moving images and digital audio.

[0019]

According to a first aspect of the present invention, there is provided a digital moving image and digital audio reproducing apparatus for recording digital moving image data encoded with variable bit rate and digital audio data encoded with fixed bit rate. Mounting means for mounting the recording medium, reading means for reading data from the recording medium mounted on the mounting means at a predetermined fixed bit rate, digital moving image data and digital audio data for the data read from the reading means. Switching means for separating and outputting the digital moving image data output from the switching means, and a digital moving image data buffer memory for temporarily storing and outputting the digital moving image data output by the digital moving image data buffer memory Digital video data decoding means for decoding image data, and digital audio data of the switching means. Digital audio data buffer memory for temporarily storing the output and outputting the output, digital audio data decoding means for decoding the digital audio data output from the digital audio data buffer memory, and the digital moving image data buffer memory Control means for requesting data transfer according to the amount of data stored in the digital audio data buffer memory and the amount of data stored in the buffer memory for digital audio data, and controlling the reading of data to the reading means according to the data transfer request. The ratio value of the memory capacity of the digital moving image data buffer memory and the limit value for requesting stop of reading of the digital audio data buffer memory is the maximum bit rate value of the digital moving image data and the digital audio data. It is set to be equal to or greater than the ratio of the fixed bit rate value of data.

According to a second aspect of the present invention, there is provided the control means of the digital moving image and digital audio reproducing apparatus, wherein the data amount stored in the digital moving image data buffer memory and the data amount stored in the digital audio data buffer memory. It comprises a decoding control means for requesting data transfer according to the amount and a reading control means for controlling data reading for the reading means according to the data transfer request from the decoding control means.

According to a third aspect of the present invention, there is provided an apparatus for mounting a digital moving image and digital audio reproducing apparatus, which mounts a recording medium on which digital moving image data encoded with variable bit rate and digital audio data encoded with fixed bit rate are recorded. Means, a reading means for reading data from the recording medium attached to the attaching means at a predetermined fixed bit rate, a read buffer memory for temporarily storing the data read out from the reading means, and outputting it. Reading control means for controlling the reading of the data of the reading means according to the amount of data stored in the reading buffer memory, and switching for separating the data read from the reading means into digital moving image data and digital audio data and outputting the data. Means and a digital moving image for temporarily storing the digital moving image data output of the switching means and outputting it. An image data buffer memory, a digital moving image data decoding means for decoding the digital moving image data output from the digital moving image data buffer memory, and a digital audio data output of the switching means are temporarily stored and output. A digital audio data buffer memory, digital audio data decoding means for decoding the digital audio data output from the digital audio data buffer memory, and the amount of data stored in the digital moving image data buffer memory. Decoding control means for requesting data transfer in accordance with the amount of data stored inside the digital audio data buffer memory and controlling data transfer from the read buffer memory to the switching means in accordance with the data transfer request. And a buffer for the digital moving image data The ratio of the memory capacity of the memory and the limit value for requesting the stop of reading of the buffer memory for digital audio data is equal to or greater than the ratio of the maximum bit rate value of digital moving image data and the fixed bit rate value of audio data. It was done.

According to a fourth aspect of the present invention, the decoding control means of the digital moving image and digital audio reproducing apparatus makes a data transfer request in accordance with only the data amount of the digital audio data buffer memory.

According to a fifth aspect of the present invention, there is provided the decoding control means of the digital moving image and digital audio reproducing apparatus, when the amount of data stored in the digital moving image data buffer memory becomes smaller than a predetermined first reference value. Controlling the data transfer of the reading means when a data transfer request of the reading means is made and the amount of data stored in the digital audio data buffer memory exceeds a predetermined second reference value. Is.

In the decoding control means of the digital moving image and digital audio reproducing apparatus according to the sixth aspect, the storage data amount of the digital moving image data buffer memory becomes smaller than a predetermined first reference value, and When the amount of data stored in the digital voice data buffer memory exceeds a predetermined second reference value, the data transfer stop control of the reading means is performed.

According to a seventh aspect of the present invention, there is provided a digital moving image and digital audio reproducing apparatus, which temporarily stores digital moving image data and temporarily stores the digital moving image data buffer memory and digital audio data. The value of the ratio to the limit value that requires the reading stop of the output digital audio data buffer memory should be equal to or greater than the ratio of the maximum bit rate value of digital moving image data and the fixed bit rate value of digital audio data. is there.

[0026]

According to a first aspect of the present invention, there is provided a digital moving image and digital audio reproducing apparatus for reproducing a recording medium on which variable bit rate digital moving image data and fixed bit rate digital audio data are recorded. The value of the ratio of the memory capacity of the buffer memory to the limit value for requesting to stop reading the buffer memory for digital audio data is greater than or equal to the ratio of the maximum bit rate value of digital moving image data and the fixed bit rate value of digital audio data. Thus, the reading and transfer are controlled according to the storage data amount of the digital moving image data buffer memory and the digital audio data buffer memory.

According to a second aspect of the present invention, the control for requesting data transfer according to the amount of data stored in the buffer memory for digital audio data, and performing the data reading to the reading means according to the data transfer request is performed. Decoding control means for requesting data transfer according to the amount of data stored in the buffer memory for digital moving image data and the amount of data stored in the buffer memory for digital audio data, and according to the data transfer request from the decoding control means The reading control means controls reading of data from the reading means.

According to a third aspect of the present invention, there is provided a digital moving picture and digital sound reproducing apparatus for reproducing a recording medium on which variable bit rate digital moving picture data and fixed bit rate digital sound data are recorded. The value of the ratio of the memory capacity of the buffer memory to the limit value for requesting to stop reading the buffer memory for digital audio data is greater than or equal to the ratio of the maximum bit rate value of digital moving image data and the fixed bit rate value of digital audio data. Thus, the reading and transfer are controlled according to the storage data amount of the digital moving image data buffer memory and the digital audio data buffer memory.

According to a fourth aspect of the present invention, there is provided a digital moving image and digital audio reproducing apparatus for reproducing a recording medium on which variable bit rate digital moving image data and fixed bit rate digital audio data are recorded. The value of the ratio of the memory capacity of the buffer memory to the limit value for requesting to stop reading the buffer memory for digital audio data is greater than or equal to the ratio of the maximum bit rate value of digital moving image data and the fixed bit rate value of digital audio data. Therefore, the read and transfer are controlled only by the buffer memory for digital audio data.

According to a fifth aspect of the present invention, there is provided a digital moving image and digital audio reproducing apparatus for reproducing a recording medium on which variable bit rate digital moving image data and fixed bit rate digital audio data are recorded. The value of the ratio of the memory capacity of the buffer memory to the limit value for requesting to stop reading the buffer memory for digital audio data is greater than or equal to the ratio of the maximum bit rate value of digital moving image data and the fixed bit rate value of digital audio data. In such a manner, data read and transfer are controlled depending on the full state of the digital audio data buffer memory and the shortage state of the digital moving image data buffer memory.

According to a sixth aspect of the present invention, there is provided a digital moving image and digital audio reproducing apparatus for reproducing a recording medium on which variable bit rate digital moving image data and fixed bit rate digital audio data are recorded. The value of the ratio of the memory capacity of the buffer memory to the limit value for requesting to stop reading the buffer memory for digital audio data is greater than or equal to the ratio of the maximum bit rate value of digital moving image data and the fixed bit rate value of digital audio data. When the digital audio data buffer memory is full and the digital moving image data buffer memory is insufficient, data read / transfer control is performed. A shortage of buffer memory for moving image data occurred at the same time. It can, read data, is controlled so that the transfer is not performed is performed.

According to a seventh aspect of the present invention, the digital moving image data is temporarily stored, and the ratio of the memory capacity of the digital moving image data buffer memory to the limit value for requesting stop of reading of the digital audio data buffer memory is: Set it to be equal to or greater than the ratio of the maximum bit rate value of digital moving image data and the fixed bit rate value of digital audio data,
Reading and transfer are controlled according to the storage data amount of the digital moving image data buffer memory and the digital audio data buffer memory.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a digital moving image and digital audio reproducing apparatus of the present invention will be described below with reference to the drawings.

In the description of this embodiment, each data is simply described as digital moving image data or digital audio data. However, when the present invention is carried out, data which is compression-encoded or simply It is encoded and available in which the digital data is lossless.

[First Embodiment] FIG. 1 is a block diagram of a digital moving image and digital audio reproducing apparatus according to a first embodiment of the present invention.

In the figure, reference numeral 101 is a recording medium on which digital moving image data of variable bit rate and digital audio data of fixed bit rate are recorded. This recording medium 10
Although 1 is a disk in this embodiment, any recording medium capable of intermittently reproducing data may be used, such as an optical disk, a magnetic disk, a magneto-optical disk,
Various recording media such as a magnetic tape can be used.
Reference numeral 102 is a mounting means corresponding to the type of each recording medium 101. Reference numeral 103 is a reading unit corresponding to the type of each recording medium 101. 105 is a reading means 103
It is a switching means for separating the data read from the device into moving image data and digital audio data and outputting them. A digital moving image data buffer memory 106 temporarily stores the digital moving image data and outputs it. A digital voice data buffer memory 107 temporarily stores digital voice data and outputs the digital voice data. Reference numeral 108 denotes a moving picture decoder as a decoding means for digital moving picture data that decodes digital moving picture data. Reference numeral 109 is an audio decoder as a digital audio data decoding means for decoding digital audio data. Reference numeral 110 denotes a control unit that detects the amount of data in the buffer memories 106 and 107, determines whether to read the data by the reading unit 103 according to the data amount, and switches the switching unit 105 according to the digital moving image data and digital audio data to be read. A and B in the figure are signals for detecting the states of the buffer memories 106 and 107.

Next, the operation of the digital moving image and digital audio reproducing apparatus of this embodiment will be described.

The data read from the recording medium 101 by the reading means 103 is separated by the switching means 105 into digital moving image data of a variable bit rate and digital audio data of a fixed bit rate, which are respectively stored in the buffer memories 106 and 107. Is entered. Here, the reading means 103 controls reading according to the amount of data stored in the buffer memories 106 and 107.

Then, the data output from the buffer memories 106 and 107 is decoded by the digital moving image decoder 108 or the digital audio decoder 109, and the output of the digital moving image and the digital audio is obtained.
In this case, each data is temporarily stored in the buffer memories 106 and 107 in order to respond to a minute or macro bit rate change of the macro block.

However, it is impossible to predict what kind of bit rate the digital moving image data having a variable bit rate will appear. Therefore, the buffer memory 1
When storing 06 digital moving image data, it is necessary to determine the capacity on the assumption that data of the maximum bit rate always comes. FIG. 2 shows an example of the recording form of this variable bit rate data.

FIG. 2 shows an example of a recorded data string in which digital moving image data in the digital moving image and digital audio reproducing apparatus of this embodiment is encoded at a variable bit rate and digital audio data is encoded at a fixed bit rate. FIG.

The embodiment shown in FIG. 2 shows an example of a recorded data string in which digital moving image data is encoded at a variable bit rate and digital audio data is encoded at a fixed bit rate. The shaded data indicates digital audio data, and the other data indicates digital moving image data.
Data used for system information and other media is omitted for simplicity.

In the figure, the data string 21 shows the case where the bit rate of the moving image data is 3 times the bit rate of the digital audio data, and the data string 22 shows the case where it is 7 times.
For the synchronous reproduction of the digital moving image and the digital audio, the data is separated in consideration of the decoding timing and the arrival timing at the buffer memory. As the division unit, for example, in an optical disk such as a CD-ROM or a CD, a data unit called a sector is used.
As shown in the figure, the appearance frequency is the bit rate ratio (211: 212 (when the digital moving image bit rate is 3 times the digital audio bit rate), 221: 222.
(When the digital moving image bit rate is 7 times the digital audio bit rate)) is recorded on the recording medium 101. In this way, the ratio between digital audio data and digital moving image data is always the bit rate ratio, and the most frequent digital moving image data appears
This is when the digital moving image data has the maximum bit rate.

In order to facilitate such data reading control, the digital moving image data buffer memory 106 is provided.
Then, the value of the capacity ratio of the digital audio data buffer memory 107 is set to be equal to or more than the value of the ratio of the maximum bit rate that can appear in the variable bit rate of the digital moving image data and the fixed bit rate of the digital audio data. However, in this case, in the data read from the recording medium 101,
It is assumed that the appearance frequency of the digital audio data depends on the ratio of the bit rates of the digital moving image data and the digital audio data.

In this case, the appearance frequency is represented by [bit rate of digital moving image data] ÷ [bit rate of digital audio data]. Therefore, the largest amount of data is stored in the digital moving image buffer memory 106 when the digital audio data buffer memory 107 is full and the moving image data bit rate is the maximum value. Is.

In this case, the amount of moving image data stored in the buffer memory 106 is [the amount of data stored in the buffer memory 106] ≧ [the amount of data stored in the buffer memory that is full of digital audio data].
÷ [Fixed bit rate of digital audio data] x [Maximum bit rate of digital moving image data]. Therefore, if a buffer memory capacity larger than the storage data amount of the buffer memory 106 is prepared for the digital moving image data, the full state of the buffer of the digital moving image data, regardless of the bit rate of the digital moving image data, The shortage will not occur, and stable synchronized playback of digital moving images and digital audio can be realized.

When the buffer memory 106 is full, it means that the amount of data stored in the buffer memory 106 has exceeded a predetermined value. Normally, the next read unit (such as a sector of a CD-ROM) is read. This state occurs when the data read in the cycle exceeds the capacity of the buffer memory 106 when the data is read. Therefore, this reference value is determined by the read / transfer speed of data on the read side and the transfer side, the amount of transferred data, and the capacity of the buffer memory 106. Also,
The insufficient state indicates that the amount of stored data has become equal to or less than a predetermined value, and is usually a state in which data is read from the buffer memory 106 by decoding / playback or the like. This shows a state in which the data in the buffer memory 106 is exhausted after the instruction is given and before the data is actually transferred. Therefore, this reference value depends on the read / transfer speed of the data on the read side / transfer side that supplies the data to the buffer memory 106 and the decoding / reproduction speed from the buffer memory 106.

Although the buffer memory control is performed by the digital audio data buffer memory 107, the buffer memory control may be performed on the digital moving image data buffer memory 106 side.

That is, when the read control is performed mainly by the digital moving image data buffer memory 106, when the digital moving image data buffer memory 106 is full, the digital audio data buffer memory 107 is never full. It should be prevented.

In this situation, the storage data amount of the digital audio data buffer memory 107 is equal to the storage data amount of the digital audio data buffer memory =
[Digital video image data buffer memory] / [Digital video image data bit rate] x [Digital audio fixed bit rate]. This shows the maximum value when the digital moving image data shows the lowest bit rate. Therefore, [digital audio data buffer memory] ≧ [digital moving image data full state] is stored in the digital audio data buffer memory 107. Amount of data in the buffer memory] / [Minimum bit rate of digital video data] x
The capacity of [Constant bit rate of digital audio data] is required.

The purpose of the variable bit rate of digital moving image data is to make the ratio of the generated code amount to the entropy at the time of encoding constant and to make the overall image quality uniform. Therefore, in order to effectively achieve this purpose, the minimum bit rate of digital moving image data should not be determined. In other words, the amount of data in an image that is almost still and has no motion or image data that has almost no brightness is extremely small, and depending on the image, it is possible that it is almost only header data, and that maintains sufficient image quality. It becomes possible. Therefore, the minimum buffer rate of the digital audio data, that is, the minimum bit rate of digital moving image data, is a very small value. As a result, the capacity required for the digital voice data buffer memory 107 becomes extremely large,
The configuration is not realistic. However, usually, the maximum bit rate has to be determined by the technical limit of the reading means 103 of the recording medium 101 or the decoding device, and this value is used to utilize the buffer memory for digital moving image data as described above. A method of determining the amount is effective.

Further, when realizing the synchronous reproduction, the difference between the characteristics of the digital audio data and the digital moving image data becomes important. For example, in the case of digital moving image data, when the data in the buffer memories 106 and 107 is insufficient for decoding because the original nature is discrete, that is, a collection of still images, it is relatively natural to take measures such as thinning out images. It is possible to give the viewer various images. In the case of digital audio data, it is difficult to avoid an error such as thinning because the original property is continuity. For this reason, it is desirable that the synchronous reproduction is configured based on the decoding of digital audio data. From this point of view, the control led by the buffer memory for digital audio data shown in this embodiment is also effective.

Then, the control means 110 causes the states of the buffer memories of the decoding buffer memories 106 and 107 (A, B).
Is detected and the reading means is requested to read the data. In this case, if the digital moving image buffer memory is set as described above and the digital moving image data and the digital audio data in the data recorded on the recording medium are correctly arranged at the bit rate ratio, the digital moving image is The full state of the buffer memory cannot occur.

The reading means 103 is the recording medium 101.
The data is read at a predetermined bit rate from. This is because the bit rate control is difficult.
For example, in a data reading device for an optical disk, PLL control is performed so that the read bit rate is constant, and data is read. Therefore, in order to correspond to the variable bit rate at any time, it is necessary to change the operating frequency of the device at any time, resulting in a very complicated configuration,
Not realistic. Therefore, when reading an optical disc on which variable bit rate data is normally recorded, reading is performed at a bit rate higher than the maximum bit rate appearing in the disc, and is a configuration diagram of the present embodiment. 1
As described above, the buffer memories 106 and 107 alleviate the rate. Then, the amount of data stored in the buffer memories 106 and 107 is monitored, the data is read when it becomes less than a predetermined reference value, and read when it becomes more than another predetermined reference value. Stop and store its position to control variable bit rate readout. This operation is controlled by the control means 110.
Will be done.

In the digital moving image and digital audio reproducing apparatus of this embodiment, the recording medium 101 in which the digital moving image data encoded with variable bit rate and the digital audio data encoded with fixed bit rate are attached is attached. Medium attaching means 102, reading means 103 for reading data from the recording medium 101 attached to the attaching means 102 at a predetermined fixed bit rate, and data read from the reading means 103 for moving image data and digital audio. Switching means 105 for separating and outputting according to data discrimination, digital moving image data buffer memory 106 for storing and outputting the digital moving image data output of the switching means 105,
Decoding means comprising a moving picture decoder 108 for digital moving picture data for decoding the digital moving picture data output from the digital moving picture data buffer memory 106, and digital sound data for storing and outputting the digital sound data output of the switching means 105. Buffer memory 107, a decoding unit including an audio decoder 109 for decoding audio data output from the digital audio data buffer memory 107, the amount of data stored in the digital moving image data buffer memory 106, and the digital And a control unit 110 for requesting data transfer according to the amount of data stored in the audio data buffer memory 107, and for controlling the reading unit 103 to read data according to the data transfer request. This is an embodiment of claim 1. Door can be.

In particular, in the present embodiment, the ratio of the memory capacity of the digital moving image data buffer memory 106 to the limit value for requesting the reading stop of the digital audio data buffer memory 107 is the digital moving image data. Of the maximum bit rate value and the fixed bit rate value of the digital audio data.

When the present invention is implemented, the control means 110 of this embodiment is stored in the digital moving image data buffer memory 106 and the digital audio data buffer memory 107. The decoding control means for requesting data transfer according to the amount of data, and the reading control means for controlling the reading of data to the reading means 103 according to the data transfer request from the decoding control means can be divided. Can be used as an example. These can be incorporated in the independent circuit or the reading means 103 and the switching means 105, and the degree of freedom in designing is increased.

[Second Embodiment] FIG. 3 is a block diagram of a reproducing apparatus for digital moving images and digital sounds according to a second embodiment of the present invention.

In the figure, reference numeral 301 denotes a recording medium on which digital moving image data of variable bit rate and digital audio data of fixed bit rate are recorded. Although the recording medium 301 of the present embodiment has shown the example of a disc, any recording medium capable of intermittently reproducing data may be used, such as an optical disc, a magnetic disc, a magneto-optical disc, and a magnetic tape. The recording medium of can be used. Reference numeral 302 is a mounting means corresponding to the type of each recording medium 301. Reference numeral 303 is a reading means 302 corresponding to the type of each recording medium 301. A read buffer memory 312 temporarily stores and outputs the read data. A switching unit 305 separates the data output from the read buffer memory 312 into digital moving image data and digital audio data and outputs the data. Reference numeral 306 denotes a digital moving image data buffer memory that stores and outputs digital moving image data. A digital voice data buffer memory 307 stores and outputs digital voice data. Reference numeral 308 is a digital moving image decoder as a decoding unit for digital moving image data that decodes the digital moving image data. Reference numeral 309 is a digital audio decoder as a decoding unit for digital audio data that decodes digital audio data. 310 is the buffer memory 30
Decoding control means for observing the data amount of 6, 307, determining data transfer from the read buffer memory 312 to the switching means 305 according to the data amount, and outputting a switching signal of digital audio data and digital moving image data. 311
Detects the amount of data stored in the read buffer memory 312,
It is a read control unit that determines the read of data by the read unit 303 according to the data amount. In the figure, A and B are signals for detecting the states of the buffer memories 306 and 307.

The structure of this embodiment is the same as the buffer memories 306 and 307 of the first embodiment except that the read buffer memory 312 for buffering the read speed, the buffer memory 306 for digital moving image data, and the buffer for digital audio data are used. The operation of the memory 307 corresponds to a divided function.

Next, the operation of the digital moving image and digital audio reproducing apparatus of this embodiment will be described.

The data read by the reading means 303 from the recording medium 301 is temporarily stored in the read buffer memory 312. Then, this read buffer memory 312
Data is transferred from the switching unit 305 to the switching unit 305, and each data is temporarily stored in the buffer memories 306 and 307.
The output data is decoded by the moving image decoder 308 or the audio decoder 309, respectively. Also in this case,
As in the first embodiment, the decoding control means 310 gives an instruction for the transfer while detecting the amount of data stored in the buffer memories 306 and 307. In this configuration, data transfer between the read buffer memory 312 and the buffer memories 306 and 307 becomes important.

However, since the data recorded inside the read buffer memory 312 is the same as the data recording order on the recording medium 301, the read buffer memory 3 is the same.
The changes in the accumulated amount of 12 are the same. However, unlike the case of directly reading data from the recording medium 301 as in the first embodiment, a large decoding buffer memory (buffer memories 306 and 307) is prepared because there is no delay in reading the recording medium 301. There is no need.

Therefore, also in this case, similarly to the first embodiment, the digital voice data buffer memory 30 is used.
The capacity of 7 is [the buffer memory for digital audio data] ≧ [the amount of data in the buffer memory indicating the full state of digital moving image data] ÷ [the minimum bit rate of digital moving image data] ×
[Constant bit rate of digital audio data] is required.

The buffer capacity for digital moving image data is as follows: [buffer memory for digital moving image data] ≧ [amount of data in buffer memory indicating full state of digital moving image data] ÷ [fixed bit of digital moving image data] Rate] ×
If the digital moving image data buffer memory 306 of [maximum bit rate of digital audio data] is prepared, the full state and the insufficient state of the digital moving image data buffer will appear regardless of the bit rate of any digital moving image data. And stable, synchronized playback of digital moving images and digital audio can be realized.

In this case, the buffer memories 306, 3
Since the configuration after 07 is highly independent, the recording medium attaching unit 302, the read buffer 312, and the read control unit 311 can be separated as separate reading devices. In this case, the reading means 303 of this recording medium 301 and the structure connected to it are used.

As described above, in the digital moving image and digital audio reproducing apparatus of this embodiment, the recording medium in which the digital moving image data encoded at the variable bit rate and the digital audio data encoded at the fixed bit rate are recorded. A mounting means 302 for mounting 301, a reading means 303 for constantly reading data from the recording medium 301 mounted on the mounting means 302 at the maximum speed possible, and a reading buffer for storing and outputting the data read by the reading means 303. Memory 31
2, read control means 311 for controlling the reading of data from the read means 303 according to the amount of data stored in the read buffer memory 312, and the read means 303.
Switching means 305 for separating the data read out from the digital moving image data and the digital audio data and outputting the data.
Digital moving image data buffer memory 306 for storing and outputting the digital moving image data output of the switching means 305.
And the buffer memory 306 for digital moving image data
Digital video data decoding means comprising a video video decoder 308 for decoding the digital video data output by the digital audio data output buffer and digital audio data buffer memory 307 for storing and outputting the digital audio data output of the switching means 305.
And an audio decoder 3 for decoding the digital audio data output from the digital audio data buffer memory 307.
09, digital audio data decoding means, the amount of data stored in the digital moving image data buffer memory 306, and the amount of data stored in the digital audio data buffer memory 307. And the read buffer memory 3
12 has a decoding buffer memory control unit 310 as a data transfer unit for controlling the transfer of data from the switching unit 305 to the switching unit 305, and the capacity of the digital moving image data and the buffer memory 306 and the buffer memory 307 for the digital audio data. The value of the ratio to the limit value for requesting the stop of reading is equal to or greater than the ratio of the maximum bit rate value of digital moving image data and the fixed bit rate value of digital audio data. It can be an example.

[Third Embodiment] As described in the first and second embodiments, the digital moving image data buffer memory 106 and the digital moving image data buffer memory 306 satisfy the above-mentioned conditions as capacities. If so, it is unlikely that a shortage state or a full state will occur during reading. Therefore, the digital voice data buffer memories 107, 3
It is also possible to observe only the data amount state B of 07 and control the data transfer. This is an embodiment corresponding to claim 4.

That is, in the case of this kind of embodiment, the setting of the insufficient state of the digital voice data buffer memories 107 and 307 must be determined on the premise of the maximum bit rate of the moving image data. This is because when the bit rate of the moving image data is high, the frequency of appearance of the digital audio data in the stream decreases, and because the read speed of the recording medium 301 is constant, the higher the bit rate of the digital moving image data, the higher the digital rate. This is because the transfer rate of audio data will be slowed down.

[Fourth Embodiment] As described in the first and second embodiments, the digital moving image data buffer memories 106 and 306 are in an insufficient state at the time of reading if the above-mentioned conditions are satisfied as the capacity. Although the full state is unlikely to occur, the shortage state of the buffer memories 106 and 306 for digital moving image data always occurs earlier than the shortage state of digital audio data, assuming the maximum bit rate. That is, the condition for determining the shortage state is that the digital voice data buffer memories 107, 30
7 may be constant because of a fixed bit rate, but in the digital moving image data buffer memories 106 and 306, the bit rate of the data in the buffer memories 106 and 306 may be always the maximum bit rate. This is because the shortage state must be detected by inserting it. For this reason, the shortage state is detected by the digital moving image data buffer memory (A (empty)), and the full state is detected by the digital audio data buffer memory (B (f).
It can be said that it is carried out with In order to prevent the buffer memory shortage and excess, more safe control becomes possible. This corresponds to the embodiment as claimed in claim 5.

[Fifth Embodiment] In the fourth embodiment, a shortage state of the digital moving image data buffer memory 306 and a full state of the digital audio data buffer memory 307 may occur at the same time. This is a case where the digital moving image is in a state of almost a still image and almost no code is generated. For example, even if the digital audio data can store one second of data, the image data may have a smaller data amount than the digital audio data in the one second. In this case, as described above, the digital moving image buffer memory 306 always indicates the shortage state in consideration of the maximum bit rate, so this is usually the shortage state. But,
When the reading is executed in this state, the digital voice data buffer memory 307 is immediately filled. In this case, the digital audio data has a constant bit rate,
It goes without saying that the digital moving image data does not disappear from the buffer memory 307 while the data is completely processed. On the contrary, it is necessary to prevent the excess of digital audio data. For this purpose, the full state of the digital audio data buffer memory 307 is prioritized, and in such a case, the data read instruction (first embodiment) or transfer (second embodiment) is not performed. This can be the embodiment of claim 6.

By the way, in the compression method of the digital moving image and the digital audio which can be used in the first to fifth embodiments, the digital moving image can be variable bit rate encoded and the digital audio can be fixed bit. Any combination that allows rate coding can be used. In a valid example, for example, MPEG (ISO / IEC
There are cases where compression is performed using 11172 (MPEG1), ISO / IEC 13818 (MPEG2)). In MPEG, it is allowed that the digital moving image data has a variable bit rate with a minimum period from the compression data within an image unit called I Picture to the next I Picture. In addition, digital audio data is usually to be encoded at a fixed bit rate, and as in this embodiment,
The condition that the digital moving image data is a variable bit rate and the digital audio data is a fixed bit rate is met.

In addition, an encoding method (H.26) in which other intra-image unit compression and inter-image unit compression are mixed and encoded.
1) can be used as compressed data for digital moving images. Although not originally a moving image standard, there is also a method of decoding all still images by using a still image compression standard called JPEG (ISO / IEC 10918). In this case, the generated digital moving image data has a variable bit rate.

Furthermore, in each of the above-described embodiments, the case where digital audio data and digital moving image data are recorded for each data recording unit such as a sector such as a CD-ROM has been described, but the present invention is embodied. This is not the only case, but for example, in the case where both digital audio data and digital moving image data are recorded in one sector, or when these are irregularly recorded alternately on a tape. Can also be applied. In particular, the condition required for the recording medium for carrying out the present invention is the appearance frequency according to the bit rate at any time within a predetermined time (bit rate of digital moving image data at that time: fixed bit rate of digital audio compressed data). The data is recorded in.

By the way, in each of the above embodiments, the switching means 105 and 305 obtain the switching signal between the digital moving image data and the digital audio data by the control means 110 or the decoding control means 310. However, when implementing the present invention, switching may be performed by the switching means 105, 305 depending on the type of data written in the header of the digital moving image data and the digital audio data.

The digital moving image and digital audio reproducing apparatus of each of the above-described embodiments temporarily stores the digital moving image data, and the digital moving image data buffer memories 106 and 3 are provided.
The value of the ratio of the memory capacity of 06 and the limit value for requesting the reading stop of the digital audio data buffer memories 107 and 307 is the ratio of the maximum bit rate value of digital moving image data to the fixed bit rate value of digital audio data. A value greater than or equal to a value is read out and transfer-controlled in accordance with the amount of data stored in the digital moving image data buffer memories 106 and 306 and the digital audio data buffer memories 107 and 307. It can be an example. Therefore, by defining the relationship between the memory capacities of the digital moving image data buffer memories 106 and 306 and the digital audio data buffer memories 107 and 307, the shortage state of the variable moving bit rate digital moving image data buffer memories 106 and 306 is determined. Since the full state does not occur, simple read control and synchronized playback of the digital moving image and digital audio can be realized.

[0077]

As described above, in the digital moving image and digital audio reproducing apparatus according to the first aspect, the memory capacity of the digital moving image data buffer memory and the restriction for requesting the reading and stopping of the digital audio data buffer memory. Since the value of the ratio with the value is equal to or greater than the value of the ratio of the maximum bit rate value of digital moving image data and the fixed bit rate value of digital audio data, by defining the relationship of the buffer memory capacity, Since the buffer memory for the digital moving image data of the variable bit rate does not become insufficient or full, simple read control and synchronous reproduction of the digital moving image and digital audio can be realized.

In the digital moving image and digital audio reproducing apparatus of the second aspect, the control means can be divided into the decoding control means and the read control means, and the degree of freedom in designing the configuration is increased.

According to a third aspect of the present invention, there is provided a digital moving image and digital audio reproducing apparatus, wherein the relationship between the memory capacity of the digital moving image data buffer memory and the capacity of the digital audio data buffer memory is defined so that the variable bit rate digital memory can be used. Since the shortage and full states of the moving image data buffer memory do not occur, simple data transfer control and synchronous playback of digital moving images and digital audio can be realized.

According to the fourth aspect of the present invention, there is provided a digital moving image and digital audio reproducing apparatus in which the relationship between the memory capacity of the buffer memory for digital moving image data and the capacity of the buffer memory for digital audio data is set to be variable. Since the buffer memory for the bit rate digital moving image data does not become insufficient or full, simple control of reading and transfer and synchronous reproduction of the digital moving image and digital audio can be realized.

According to a seventh aspect of the present invention, there is provided a digital moving image and digital audio reproducing apparatus, which temporarily stores digital moving image data and requests the memory capacity of the digital moving image data buffer memory and the reading stop of the digital audio data buffer memory. Make sure that the ratio value to the limit value is equal to or greater than the ratio value of the maximum bit rate value of digital moving image data and the fixed bit rate value of digital audio data, and the buffer memory for digital moving image data and digital audio data Since the read and transfer are controlled according to the amount of data stored in the buffer memory, the buffer memory for variable-bit-rate digital moving image data may become insufficient or full by defining the relationship between the buffer memory capacities. There is no such thing, simple readout control and synchronized playback of digital video and digital audio. It can be realized.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a digital moving image and digital audio reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is data in which digital moving image data in a digital moving image and digital audio reproducing apparatus according to the first embodiment of the present invention is encoded at a variable bit rate and digital audio data is encoded at a fixed bit rate and recorded. It is explanatory drawing which showed the row.

FIG. 3 is a block diagram showing a digital moving image and digital audio reproducing apparatus according to a second embodiment of the present invention.

FIG. 4 is a block diagram showing an example of a conventional digital moving image digital audio decoding apparatus.

[Brief description of reference numerals]

102 recording medium attaching means 103, 303 reading means 105, 305 switching means 106, 306 digital moving image data buffer memory 107, 307 digital audio data buffer memory 108, 308 moving image decoder 109, 309 audio decoder 310 decoding control means 302 Recording medium mounting means 311 Read control means 312 Read buffer memory

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Claims (7)

[Claims] 1. A mounting means for mounting a recording medium on which digital moving image data encoded with variable bit rate and digital audio data encoded with fixed bit rate are mounted, and a predetermined one from the recording medium mounted on the mounting means. Reading means for reading data at a fixed bit rate, switching means for separating the data read from the reading means into digital moving image data and digital audio data, and outputting the digital moving image data by the switching means. A buffer memory for digital moving image data that stores once and outputs it, a decoding unit for digital moving image data that decodes the digital moving image data output from the buffer memory for digital moving image data, and a digital audio of the switching unit Store the data output once,
Digital audio data buffer memory for outputting it, digital audio data decoding means for decoding digital audio data output by the digital audio data buffer memory, and amount of data stored in the digital moving image data buffer memory And a control means for requesting data transfer in accordance with the amount of data stored in the digital audio data buffer memory and for controlling the data read to the reading means in accordance with the data transfer request. The ratio value of the memory capacity of the moving image data buffer memory and the limit value for requesting the reading stop of the digital audio data buffer memory is the maximum bit rate value of the digital moving image data and the fixed bit rate value of the digital audio data. A digital moving image characterized by being set to be equal to or greater than the ratio value of Digital audio playback device. 2. The decoding means for requesting data transfer according to the amount of data stored in the buffer memory for digital moving image data and the amount of data stored in the buffer memory for digital audio data. 2. The digital moving image reproducing apparatus according to claim 1, further comprising: a read control unit for performing read control of data to the read unit according to a data transfer request from the decoding control unit. 3. A mounting means for mounting a recording medium on which digital moving image data encoded with variable bit rate and digital audio data encoded with fixed bit rate are mounted, and a predetermined one from the recording medium mounted on the mounting means. Reading means for reading data at a fixed bit rate, a reading buffer memory for temporarily storing the data read from the reading means, and outputting it, and the reading means according to the amount of data stored in the reading buffer memory. Reading control means for controlling the reading of the data, the switching means for separating the data read from the reading means into digital moving image data and digital audio data, and outputting the digital moving image data output from the switching means. A buffer memory for digital moving image data that stores and outputs the digital moving image data, A digital moving image data decoding means for decoding the digital moving image data output by the buffer memory for memory, and temporarily storing the digital audio data output of the switching means,
A digital audio data buffer memory for outputting it, a digital audio data decoding means for decoding the digital audio data output by the digital audio data buffer memory, and a digital moving image data buffer memory Decoding control for requesting data transfer according to the data amount and the data amount stored inside the digital audio data buffer memory, and controlling the data transfer from the read buffer memory to the switching means in accordance with the data transfer request. The ratio of the memory capacity of the digital moving image data buffer memory to the limit value for requesting stop of reading of the digital audio data buffer memory is the maximum bit rate value of the digital moving image data. Must be greater than or equal to the ratio of the fixed bit rate value of audio data Reproducing apparatus for digital motion picture and digital audio, wherein. 4. The digital moving image reproducing apparatus according to claim 2, wherein the decoding control means makes a data transfer request only in accordance with the data amount of the digital audio data buffer memory. 5. The decoding control means issues a data transfer request of the reading means when the storage data amount of the digital moving image data buffer memory becomes smaller than a predetermined first reference value, 5. The data transfer stop control of the reading means is performed when the amount of data stored in the digital voice data buffer memory exceeds a predetermined second reference value. Or 1
A playback device for digital moving images and digital audio described in 1. 6. The decoding control means has a storage data amount of the digital moving image data buffer memory smaller than a predetermined first reference value and a storage data amount of the digital audio data buffer memory. The digital moving image according to any one of claims 2 to 4, characterized in that the transfer stop control of the data of the reading means is performed when the number exceeds a predetermined second reference value. Digital audio playback device. 7. A digital moving image and digital audio reproducing apparatus for reproducing digital moving image data and digital audio data, and a memory capacity of a buffer memory for digital moving image data for temporarily storing and outputting the digital moving image data, The value of the ratio of the maximum value of the digital moving image data and the fixed bit rate value of the digital audio data is the ratio of the limit value to the reading stop of the buffer memory for digital audio data that temporarily stores and outputs the digital audio data. A device for reproducing a digital moving image and a digital sound, characterized by having a ratio value or more.