JPH08205093A - Computer system - Google Patents

Abstract

PURPOSE: To display moving image data with sub-video image and audio signal through simple configuration. CONSTITUTION: An SD-ROM drive 21 stores moving image data with sub-video image and an audio signal. Video data and audio data including the MPEG stream from the SD-ROM drive 21 are decoded by an MPEG2 decoder 18 provided in the system and the sub-picture is decoded by software processing by a CPU 11. The decoded sub-picture is drawn in a VRAM 20 similarly to the case with a conventional VGA graphics. The image of the sub-picture drawn in the VRAM 20 is synthesized with the video data from the MPEG 2 decoder 18 by a multi-medium display controller 19 and the result is displayed on a screen.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a computer system, and more particularly to a disk drive device for driving a recording medium having a high recording density in which moving image data and audio data including a main image and a sub image are digitally compressed and recorded. The present invention relates to a multimedia-compatible computer system for displaying moving images and reproducing audio by using.

[0002]

2. Description of the Related Art With the recent development of computer technology,
Various so-called multimedia-compatible personal computers have been developed. This type of personal computer can reproduce moving image and audio data in addition to text data and graphics data.

Usually, moving image data is compressed and encoded by MPEG1 and stored in a CD-ROM or the like, and a dedicated expansion board is used for decoding and displaying / reproducing the moving image data. As an expansion board for decoding and displaying / reproducing moving image data, for example, “REAL magic” manufactured by Sigma Design Co. of the United States is well known. This "REAL magic" is MPEG1
It has a video decoding function in conformity with the standard, and the decoded moving image data is displayed after being combined with the VGA graphics captured from the video card via the feature connector.

However, the MPEG1 standard is 1.5 Mb.
This is a standard on the assumption that a CD-ROM having a data transfer rate of about ps is used, and handling moving image data including a large amount of image information such as a movie causes a problem such as deterioration of image quality.

Therefore, recently, a new generation storage medium having a data transfer rate which is several times to several tens times that of a CD-ROM has been developed. As such a new generation storage medium, a system capable of digitally recording an information amount of about 10 GB on one disk and realizing a data transfer rate of about 10 Mbps at maximum has been proposed as a media player.

This media player records moving image data and audio data, which are digitally compressed and coded according to the MPEG2 standard, on a disk medium such as an optical disk, decodes the moving image data with audio, and outputs the decoded data to a television receiver. It is what is output.

This media player is provided with a disk drive device, a data buffer, a video decoder, an audio decoder, an NTSC encoder and the like. In this media player, the optical disc is driven by the disc drive device to read moving image data and audio data from the optical disc.
It is stored in the data buffer.

The moving image data and audio data stored in the data buffer are decoded by a video decoder and an audio decoder, respectively. The moving picture data decoded by the video decoder is converted into an NTSC signal by the NTSC encoder and sent to the video input of the television receiver. On the other hand, the audio data decoded by the audio decoder is D / A converted and then sent to the audio input of the television receiver.

Since the data transfer rate of this media player is as extremely high as about 10 Mbps, as described above, when this media player is used, in addition to the main video, sub-video such as subtitles and a movie including a plurality of audio channels are provided. Information can be recorded on a single disc having a size similar to that of a CD, and the main video, sub-video and audio can be synchronized and reproduced on a television receiver.

However, when this media player is mounted on a personal computer, it is necessary to provide a video decoder and the like inside the system of the personal computer in addition to the media player.

This is because the video decoder inside the media player is dedicated to that player, and media other than the media player, such as a hard disk or a CD, is used.
This is because the MPEG title recorded in the ROM or the like cannot be decoded using the video decoder inside the player.

Therefore, it is desirable to provide the functions for decoding and reproducing the main video, the sub video and the audio, respectively, inside the personal computer. However, in order to decode and reproduce moving picture data with sub-picture and sound, a decoder for sub-picture and an audio decoder are required in addition to the video decoder for decoding the moving picture data, which increases the cost of the personal computer. The drawback is that it is triggered.

[0013]

As described above, recently, a media player having a large capacity and a high transfer rate has been proposed. However, in order to directly provide a decoder function inside the media player to a personal computer,
In addition to a video decoder for decoding moving image data, you must prepare a decoder for sub-pictures,
There is a drawback that the cost of the personal computer is increased.

The present invention has been made in view of the above circumstances, and is capable of decoding and reproducing large-capacity multimedia information including main video, sub-video and audio data with a simple hardware configuration. The purpose of the present invention is to provide a reliable computer system.

[0015]

Means and Actions for Solving the Problems
In a computer system capable of connecting to a disk drive device capable of driving a recording medium on which moving picture data with sub-picture is digitally compressed and encoded, a moving picture data is coupled to a CPU and a bus of the computer system. A video decoder for decoding, a display controller that is coupled to the bus, synthesizes the moving image data decoded by the video decoder on the graphics drawn in the video memory, and displays the synthesized data on the screen of the display monitor, and the CPU, Means for decoding sub-picture data included in a digital data string read from the disk drive device, and the decoded sub-picture in the CPU so that moving picture data with the sub-picture is displayed on the screen by the display controller. Characterized by comprising a means for rendering said video memory.

The disk drive device used in this computer system is composed not of the entire media player described above but only of the part corresponding to the disk drive unit of the media player, and the recording medium of the disk drive unit is mainly composed of A large amount of moving image data and audio data including video and sub-video are encoded and stored by high-efficiency digital compression encoding such as MPEG2 standard.

The moving picture data read from the disk drive unit is decoded by the video decoder provided inside the system, while the sub-picture is decoded by software processing by the CPU. In this case, the decoded sub-picture is drawn in the video memory in the same manner as normal VGA graphics. The sub-image drawn in the video memory is combined with the moving image data by the display controller and displayed on the screen.

Since the sub-picture is decoded and drawn in the video memory by the software processing by the CPU as described above, it is not necessary to provide a logic for decoding the sub-picture, and the hardware structure can be simplified.

Further, since the decoding of the moving picture data is realized by the video decoder composed of the hardware logic, for example, when reproducing the normal moving picture data which does not include the sub-picture recorded on the CD-ROM or the like. ,
Only the video decoder can handle it.

Further, when the moving image reproduction is realized on the laptop type or notebook type personal computer, it is preferable that the above video decoder is realized by a card such as a PC card.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the system configuration of a personal computer according to an embodiment of the present invention. This system corresponds to a desktop personal computer, and as shown in the figure, the system bus 10, C
PU11, system memory (MEM) 12, HDD1
3, FDD 14, keyboard (KB) 15, SCSI interface 16, audio controller 17, MP
EG2 decoder 18, multimedia display controller 19, and video memory (VRAM) 20
The SD-ROM drive 21 that stores the moving image data encoded by MPEG2 is
It is connected to the SI interface 16.

SD-ROM (Super Densit)
y ROM) drive 21 corresponds to the disc drive unit of the media player described above,
Both sides of the disk have a storage capacity of about 10 GB and a maximum data transfer rate of about 10 Mbps. This SD
The ROM drive 21, as shown in FIG.
Optical disk 211, motor 212, pickup 2
13, pickup drive 214, servo controller 215, ECC for error detection and correction
And a drive controller 216 including a circuit. The motor 212, the pickup 213, the pickup drive 214, the servo controller 215, and the drive controller 216 function as a drive device for driving the optical disc 211 and reading the data recorded on the optical disc 211.

The optical disc 211 has, for example, one side with one side.
A movie of about 35 minutes can be recorded. This movie information can include main video (video), sub-video up to 16 channels (sub-picture), and audio up to 8 channels (audio).

In this case, these videos, sub-pictures,
And audio are digitally encoded and recorded according to the MPEG2 standard. In the MPEG2 standard, M
The data coded by PEG2 can include other coded data, and these coded data are handled as one MPEG bit stream (digital data string).

Therefore, in this embodiment, MPEG2 is used for video coding, and run-length coding and D coding are used for sub-picture and audio coding, respectively.
OLBY AC3 shall be used. Even in this case, the encoded video, sub-picture, and audio are treated as one MPEG bit stream.

The MPEG2 standard coding process is variable speed coding, and the data transfer rate can be varied.
Therefore, with respect to video data, the amount of information recorded / reproduced per unit time can be made different. Therefore,
The higher the moving rate of the scene, the higher the transfer rate of the MPEG bit stream forming the corresponding frame group, and the higher quality moving image reproduction becomes possible.

In order to utilize the characteristics of MPEG2 as described above, in this embodiment, the movie information is recorded on the disk 211 by using the data format as shown in FIG.

As shown in FIG. 3, one piece of movie information is composed of a file management information section and a data section, and the data section has a large number of data blocks (block # 0).
~ # N) are included. D at the beginning of each data block
There is an SI (Disk Serh Information) pack, and one data block is from the DSI pack to the next DSI pack. The storage location of each DSI pack is managed by the disc search map information in the file management information section.

One data block is
For example, it constitutes 15 frames of information required to reproduce a moving image of 0.5 seconds, and GOP (Group of
picture). Each data block has a video pack (VIDEO pack), a sub-picture pack (SP pack), and an audio pack (A pack).
(UDIO pack) is recorded in a multiplexed form. These video packs (VIDEO packs), sub-picture packs (SP packs), and audio packs (AU packs)
A DIO pack) is a data unit of encoded video, sub-picture, and audio. The data size of these packs is fixed, but the number of packs that can be included in one data block is variable. Therefore, a larger number of video packs are included in a data block corresponding to a scene with a lot of motion.

Each of the video pack, sub-picture pack, and audio pack is composed of a header part and a packet part (video packet, sub-picture packet, audio packet). The packet part is the encoded data itself. The header portion is composed of a pack header, a system header, and a packet header. A stream ID indicating whether the corresponding packet is a video packet, subpicture packet, or audio packet is registered in the packet header. .

Next, each unit of the system shown in FIG. 1 will be described. The CPU 11 controls the operation of the entire system, and executes the operating system and the application programs to be executed, which are stored in the system memory (MEM) 12. SD-ROM
The reproduction of the movie recorded in the drive 21 is performed by causing the CPU 11 to execute the MPEG driver 121. The MPEG driver 121 has a sub-picture decoding function.

The sub-picture decoding function of the MPEG driver 121 provides the following three functions. (1) Decomposition of MPEG Bit Stream The MPEG bit stream decomposition function separates an MPEG bit stream into a video pack, a sub-picture pack, and an audio pack, and transfers the video pack and the audio pack to the MPEG2 decoder 18.
This separation process is executed for each pack based on the stream ID in FIG. (2) Decoding of sub-picture The sub-picture decoding function decodes the separated sub-picture pack on the system memory 12. (3) Sub-picture transfer to VGA The sub-picture transfer function to VGA uses the decoded sub-picture as multimedia display controller 1.
9 is a function to transfer to 9 and draw a sub-picture in the video memory (VRAM) 20.

The SCSI interface 16 is a peripheral interface for connecting peripheral devices such as an HDD and a CD-ROM to the system bus 10. In this embodiment, data between the SD-ROM drive 21 and the system memory 12 is used. Transfer. SCSI interface 16
The SCSI controller (SCSI
CONT) 161 and data buffer (BUFF)
162 is provided. SCSI controller 161
SD-ROM drive 21 under the control of CPU 11.
Control data transfer to and from. Data buffer (BU
FF) 162 is used to make the data transfer rate with the host system variable, and SD-R
An MPEG bit stream including video, sub-picture, and audio read from the OM drive 21 is transferred to the CPU 11 via a data buffer (BUFF) 162.

In this case, the data transfer rate from the SD-ROM drive 21 to the data buffer 16 is SD-RO.
Maximum data transfer rate of M drive 21, eg 9.5
It runs at Mbps.

On the other hand, from the data buffer 16 to the CPU 11
The data transfer rate to the is variable, and the average transfer rate at that time increases as the data block having a large amount of information is transferred. This is because a data block having a large amount of information increases the number of times of data transfer executed per fixed time.

The audio controller 17 includes the CPU 1
The sound data input / output control is performed under the control of No. 1 and the PCM sound sources 171 and F are used for sound output.
An M sound source 172, a multiplexer 173, and a D / A converter 174 are provided. Outputs from the PCM sound source 171 and the FM sound source 172 and digital audio data transferred from the MPEG2 decoder 18 are input to the multiplexer 173, and one of them is selected.

The digital audio data is SD-RO.
The audio data read from the M drive 21 is decoded. The audio bus 18a is used to transfer the digital audio data from the MPEG2 decoder 18 to the audio controller 17, and the system bus 10 is not used. Therefore, high-speed transfer of digital audio data becomes possible.

The MPEG2 decoder 18 includes the CPU 11
Under the control of (1), it decodes video and audio respectively and outputs them in synchronization with each other. No sub-picture decoding function is provided here.

The decoded audio data is transferred to the audio controller 18a via the audio bus 18a as digital audio data as described above. The decoded video data is digital Y
It is sent to the multimedia display controller 19 as UV data. In this case, the MPEG2 decoder 18 to the multimedia display controller 19
To transfer digital YUV data to the
b is used and the system bus 10 is not used. Therefore, the transfer of the digital YUV data can be performed at a high speed like the digital audio data.

The video bus 18b is a VAFC (VESA Advanced Feature) of the VESA standard.
reConnector), or VM-Channel
el (VESA Media Channel) can be used.

The multimedia display controller 19 controls the CRT display used as a display monitor of this system under the control of the CPU 11, and supports the display of moving images in addition to the VGA specification text and graphics display. .

In this multimedia display controller 19, as shown in the figure, a graphics display control circuit (Graphics) 191, a video display control circuit 192,
The multiplexer 193 and the D / A converter 194
Etc. are provided.

The graphics display control circuit 191 uses V
GA compatible graphics controller, CPU
VGA graphics data and sub-pictures drawn in the video memory (VRAM) 20 by the R 11
Convert to GB video data and output. The video display control circuit 192 stores the video buffer for storing the digital YUV data, and the YUB data stored in the buffer for the R buffer.
It has a YUB-RGB conversion circuit for converting to GB video data.

The multiplexer 193 selects one of the output data of the graphics display control circuit 191 and the video display control circuit 192, or outputs the video output from the video display control circuit 192 on the VGA graphics from the graphics display control circuit 191. Are combined and sent to the D / A converter 194. The D / A converter 194 converts the video data from the multiplexer 194 into an analog RGB signal and outputs it to a CRT display.

FIG. 4 shows a concrete structure of the MPEG2 decoder 18. The MPEG2 decoder 18 corresponds to video and audio in order to synchronously decode and reproduce the video and audio bit streams separated by the CPU 11 and 2
There are two decoders, namely an MPEG2 video decoder 181 and an audio decoder 183.

These MPEG2 video decoders 18
1 and audio decoder 183 are each coupled to system bus 10. The MPEG2 video decoder 181 is an R that is used for its decoding processing and the like.
AM184 is provided.

The MPEG2 video decoder 181 is a C
The video data transferred from the PU 11 is decoded and output as digital YUV data. The audio decoder 183 decodes the audio data transferred from the CPU 11. The type of decoding processing executed here corresponds to the encoding processing applied to the audio data, that is, DOLBY AC3.
The decoded audio data is output as digital audio data.

Next, referring to the flowchart of FIG.
A procedure of moving image reproduction processing performed by the CPU 11 executing the MPEG driver 121 will be described. CPU
First, the file reading unit 11 reads the file management information from the SD-ROM drive 21 and recognizes the data recording format on the SD-ROM drive 21 (step S101). Next, the CPU 11 starts reading the data section, that is, the MPEG bit stream, from the SD-ROM drive 21 (step S102). Then, each time one pack is received, the stream ID recorded in the header part is recognized, and the MPEG bit stream is classified into a video pack, an audio pack, and a sub-picture pack based on the recognition result (steps S103 and S104). ).

If the received pack is a video pack, the CPU 11 sends it to the MPEG2 video decoder 18
1 (step S105), and if it is an audio pack, it is transferred to the audio decoder 183 (step S106).

When the received pack is a sub-picture pack, the CPU 11 recognizes the position on the video where the sub-picture should be combined, based on the header information added to the sub-picture pack (step S1).
07). Next, the CPU 11 calculates the relative position of the sub picture with respect to the VGA graphics screen based on the recognized position on the video and the display position of the video on the VGA graphics screen (step S10).
8). As a result, the address value when writing the sub-picture in the VRAM 20 is determined.

Next, the CPU 11 decodes the sub-picture and restores the sub-picture to the image before encoding on the memory 12 (step S109). The decoding process executed here corresponds to the run-length encoding applied to the sub-picture.

After that, the CPU 11 transfers the sub-picture image on the memory 12 to the multimedia display controller 19 and writes it in the VRAM 20 (step S110).

The processes of steps S102 to S110 are repeatedly executed for the MPEG bit stream from the SD-ROM drive 21 until the reproduction of the moving image is completed (step S111).

Next, with reference to FIG. 6, a data flow when a movie is reproduced in the system of FIG. 1 will be described. CPU1
When the transfer command is issued from 1, the MPEG stream is read from the SD-ROM drive 21 and transferred to the SCSI interface data buffer 162 at a transfer rate of 9.5 Mbps. Then the MP
The EG stream is sent to the CPU 11, where the packs are distributed as described in FIG.

The MPEG video is sent to the MPEG2 video decoder 181, where it is restored to the original main video before encoding. Sub-pictures such as subtitles are restored to a character pattern on the memory 12 by the CPU 11 and sent to the multimedia display controller 19. As a result, as shown in the figure, the character pattern is drawn at a predetermined position on the color key area of VGA graphics (shown by hatching). The audio is decoded by the audio decoder 183 and reproduced.

The restored main video is sent to the multimedia display controller 19 as digital YUV data, and is composited there on the VGA graphics color key area (shown by hatching) including the sub-picture.

In this way, the main image including the subtitles is displayed on the VGA graphics, and the sound is reproduced in synchronization with the screen. As described above, in this embodiment, MPE read from the SD-ROM drive 21.
The video data and audio data included in the G bit stream are decoded by the MPEG2 video decoder 181 and the audio decoder 183 provided inside the system, but the sub-picture is decoded by the software processing by the CPU 11. In this case, the decoded sub-picture is rendered in the VRAM 20 in the same manner as normal VGA graphics. The image of the sub-picture drawn in the VRAM 20 is combined with the video from the MPEG2 video decoder 181 by the multimedia display controller 19 and displayed on the screen.

As described above, the sub-picture decoding and the VRAM 2 are performed by the software processing by the CPU 11.
Since the drawing to 0 is performed, it is not necessary to provide a sub picture decoding logic inside the system, and the hardware configuration can be simplified.

Next, the system configuration according to the second embodiment of the present invention will be described with reference to FIG. The system of FIG. 7 is obtained by applying the system configuration of the desktop personal computer of FIG. 1 to a notebook type portable computer. The system of FIG. 7 is similar to that of FIG.
Compared with the system of, only the following points are different.

That is, here, the MPEG2 video decoder 18 is realized on the PC card 22 instead of on the system board as shown in FIG. 1, and the PC card controller 23 includes the audio controller 17 and the multimedia display controller 19 respectively. It has an interface with.

The PC card 22 complies with the PCMCIA specification, is mounted in a card slot of the notebook type portable computer main body, and is connected to a PC card interface (connector) in the slot.

The PC card 22 has a CIS (Card Infor
mation structure) 221 and an MPEG2 decoder 222. MPEG2 decoder 22
2 is an MPEG2 video decoder 18 of FIG. 1 except for interfaces with the audio controller 17 and the multimedia display controller 19, respectively.
It has exactly the same function as, and its configuration is as described in FIG.

The PC card controller 23 is the CPU 1
Under control of 1, various Ps installed in the PC card slot
It is for controlling the C card and has two operation modes, mode 1 and mode 2. Mode 1 is for controlling a normal PC card such as a modem card, transfers data between the system bus 10 and the PC card, and does not use the audio bus 18a and the video bus 18b.

Mode 2 is a mode used when the PC card 22 is inserted in the PC card slot. In this mode 2, the PC card controller 23 transfers the video and audio streams transferred from the CPU 11 to the PC card 22, and
Digital audio data and digital YUV returned from the card 22 via, for example, different signal lines
The data is transferred to the audio controller 17 and the multimedia display controller 19 via the audio bus 18a and the video bus 18b, respectively.

FIG. 8 shows the configuration of the PC card controller 21. The PC card controller 21 includes a data transfer control logic 231 and a mode register 2
32 is provided, and the operation mode of the PC card controller 23 is switched by setting a mode designation flag in the mode register 232.

The mode specifying flag is set by the CPU 11 when the system power is turned on, for example. That is, the CPU 11 reads the attribute information from the PC card installed in the PC card slot and detects the type of the installed PC card based on the attribute information. If the installed PC card is PC card 22, CP
U11 sets the mode designation flag indicating the mode 2 in the mode register 232.

[0067]

As described above, according to the present invention, since the sub-picture is decoded and drawn in the video memory by the software processing by the CPU, it is not necessary to provide the logic for sub-picture decoding, and the hardware is not required. The ware configuration can be simplified.

[Brief description of drawings]

FIG. 1 is a multimedia P according to a first embodiment of the present invention.
The block diagram which shows the system configuration of C.

FIG. 2 is an SD-R used in the system of the first embodiment.
The block diagram which shows the structure of OM drive.

FIG. 3 is a diagram showing a recording format of moving image data used in the system of the first embodiment.

FIG. 4 is an MPEG provided in the system of the first embodiment.
2 A block diagram showing an example of a specific configuration of a decoder.

FIG. 5 is a flowchart illustrating a sub-picture decoding operation executed by a CPU in the system of the first embodiment.

FIG. 6 is a diagram for explaining the flow of data when a moving image is reproduced in the system of the first embodiment.

FIG. 7 is a multimedia P according to a second embodiment of the present invention.
The block diagram which shows the system configuration of C.

FIG. 8 is a block diagram showing a configuration of a PC card controller provided in the system of the second embodiment.

[Explanation of symbols]

10 ... System bus, 11 ... CPU, 12 ... System memory, 16 ... SCSI interface, 17 ... Audio controller, 18 ... MPEG2 decoder, 19 ...
Multimedia display controller, 20 ... video memory, 21 ... SD-ROM drive, 22 ... PC card, 23 ... PC card controller, 121 ... MPE
G driver, 161 ... SCSI controller, 162 ...
Data buffer, 181 ... MPEG2 video decoder, 182 ... Sub-picture decoder, 183 ... Audio decoder.

Claims (16)

[Claims] 1. A computer system capable of connecting to a disk drive device capable of driving a recording medium in which moving image data with sub-pictures is digitally compressed and encoded is connected to a CPU and a bus of the computer system. A video decoder that decodes the moving image data, and a display controller that is coupled to the bus and that combines the moving image data decoded by the video decoder with the graphics drawn in the video memory to display on the screen of the display monitor. Means for causing the CPU to decode the sub-picture data included in the digital data string read from the disk drive device; and the CPU for displaying the moving picture data with the sub-picture on the screen by the display controller. Deco Computer system, wherein a sub-picture which has been de and means for rendering said video memory. 2. The CPU further comprises means for separating a digital data string read from the disk drive device into sub-picture and moving picture data, and transferring the separated moving picture data to the video decoder. The computer system according to claim 1. 3. An audio decoder for decoding digitally encoded audio data, which is multiplexed with the moving image data with sub-picture and recorded on the recording medium, and which is connected to the bus and decodes the audio data. And causing the CPU to separate the digital data string read from the disk drive device into sub-picture, moving image data, and audio data, and transfer the separated moving image data and audio data to the video decoder and audio decoder, respectively. The computer system according to claim 1, further comprising means for performing the operation. 4. The moving image data is stored in a recording medium of the disk drive device after being subjected to variable speed encoding, and the video decoder decodes the variable speed encoded data. The computer system according to item 1. 5. An audio controller connected to the system bus for controlling audio reproduction, further comprising an audio controller for receiving and reproducing audio data decoded by the audio decoder. The computer system according to claim 3. 6. The video decoder further comprises a video bus connecting the video decoder and the display controller, and the video decoder transfers the decoded moving image data to the display controller via the video bus. The computer system according to claim 1. 7. The audio decoder further comprises an audio bus connecting the audio decoder and the audio controller, wherein the audio decoder transfers the decoded audio data to the audio controller via the audio bus. The computer system according to claim 5. 8. The audio controller comprises a sound source unit, means for selectively reproducing output from the sound source unit and audio data transferred from the audio decoder via the audio bus. The computer system according to claim 5, wherein: 9. A computer system capable of connecting to a disc drive device capable of driving a recording medium in which moving image data with sub-picture is digitally compressed and encoded, and a CPU and a card provided in the computer body. A slot, a card controller that is connected to the bus of the computer system and controls a card mounted in the card slot, and a card that is mountable in the card slot and includes a video decoder that decodes moving image data. A display controller which is coupled to the bus and combines the moving image data decoded by the video decoder of the card with the graphics drawn in the video memory and displays the synthesized image data on the screen of the display monitor; Equipment Means for decoding sub-picture data included in a digital data string read from the video memory, and the CPU for displaying the decoded sub-picture in the video memory so that moving picture data with the sub-picture is displayed on the screen by the display controller. A computer system comprising: means for drawing on the computer. 10. The CPU further comprises means for separating a digital data string read from the disk drive device into sub-picture and moving picture data, and transferring the separated moving picture data to a video decoder of the card. The computer system according to claim 9, characterized in that: 11. An audio decoder which is provided on the card and which decodes the audio data, wherein digital compression-encoded audio data is multiplexed with the moving image data with the sub-picture and recorded on the recording medium. And means for causing the CPU to separate the digital data string read from the disk drive device into sub-picture, moving image data, and audio data, and transferring the separated moving image data and audio data to the card. The computer system according to claim 9, wherein the computer system comprises: 12. The moving picture data is variable-speed coded and stored in a recording medium of the disk drive device, and a video decoder of the card decodes the variable-speed coded data. The computer system according to claim 9. 13. An audio controller connected to the system bus for controlling audio reproduction, comprising:
The computer system according to claim 11, further comprising an audio controller that receives and reproduces audio data decoded by the audio decoder of the card. 14. The video controller further comprises a video bus connecting between the card controller and the display controller, wherein the card controller transfers moving image data decoded by a video decoder of the card to the display controller via the video bus. The computer system according to claim 9, wherein the computer system transfers. 15. The audio controller further comprises an audio bus connecting the card controller and the audio controller, wherein the card controller sends audio data decoded by an audio decoder of the card to the audio controller via the audio bus. 14. The computer system according to claim 13, wherein the computer system transfers. 16. The audio controller comprises a sound source unit, means for selectively reproducing output from the sound source unit and audio data transferred from the audio decoder via the audio bus. 14. The computer system according to claim 13, wherein: