JPH05145892A - Method and circuit for reproducing image data - Google Patents

Abstract

PURPOSE:To prevent an image which is displayed from being disordered even if the reproduction speed of image data from a recording medium is faster than the reproduction speed of the image data. CONSTITUTION:A buffer memory which has larger capacity than one frame of the image data reproduced from the recording medium 4 is provided as a buffer memory wherein the image data from the recording medium 4 are written. It is checked whether or not there is a vacancy of one frame left in the buffer memory before the image data reproduced from the recording medium 4 are written in the buffer memory. When there is the vacancy, the image data reproduced from the recording medium 4 are written in the buffer memory. When not, on the other hand, the image data reproduced from the recording medium are discarded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of reproducing image data and a reproducing circuit thereof.

[0002]

2. Description of the Related Art There is a CD-ROM as a large-capacity storage medium, which is used as an external storage medium in game machines and personal computers using microcomputers.

FIG. 11 shows an example of a microcomputer which can use such a CD-ROM.

That is, FIG. 11 shows an example in which such a microcomputer is applied to a game machine,
1 is the main body of the game machine, 3 is a sub-processing unit, 4 is a CD-RO
M and 5 are program cartridges.

The game console body 1 is composed of a microcomputer, and 11 is its CP.
U and 13 are RAM for work area and buffer, 1
4 is a PPU (picture processing unit), 1
5 is a video RAM. The circuits 11 to 14 are connected to the system bus 19, and the PPU 14 is connected to the video RAM 15 and the CRT display 6.

Further, in the main body 1, 20 is a main processing unit for audio data, 21 is its APU (audio processing unit), 24 is a D / A converter, 25
Is an audio output terminal. The APU 21 is connected to the bus 19 and the D / A converter 24.

The sub-processing unit 3 is for enabling the use of the CD-ROM 4, and includes a CD player and a CD-ROM.
The image data and the program, which have a ROM decoder and the like and are read from the CD-ROM 4, are supplied to the bus 19 after necessary processing is performed in the processing unit 3.

Further, the program cartridge 5 is R
It has an OM 51 and a RAM 52, and programs and the like are written in the ROM 51. Also RAM
Reference numeral 52 is used to hold various data relating to the state at that time, for example, when the game is temporarily interrupted in the middle of the game, and is backed up by a battery 53.

When the cartridge 5 is inserted into the slot 2 of the game machine body 1, the ROM 51 and the RAM 52 are connected to the bus 19 through a connector (not shown).

If the game can be executed only by the program cartridge 5, the cartridge 5
Is set in the slot 2 and the power of the game machine main body 1 is turned on (or reset is performed. The same applies hereinafter).

Then, the CPU 11 executes the program of the ROM 51 to form image data, the PPU 14 writes the image data in the video RAM 15, and the image data in the video RAM 15 is read in synchronization with the horizontal and vertical scanning. Then, the read image data is supplied to the display 6 to display the image.

Further, the CPU 11 loads the audio data and the program for decoding the audio data into the APU 21,
The audio data is decoded into a digital audio signal, and the digital audio signal is D / A converted into an analog audio signal by the converter 24 and then output to the terminal 25.

On the other hand, when a game or the like is executed using the CD-ROM 4, the CD-ROM 4 is processed by the processing unit 3.
System cartridge 5 as a program cartridge 5 in the slot 2
Set to.

In this case, the system cartridge 5 is also RO
The ROM 51 has an M51 and a RAM 52, and the IPL is prepared in the ROM 51. The RAM 52 is used to hold various data until the next game is restarted, for example, when the game is temporarily suspended, as described above. Also, CD-ROM
An OS and a game program for using the CD-ROM 4 are prepared in 4.

When the power is turned on, the CPU 11
Executes the IPL of ROM 51, and the CD-RO
The OS and game programs are loaded into the RAM 13 from M4, and then the CPU 11 executes the loaded programs in the RAM 13. Therefore, the game can be played.

[0016]

By the way, for example, referring to FIG.
1 of the images displayed on the display 6 as shown in A.
If a frame (1 screen) is composed of 256 pixels (horizontal) x 192 pixels (vertical), and each of the red, green, and blue of that pixel is represented by 5 bits, the amount of image data for one frame Is Becomes

However, the capacity of one sector of the CD-ROM 4 is 2 Kbytes in the mode 1, and the reproduction speed is
It is 75 sectors / second. That is, the data transmission rate of the CD-ROM 4 is 150 Kbytes / second.

Therefore, if the above image data is
When recorded on the CD-ROM 4 as it is, during playback,
The number of frames (the number of frames) per second is 150K / 90K = just under 1.7 frames, and even if you try to display a moving image, the number of frames will be insufficient.

Therefore, when displaying a moving image, the CD-
By increasing the rotation speed of ROM4, CD-ROM
It is possible to increase the data transmission rate of 4 and increase the number of frames per second.

However, when displaying the image data of the CD-ROM 4, the image data is reproduced from the CD-ROM 4.

Once the reproduced image data is
Write to M13.

The image data in the RAM 13 is sent to the PPU 14 during the vertical blanking period. Will be performed.

However, when performing such processing, C
If the data transfer rate of the D-ROM 4 is increased, the reproduction speed of the term becomes faster than the transfer speed of the image data of the term, and the RAM 13 of the term may overflow.

In this case, the capacity of the RAM 13 is set to CD-RO.
If the capacity of the RAM 13 is increased to about M4, the RAM 13 will not overflow, but it is impossible to increase the capacity of the RAM 13 in terms of cost.

The present invention is intended to solve the above problems.

[0026]

Therefore, in the present invention, when the reference numerals of the respective parts correspond to the embodiments described later, the image data RECD reproduced from the recording medium 4 is written in the buffer memory BUFM, and the buffer memory BUFM is written. When converting the image data RECD written in the BUFM into the image data for display, the buffer memory BUFM is configured by a buffer memory having a capacity larger than one frame of the image data RECD reproduced from the recording medium 4, Before writing the image data RECD reproduced from No. 4 into the buffer memory BUFM, a circuit 11 for checking whether or not the buffer memory BUFM has an empty space for one frame, and as a result of this check, if there is an empty space, the recording medium 4 The image data RECD reproduced from is written in the buffer memory BUFM, but as a result of the above check, when there is no space Providing a circuit 11 to discard the image data RECD reproduced from the recording medium 4.

[0027]

[Operation] The reproduced image data RECD is stored in the buffer memory BUFM.
When writing to, if there is a space for one frame, the image data RECD is written to the buffer memory BUFM.
When there is no space for one frame, the image data RE
The CD is discarded.

[0028]

[Embodiment] << Recording process of image data >> First, CD-RO
FIG. 3 shows an example of image data recorded in M4.
~ It demonstrates by FIG.

3 and 4 are flowcharts showing the process of recording the image data. Also, FIG.
Is one frame (one screen) of the screen to be recorded.
This one frame is 256 pixels (horizontal) x 19
It consists of 2 pixels (vertical), and the red, green, and blue of each pixel are represented by 5 bits. Then, in actuality, a dummy 1 bit is added to the highest order for the convenience of processing, and 1 pixel is 1 bit (dummy) +5 bits × 3.
Color, that is, 16 bits. In addition, the original image data is recorded on a frame-by-frame basis.

That is, in step 81 (FIG. 3), the original image data of one frame shown in FIG.
As shown in, each pixel is 8 pixels (horizontal) x 8 pixels (vertical)
Is divided into blocks of the size (hereinafter, this block is referred to as a "character"). Therefore, as shown in FIG. 5B, one frame image is divided into 32 × 24 = 768 characters C0 to C767, and original image data is divided into character data CHR (0) to CHR (767). .. One character data CHR (i) (i = 0 to 767) is 8 pixels × 8 pixels × 16 bits = 128 bytes.

Then, in step 82, first-order vector quantization is performed on the character data CHR (i). In this vector quantization, each character Ci is quantized so that the number of colors of pixels in the character becomes four or less. As the vector quantization method, the method already proposed can be adopted, but in this example, red,
Considering a three-dimensional color space in which the green and blue color components are set on three coordinate axes that are orthogonal to each other, the distance between each pixel is found in this color space, and pixels with short distances are grouped together. The pixel data is rounded so that the number of colors of pixels in one character Ci falls within the "representative color" of 4 colors or less.

Further, at the time of this quantization, the maximum value of the quantization error (corresponding to the distance between the representative color and each pixel in the color space) of each character Ci in each frame is Emax.
In this case, vector quantization is performed until immediately before the quantization error exceeds the maximum value Emax in each character Ci, and the S / N of all the characters C0 to C767 are made uniform for each frame.

Further, if the quantization is performed in this way, the number of colors is reduced in a character with a flat color change,
This is because the quantization error does not increase so much even if the number of colors decreases.

Thus, the character data CHR (i) is quantized so that each character Ci has four or less colors.

Then, the quantized character data CHR (i) is classified into eight groups by grouping together characters having similar colors in step 83 (hereinafter, this group is referred to as "palette"). ")). That is, each character data CHR (i) is classified so as to belong to any of the eight palettes P0 to P7.
In this case, each character Ci is only classified,
The order is never changed. Therefore, the palette Pj (j = 0 to 7) does not have to be an area of continuous characters, and the characters that are scattered are 1
One palette may be configured. For example, as shown in FIG. 5C, when areas A to E having similar color tones are generated, the palette Pj may be configured for each of the areas A to E.

Then, in step 84, the second-order vector quantization is performed for each palette Pj on the character data CHR (i) classified into this palette Pj.

That is, the representative color of each character Ci is 4
Even in the case of colors, the number of colors in the palette Pj, which is a collection of the characters Ci, may exceed 16. Therefore, if the number of colors in one palette Pj is more than 16, the first-order vector quantization is performed. In the same manner as in the case of, the second-order vector quantization is performed and the colors in the palette Pj are rounded so that the maximum number of colors is 16, and the resulting 16 colors are set as new representative colors.

Therefore, for each palette Pj, the character data C of the character Ci belonging to that palette Pj
HR (i) is quantized into color data (15-bit color data) of any one of the 16 representative colors of the palette Pj.

Then, in step 85, a color number conversion table COL (j) is created for each palette Pj. In this table COL (j), as shown in FIG. 6, for each palette Pj, color data (15-bit color data) of the 16 representative colors and a 4-bit color number (15-bit color data) designating the color data ( 0 to 15). Therefore, at this point, the character data CHR (i) is the table COL (j) of the palette to which the character data belongs.
Equal to any of the color data of.

Then, in step 86, as shown in FIG. 7, the second-order quantized character data
Each color data of CHR (i) is converted into a color number of the color number conversion table by referring to the color number conversion table COL (j) of the palette Pj to which the character data CHR (i) belongs. Therefore, at this time, the pixel of each character Ci indicates the color number of the 4-bit color and the table of the color number conversion table COL (j) (for each character Ci). Data) and data.

Therefore, in step 87, the screen table SCR is formed. This screen table
As shown in FIG. 8, the SCR has an address of 24 characters × 32 characters corresponding to one frame of the original image data, that is, a total of 768 addresses. As shown in FIG. 9, each address has a size of 2 bytes, the lower 10 bits of the 2 bytes are the number Ci of the character Ci, and the upper 3 bits are the character data of the character number Ci. The palette number Pj of the palette Pj to which CHR (i) belongs is set.

Further, in this example, step 88.
The screen table SCR character number Ci
Is shifted to the larger side by 16 and the character number Ci
0 to 15 are assigned to the color numbers of the monochromatic character Ci. That is, depending on the character Ci,
The color of all its pixels may be equal and therefore the character Ci may be monochromatic. In the case of such a character Ci, if the palette number Pj and the color number are given to the character Ci, the colors of all the pixels of the character Ci can be specified.

Therefore, for the monochromatic character Ci, the palette number Pj is the original palette number Pj of the character Ci, but the character number Ci is the color number. At this time, the monochromatic character C
The address of i in the table SCR indicates the character number Ci. Even in this case, the maximum value of the character number Ci before shifting is 767, so
Character number Ci
Can still be represented by 10 bits.

As described above, the image data is converted into the color number conversion table COL (j), the screen table SCR, and the 4-bit color number for each pixel for each frame. In the following description, the color number conversion table COL (j) is called the color number conversion table COL,
The 4-bit color number for each pixel is called color number data DAT.

Then, these data DAT, SCR, COL
Are assembled into recording data RECD having a format as shown in FIG. 10, and this recording data RECD is a CD-R.
Recorded in OM4. In this case, the recorded data RECD
Is recorded in the CD-ROM 4 after encoding processing for recording in mode 1 such as addition of an error correction code is performed. The CD-ROM 4 is also provided with a program for displaying or using the image data (recording data) RECD recorded on the CD-ROM 4, if necessary.

Here, when the data amount per frame of the recorded image data RECD is obtained, it becomes as follows. That is, since there are eight palettes Pj per frame and one palette has 16 colors and one color has 16 bits (1 bit is a dummy), the color number conversion table COL has a total of 8 palettes × 16 colors × 16 bits = It will be 256 bytes.

Further, since the screen table SCR has 768 characters and each character has 2 bytes, 2 bytes × 768 = 1536 bytes.

Further, since the color number data DAT has 4 bits for each pixel, the data amount of the data DAT per character is 4 bits × 64 pixels = 32 bytes.

Since the data of the monochrome character Ci is transmitted as a part of the screen table SCR, it is not necessary to separately transmit it separately.

Therefore, for example, if 1/4 of 768 characters in one frame is a monochromatic character, color number conversion table COL = 256 bytes screen table SCR = 1536 bytes color number data DAT = 32 bytes × 768 x 3/4 = 18432 bytes −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− Total = 20224 bytes. That is, it becomes a little less than 20 Kbytes.

Then, the CD-ROM 4 is, for example, an ordinary 2
If the rotation speed is doubled, the data transmission rate is 300
It becomes K bytes / second.

Therefore, in the case of the data amount of the above image data, a moving image can be recorded or reproduced at a rate of 300 Kbytes / 20224 bytes = 15.2 frames.

If the moving image can be reproduced at such a frame speed, the moving image can be satisfied. Moreover, when the image data is recorded as described above, the color number data DAT can be converted into the image data of the original color by simply referring to the color number conversion table COL at the time of reproduction. It will be easy.

Furthermore, since no special IC is required,
CD can be provided at low cost and as a recording medium
-Because ROM can be used, it is effective when applied to software of a computer game machine.

<< Reproduction Circuit >> Next, the above-mentioned image data RECD
The basic configuration and operation of a microcomputer capable of reproducing original image data to display a moving image from the recorded CD-ROM 4 will be described with reference to FIG. Note that some circuits are the same as those in FIG.

FIG. 1 shows an example in which such a microcomputer is applied to a game machine, 1 is the main body of the game machine, 3 is a sub-processing unit, 4 is a CD-ROM, and 5 is a program cartridge.

The game machine body 1 is composed of a microcomputer, and 11 is its CP.
U and 12 are DMACs (DMA controllers), 13 is a main RAM serving as a work area, 14 is a PPU, and 15 is a video RAM.

In this case, the video RAM 15 has a screen area of two frames or more (two screens or more), and the image data of one screen area is CRT by the PPU 14.
The data read out in synchronization with the vertical and horizontal scanning of the display 6 is displayed as an image on the display 6, and while this display is being performed, the image data of the image to be displayed next in another screen area is displayed. Written. In addition,
Part of the area of the video RAM 15 is also a work area of the PPU 14 and is also used as an area of the color number conversion table COL (area for palette).

The sub-processing section 3 has a CD player and enables the use of the CD-ROM 4.
1 is the CD player, 32 is a DSP, 33 is a CD-R
OM decoder, 34 is a RAM for the work area, 3
Reference numeral 5 is a controller. As described above, the CD-ROM 4 stores the audio data, the image data RECD, the program for reproducing the image data RECD, the game program, and the OS. In addition, CD
-The ROM 4 reproduces the sector of the image data RECD at a rotation speed twice the normal speed.

Further, the DSP 32 performs error correction on the reproduction signal of the player 31, and separates user data such as image data RECD from control data such as track number from the reproduction signal. Reference numeral 35 is for controlling the player 31 based on the control data from the DSP 32 and the instruction data from the CPU 11 to reproduce the desired data. The decoder 33 is for performing processing such as error correction in the mode 1 when the reproduction signal of the player 31 is the mode 1 reproduction signal of the CD-ROM 4.

Further, in this example, the processing unit 3 is provided with a general-purpose DSP 44, and when necessary, this DS 44 is used.
P44 allows a part of the processing of the CPU 11 to be borne. Although the processing unit 3 is integrated with the game machine main body 1 in this example, it may be in the form of an adapter for the game machine main body 1.

Then, the image data RECD of the CD-ROM 4
When is displayed as a moving image, the procedure of the reproduction process for the image data RECD is as follows.

That is, (1) The CD player 31 reproduces one frame of the image data RECD from the CD-ROM 4, and this image data
RECD from player 31 to DSP 32 and decoder 33
Are sequentially supplied to the DMAC 12 for error correction processing and the error-corrected image data RECD
Thus, DMA transfer is performed from the decoder 33 to the buffer area of the RAM 13.

(2) DM in the buffer area of RAM 13
A Color number data DAT of the transferred image data RECD
However, during the vertical blanking period of the CRT display 6,
Video RAM 1 through PPU 14 by DMAC 12
5 is DMA-transferred.

(3) When the processing of (2) is completed, the screen table SCR of the image data RECD DMA-transferred to the buffer area of the RAM 13 in the vertical blanking period of the CRT display 6 is transferred to the PC by the DMAC 12.
It is DMA-transferred to the video RAM 15 through the PU 14.

(4) Color number conversion table CO of the image data RECD DMA-transferred to the buffer area of the RAM 13 during the horizontal blanking period of the CRT display 6.
L is video R through PPU 14 by DMAC 12
DMA transfer is made to AM15.

(5) When the above processing is performed, the PPU 14
Refers to the color number conversion table COL (j) in real time, and the color number data DAT transferred by (2)
Is converted into pixel data of an actual color, and this pixel data is written in the address corresponding to the original character position in the video RAM 15 by referring to the screen table SCR.

(6) When the pixel data for one frame is written in the video RAM 15 as described above, the video RAM 15
The display area 15 is switched, the area in which the pixel data is written is activated, and the image of the activated area is displayed on the display 6.

(7) The process returns to (1), and thereafter, the processes of (1) to (6) are repeated frame by frame.

The image data reproduced from the CD-ROM 4 is sent from the RAM 13 to the video RAM 15 through the PPU 14 one after another, and the PPU 14
Is reproduced. Therefore, on the display 6, the image based on the image data RECD of the CD-ROM 4 is displayed as a moving image.

<< Preventing Buffer Area of RAM 13 from Overflowing >> RAM
13 is the image data RECD reproduced from the CD-ROM 4.
The image data RECD from the CD-ROM 4 is used as a buffer area for
Writes to its buffer area as follows:

That is, as described above, the image data RECD for one frame is about 20 Kbytes, which is the CD-R.
It corresponds to 10 sectors of OM4.

Therefore, as shown in FIG. 2, when the buffer area of the RAM 13 is the memory BUFM, this memory BU
The FM has a size of, for example, 32 sectors of the CD-ROM 4, that is, 64 Kbytes (= 2 Kbytes × 32 sectors). In FIG. 2, # 0 to # 31 are memory BUFMs 1
Indicates the area number when divided into areas for each sector (2 Kbytes).

Further, the memory BUFM is a ring buffer, and when the image data RECD for one frame is written in the memory BUFM, the image data RECD is written in the address order (area order) and the highest address thereof. Next to, is written to the lowest address.

For example, when the image data RECD of the Qth frame from the CD-ROM 4 is being written from the area # 25 of the memory BUFM, as indicated by the diagonal lines in FIG.
5 → # 26 → ……… → # 31 → # 0 → # 1 → # 2.

Then, the next (Q +
1) When the image data RECD of the frame is written to the memory BUFM, it is checked whether the area # 12, which is 10 sectors behind the last area # 2 where the image data RECD of the Qth frame is written, is free. Then, the image data RECD of the (Q + 1) th frame is written in order from area # 3 following area # 2.

However, as a result of checking whether area # 12 is vacant, when it is not vacant, its (Q +
1) The image data RECD of the frame is discarded (read) without being written in the memory BUFM.

That is, when the image data RECD of the Qth frame from the CD-ROM 4 is written in the memory BUFM, the last data of the image data RECD (the last byte of the data COL) is the area # of the buffer memory BUFM. 0 ~ # 3
It is assumed that the data is written in the Rth area #R of 1 (R is any of 0 to 31). Then, when writing the image data RECD of the next (Q + 1) th frame to the buffer memory BUFM,
It is checked whether or not the unprocessed image data RECD remains in the area 1 frame behind the FM area #R, that is, the area # (R + 10) which is on average 10 sectors behind (R + When 10 ≧ 32, R + 10 is the value obtained by subtracting 32. The same shall apply hereinafter).

2.1. As a result of the check in section 1, area # (R + 1
If no unprocessed image data RECD remains in (0), the image data RE from the area # (R + 1) to the (Q + 1) th frame
Burn the CDs in order.

3.1. As a result of the check in section 1, area # (R + 1
When there is unprocessed image data RECD in (0),
The image data RECD of the (Q + 1) th frame is skipped and is not written in the memory BUFM.

4. Thereafter, the same processing is repeated. And

The check of the empty area in section 1 is CP
U11 performs the writing and reading of the image data RECD in the items 2 and 3 by the DMAC 12 based on the instruction of the CPU 11.

The check of item 1 can be realized by preparing a flag. That is, areas # 0 to # 3
A flag is prepared for each 1 and a corresponding flag is set when new image data RECD (one sector) is written in a certain area, and when the image data RECD is sent to the PPU 14, the corresponding flag is set. To reset. And if the flag is set, the corresponding area is not empty, but if it is reset,
Suppose the corresponding area is empty.

In this way, even if the processing speed of the image data RECD in the PPU 14 is slower than the reproduction speed of the image data RECD from the CD-ROM 4, the buffer memory
The BUFM does not overflow, and the image data RECD can be correctly converted to the original image data.

Moreover, in this case, as is clear from the above, the size of the buffer memory BUFM may be the size of several frames of the image data RECD, which is low cost.

Further, when checking whether or not there is a space for writing new image data RECD in the buffer memory BUFM, since it is checked whether or not there is a space for one frame, the processing becomes simple.

That is, when checking whether or not there is a space for writing new image data RECD in the buffer memory BUFM, it is checked whether or not there is a space for each area. If there is a space, new image data is written in that area.
When writing one sector of RECD, when the empty area runs out in the middle of one frame, it is necessary to instruct the PPU 14 to invalidate the portion written up to that point, which makes the process complicated. Become.

However, in the present invention, when checking whether or not there is a space for writing new image data RECD in the buffer memory BUFM, it is checked whether or not there is a space for one frame. Processing when there is no is very easy.

[0089]

According to the present invention, when the image data RECD reproduced from the CD-ROM 4 is written in the buffer memory BUFM, it is determined whether or not there is a free area in which one frame of the image data RECD is written in the buffer memory BUFM. If there is a vacancy, the writing is performed if there is a vacancy, but if there is no vacancy, the image data RECD is skipped. Therefore, even if the processing speed after the PPU 14 is slower than the reproduction speed of the image data RECD from the CD-ROM 4, the buffer memory BUFM does not overflow and the image data RECD can be correctly displayed on the original image.

Moreover, in this case, the size of the buffer memory BUFM may be the size of several frames of the image data RECD, which is low cost.

Further, when it is checked whether or not there is a space for writing new image data RECD in the buffer memory BUFM, it is checked whether or not there is a space for one frame. Very easy.

The image data RECD has a variable length, and the time required for the display processing of the image data RECD changes depending on the content of the image. However, the programmer considers the time required for the display processing. It is not necessary to build a program by doing so, and the burden on the programmer can be reduced.

[Brief description of drawings]

FIG. 1 is a system diagram of an example of the present invention.

FIG. 2 is a diagram for explaining a usage state of a memory according to the present invention.

FIG. 3 is a flowchart showing an example of a part of a recording process of image data.

FIG. 4 is a view showing a sequel to FIG. 3;

FIG. 5 is a diagram for explaining terms in image data.

FIG. 6 is a diagram for explaining a color number conversion table.

FIG. 7 is a diagram for explaining recorded data.

FIG. 8 is a diagram for explaining a screen table.

FIG. 9 is a diagram for explaining a data structure of a screen table.

FIG. 10 is a diagram showing an example of a format of recording data.

FIG. 11 is a system diagram of a conventional example.

[Explanation of symbols]

 1 Game Machine Main Body 2 Slot 3 Sub Processing Unit 4 CD-ROM 5 Program Cartridge 6 CRT Display 11 CPU 12 DMA Controller 13 RAM 14 PPU 15 Video RAM 19 System Bus 20 Main Processing Unit 21 APU 24 D / A Converter 31 CD Player 32 DSP 33 CD-ROM decoder 35 Controller 51 ROM 52 RAM

Claims (4)

[Claims] 1. When the image data reproduced from the recording medium is written in a buffer memory and the image data written in the buffer memory is converted into image data for display, the image reproduced from the recording medium is used as the buffer memory. A buffer memory having a capacity larger than one frame of data is provided, and before writing the image data reproduced from the recording medium in the buffer memory, it is checked whether or not there is a space for the one frame in the buffer memory. If the result of this check is that there is free space, the image data reproduced from the recording medium is written to the buffer memory, and if there is no free space as a result of the above check, the image data reproduced from the recording medium is discarded. How to play back the recorded image data. 2. When writing image data reproduced from a CD-ROM into a buffer memory and converting the image data written into the buffer memory into image data for display, the image data reproduced from the CD-ROM is used as the buffer memory. A buffer memory having a capacity larger than one frame of the image data is provided, and whether there is a space for the one frame in the buffer memory before writing the image data reproduced from the CD-ROM into the buffer memory. If the result of this check is that there is any vacancy, the above C
The image data reproduced from the D-ROM is written in the buffer memory. If the result of the above check is that there is no free space, the above C
A method of reproducing image data in which the image data reproduced from the D-ROM is discarded. 3. A circuit for writing image data reproduced from a recording medium into a buffer memory and converting the image data written in the buffer memory into image data for display, wherein the image reproduced from the recording medium is reproduced from the buffer memory. It is composed of a buffer memory having a capacity larger than one frame of data, and before writing the image data reproduced from the recording medium to the buffer memory, it is checked whether or not there is a space for the one frame in the buffer memory. Circuit and the result of this check, if there is any free space, the image data reproduced from the recording medium is written to the buffer memory. If, as a result of the above check, there is no free space, the image data reproduced from the recording medium. And a circuit for discarding image data, the circuit for reproducing image data. 4. A circuit for writing image data reproduced from a CD-ROM into a buffer memory and converting the image data written in the buffer memory into image data for display, wherein the buffer memory is reproduced from the CD-ROM. It is configured with a buffer memory having a capacity larger than one frame of the recorded image data, and whether there is a space for the one frame in the buffer memory before writing the image data reproduced from the CD-ROM into the buffer memory. The circuit to check whether or not the result of this check is the above C
The image data reproduced from the D-ROM is written in the buffer memory, but when the result of the above check is that there is no free space, the above C
A circuit for discarding image data reproduced from a D-ROM, and a circuit for reproducing image data.