JP2004007515A - Moving picture reproduction system and display control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a moving picture reproduction system and a display control device capable of reducing power consumption, size and costs and improving a processing speed and allowed to be suitably applied to a portable terminal. <P>SOLUTION: In the moving picture reproduction system 500, a DSP 100 is connected to an LCD driver 250 through a signal line 198. The DSP 100 comprises a variable length decoding part 40 for performing variable length decoding for MPEG data, a reverse quantization part 42 for performing reverse quantization and an IDCT part 44 for performing reverse discrete cosine transformation for the reversely quantized data and outputs data from the IDCT part 44 to the LCD driver 200 through the signal line 198. The LCD driver 200 comprises a movement compensation part 52 for compensating the movement of the data from the DSP 100, a reference frame memory 54 for storing the data from the DSP 100 as reference frame data and an RGB conversion part 46 for converting YUV components in the data from the DSP 100 or the movement compensation part 52 into RGB components. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a system that decodes compressed moving image data and reproduces a moving image on a display device such as an LCD (Liquid Crystal Display) based on the frame data obtained by decoding, and an apparatus applied to the system. In particular, the present invention relates to a moving image playback system that decodes MPEG (Moving Picture Experts Group) data and reproduces a moving image in a portable terminal, and a display control device applied to the system. More specifically, the present invention relates to a moving image reproduction system and a display control device which can reduce power consumption, reduce size, reduce cost, and improve processing speed, and can be suitably applied to a portable terminal.
[0002]
[Prior art]
When an image is digitized and stored in a storage medium such as a CD-ROM or a hard disk, the amount of data is enormous. Among various compression encoding methods, an encoding method based on DCT (Digital Cosine Transform), which performs compression using the property that the spatial frequency of an image is concentrated at a low frequency, is used relatively frequently. . That is, DCT is adopted by an encoding method which is an international standard such as JPEG (Joint Photographic Experts Group) or MPEG.
[0003]
First, a code format conforming to the MPEG will be described with reference to FIG. FIG. 2 is a diagram showing a hierarchy of a code format conforming to MPEG.
As shown in FIG. 2, the MPEG code has several hierarchical structures, and the highest hierarchy of the moving image portion is a video sequence, and is composed of a plurality of GOPs (Group Of Pictures). The GOP is composed of a plurality of pictures, and one picture indicates one image. Note that one image may be referred to as a frame in addition to a picture.
[0004]
There are three types of pictures: an I picture (Intra coded Picture), which is an intra-frame prediction image, a P picture (Predictive coded Picture), which is a forward inter-frame prediction image, and a preceding and following bidirectional inter-frame prediction image. There are three types of B-pictures (Bi-directionally predictive coded Pictures).
An I picture is data that can decode an image independently.
[0005]
In the P picture, one of an intra-frame prediction mode and a forward inter-frame prediction mode is set for each macroblock. The data of the block in which the forward inter-frame prediction mode is set refers to a forward frame with respect to the playback time when a moving image is played, and decodes a frame that is more backward than the forward frame. And a difference value of the pixel value between the frame in the forward direction and the frame in the backward direction. A block whose difference values are all “0” among the blocks constituting the P-picture is called an invalid block, and a block whose difference value is not “0” is called an effective block.
[0006]
In the B picture, one of an intra-frame prediction mode, a forward inter-frame prediction mode, a backward inter-frame prediction mode, and a bidirectional inter-frame prediction mode is set for each macroblock. The data of the block in which the forward inter-frame prediction mode is set refers to a forward frame with respect to the playback time when a moving image is played, and decodes a frame that is more backward than the forward frame. And a difference value of the pixel value between the frame in the forward direction and the frame in the backward direction. The data of the block for which the backward inter-frame prediction mode is set refers to the backward frame with respect to the playback time when the moving image is played, and decodes the frame that is more forward than the backward frame. , And is composed of a difference value of pixel values between the frame in the backward direction and the frame in the forward direction. The data of the block for which the bidirectional inter-frame prediction mode is set refers to the forward frame and the backward frame with respect to the playback time when the moving image is played, and the forward frame. This is data for decoding an image that complements between the frame in the backward direction and the frame in the backward direction, and is composed of a difference value of the pixel value between the frame in the forward / rearward direction and the frame in between. Among the blocks constituting the B picture, a block whose difference value is all “0” is called an invalid block, and a block whose difference value is not “0” is called an effective block.
[0007]
It should be noted that there are two types of encoding systems based on MPEG that do not use data corresponding to P pictures and that do not use data corresponding to B pictures.
The picture is further composed of a plurality of slices divided into arbitrary regions.
A slice is composed of a plurality of macroblocks arranged in left-to-right and top-to-bottom order. In the macro block, a block of 16 dots in the horizontal direction and 16 dots in the vertical direction (hereinafter abbreviated as 16 × 16 dots) is further divided into blocks of 8 × 8 dots, and luminance components (Y1, Y2) of 8 × 8 dots are formed. , Y3, Y4) and a color difference component (Cb, Cr) of a block of 8 × 8 dots in an area matching the luminance component. An 8 × 8 dot block is the minimum unit of encoding.
[0008]
Next, image compression by a conventional DCT-based coding method will be described with reference to FIG. 3 using MPEG as an example. FIG. 3 is a block diagram illustrating a configuration of a moving image compression apparatus that compresses an image according to an encoding method conforming to MPEG.
As shown in FIG. 3, the moving image compression device 400 includes a YUV conversion unit 10 that performs dye conversion on the moving image data, and a motion search unit 12 that searches for image motion based on the data from the YUV conversion unit 10. A motion prediction unit 14 for predicting the motion of an image with respect to the data from the YUV conversion unit 10 based on the search result of the motion search unit 12, and data from the YUV conversion unit 10 or data from the motion prediction unit 14. A DCT unit 16 that performs discrete cosine transform, a quantization unit 18 that performs quantization on data from the DCT unit 16, and a variable-length Huffman code compression on the data from the quantization unit 18. A variable length coding unit 20, an inverse quantization unit 22 that performs inverse quantization on the data from the quantization unit 18, and an IDCT (Inverse Discrete) on the data from the inverse quantization unit 22. IDCT unit 24 that generates frame data by performing an Osine Transform (inverse discrete cosine transform), a motion compensation unit 26 that performs motion compensation on the frame data from the IDCT unit 24, and a frame data from the motion compensation unit 26. The reference frame memory 28 stores the reference frame data.
[0009]
In MPEG, there are three types: I picture, P picture, and B picture. Therefore, the moving picture compression apparatus 400 performs compression according to I picture, P picture, and B picture, respectively. Specifically, it operates as follows.
When the moving image data is compressed as an I picture, the RGB components of the given moving image data are dye-converted into YUV components by the YUV converting unit 10, and each of the current frames input from the YUV converting unit 10 is converted by the DCT unit 16. A discrete cosine transform is performed on the pixel values of the block. Then, the quantization unit 18 performs quantization on the data from the DCT unit 16, and the variable length coding unit 20 compresses the data with a variable length Huffman code and outputs the data as MPEG data. On the other hand, in order to decode the compressed image as a reference frame, the inverse quantization unit 22 performs inverse quantization on the data from the quantization unit 18, and the IDCT unit 24 performs an inverse quantization on the data from the inverse quantization unit 22. Inverse discrete cosine transform is performed on the data to generate frame data, which is stored in the reference frame memory 28.
[0010]
When the moving image data is compressed as a P picture, the RGB components of the given moving image data are converted to YUV components by the YUV conversion unit 10. Next, the motion search unit 12 searches the motion of the current frame with respect to the previous / next frame for each block with reference to the data from the YUV conversion unit 10. Next, the motion prediction unit 14 refers to the previous frame data of the reference frame memory 22 based on the search result of the motion search unit 12 to determine the pixel value of each block of the current frame and the block of the referenced previous frame. A difference value from the pixel value is calculated, and the DCT unit 16 performs discrete cosine transform on the difference value from the motion prediction unit 14. Then, the quantization unit 18 performs quantization on the data from the DCT unit 16, and the variable length coding unit 20 compresses the data with a variable length Huffman code and outputs the data as MPEG data. On the other hand, in order to decode the compressed image as a reference frame, the inverse quantization unit 22 performs inverse quantization on the data from the quantization unit 18, and the IDCT unit 24 performs an inverse quantization on the data from the inverse quantization unit 22. Inverse discrete cosine transform is performed on the data to generate frame data, which is stored in the reference frame memory 28.
[0011]
When the moving image data is compressed as a B picture, the RGB component of the given moving image data is converted to a YUV component by the YUV conversion unit 10. Next, the motion search unit 12 searches the motion of the current frame with respect to the previous / next frame for each block with reference to the data from the YUV conversion unit 10. Next, the motion prediction unit 14 refers to the previous / next frame data of the reference frame memory 22 based on the search result of the motion search unit 12 to determine the pixel value of each block of the current frame and the referenced previous / next frame. A difference value from the pixel value of the frame block is calculated, and the DCT unit 16 performs discrete cosine transform on the difference value from the motion prediction unit 14. Then, the quantization unit 18 performs quantization on the data from the DCT unit 16, and the variable length coding unit 20 compresses the data with a variable length Huffman code and outputs the data as MPEG data. In the case of a B picture, since it is not used as a reference frame, decoding of an image is not performed.
[0012]
Next, a conventional image decoding based on a DCT-based coding method will be described with reference to FIG. 4 using MPEG as an example. FIG. 4 is a block diagram showing a configuration of a moving image reproduction system 600 that performs image decoding by an encoding method conforming to MPEG.
As shown in FIG. 4, the moving image reproducing system 600 includes a DSP 150 for decoding MPEG data, a reference frame memory 55 for storing reference frame data, and an LCD for controlling display of the LCD 300 based on data from the DSP 150. The driver 250 is connected by a signal line 199.
[0013]
The DSP 150 includes a variable length decoding unit 40 that decodes MPEG data with a variable length Huffman code, an inverse quantization unit 42 that performs inverse quantization on data from the variable length decoding unit 40, and an inverse quantization unit. An IDCT unit 44 that performs inverse discrete cosine transform on the data from the unit 42 to generate frame data, and performs motion compensation on the frame data from the IDCT unit 44 with reference to the frame data in the reference frame memory 55. It comprises a motion compensating unit 52 and an RGB converting unit 46 that performs a dye conversion on the frame data from the IDCT unit 44 or the frame data from the motion compensating unit 52, and uses the frame data from the IDCT unit 44 as a reference frame. The frame data from the RGB converter 46 is stored in the memory 55 and the LCD It is adapted to output to 250.
[0014]
The LCD driver 250 includes a display memory 48 that stores data from the DSP 150 as display data, and a display data output unit 50 that outputs the display data of the display memory 48 to the LCD 300.
In MPEG, there are three types: I picture, P picture, and B picture. Therefore, in the moving picture reproduction system 600, decoding is performed according to the I picture, P picture, and B picture, respectively. Specifically, it operates as follows.
[0015]
When an I picture is reproduced, in the DSP 150, the given MPEG data is decoded by the variable length decoding unit 40 using the variable length Huffman code, and the inverse quantization unit 42 converts the MPEG data into data from the variable length decoding unit 40. On the other hand, inverse quantization is performed. Next, the IDCT unit 44 performs inverse discrete cosine transform on the data from the inverse quantization unit 42 to generate frame data, which is stored in the reference frame memory 55 and output to the RGB conversion unit 46. Then, the YUV component of the frame data from the IDCT unit 44 is dye-converted into the RGB component by the RGB conversion unit 46, and the frame data from the RGB conversion unit 46 is output to the LCD driver 250 via the signal line 199.
[0016]
When a P picture is reproduced, in the DSP 150, the given MPEG data is decoded by a variable length Huffman code by the variable length decoding unit 40, and the data from the variable length decoding unit 40 is decoded by the inverse quantization unit 42. On the other hand, inverse quantization is performed. Next, the IDCT unit 44 performs an inverse discrete cosine transform on the data from the inverse quantization unit 42 to generate frame data, and the motion compensation unit 52 refers to the previous frame data in the reference frame memory 55. , The difference value of each block of the current frame input from the IDCT unit 44 and the pixel value of the referenced block of the previous frame are added, stored in the reference frame memory 55 and output to the RGB conversion unit 46. The RGB converter 46 converts the YUV component of the frame data from the motion compensator 52 into an RGB component by dye conversion, and outputs the frame data from the RGB converter 46 to the LCD driver 250 via the signal line 199.
[0017]
When reproducing a B picture, in the DSP 150, the given MPEG data is decoded by a variable length Huffman code by the variable length decoding unit 40, and the data from the variable length decoding unit 40 is decoded by the inverse quantization unit 42. On the other hand, inverse quantization is performed. Next, the IDCT unit 44 performs inverse discrete cosine transform on the data from the inverse quantization unit 42 to generate frame data, and the motion compensation unit 52 refers to the previous / next frame data in the reference frame memory 55. Then, the difference value of each block of the current frame input from the IDCT unit 44 and the pixel value of the referenced block of the previous / next frame are added and output to the RGB conversion unit 46. The RGB converter 46 converts the YUV component of the frame data from the motion compensator 52 into an RGB component by dye conversion, and outputs the frame data from the RGB converter 46 to the LCD driver 250 via the signal line 199.
[0018]
[Problems to be solved by the invention]
However, in the conventional moving image reproducing system 600, since the bit rate of the frame data output from the RGB converter 46 is extremely high with respect to the bit rate of the given MPEG data, there is a problem that the power consumption is large. Was. That is, since the DSP 150 consumes power corresponding to the output bit rate, if the output of the RGB conversion unit 46 has a high bit rate, the power consumption increases in the output stage. In addition, in the DSP 150, in order to process the high bit rate frame data, the operating clock must be increased to some extent, which also increases power consumption.
[0019]
Further, since the reference frame memory 55 is used as an external memory, there is a problem in that it is not possible to reduce the size of the system, reduce the cost, and improve the processing speed. That is, since the external memory is used, a space for providing the external memory is required, and it is difficult to reduce the size of the system. In addition, since the external type memory generally has its memory capacity set for each predetermined unit, the conventional moving image reproducing system 600 has a minimum memory capacity necessary for storing the reference frame data. Larger memory capacity has to be adopted, and there is room for cost reduction for memory capacity larger than necessary. In addition, since the external memory is generally connected to the DSP 150 via a bus, writing and reading of data, writing of a plurality of data, or reading of a plurality of data are simultaneously performed. It cannot be performed, and there is a certain limit in improving the processing speed.
[0020]
By the way, in recent years, it has become possible to use various multimedia data such as audio and moving images by using a mobile terminal such as a mobile phone. The i-mode provided by NTT Mobile Communication Network Corporation (NTT DoCoMo) is a pioneering example. However, since a mobile terminal is required to reduce power consumption, size, cost, and weight in practice, for example, in order to play a moving image on a mobile terminal, the conventional moving image playback system When considering the application of 600 to a mobile terminal, it is difficult to suitably apply 600 due to the problems described above.
[0021]
Therefore, the present invention has been made by focusing on such unresolved problems of the conventional technology, and aims to reduce power consumption, reduce size, reduce cost, and improve processing speed, It is an object of the present invention to provide a moving image reproduction system and a display control device that can be suitably applied to a video game.
[0022]
[Means for Solving the Problems]
As a result of intensive studies, the present inventors have focused on the fact that the output bit rate of the DSP 150 is extremely high as a cause of the large power consumption. The output bit rate of the variable length decoding unit 40 and the output bit rate of the inverse quantization When comparing the output bit rate, the output bit rate of the IDCT unit 44, and the output bit rate of the RGB conversion unit 46, the output bit rate was found to be variable length decoding unit 40, inverse quantization unit 42, IDCT unit 44, and It has been found that the height gradually increases in the order of the RGB converter 46. Therefore, in order to reduce the output bit rate of the DSP 150, a part of the circuit constituting the DSP 150 (the variable length decoding unit 40, the inverse quantization unit 42, the IDCT unit 44, or the RGB conversion unit 46) is provided on the LCD driver 250 side. I came to the conclusion that I should move. In this case, from the viewpoint of reducing the output bit rate, it is preferable to preferentially move from a circuit having a higher output bit rate.
[0023]
Based on such a conclusion, in order to achieve the above object, the moving picture reproduction system according to claim 1 of the present invention comprises: a variable length decoding means for performing variable length decoding on compressed moving image data; An inverse quantization means for performing inverse quantization on the data from the means; an inverse discrete cosine transform means for performing an inverse discrete cosine transform on the data from the inverse quantization means to generate frame data; Frame data storage means for storing frame data previously input from the discrete cosine transform means; and motion compensation for performing motion compensation on the frame data from the inverse discrete cosine transform means with reference to the frame data in the frame data storage means. Means for displaying frame data from the inverse discrete cosine transform means or frame data from the motion compensation means. A dye conversion unit for performing a dye conversion so as to be a displayable dye system, decoding the compressed moving image data, and reproducing the moving image on the display unit based on the decoded frame data. A decoding device that decodes the compressed moving image data, and a display control device that performs display control of the display unit based on data from the decoding device, are connected by a data transmission medium, and the display control device is , The inverse quantization means, the inverse discrete cosine transform means, the frame data storage means, the motion compensation means and the dye conversion means, at least the dye conversion means, the frame data from the dye conversion means The decoding device is configured to display the variable length decoding unit, the inverse quantization unit, and the inverse discrete cosine transform unit. , Among the frame data storage means and said motion compensation means comprises at least the variable length decoding unit.
[0024]
With such a configuration, in the decoding device, when the compressed moving image data is provided, the variable length decoding unit performs variable length decoding on the compressed moving image data.
When variable-length decoding is performed, operations by the inverse quantization means, the inverse discrete cosine transform means, and the motion compensation means are performed. These operations are performed by any one of the decoding device and the display control device, or a device other than those devices. Done in Specifically, in the case where decoding is performed without referring to the frame data in the frame data storage unit, when the variable length decoding is performed, the data from the variable length decoding unit is dequantized by the inverse quantization unit. Is performed, and inverse discrete cosine transform is performed on the data from the inverse quantization means by the inverse discrete cosine transform means to generate frame data. On the other hand, the frame data from the inverse discrete cosine transform means is stored in the frame data storage means.
[0025]
In the display control device, when the inverse discrete cosine transform is performed, the dye conversion unit performs the dye conversion so that the display unit can display the frame data from the inverse discrete cosine transform unit so that the display unit can display the dye data. The frame data from the conversion means is displayed on the display means.
Also, when decoding with reference to the frame data of the frame data storage means, when variable length decoding is performed, the inverse quantization means performs inverse quantization on the data from the variable length decoding means, The inverse discrete cosine transform unit performs an inverse discrete cosine transform on the data from the inverse quantization unit to generate frame data, and the motion compensation unit refers to the frame data in the frame data storage unit to perform inverse discrete cosine transform. Motion compensation is performed on the frame data from the cosine transform means. On the other hand, the frame data from the inverse discrete cosine transform means or the frame data from the motion compensation means is stored in the frame data storage means.
[0026]
In the display control device, when the motion compensation is performed, the dye conversion unit performs the dye conversion on the frame data from the motion compensation unit so that the display unit becomes a displayable dye system. The frame data is displayed on the display.
Here, the decoding device may be configured by a combination of hardware such as a CPU or a DSP and software that defines its operation, or may be configured only by hardware such as a logic.
[0027]
Further, the frame data storage means stores the frame data by all means and at all times, and stores the frame data by an external input or the like during the operation of the present system without storing the frame data in advance. It is something that has become. Hereinafter, the same applies to the display control device according to the third aspect.
[0028]
Further, the inverse quantization means, the inverse discrete cosine transform means, the frame data storage means or the motion compensation means may be provided in any one of the decoding device and the display control device, or a device other than these devices. Examples of the form by these combinations include the following.
As a first mode, the display control device includes a dye conversion unit, and the decoding device includes a variable length decoding unit, an inverse quantization unit, an inverse discrete cosine conversion unit, a frame data storage unit, a motion compensation unit, Means.
[0029]
As a second mode, the display control device includes a frame data storage unit, a motion compensation unit, and a dye conversion unit, and the decoding device includes a variable length decoding unit, an inverse quantization unit, an inverse discrete cosine Conversion means.
As a third mode, the display control device includes an inverse discrete cosine transform unit, a frame data storage unit, a motion compensation unit, and a dye conversion unit, and the decoding device includes a variable length decoding unit, an inverse quantum Means.
[0030]
As a fourth mode, the display control device has an inverse quantization means, an inverse discrete cosine transform means, a frame data storage means, a motion compensation means, and a dye conversion means, and the decoding device has a variable length It has decoding means.
As a fifth mode, in the second mode, not only the frame data storage means and the motion compensation means are provided in the display control device, but also the motion compensation means is provided in the display control device, and the frame data storage means is provided in the decoding device. Alternatively, conversely, the frame data storage means may be provided in the display control device, and the motion compensation means may be provided in the decoding device.
[0031]
As a sixth form, in the first to fifth forms, all of the inverse quantization means, the inverse discrete cosine transform means, the frame data storage means and the motion compensation means are provided in the decoding device or the display control device. Instead, some or all of the inverse quantization means, inverse discrete cosine transform means, frame data storage means and motion compensation means may be provided in a device other than the decoding device and the display control device.
[0032]
Further, in the moving image reproducing system according to claim 2 according to the present invention, in the moving image reproducing system according to claim 1, the display control device includes the frame data storage unit, the motion compensation unit, and the dye conversion unit. The decoding device has the variable length decoding means, the inverse quantization means, and the inverse discrete cosine transform means, and transmits the frame data from the inverse discrete cosine transform means to the data transmission medium. The data is output to the display control device via the display control device.
[0033]
With such a configuration, when decoding without reference to the frame data in the frame data storage unit, when the compressed moving image data is given, the decoding device performs variable-length decoding on the compressed moving image data. Variable length decoding is performed, inverse quantization is performed on the data from the variable length decoding means by the inverse quantization means, and inverse discrete cosine is performed on the data from the inverse quantization means by the inverse discrete cosine transform means. The conversion is performed to generate frame data. Then, the frame data from the inverse discrete cosine transform means is output to the display control device via the data transmission medium.
[0034]
In the display control device, when the frame data is input, the dye conversion unit performs dye conversion on the frame data from the inverse discrete cosine conversion unit so that the display unit can display the dye system. Is displayed on the display means. On the other hand, the frame data from the inverse discrete cosine transform means is stored in the frame data storage means.
[0035]
Further, when decoding with reference to the frame data in the frame data storage means, in the decoding device, when the compressed moving image data is given, the variable length decoding means performs variable length decoding on the compressed moving image data, The inverse quantization means performs inverse quantization on the data from the variable length decoding means, and the inverse discrete cosine transform means performs an inverse discrete cosine transform on the data from the inverse quantization means to obtain frame data. Is generated. Then, the frame data from the inverse discrete cosine transform means is output to the display control device via the data transmission medium.
[0036]
In the display control device, when the frame data is input, the motion compensation unit performs motion compensation on the frame data from the inverse discrete cosine transform unit with reference to the frame data in the frame data storage unit. The dye conversion is performed on the frame data from the motion compensator so as to be a dye system that can be displayed by the display, and the frame data from the dye converter is displayed on the display. On the other hand, the frame data from the inverse discrete cosine transform means or the frame data from the motion compensation means is stored in the frame data storage means.
[0037]
On the other hand, in order to achieve the above object, a display control device according to claim 3 of the present invention comprises: a variable length decoding unit that performs variable length decoding on compressed moving image data; Inverse quantizing means for performing inverse quantization on the data, inverse discrete cosine transform means for performing inverse discrete cosine transform on the data from the inverse quantizing means to generate frame data, and inverse discrete cosine transform means. Frame data storage means for storing previously input frame data; motion compensation means for performing motion compensation on frame data from the inverse discrete cosine transform means with reference to frame data in the frame data storage means; It becomes a dye system that can be displayed by the display means for the frame data from the discrete cosine transform means or the frame data from the motion compensation means. A dye conversion means for performing a dye conversion, decoding the compressed moving image data, an apparatus applied to a moving image reproduction system for reproducing a moving image on the display means based on the decoded frame data, The variable length decoding means, the inverse quantization means, the inverse discrete cosine transform means, the frame data storage means, the motion compensation means and the dye conversion means, at least the dye conversion means, Is displayed on the display means.
[0038]
With such a configuration, in the moving image reproducing system, when decoding without referring to the frame data in the frame data storage unit, when the compressed moving image data is given, the variable length decoding unit The data from the variable length decoding means is inversely quantized by the inverse quantization means, and the inverse discrete cosine transform means performs inverse discrete on the data from the inverse quantization means. Cosine transform is performed to generate frame data. Then, the dye conversion unit performs dye conversion on the frame data from the inverse discrete cosine conversion unit so that the display unit becomes a displayable dye system, and the frame data from the dye conversion unit is displayed on the display unit. You. On the other hand, the frame data from the inverse discrete cosine transform means is stored in the frame data storage means.
[0039]
In the display control device according to the present invention, at least the operation by the dye conversion means is performed among such operations in the moving image reproduction system.
Further, in the moving image reproducing system, when decoding with reference to the frame data in the frame data storage unit, when the compressed moving image data is given, the variable length decoding unit performs variable length decoding on the compressed moving image data. The inverse quantization means performs inverse quantization on the data from the variable length decoding means, and the inverse discrete cosine transform means performs an inverse discrete cosine transform on the data from the inverse quantization means. Data is generated. Then, the frame data from the inverse discrete cosine transform means is output to the display control device via the data transmission medium. Then, the motion compensation unit refers to the frame data in the frame data storage unit, and performs motion compensation on the frame data from the inverse discrete cosine transform unit. On the other hand, dye conversion is performed so that the display means becomes a displayable dye system, and the frame data from the dye conversion means is displayed on the display means. On the other hand, the frame data from the inverse discrete cosine transform means or the frame data from the motion compensation means is stored in the frame data storage means.
[0040]
In the display control device according to the present invention, at least the operation by the dye conversion means is performed among such operations in the moving image reproduction system.
Here, the variable length decoding means, the inverse quantization means, the inverse discrete cosine transform means, the frame data storage means or the motion compensation means may be provided in the display control device according to the present invention or other devices. Examples of the form by these combinations include the following.
[0041]
As a first mode, a display control device according to the present invention includes a dye conversion unit, and another device (for example, a decoding device) includes a variable length decoding unit, an inverse quantization unit, and an inverse discrete cosine transform. Means, frame data storage means, and motion compensation means.
As a second mode, a display control device according to the present invention includes a frame data storage unit, a motion compensation unit, and a dye conversion unit, and the other devices include a variable length decoding unit, an inverse quantization unit And an inverse discrete cosine transform unit.
[0042]
As a third mode, a display control device according to the present invention includes an inverse discrete cosine transform unit, a frame data storage unit, a motion compensation unit, and a dye conversion unit. Means and an inverse quantization means.
As a fourth mode, a display control device according to the present invention includes an inverse quantization unit, an inverse discrete cosine transform unit, a frame data storage unit, a motion compensation unit, and a dye conversion unit. The device has variable length decoding means.
[0043]
As a fifth mode, in the second mode, not only the frame data storage means and the motion compensation means are provided in the display control device according to the present invention, but also the motion compensation means is provided in the display control device according to the present invention. The data storage means may be provided in another device, or conversely, the frame data storage means may be provided in the display control device according to the present invention, and the motion compensation means may be provided in another device.
[0044]
Further, a display control device according to a fourth aspect of the present invention is the display control device according to the third aspect, further comprising the frame data storage unit, the motion compensation unit, and the dye conversion unit.
With such a configuration, when decoding without reference to the frame data in the frame data storage means, when the frame data is input from the inverse discrete cosine transform means, the pigment conversion means causes Dye conversion is performed on the frame data so that the display means becomes a displayable dye system, and the frame data from the dye conversion means is displayed on the display means. On the other hand, the frame data from the inverse discrete cosine transform means is stored in the frame data storage means.
[0045]
When decoding with reference to the frame data in the frame data storage means, when the frame data is input from the inverse discrete cosine transform means, the motion compensation means refers to the frame data in the frame data storage means to perform inverse discrete The motion compensation is performed on the frame data from the cosine conversion means, and the dye conversion means performs the dye conversion on the frame data from the motion compensation means so that the display means can display the dye system. The frame data from the conversion means is displayed on the display means. On the other hand, the frame data from the inverse discrete cosine transform means or the frame data from the motion compensation means is stored in the frame data storage means.
[0046]
According to a fifth aspect of the present invention, in the display control device according to the fourth aspect, the frame data storage means is a built-in memory built in the device.
With such a configuration, the frame data from the inverse discrete cosine transform means is stored in a built-in memory built in the display control device according to the present invention.
[0047]
The display control device according to a sixth aspect of the present invention is the display control device according to any one of the third to fifth aspects, wherein the display means stores display data in accordance with a dye system that can be displayed. Data storage means, comprising display data output means for outputting the display data of the display data storage means to the display means, to write the frame data from the dye conversion means to the display data storage means, The display data storage means further includes an input terminal for writing data from outside.
[0048]
With this configuration, the frame data from the dye conversion unit is written to the display data storage unit, and the display data output unit outputs the display data in the display data storage unit to the display unit.
When characters and still images are displayed on the display means, the display data may be input from the input terminal. When the display data is input from the input terminal, the input display data is written to the display data storage.
[0049]
Further, the display control device according to claim 7 of the present invention is applied to a portable terminal in the display control device according to any one of claims 3 to 6.
With such a configuration, in the portable terminal, the moving image is reproduced by the display control device according to the present invention.
[0050]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an embodiment of a moving image reproducing apparatus according to the present invention.
In the present embodiment, as shown in FIG. 1, a moving picture reproducing system and a display control device according to the present invention reproduce a moving picture on LCD 300 by decoding MPEG data in a coding method conforming to MPEG in a portable terminal. Applied for the case.
[0051]
Next, the configuration of a moving image reproducing system 500 to which the present invention is applied will be described with reference to FIG. FIG. 1 is a block diagram showing a configuration of a moving image reproducing system 500 to which the present invention is applied. Note that the MPEG data adopts a conventional MPEG-compliant code format.
As shown in FIG. 1, the moving image reproducing system 500 is configured by connecting a DSP 100 that decodes MPEG data and an LCD driver 200 that controls display of the LCD 300 based on data from the DSP 100 via a signal line 198. .
[0052]
The DSP 100 includes a variable length decoding unit 40 that decodes MPEG data using a variable length Huffman code, an inverse quantization unit 42 that performs inverse quantization on data from the variable length decoding unit 40, and an inverse quantization unit. And an IDCT unit 44 that performs inverse discrete cosine transform on the data from the unit 42 to generate frame data, and outputs the frame data from the IDCT unit 44 to the LCD driver 200 via a signal line 198. It has become.
[0053]
The LCD driver 200 includes a reference frame memory 54 which is a built-in memory for storing the frame data from the DSP 100 as reference frame data, and a motion compensation for the frame data from the DSP 100 by referring to the frame data in the reference frame memory 54. , An RGB conversion unit 46 that performs dye conversion on the frame data from the DSP 100 or the frame data from the motion compensation unit 52, and a display that stores the frame data from the RGB conversion unit 46 as display data. It comprises a memory 48 and a display data output unit 50 for outputting display data of the display memory 48 to the LCD 300.
[0054]
Next, the operation of the above embodiment will be described.
In MPEG, there are three types: I picture, P picture, and B picture. Therefore, in the moving picture reproduction system 500, decoding is performed according to the I picture, P picture, and B picture, respectively. Specifically, it operates as follows.
When an I picture is reproduced, in the DSP 100, the given MPEG data is decoded by the variable length decoding unit 40 using a variable length Huffman code, and the inverse quantization unit 42 converts the MPEG data into data from the variable length decoding unit 40. On the other hand, inverse quantization is performed. The IDCT unit 44 performs an inverse discrete cosine transform on the data from the inverse quantization unit 42 to generate frame data. The frame data from the IDCT unit 44 is transmitted to the LCD driver 200 via the signal line 198. Is output.
[0055]
In the LCD driver 200, when frame data is input from the DSP 100, the input frame data is stored in the reference frame memory 54 and output to the RGB converter 46. Then, the YUV component of the frame data from the DSP 100 is dye-converted into the RGB component by the RGB conversion unit 46, and the frame data from the RGB conversion unit 46 is written to the display memory 48 as display data, and the display data output unit 50 The display data of the display memory 48 is output to the LCD 300.
[0056]
When a P picture is reproduced, in the DSP 100, the given MPEG data is decoded by a variable length Huffman code by a variable length decoding unit 40, and the data from the variable length decoding unit 40 is decoded by an inverse quantization unit 42. On the other hand, inverse quantization is performed. The IDCT unit 44 performs an inverse discrete cosine transform on the data from the inverse quantization unit 42 to generate frame data. The frame data from the IDCT unit 44 is transmitted to the LCD driver 200 via the signal line 198. Is output.
[0057]
In the LCD driver 200, when the frame data is input from the DSP 100, the motion compensation unit 52 refers to the previous frame data in the reference frame memory 54, and calculates the difference value of each block of the current frame input from the DSP 100 and the current reference value. The pixel values of the blocks of the frame are added, stored in the reference frame memory 54, and output to the RGB converter 46. Then, the YUV component of the frame data from the motion compensator 52 is converted to the RGB component by the RGB converter 46, and the frame data from the RGB converter 46 is written into the display memory 48 as display data, and the display data output unit Due to 50, the display data of the display memory 48 is output to the LCD 300.
[0058]
When a B picture is reproduced, in the DSP 100, the given MPEG data is decoded by the variable length Huffman code by the variable length decoding unit 40, and the data from the variable length decoding unit 40 is decoded by the inverse quantization unit 42. On the other hand, inverse quantization is performed. The IDCT unit 44 performs an inverse discrete cosine transform on the data from the inverse quantization unit 42 to generate frame data. The frame data from the IDCT unit 44 is transmitted to the LCD driver 200 via the signal line 198. Is output.
[0059]
In the LCD driver 200, when the frame data is input from the DSP 100, the motion compensation unit 52 refers to the previous / next frame data in the reference frame memory 54 and refers to the difference value of each block of the current frame input from the DSP 100. The pixel values of the blocks of the previous / next frame are added and output to the RGB conversion unit 46. Then, the YUV component of the frame data from the motion compensator 52 is converted to the RGB component by the RGB converter 46, and the frame data from the RGB converter 46 is written into the display memory 48 as display data, and the display data output unit Due to 50, the display data of the display memory 48 is output to the LCD 300.
[0060]
【Example】
Next, an example of the above embodiment will be described.
In the present embodiment, taking as an example a case where a portable terminal receives MPEG data at 64-128 [kbps] and reproduces a moving image with an accuracy of 8 bits per pixel, the power consumption is reduced as compared with the conventional case. Is explained.
[0061]
First, how the power consumption is reduced in the output stage of the DSP 100 will be described.
When receiving MPEG data at 64 to 128 [kbps], it is necessary to give priority to speed over image quality. Therefore, on the transmission side, moving image data should be generated so that effective blocks do not appear as much as possible in P pictures or B pictures. Compress. As a result, only about 20% of the effective blocks appear in the whole. From these characteristics, the output bit rate of the IDCT unit 44 is 0.91 [Mbps] on average, and the output bit rate of the motion compensation unit 52 is 4.5 [Mbps] on average. Since the output bit rates of the RGB conversion unit 46 and thereafter do not depend on the type of picture, the output bit rate of the RGB conversion unit 46 is 9.1 [Mbps], and the output bit rate of the display data output unit 50 is 36.5. [Mbps].
[0062]
Therefore, in the case of the present invention, the output bit rate of the DSP 100 is the output bit rate of the IDCT unit 44, and is 0.91 [Mbps]. Since the DSP 100 consumes power according to the output bit rate, the power consumption at the output stage is approximately 1 [mW] in the above example. In the present invention, since the motion compensation unit 52 and the RGB conversion unit 54 are provided in the LCD driver 200 instead of being provided in the DSP 100, the power consumption of the LCD driver 200 is approximately 2 [ mW].
[0063]
On the other hand, in the conventional case, the output bit rate of the DSP 150 is the output bit rate of the RGB conversion unit 46, and therefore, is 9.1 [Mbps]. Since the DSP 150 consumes power according to the output bit rate, in the case of the above example, the power consumption at the output stage is approximately 10 [mW].
Next, how the power consumption is reduced inside the DSP 100 will be described.
[0064]
In the conventional case, the DSP 150 requires about 20% of processing capacity to execute the processing of the variable length decoding unit 40, and reduces the processing capacity by about 20% to execute the processing of the inverse quantization unit 42 and the IDCT unit 44. The processing required by the motion compensator 52 requires about 40% of the processing capacity, and the processing performed by the RGB converter 46 requires about 20% of the processing capacity. As a result, in the case of the above example, the clock supplied to the DSP 150 is about 80 [MHz], and the power consumption inside the DSP 150 is about 80 [mW].
[0065]
On the other hand, in the case of the present invention, the DSP 100 is not provided with the motion compensation unit 52 and the RGB conversion unit 46, so that the processing capability as a whole is 40% of that of the conventional DSP 150. Therefore, when the same processing is performed, the clock of the DSP 100 can be reduced to 40% of that of the conventional DSP 150. As a result, in the case of the above example, the clock supplied to the DSP 150 can be set to about 40 [MHz], and the power consumption inside the DSP 150 is about 40 [mW].
[0066]
Therefore, according to the present invention, the power of 9 [mW] can be reduced at the output stage of the DSP 100 and the power of 40 [mW] can be reduced inside the DSP 100 as compared with the related art. Therefore, even if the increase of 2 [mW] in the LCD driver 200 is considered, the power of 47 [mW] can be reduced as a whole.
[0067]
As described above, in the present embodiment, the DSP 100 includes the variable length decoding unit 40, the inverse quantization unit 42, and the IDCT unit 44, and the LCD driver 200 includes the motion compensation unit 52 The frame memory 54 and the RGB converter 46 are configured.
As a result, the output bit rate of the DSP 100 can be reduced, so that power consumption at the output stage of the DSP 100 can be reduced. Further, since the number of clocks supplied to the DSP 100 can be reduced, the power consumption can be reduced inside the DSP 100.
[0068]
Therefore, power consumption can be reduced to some extent as compared with the related art. Thereby, it can be applied to a mobile terminal relatively suitably.
Further, in the present embodiment, the reference frame memory 54 is provided in the LCD driver 200 as a built-in memory.
As a result, as compared with the case where an external memory is adopted, much space for providing the reference frame memory 54 is not required, and a minimum memory capacity required for storing the reference frame data is secured. Can reduce costs to some extent. Further, since writing and reading of data can be performed at the same time, writing of a plurality of data can be performed at the same time, or reading of a plurality of data can be performed at the same time, the processing speed can be relatively improved.
[0069]
Therefore, size reduction, cost reduction, and improvement in processing speed can be achieved to some extent as compared with the related art. Thereby, it can be applied to a mobile terminal relatively suitably.
In the above embodiment, the MPEG data corresponds to the compressed moving image data according to claim 1 or 3, the DSP 100 corresponds to the decoding device according to claim 1 or 3, and the LCD driver 200 corresponds to the claim 1 or 3. The LCD 300 corresponds to the display means, and the signal line 198 corresponds to the data transmission medium according to the first or second aspect. Further, the variable length decoding unit 40 corresponds to the variable length decoding unit according to claim 1, 2, or 3, and the inverse quantization unit 42 corresponds to the inverse quantization unit according to claim 1, 2, or 3. The IDCT unit 44 corresponds to the inverse discrete cosine transform unit of the present invention. Further, the reference frame memory 54 corresponds to the frame data storage unit according to claims 1 to 5, the motion compensation unit 52 corresponds to the motion compensation unit according to claims 1 to 4, and the RGB conversion unit 46 corresponds to It corresponds to the dye conversion means described in items 1 to 4.
[0070]
In the above-described embodiment, the LCD driver 200 is configured by the motion compensation unit 52, the reference frame memory 54, and the RGB conversion unit 46. However, with such a configuration, only a moving image is displayed on the LCD 300. In order to display anything other than moving images such as characters and still images on the LCD 300, for example, the following configuration may be used.
[0071]
That is, the LCD driver 200 further includes an input terminal for writing data to the display memory 48 from outside. With such a configuration, when the CPU, the ROM, and the RAM are connected to a bus, the input side of the DSP 100 and the input terminal of the LCD driver 200 are connected to the bus. Accordingly, the CPU outputs MPEG data to the DSP 100 when playing back a moving image on the LCD 300, and inputs the display data to the LCD driver 200 when displaying anything other than moving images such as characters and still images on the LCD 300. If output to the terminal, any other than a moving image such as a moving image and a character or a still image can be displayed on the LCD 300.
[0072]
Further, in the above embodiment, the function including the variable length decoding unit 40, the inverse quantization unit 42, and the IDCT unit 44 is realized by the DSP 100. However, the present invention is not limited to this. It may be realized by hardware.
Further, in the above embodiment, as shown in FIG. 1, the moving image reproduction system and the display control device according to the present invention are configured to decode the MPEG data in the portable terminal into a moving image on the LCD 300 by decoding the MPEG data using an encoding method conforming to the MPEG. Although the present invention has been applied to the case of reproduction, the present invention is not limited to this, and can be applied to other cases without departing from the gist of the present invention. For example, the present invention can be applied to a device other than a portable terminal such as a desktop personal computer, and can also be applied to a method other than an encoding method conforming to MPEG.
[0073]
【The invention's effect】
As described above, according to the moving image reproduction system according to the first or second aspect of the present invention, an effect is obtained that power consumption can be reduced to some extent as compared with the related art. As a result, there is also obtained an advantage that the present invention can be applied to a mobile terminal relatively suitably.
[0074]
On the other hand, according to the display control device according to claims 3 to 7 of the present invention, an effect is obtained that the power consumption can be reduced to some extent as compared with the related art. As a result, there is also obtained an advantage that the present invention can be applied to a mobile terminal relatively suitably. Further, according to the display control device according to the fifth aspect of the present invention, it is possible to obtain an effect that it is possible to reduce the size, reduce the cost, and improve the processing speed to some extent as compared with the related art. As a result, an effect that the present invention can be more suitably applied to a portable terminal can be obtained.
[0075]
Further, according to the display control device of the sixth aspect of the present invention, there is obtained an effect that not only moving images but also moving images such as characters and still images can be displayed on the display means.
Further, according to the display control device of the seventh aspect of the present invention, it is possible to obtain an effect that a moving image can be advantageously reproduced in a portable terminal in terms of power consumption, miniaturization, cost, and processing speed. .
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a moving image playback system 500 to which the present invention has been applied.
FIG. 2 is a diagram illustrating a hierarchy of a code format conforming to MPEG.
FIG. 3 is a block diagram illustrating a configuration of a moving image compression apparatus that performs image compression by an encoding method conforming to MPEG.
FIG. 4 is a block diagram illustrating a configuration of a moving image reproduction system 600 that performs image decoding by an encoding method based on MPEG.
[Explanation of symbols]
100,150 DSP
200, 250 LCD driver
300 LCD
40 Variable Length Decoding Unit
42,22 inverse quantization unit
44,24 IDCT part
46 RGB converter
48 display memory
50 Display data output unit
52,26 motion compensator
54, 55, 28 Reference frame memory
400 Image compression device
10 YUV converter
12 Motion search unit
14 Motion prediction unit
16 DCT section
18 Quantization unit
20 Variable length code section

Claims (7)

Variable-length decoding means for performing variable-length decoding on the compressed moving image data; inverse-quantizing means for performing inverse quantization on the data from the variable-length decoding means; and data from the inverse-quantizing means. Inverse discrete cosine transform means for performing inverse discrete cosine transform to generate frame data, frame data storage means for storing frame data previously input from the inverse discrete cosine transform means, and frame data in the frame data storage means. A motion compensation unit for performing motion compensation on the frame data from the inverse discrete cosine transform unit, and a display unit for displaying the frame data from the inverse discrete cosine transform unit or the frame data from the motion compensation unit. Dye conversion means for performing dye conversion so as to be a possible dye system, and decodes the compressed moving image data. A system for playing the video on the display means based on the frame data obtained by decoding,
A decoding device that decodes the compressed moving image data, and a display control device that performs display control of the display unit based on data from the decoding device, connected by a data transmission medium,
The display control device includes at least the dye conversion unit among the inverse quantization unit, the inverse discrete cosine conversion unit, the frame data storage unit, the motion compensation unit, and the dye conversion unit, and the dye conversion unit To display the frame data from the display means,
The decoding device is characterized by having at least the variable length decoding unit among the variable length decoding unit, the inverse quantization unit, the inverse discrete cosine transform unit, the frame data storage unit, and the motion compensation unit. Video playback system. In claim 1,
The display control device has the frame data storage unit, the motion compensation unit, and the dye conversion unit,
The decoding device includes the variable-length decoding unit, the inverse quantization unit, and the inverse discrete cosine transform unit, and displays the frame data from the inverse discrete cosine transform unit via the data transmission medium. A moving image playback system characterized by outputting to a control device. Variable-length decoding means for performing variable-length decoding on the compressed moving image data; inverse-quantizing means for performing inverse quantization on the data from the variable-length decoding means; and data from the inverse-quantizing means. Inverse discrete cosine transform means for performing inverse discrete cosine transform to generate frame data, frame data storage means for storing frame data previously input from the inverse discrete cosine transform means, and frame data in the frame data storage means. A motion compensation unit for performing motion compensation on the frame data from the inverse discrete cosine transform unit, and a display unit for displaying the frame data from the inverse discrete cosine transform unit or the frame data from the motion compensation unit. Dye conversion means for performing dye conversion so as to be a possible dye system, and decodes the compressed moving image data. An apparatus for applying a video reproducing system for reproducing the video on the display means based on the frame data obtained by decoding,
The variable length decoding unit, the inverse quantization unit, the inverse discrete cosine transform unit, the frame data storage unit, the motion compensation unit and the dye conversion unit, at least the dye conversion unit, from the dye conversion unit A display control device for displaying the frame data on the display means. In claim 3,
A display control device comprising: the frame data storage unit; the motion compensation unit; and the dye conversion unit. In claim 4,
The display control device, wherein the frame data storage means is a built-in memory built in the device. In any one of claims 3 to 5,
A display data storage unit that stores display data in accordance with a dye system that can be displayed by the display unit; and a display data output unit that outputs display data of the display data storage unit to the display unit. To write the frame data from the display data storage means,
The display control device further comprises an input terminal for externally writing data to the display data storage means. In any one of claims 3 to 6,
A display control device characterized by being applied to a mobile terminal.

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