JPH0514859A - Decoding method for image data and image reproducing device for it - Google Patents

Abstract

PURPOSE:To obtain an image of more stereoscopic effect by recording one frame of two moving images in a recording area for a one frame of a recording medium in separably state, transferring data for the one frame to another memory area of a memory quantity for one frame at the time of decoding, obtaining the two moving images and synthesizing them. CONSTITUTION:The recording medium 5 where the one frame of first and second image data which is compressed are recorded in a state where the first and second image data can be separated with an adding information is prepared. The compressed image data is read from the recording medium 5 and DMA- transferred to a first memory 13. The first and second image data is DMA- transferred to the memory area the screen of the second memory 15 having the memory area for two screens. The first and second screen data of the second memory 15 is decoding-processed and data of one frame before the first and second screen data is compressed. The screen of one frame is obtained by superposing the first and second screen data and set it to be a display screen.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of decoding data from a recording medium, such as a CD-ROM, on which image data such as a moving image is recorded, and an image reproducing apparatus for reproducing the image data.

[0002]

2. Description of the Related Art A CD-ROM has a large recording capacity and is used as an external storage medium in a game machine or a personal computer using a microcomputer.
It is considered that the image data of (1) is recorded, the image data is read out and supplied to the host computer to display a moving image (animation) on the CRT display.

In this case, in a conventional game machine, a CD-ROM decoder is connected to a single system bus connected to a CPU as a host computer of the game machine body. As a method of reading the image data from the CD-ROM, instead of continuously reading the image data from the CD-ROM and displaying a moving image on the display, it is recorded in a predetermined recording area of the CD-ROM. Image data of a moving image composed of a plurality of frames is read out and transferred to a large-capacity RAM prepared on the host computer side, and an animation is created from the image data of a plurality of frames stored in this RAM and displayed. There is.

[0004]

However, in the case of this method, the number of frames per second of the moving image is small,
You can't get a smooth animation of the movement.

Therefore, the inventors of the present invention, for example, as Japanese Patent Application No. 3-74555, reproduce a moving image while continuously reading image data from a CD-ROM, and have a large number of frames and a smooth movement. We are proposing a method that can realize animation.

By the way, in an image reproducing apparatus such as a conventional game machine, one screen is generally prepared as a memory area of a video RAM for displaying a moving image. The animation contents for one screen are realized by sequentially rewriting the image contents (referred to) as the image data for one frame read from the CD-ROM for each frame.

By the way, in the case of a game machine, if an image having a stereoscopic effect can be obtained, the possibility of enjoying a game with a more realistic feeling is expanded. However,
It is difficult to obtain an image having a stereoscopic effect with an image formed by only one plane.

In view of the above points, an object of the present invention is to provide a method of decoding image data and an image reproducing apparatus therefor capable of obtaining an image having a stereoscopic effect.

[0009]

In order to solve the above-mentioned problems, in the present invention, referring to the reference numerals of the embodiments described later, different first and second images are provided as image data recorded as one frame. Each compressed one frame of data is added to the first information by the additional information.
Also, a recording medium 5 in which the second image data and the second image data are recorded in a separable state is prepared, the compressed image data is read from the recording medium 5 and DMA-transferred to the first memory 13, and the first The first image data and the second image data from the memory 13 are DMA-transferred to the different screen memory areas of the second memory 15 having a memory area for two screens. Each of the first and second image data of 15 is decoded,
Data of one frame before compression of the first and second image data are obtained, respectively. The first and second image data are superposed to obtain an image of one frame, which is used as a display image.

[0010]

The image data for two screens is recorded as one frame on the recording medium. Then, at the time of decoding, the image data from the recording medium is once written in the first memory and transferred from the first memory to the second memory for image data decoding. In this case, the additional information recorded together with the image data causes the first and second image data to be written in the first and second memory planes of the second memory, respectively. Then, the first and second image data in the second memory are decoded respectively, and the image data for one frame is decoded respectively.

The image data of the first and second memory planes are combined and displayed on the display. Second
The images in the first and second memory planes of the memory are rewritten by the first and second image data from the recording medium, so that the display screen displays an image in which two moving images are overlapped. Therefore, a three-dimensional animation can be obtained.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the image data decoding method and the image reproducing apparatus according to the present invention will be described below with reference to a CD-ROM.
An example will be described in which the image data of the moving image recorded in [3] is reproduced so that the animation can be displayed in real time.

First, a data compression method of moving image data and a method of recording the compressed moving image data and other data other than the moving image on a recording medium will be described.

[Data compression method of moving image data] FIGS. 4 and 5 are block diagrams of an example of an encoding apparatus for executing the image data compression method of this example. In this example, the compressed image data is recorded on the CD-ROM. This CD-ROM is used as software for a game machine as described later, and image data is highly efficiently compressed so that a moving image can be reproduced.

In this example, one frame (one screen)
As shown in FIG. 6A, horizontal × vertical = 256 pixels × 192
Each of the three primary colors is represented by 5 bits. Actually, 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 colors, that is, 16 bits. Then, the original image data is subjected to data compression processing in the unit of one frame as follows.

That is, the data of one frame of the original image is supplied to the character dividing means 22 through the input terminal 21, and as shown in FIG. 6B, the image of one frame consists of horizontal × vertical = 8 pixels × 8 pixels. It is divided into small area blocks (hereinafter this block is referred to as a character).
Therefore, as shown in FIG. 6B, one frame image is divided into 32 × 24 = 768 characters. Then, the image data C (0) to C (76
7) is temporarily stored in the register 23.

The image data C (0) to C (767) of each character from the register 23 are supplied to the first vector quantizing means 24. Also in this example, the vector quantization means 24 processes the image data C (0) to C (767) of each character in parallel. As a matter of course, the image data C (0) to C (767) may be sequentially vector-quantized without performing the parallel processing. The same applies to each processing described later.

In the vector quantizing means 24, for each character image data C (k) (k = 0 to 767), vector quantization is performed so that the number of colors represented by pixels in the character is within 4 colors. Done. Although various proposed methods can be used as this vector quantization method,
In this example, when the three-dimensional color space is considered with the color components of the three primary colors of red, blue, and green being orthogonal to each other, the distance between each pixel in that color space is calculated, and pixels with short distances are identified. By grouping together, that is, processing for grouping pixels of similar colors into one representative color, the pixel data is rounded so that the colors of the pixels in the character fall within four representative colors.

Then, for all the characters in one frame, vector quantization is performed so that the color of the pixels in the character fits into four colors, and then the quantization error (representative color position) in all the characters in the one frame. (Corresponding to the distance in the color space between the representative color and each pixel) is determined as the center, and the maximum value Emax is obtained. At this time, the threshold value Eth that is allowed as the maximum value of the quantization error in one frame is set in advance. Then, the maximum value Emax of the quantization error is compared with the threshold value Eth. Then, when the maximum value Emax of the quantization error is larger than the threshold value Eth, the quantization error of the image data in each character is further increased to the maximum value Emax.
Vector quantization is performed until just before, and the number of colors in the character is reduced. This is to make the S / N of the image data in all characters within one frame uniform. This is performed until just before the maximum value Emax of the quantization error exceeds the threshold value Eth. If you do this,
The S / N ratio in all frames is kept constant.

Quantizing in this way reduces the number of pixel colors in a character with a flat color change. This is because in a character with a flat color change, the quantization error does not increase so much even if the number of colors decreases. In this process, there are some characters in which the number of colors in the character is two, and even only one. Then, the color selected in each character is set as the representative color.

In this way, from the vector quantizing means 24, image data compressed into 4 colors or less in each character is obtained. The image data in character units from the vector quantizing means 24 is supplied to the palette dividing means 25.

The palette dividing means 25 classifies a character into eight groups (each group is referred to as a palette) by grouping together characters having similar colors according to the color distribution within the character. For example, as shown in FIG. 6C, when a group of characters having similar color tones depending on the contents of the image occurs as A, B, C, D, E ..., the groups A, B, C, D,
A palette is constructed for each E.

In the case of this example, the method of allocating eight palettes is as follows: (1) The representative color of each character (the average value of the colors in the character) is calculated, and it is assumed that each character consists of the representative color. (2) Vector quantization is performed to quantize all characters in one frame into eight colors. That is, since the number of characters is 768, the representative color of the character is 768 at maximum.
Although it becomes a color, it is quantized into an 8-color character. (3) Characters having the same label (representative color) are put together into one palette. It is performed in three steps.

The group of characters forming this palette does not have to be a continuous character area, and scattered characters may form one palette group.

Data P (0) to P (7) of eight pallets
Are temporarily stored in the register 26, supplied to the second vector quantizing means 27, and processed in parallel.

The second vector quantizing means 27 determines the representative colors of the 16-color pixels for each palette. At this time, if the number of colors of pixels in one palette is more than 16 colors, vector quantization is performed in the same manner as in the character, and the colors in the palette are rounded to 16 colors. Then, the resulting 16 colors are set as the representative color of the pixel.

In this way, 8 rounded into 16 colors
Image data P (0) to P for each palette in character units
(7) is supplied to the labeling means 28 and processed in parallel. In each labeling means 28, color conversion tables COL (0) to COL (0) to C of 16 colors or 16 or less color data selected as representative colors of pixels for each palette
OL (7) is created and temporarily stored in the register 29 (see FIG. 7). The data of the color conversion tables COL (0) to COL (7) from the register 29 are supplied to the recording processing means 38 as recording data.

Further, in each labeling means 28, each color conversion table COL (0) to COL (7) is referred to, and for each character included in each palette, 16 are respectively provided.
The pixel data rounded to color is converted into label image data LAB (0) to LAB (7) in which the color of the pixel is represented by the corresponding color number on the color conversion table of the palette (FIG. 8). reference). Then, the label image data LAB
(0) to LAB (7) are temporarily stored in the register 30.

In this case, as described above, the character may be composed of 4 or 3 colors (FIG. 8A), composed of 2 colors (FIG. 8B), or composed of only one color (FIG. 8C). If the character has 4 or 3 colors, then 4 or 3
If there is a table showing the color number of each color, each pixel data can be represented by 2-bit data indicating which one of the color number table. Therefore, each pixel data of a character consisting of 4 or 3 colors can be represented by 2 bits. Similarly, if the character has two colors,
The color number table for the character's two colors and 1 for each
It can be represented by bit pixel data. Furthermore, if there is only one color, it is possible to use only that color data, as described later.

A character that can be represented by 2 bits is referred to as a 2-bit mode character, a character that can be represented by 1 bit is referred to as a 1-bit mode character, and a character having only one color is referred to as a monochrome character.

In consideration of the decoding process, the 2-bit mode character, the 1-bit mode character, and the monochromatic character can be processed together at a high speed. However, in 768 characters in one frame, generally, the mode characters are dispersed and mixed as shown in FIG. 9A. In FIG. 9, is a 1-bit mode character, is a 2-bit mode character,
○ indicates a single color character.

Therefore, the label image data LAB (0) to LAB (7) of each pallet from the register 30 is supplied to the sorting means 31, and as shown in FIG. 9B, the 2-bit mode character, the 1-bit mode character, Character data of one frame is rearranged in the order of monochromatic characters.

In the sorting means 31, a table for rearranging the characters of one frame to the original order (hereinafter referred to as a screen table) s
cr is formed. This screen table scr
As shown in FIG. 10, when an image of one frame is divided into small areas of the same size as the character, a character number CNo. And a palette number PNo. Are defined for each small area. The character number CNo. Is the character rank in one frame after the character to be displayed at the position of the small area is sorted. The pallet number PNo. Indicates which of the eight pallets the character displayed in the small area is included in. That is, it indicates which color conversion table is used for decoding. In this case, the character number CNo. And pallet number PNo. Of one small area are composed of, for example, 2-byte data.

In the case of this example, the character number CN
0 to 15 of o. are assigned only to a monochrome character. That is, when the character displayed at the position of a certain small area in the table scr is a monochromatic character, the pallet number PNo. Is assigned to that small area in the same manner as the 2-bit mode or 1-bit mode character. , Character number C
Instead of No., 0 to 0 in the palette color conversion table
The color number of the color of the character out of the 15 color numbers is assigned. As a result, the color (single color) of the small area is determined. Therefore, for a single-color character, the color data of the character is registered and recorded in the screen table scr as described above, and is not recorded as compressed image data for each character described later.

Because of the above-described monochrome characters, the character numbers for the 2-bit mode and 1-bit mode characters start from 16. Originally, 10 bits are assigned to the character number, so
There is plenty of room to shift such numbers.

The data of the screen table scr is supplied to the recording processing means 38 as recording data.

Then, the sorting means 31 is operated as described above.
Of the image data in character units sorted and rearranged in (2), the character data C2 (0) to C2 (N-1) of N pieces (N is an integer of 768 or less) in each 2-bit mode.
Are supplied to the labeling means 33 via the register 32. In the labeling means 33, as to the data C2 (0) to C2 (N-1) of each character in the 2-bit mode, as shown in FIG. 11A, a color number table of 4 colors or 3 colors of the character and its color number table are shown. Compressed image data dat2 (0) to dat2 (N-1) consisting of 2-bit index number data indicating each color number position on the color number table are formed. Then, these compressed image data dat2 (0)
~ Dat2 (N-1) is temporarily stored in the register 34.

Similarly, M sorts from the sorting means 31 (M is 7)
Character data C1 (0) to C1 (M-1) of each 1-bit mode of an integer of 68 or less) is supplied to the labeling means 36 via the register 35. In the labeling means 36, character data C1 of each 1-bit mode
For (0) to C1 (M-1), as shown in FIG. 11B, from the color number table of the two colors of the character and the 1-bit index number data indicating each color number position on the color number table, Compressed image data dat1 (0) to da
t1 (M-1) is formed. Then, these compressed image data dat1 (0) to dat1 (M-1) are temporarily stored in the register 37.

All the 2-bit mode compressed image data from the register 34 and the 1-bit mode compressed image data from the register 37 are supplied to the recording processing means 38 as recording data.

Further, data such as resident characters and game condition changes are supplied to the recording processing means 38 through the terminal 39.

[Generation of Recording Data] The recording processing means 38 creates data to be recorded in the CD-ROM. In this example, the recorded data is processed as one block in one frame. However, the data recording mode on the CD-ROM is CD-ROM.
It goes without saying that it follows the ROM data format.

For example, when the recording mode of the CD-ROM is the mode 1, the sectors are as shown in FIG. That is, a sync (synchronization) pattern is arranged at the head of the sector, and subsequently, a header including a sector number, a track number, etc. is arranged. And 2K after this header
The user data is composed of bytes, and the last is auxiliary data composed of error detection and error correction codes of the user data.

In the case of this example, the above-mentioned moving image data and other data are recorded in the user data area of the sector. Then, the first 32 bytes of this 2 Kbyte user data is used as the identification information ID. The identification information ID includes information indicating what kind of data is recorded in the user data area and how many sectors the data having the same content continues. Of course, the identification information ID may include other information.

As will be described later, as the contents of the data indicated by the identification information ID, the user data of the sector is the image data of one moving image, the image data of two moving images, the color conversion table and the screen. Table scr
Information, video image data and screen table s
Information about cr, other data such as so-called resident character data and game condition change data is prepared.

[1.1 Recording of Image Data of Moving Image] The above-mentioned data for one frame of image is 2
The color conversion tables COL (0) to COL (shown in FIG. 7 for the compressed image data relating to the pixels of each character in the bit mode and the 1-bit mode and the 8 palettes of the 1 frame which is data other than the image data. 7) and
It is composed of the screen table scr shown in FIG.

In this example, the compressed image data for one frame to be recorded is, as shown in FIG. 12, a mode in which the number of characters N in the 2-bit mode and the number of characters M in the 1-bit mode are shown at the head thereof. Numerical information and compressed image data dat2 (n) (n) of N 2-bit mode characters
= 0,1,2 ... N-1) and compressed image data dat1 (m) (m = 0,1,2 ... M-1) of M 1-bit mode characters. By registering the color information of the single color character in the screen table scr as described above,
It is not recorded as pixel data.

The information for one character is shown in FIG.
As shown on the lower side, the color number table information and the index number data for 64 pixels are used. As shown in FIG. 11, the index number data corresponding to each pixel is 2 bits in the 2-bit mode and 1 bit in the 1-bit mode. In this case, since the number of characters N in the 2-bit mode and the number of characters M in the 1-bit mode change according to the content of the pixel, the data length of the data regarding the character pixel for one frame is variable.

In this example, the number of characters in each mode is recorded as the mode number information. However, instead of this mode number information, the last character of the 2-bit mode and the first character of the 1-bit mode are recorded. In the meantime, mode delimiter information of a bit pattern that does not occur as character data may be recorded.

In the case of this example, the data amount relating to the moving image compressed as described above is as follows per frame.

Since there are 8 pallets per frame,
The total color conversion table is 16 (color) × 8 (palette) × 2 (byte) = 256 (byte). Further, since the screen table scr has 2 bytes per character, 768 × 2 (bytes) = 1536 (bytes).

Therefore, the total data amount of the color conversion table and the screen table scr is 2 Kbytes or less, which is within one sector.

Further, in the image data of the moving image, in the character in the 2-bit mode, since there are four kinds of color numbers represented by 4 bits, the color number table is 4 (bits) × 4 = 16 (bits). = 2 (bytes). Since the index number data has 2 bits, 2 (bits) * 64 = 128 (bits) = 16 (bytes). Therefore, the 1 of 2 bit mode character
The amount of data per character is 18 bytes.

Further, since the color number of the character in the 1-bit mode may be two colors, the color number table is 4 (bits) × 2 = 8 (bits) = 1 (bytes). Since the index number data is 1 bit, 1 (bit) × 64 = 64 (bit) = 8 (byte). Therefore, 1 for 1-bit mode characters
The data amount per character is 9 bytes.

Since each pixel data of a character is not transmitted for a monochromatic character, the compression rate of the image data of one frame is the ratio of the number of characters in two-bit mode and one-bit mode in one frame to the number of monochromatic characters. Determined by. For example, in the case of 2-bit mode: 1-bit mode: monochrome = 3: 3: 2 = 288: 288: 192, Since it is 8 Kbytes or less, it fits within 4 sectors.

From the above, in the case of this example, FIG.
As shown in, the data regarding the moving image can be recorded as 5 sectors for each frame. That is, 5
Character data of 2-bit mode and 1-bit mode (mode number information is included in the first sector) is recorded as user data of the first 4 sectors of the sector. Then, the data of the screen table scr and the color conversion table are recorded in the fifth sector shown by hatching in FIG. 14A.

As the 32-byte identification information ID in the user data area of each sector, the first four sectors have information indicating that the data is moving image data.
Information is recorded on the number of sectors that follow (4 in the case of the first sector). Further, in the last fifth sector, information indicating that it is data of the screen table scr and the color conversion table and information of the number of sectors following it (1 in this case) are recorded.

In this way, the data relating to the moving image for one frame is repeatedly recorded every 5 sectors. In the case of this example, considering that the transmission rate of the CD-ROM is 150 Kbytes (75 sectors) / second, 1
It is possible to record or reproduce a moving image of 5 frames (frames) / second.

In the case of this example, the CD-ROM contains:
The resident character and other data input from the terminal 39 are also recorded in the user data area of this sector. Furthermore, in the game machine of this example, a background image of a moving image can be separately created as a still image, and a composite image of both can be displayed on the CRT display. Therefore, the image data of the still image is also recorded in the CD-ROM. In this case, as the still image data, for example, 16-bit data for each pixel is compressed into 4 bits and recorded. Similarly, the resident character is also compressed and recorded in 4 bits.

These data are inserted and recorded between the data of one frame related to the above-mentioned moving picture. Then, as the first identification information ID in the user data area of each sector, the data content and the number of sectors following it are recorded.

In addition to the compressed image information as described above, a program for decoding the compressed image information and a game program are recorded on the CD-ROM. Furthermore, audio information is also recorded as appropriate. As the decoding program, a 2-bit mode decoding program and a 1-bit mode decoding program are recorded. Also, a character rearrangement program is recorded. These program data are recorded separately from the above-mentioned data, and at the time of decoding, before playing a moving image or the like,
It is designed so that they can be read in a batch. Note that these program data can also be recorded in the middle of the moving image data as data other than the image data of the moving image in the above example.

[2.2 Recording of Image Data of Moving Image] In this example, the recording processing circuit 38 uses the CD-
In the ROM, one frame of each of two moving images is recorded in the above-mentioned one frame / 5 sectors.

In this case, since one frame of the first and second images is included in the recording area of the image data of one frame and the image data of two frames in total is recorded, the image data is Further data compression is required. The method is as follows. A method of reducing the number of pixels per frame, for example, one screen is 256 (horizontal) x 1
28 (vertical). A method for increasing the compression rate of data compression by vector quantization ,.
The method and the method of using the method in combination are adopted.

In this case, as the data to be recorded, 2-bit mode character data for one frame of the first image data, 1-bit mode character data, its screen table scr1 and its color conversion table, 2-bit mode character data for 1 frame of data of the second image, 1-bit mode character data, and its screen table sc
r2 and its color conversion table are required.

The color conversion table can be commonly used if the number of colors used is 8 (palette) × 16 (color) = 128. That is, if the color numbers for the common color conversion table are registered as the data of the color number table, the screen tables scr1 and scr2 are registered.
This is because the common color conversion table can be designated in.

In the case of this example, 1 of the CD-ROM is used.
When recording image data of one frame each of the first and second images in frame = 5 sectors,
Record as shown in FIG. 14B.

That is, first, the number N1 of 2-bit mode character data and the number M1 of 1-bit mode character data to be recorded as one frame of the first image are recorded, and subsequently, one frame of the first image is recorded. Character data in the 2-bit mode and the 1-bit mode is recorded. Next, the number N2 of character data in the 2-bit mode and the number M2 of character data in the 1-bit mode, which are subsequently recorded as one frame of the second image, are recorded, and subsequently two bits of one frame of the first image are recorded. Character data of mode and 1-bit mode is recorded. And
After that, the screen table s for the first image
cr1, the second screen table scr2, and the color conversion table COL (j) common to the first and second images.
Is recorded.

In the case of the example shown in the figure, the first 2 of the 5 sectors are
Image data for one frame of the first image is recorded halfway through the sector, and then the second data is recorded halfway through four sectors.
The image data for one frame of the image is recorded, and then the screen tables scr1 and scr2 and the color conversion table COL (j) are recorded. Therefore,
In FIG. 14B, the 32-byte identification information ID in the user data area of the first three sectors of the five sectors includes information indicating that the image data is two moving images. Then, the identification information ID of the fourth sector includes the image data of the image data of the two moving images and the information indicating that it is the information of the screen table scr. Identification information ID of the last 5th sector
Includes information indicating that the information is the screen table scr and the color conversion table for the image data of the two moving images.

The number of characters N1, M1, N2, M
Instead of recording 2, at the border between the first and second images,
A flag indicating that is recorded, and at the boundary between the second image and the screen table scr and the color conversion table,
You may make it record the flag which shows that.

As described above, one frame of each of the image data of the first and second moving images is repeatedly recorded every 5 sectors in which the image data of one moving image is recorded. Therefore, if this is decoded, the first and second moving images can be displayed at 15 frames / sec.

According to the data compression method described above, 1
The image is hierarchically divided into small areas in frame units, and the vector quantization is performed on the image data of each layer, so that the compression rate of the image data can be increased.

In this case, one group (palette) is formed by grouping characters having similar colors, and a plurality of such groups are formed for one screen, and the image data is divided into palettes (groups). There is. And
Since the vector quantization process is performed in the palette composed of image parts of similar colors, the quantization error is reduced.

Further, at the time of decoding, the decoding process can be carried out only by referring to the table, so that the structure of the decoder is simplified. Further, since a large capacity buffer memory is not required, a general-purpose DSP having a limited capacity of the built-in RAM can be used as a decoder, and the cost of the decoder can be reduced.

Moreover, since the compression processing is performed without utilizing the frame correlation, even if an error occurs during decoding, the error is completed within one frame and does not affect the subsequent frames.

Further, since the decoder circuit can be provided at low cost and the CD-ROM can be used as the recording medium, it is effective when applied to software of a computer game machine.

Further, in the above example, for the data of the character having one color, the screen table scr
Since only the color data is transmitted and the pixel-based data is not transmitted by registering in, the traffic on the data transmission path can be reduced.

The processing unit when dividing the palette is 1
Instead of a frame, a plurality of frames may be used for three-dimensional palette division.

[Description of Decoding Device as One Embodiment of the Present Invention] Next, the CD-R compressed as described above will be described.
A case of a game machine as an example in which the present invention is applied to a device for decoding image data recorded in an OM will be described.

That is, FIG. 1 shows an example in which the present invention is applied to a game machine using a microcomputer, 1 is the main body of the game machine, 4 is a sub-processing unit, and 5 is a CD.
-ROM, 6 is a program cartridge, and 7 is a main processing unit for audio data.

The game machine body 1 is composed of a microcomputer, 11 is its CPU, 12
Is a DMAC (DMA controller), 13 is a work area RAM, 14 is a PPU (picture processing unit), and 15 is a video RAM.

The game machine main body 1 has the first and second
It has a two-bus configuration including the system buses 18 and 19 of FIG. The two system buses have a common data bus, but the address buses are the first system bus and the second system bus.
The system bus is separate. And DMAC
12, the DMA transfer is possible only between the first and second system buses 18 and 19.

In this case, the CPU 11 and the second system bus 19 are connected via the port 16.
The devices connected to the first and second system buses 19 can be accessed via the port 16.

The CPU 1 is connected to the first system bus 18.
1, the DMAC 12 and the RAM 13 are connected. Also,
The second system bus 19 has a DMAC 12 and a PPU.
14 is connected and video RAM is connected to the PPU 14.
15 and the CRT display 6 are connected. Further, the sub-processing unit 4 and the main processing unit 7 for audio data are connected to the second system bus 19.

In the case of this example, the video RAM 15 is divided into a plurality of, for example, four memory areas M1 to M4 as shown in FIG. In the case of this example, each of the memory areas M1 and M2 is an area (memory plane) for reproducing one image, and the memory area M3 is an area (memory plane) for a resident character, for example. Each of these memory areas M1 to M3 has a screen area of two frames (two screens), and the image data of one screen area is read by the PPU 14 in synchronization with vertical and horizontal scanning of the CRT display 8. While being displayed, it is displayed as an image on the display 8. While this display is being performed, the image data of the image to be displayed next is written in the other screen area.

The memory area M4 is a work area of the PPU 14 and is used as an area for the screen table scr, the color conversion table, and other data.

Further, in the main processing unit 7 of the audio data of the game machine body 1, 71 is the APU (audio processing unit), 72 is a D / A converter, and 7
Reference numeral 3 denotes an audio output terminal, which connects the APU 71 to the bus 19 and the D / A converter 72. When the audio data and the program for decoding the audio data are loaded into the APU 71, 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 72, and then the output terminal. It is output to 73.

The sub-processing unit 4 has a CD player to enable the use of the CD-ROM 5, and
1 is the CD player, 42 is DSP, 43 is CD-R
OM decoder, 44 is RAM for the work area, 4
Reference numeral 5 is a controller. Audio data and image data are recorded in the CD-ROM 5, and these audio data and image data, especially image data, are compressed as image data by the above-described method and recorded.

The DSP 42 is for performing error correction on the reproduction signal of the player 41 and separating user data such as image data and control data such as track number from the reproduction signal, and the controller 4
5 is the control data from the DSP 42 and the CPU 11
Control the player 41 based on the instruction data from
It is for reproducing target data. Also,
The decoder 43 outputs the reproduction signal of the player 41 to the CD-RO.
This is for performing processing such as error correction for the CD-ROM when the reproduced signal is M5.

Further, in the sub processing unit 4, 50 is DS
P, which is a general-purpose DSP, is for processing image data. Although the sub-processing unit 4 is integrated with the game machine body 1 in this example, it may be in the form of an adapter for the game machine body 1. Although not shown, the DSP 50 includes a program RAM and a buffer RAM (which can be configured by one RAM).

The program cartridge 6 is used by inserting it into the slot 2 of the game machine main body 1 when using this game machine. When the CD-ROM 5 is not used, a program cartridge for general game software is inserted into the program cartridge 6 and the CD-ROM 5
When using, a special one is inserted.

The cartridge 6 has a ROM 61
And a RAM 62, and in the case of a cartridge for the CD-ROM 5, the ROM 61 includes the CD-ROM 5
A program for a so-called initialization process for the game machine main body 1 to capture the recorded data of 1 to execute the game is written. Further, the RAM 62 is used for holding various data regarding the state at that time, for example, when the game is temporarily interrupted midway, and is backed up by the battery 63.

Then, when the cartridge 6 is inserted into the slot 2 of the game machine body 1, the ROM 61 and the RAM 62 are connected to the bus 18 through a connector (not shown).

Then, the program of the ROM 61 of the cartridge 6 is executed by the CPU 11, and the CD-ROM 5
Data is fetched into the RAM 13 of the game machine main body 1 and the user data is decoded based on the identification information ID in the user data of each sector. Thereby, the moving image is displayed.

In other words, the CD player 41 makes a CD-
When the data is reproduced from the ROM 5, the reproduced data is sequentially supplied from the player 41 to the DSP 42 and the decoder 43 and subjected to processing such as error correction, and the error-corrected data is output from the decoder 43 by the DMAC 12. DMA in the first buffer area of RAM 13
Transferred.

Next, the CPU 11 checks the identification information ID of each sector of the data taken into the RAM 13. Based on this check result, the CPU 11
Performs the procedure of the decoding process according to the reproduction data having the content indicated by each ID.

Incidentally, from the CD-ROM 5, the decoding program and the game program described above are loaded into the RAM 13 prior to the reproduction of image data and the like.

[Decoding process for moving image data] [1.1 Decoding process for moving image] As a result of checking the identification information ID in the CPU 11, the content of the user data in the sector is one moving image. When it is determined that the data is data, the moving image is decoded and displayed in the following manner.

That is, the decoding process is performed on the data of 5 sectors including the compressed image data for one frame as follows. The procedure for decoding the image data of this moving image basically consists of the following three steps.

A. For each character, referring to the color number table, the 2-bit or 1-bit index number data is converted into 4-bit color number data of the color conversion table COL (j). For each pixel of each pallet character, refer to the pallet color conversion table, and convert the data of the color number decoded in section A into the actual color data. The step of rearranging the sorted characters, that is, referring to the screen table scr, B
The step of rearranging the pixel data decoded by the item to the original character position, and the DSP 50 performs the step of the A term among the steps of the A term to the C term, and the step of the B term and the C term.
U14 does.

[1-1 Step A] First, the DSP 50 decodes the user data of 4 sectors including the compressed image data for one frame into the data of the color number as follows. The procedure for performing the operation and writing it in the memory area M1 of the video RAM 15 will be described. That is, (1) A program for decoding a 2-bit mode character is loaded from the RAM 13 into the DSP 50.

(2) Of the 2-bit mode character data of the image data DMA-transferred to the first buffer area of the RAM 13, the 8-character data from the beginning is DMA-transferred to the DSP 50 by the DMAC 12.

(3) In the DSP 50, the step (A) is executed by the program of (1), and the index number data DMA-transferred is converted into color number data (FIG. 11A) by the color number table. By this conversion, the index number data for 8 characters (=
18 bytes x 8) is 4 bits x 8 pixels x 8 pixels (= 25
It is decoded into color number data of 6 bytes.

(4) This decoded color number is DM
D in the second buffer area of RAM13 by AC12
MA is transferred.

After (5), the processes of (2) to (4) are repeated, and all the index number data of the character in the 2-bit mode is decoded into the color number and DMA-transferred to the second buffer area of the RAM 13. It

(6) The data of all color numbers in the 2-bit mode DMA-transferred to the second buffer area of the RAM 13 are transferred to the video R through the PPU 14 by the DMAC 12 during the vertical blanking period of the CRT display 8.
The data is DMA-transferred to the AM 15 and written in the memory area M1.

(7) When the processes up to (6) are completed, the program for decoding the 1-bit mode character is loaded from the RAM 13 to the DSP 50.

(8) Of the character data in the 1-bit mode of the image data DMA-transferred to the first buffer area of the RAM 13, the data for 8 characters from the beginning is DMA-transferred to the DSP 50 by the DMAC 12.

(9) In the DSP 50, the step (A) is executed by the program of (7), and the index number data DMA-transferred is converted into color number data (FIG. 11B) by the color number table. By this conversion, the index number data for 8 characters (=
9 bytes x 8) is 4 bits x 8 pixels x 8 pixels (= 25
It is decoded into color number data of 6 bytes.

(10) This decoded color number is DM
D in the second buffer area of RAM13 by AC12
MA is transferred.

After (11), the processes of (8) to (10) are repeated, and all the index number data of the character in the 1-bit mode is decoded into the data of the color number and the RAM is stored.
DMA transfer is performed to the second buffer area 13 in FIG.

(12) The data of all color numbers in the 1-bit mode DMA-transferred to the second buffer area of the RAM 13 are transferred to the video R through the PPU 14 by the DMAC 12 during the vertical blanking period of the CRT display 8.
The data is DMA-transferred to the AM 15 and written in the memory area M1.

The DMA transfer of the color number in the 2-bit mode in (6) can also be performed immediately before this (12) (between (12) and (11)).

[1-2. Steps in terms B and C] (13)
When the processes up to (12) are finished, the process for the fifth sector of the image data of one frame is started. That is, C
The PU 11 detects that the fifth sector is a sector of the data of the screen table scr and the color conversion table based on the identification information ID. Therefore, the CPU 11
Sends the data of the screen table scr and the color conversion table DMA-transferred to the first buffer area of the RAM 13 to the DMAC 1 without passing through the DSP 50.
2 to PRAM 14 and DMA to video RAM 15
Forward. In this case, these screen table scr
The data of the color conversion table is written in the memory area M4 of the video RAM 15.

(14) When the above transfer processing is performed, the PPU
14 executes the steps of the B term and the C term described above in real time. That is, by referring to the color conversion table COL (j), the data of the color number of the memory area M1 processed by (2) to (5) and (8) to (11) is converted into the pixel data of the actual color. Pixel data of each character is written to the address corresponding to the original character position by being decoded into the screen table scr.

(15) When pixel data for one frame is written in one screen area of the memory area M1 of the video RAM 15 as described above, the display area of the video RAM 15 is switched to that screen area and the pixel data is written. Area is activated and its screen is displayed on the display 8.

(16) The process returns to (1), and thereafter, the processes of (1) to (16) are repeated for each frame.

The image data reproduced from the CD-ROM 5 as described above is stored in the RAM 13 and the DSP 50 as described above.
And PPU 14 are sequentially sent to the video RAM 15 while being processed in a pipeline process. Therefore, the image based on the image data of the CD-ROM 5 is displayed as a moving image on the display 8. Note that this moving image display can be performed at a rate of 15 frames / second as described above.

[2.2 Decoding process for two moving images]
The decoding process when the image data of one frame of two moving images is recorded in five sectors is basically the same as the above-described decoding process of one moving image.

First, in this case, as shown in FIG.
The boundary P1 between the character data of the first and second images can be known from the information on the numbers N1 and M1 of the character data in the 2-bit mode and the 1-bit mode for the first image.

Further, from the information of the numbers N1 and M1 and the information of the numbers N2 and M2 of the character data in the 2-bit mode and the 1-bit mode for the second image, the image data of the second moving image and the screen are displayed. Tables scr1 and s
The boundary P2 between the cr2 and the color conversion table COL (j) can be known. Then, from these boundaries P1 and P2, the step of the item A is switched from the decoding process of the first image to the decoding process of the second image, and the screen tables scr1 and scr2 and the color conversion table are fetched, and the item B is read. And the steps of C term are first and second
Image.

[2-1. Step of Item A] (1) A program for decoding a character in the 2-bit mode is loaded from the RAM 13 to the DSP 50.

(2) The 2-bit mode character data of the first image data among the image data DMA-transferred to the first buffer area of the RAM 13 is DMAC.
The data is DMA-transferred to the DSP 50 by 12 and decoded into color number data.

(3) This decoded color number is DM
D in the second buffer area of RAM13 by AC12
MA is transferred.

(4) The data of all color numbers in the 2-bit mode of the first image DMA-transferred to the second buffer area of the RAM 13 are transferred to the PPU 14 by the DMAC 12 during the vertical blanking period of the CRT display 8.
Is transferred to the video RAM 15 via DMA and written in the memory area M1.

(5) When the processes up to (4) are completed, the program for decoding the 1-bit mode character is loaded from the RAM 13 to the DSP 50.

(6) The 1-bit mode character data of the image data of the first image DMA-transferred to the first buffer area of the RAM 13 is transferred by the DMAC 12 to D
The data is DMA-transferred to SP50 and decoded into color number data.

(7) This decoded color number is DM
D in the second buffer area of RAM13 by AC12
MA is transferred.

(8) The data of all color numbers in the 1-bit mode of the first image DMA-transferred to the second buffer area of the RAM 13 are transferred to the PPU 14 by the DMAC 12 during the vertical blanking period of the CRT display 8.
Is transferred to the video RAM 15 via DMA and written in the memory area M1.

(9) Next, regarding the second image, (1) to
By performing the processing of (8), all the data of the 2-bit mode character and the 1-bit mode character of the second image are written in the memory area M2 of the video RAM 15.

[2-2. Steps in terms B and C] (10)
When the processing up to (9) above is completed, the CPU 11 causes the R
The data of the screen tables scr1 and scr2 and the color conversion table COL (j) in the first buffer area of the AM13 are sent to the DMAC12 without passing through the DSP50.
Then, DMA transfer is performed to the video RAM 15 through the PPU 14. In this case, the data of the screen table scr and the color conversion table are written in the memory area M4 of the video RAM 15.

(11) When the above transfer processing is performed, PP
U14 executes the steps of the B and C items described above for the image data of the first and second moving images. That is, the screen table scr1 and the color conversion table COL
By referring to (j), the memory area M of the first moving image
The data of the color number 1 is decoded into the pixel data of the actual color, and the pixel data of each character is written in the address corresponding to the original character position.

Also, by referring to the screen table scr2 and the color conversion table COL (j), the data of the color number of the memory area M2 of the first moving image is decoded into the pixel data of the actual color, and The character pixel data is written to the address corresponding to the original character position.

(12) As described above, the pixel data for one frame of each of the first and second moving images is stored in the video RAM 15
When the memory areas M1 and M2 are written in one of the screen areas, the area in which these pixel data are written is activated, and the screen is displayed on the display 8 as a composite image of the first and second images. Is displayed.

(13) The process returns to (1), and thereafter, the processes of (1) to (13) are repeated in units of 5 sectors for one frame.

As described above, on the display 8,
A composite image of the first and second moving images is displayed, giving a sense of depth, and a moving image with a stereoscopic effect can be obtained. Moreover,
In the case of this example, each of the first and second moving images is performed at a rate of 15 frames / second, and the number of frames equal to one moving image can be secured.

Data of still images and resident characters,
Sectors of other data are also written in the video RAM 13 and other memories by a process different from that of the moving image based on the identification information ID.

That is, for other data, the identification information ID of the sector is checked by the CPU 11, the content of the other data and the number of consecutive sectors are detected from the identification information ID, and at the beginning position of the sector. The start pointer is set, the other data is written in an appropriate memory area or another memory, and processing is performed according to the content of the other data. Then, when the sector of the other data ends, the end pointer PE stands,
Processing of other data ends. If the subsequent sector is a moving image sector, the process of decoding the moving image data is restarted. Therefore, the video continues from the previous screen. In this case, 5 sectors = 1/15 seconds, and the insertion period of other data is a short period, so that the moving image visually appears almost continuous.

As described above, according to the example shown in the figure, the CPU 11 manages the flow of all data to read the image data from the CD-ROM 5 and
Since the CPU 11 absorbs the asynchronous processing with the processing of 11, the image data can be continuously read from the CD-ROM 5. Moreover, the structure therefor is simple as is apparent from FIG.

Further, since the DSP 50 performs the first-order decoding and the PPU 14 performs the second-order decoding for the image data of the moving picture which is data-compressed, it is a general-purpose DSP 50. Can be used, and the cost can be suppressed.

Further, since the compressed image data is decoded by the DSP 50 and the PPU 14 separately, it is possible to decode the image data at a sufficient speed and display a moving image with sufficient movement. be able to.

RAM 13, DSP 50, PP
Since the DMAC 12 performs the data transfer with the U 14, it does not place a load on the CPU 11. Furthermore, DSP50
Since the CPU 11 is idle while the decoding is being performed, it is possible to instruct processing of other data as described above. As the other data, voice data can be inserted, and in that case, the user data of the sector of the voice data is transferred to the RAM of the APU 71.

As the recording medium, not only a CD-ROM but also a tape or the like can be used.

[0142]

As described above, according to the present invention, one frame of each of two moving images is recorded in a recording area for one frame of the recording medium in a separable state, and at the time of decoding, One frame of image data of these two moving images can be transferred to separate memory areas each having a memory capacity of one screen. Therefore, you can get two videos from these memory areas at the same time,
By combining these two moving images, an image with a more stereoscopic effect can be obtained.

Moreover, in the case of the present invention, since two moving images are recorded in the area for recording one moving image, the number of frames in the moving image does not decrease, and the motion is smooth and gives a three-dimensional effect. Animations can be displayed.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a decoding device according to the present invention.

FIG. 2 is a diagram for explaining a divided storage area of a memory.

FIG. 3 is a diagram for explaining a case of picking up and decoding data from a CO-ROM that records two moving images.

FIG. 4 is a block diagram of a part of an example of an encoding apparatus for implementing an embodiment of a method of compressing image data to be recorded on a recording medium according to the present invention.

FIG. 5 is a block diagram of the remaining part of an example of an encoding device for carrying out an embodiment of a method of compressing image data to be recorded on a recording medium according to the present invention.

FIG. 6 is a diagram for explaining an example of an image data dividing method according to an embodiment of the image data compression method of FIGS. 4 and 5;

FIG. 7 is a diagram for explaining a table used in an embodiment of the image data compression method of the examples of FIGS. 4 and 5;

FIG. 8 is a diagram for explaining an example of compressed data according to an embodiment of the image data compression method of the examples of FIGS. 4 and 5;

FIG. 9 is a diagram for explaining an embodiment of the image data compression method of the examples of FIGS. 4 and 5;

FIG. 10 is a diagram for explaining an example of a table used in an embodiment of the image data compression method of the examples of FIGS. 4 and 5.

FIG. 11 is a diagram for explaining an example of recording compressed image data on a recording medium according to the present invention.

FIG. 12 is a diagram showing an example of a format of data recorded on a recording medium according to the present invention.

FIG. 13 is a diagram for explaining a sector format of a CD and identification information ID for each sector recorded on a recording medium according to the present invention.

FIG. 14 is a diagram for explaining an example of reproduction data from an example of a recording medium according to the present invention.

[Explanation of symbols]

1 Game console body 5 CD-ROM 6 program cartridges 8 CRT display 11 CPU 12 DMA controller 13 RAM 14 PPU (Picture Processing Unit) 15 Video RAM 22 Character dividing means 24 First-stage vector quantization means 25 Pallet dividing means 27 Second Stage Vector Quantization Means 38 recording processing means 39 Other data input terminals 41 CD-ROM player 50 general purpose DSP

Claims (3)

[Claims] 1. The image data recorded as one frame is obtained by compressing each one frame of different first and second image data, and the first and second image data is added by additional information. A recording medium in which is separated is prepared, the compressed image data is read from the recording medium, and DMA-transferred to a first memory, and the first image data from the first memory is read. And the second image data are DMA-transferred to the memory areas for different screens of the second memory having the memory areas for two screens by using the above-mentioned additional information, And the second image data are subjected to a decoding process to obtain the data of one frame before compression of the first and second image data, respectively. 2. The image data recorded as one frame is obtained by compressing each one frame of different first and second image data, and the first and second image data is added by additional information. A first memory to which the data is DMA transferred from a recording medium recorded in a separable state, and the first image data and the second image data from the first memory are the additional memory. Information is used to decode a second memory having two screen memory areas that are DMA-transferred to different screen memory areas, and the first and second image data in the second memory, respectively. A circuit for performing processing to obtain data of one frame before compression of the first and second image data, a DMA controller for performing the DMA transfer, and a display display. And a b, an image reproducing device by combining the first and second image obtained as a result of the decoding to be displayed on the display. 3. The recording medium is a CD-ROM,
The image reproduction according to claim 2, wherein image data of moving images having different contents are recorded as the first and second image data, and the images in which the different moving images are superimposed are displayed on the display. apparatus.