JP2006101322A - Information processing apparatus and program used for the processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an information processing apparatus capable of smoothly performing decoding of a moving picture stream. <P>SOLUTION: A video reproduction application program 201 detects a present load amount of a computer 10. When the computer 10 reaches no high load state, the video reproduction application program 201 performs all decode processing (ordinary decode processing) including weighted prediction. When the computer 10 reaches the high load state, the video reproduction application program 201 performs particular decode processing for simplifying weighted prediction. Decoding and reproduction of moving picture data can smoothly and continuously be performed without incurring a defect such as a frame drop and extremely slowing down of an object motion by simplifying the weighted prediction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an information processing apparatus such as a personal computer and a decoding program used in the apparatus.

  In recent years, personal computers having the same AV function as audio / video (AV) devices such as DVD (Digital Versatile Disc) players and TV devices have been developed.

  In such a personal computer, a software decoder that decodes a compression-coded moving image stream by software is used. By using a software decoder, it is possible to decode a compression-coded moving image stream by a processor (CPU) without providing dedicated hardware.

As a system using a software decoder, after decoding a stream encoded by motion compensation interframe predictive encoding such as MPEG2 and MPEG4, an output image signal obtained by the decoding is improved for image quality improvement. A system for performing post-filter processing is known (see, for example, Patent Document 1). In this system, in order to prevent the occurrence of frame dropping, a technique for reducing the time required for the post filter process by changing the filter process to be executed in the post filter process is used.
JP 2001-245294 A

  However, the post filter process is a process performed outside the decoder. For this reason, if a delay occurs in the decoding process itself of the software decoder, even if the time required for the post filter process is reduced, it is not possible to prevent the occurrence of frame dropping.

  Recently, as a next-generation moving image compression coding technology, H.264 has been introduced. The H.264 / AVC (AVC: Advanced Video Coding) standard has attracted attention. H. The H.264 / AVC standard is a compression encoding technique that is more efficient than conventional compression encoding techniques such as MPEG2 and MPEG4. For this reason, H.C. Each of the encoding process and the decoding process corresponding to the H.264 / AVC standard requires a larger amount of processing than the conventional compression encoding techniques such as MPEG2 and MPEG4.

  Therefore, H.H. In a personal computer designed to decode a video stream compressed and encoded by the H.264 / AVC standard by software, if the system load increases, the decoding process itself will be delayed, thereby enabling smooth video playback. There is a risk that it cannot be executed.

  The present invention has been made in consideration of the above-described circumstances, and an object thereof is to provide an information processing apparatus and a program that can smoothly decode a moving image stream.

  In order to solve the above-described problems, the present invention generates an inter-frame prediction signal corresponding to a decoding target screen from one or more decoded reference screens in an information processing apparatus that decodes a compressed and encoded moving image stream. Motion compensation means, weighted prediction means for executing weighted prediction processing for generating a weighted prediction signal by multiplying the interframe prediction signal by a weighting factor, and decoding the prediction error signal corresponding to the decoding target screen Means for decoding the decoding target screen by adding a weighted prediction signal corresponding to the target screen; load detecting means for detecting the load of the information processing apparatus; and the load detected by the load detecting means is a predetermined reference Control that executes processing for setting the weighted prediction signal to zero according to the value of the weighting coefficient when the value is larger than the value Characterized by comprising a stage.

  According to the present invention, it is possible to smoothly decode a moving image stream.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, the configuration of an information processing apparatus according to an embodiment of the present invention will be described with reference to FIG. 1 and FIG. This information processing apparatus is realized as, for example, a notebook personal computer 10.

  FIG. 1 is a front view of the notebook personal computer 10 with the display unit opened. The computer 10 includes a computer main body 11 and a display unit 12. The display unit 12 incorporates a display device composed of an LCD (Liquid Crystal Display) 17, and the display screen of the LCD 17 is positioned substantially at the center of the display unit 12.

  The display unit 12 is attached to the computer main body 11 so as to be rotatable between an open position and a closed position. The computer main body 11 has a thin box-shaped casing, and a keyboard 13, a power button 14 for turning on / off the computer 1, an input operation panel 15, and a touch pad 16 are arranged on the upper surface. Has been.

  The input operation panel 15 is an input device that inputs an event corresponding to a pressed button, and includes a plurality of buttons for starting a plurality of functions. These button groups also include a TV start button 15A and a DVD (Digital Versatile Disc) start button 15B. The TV activation button 15A is a button for activating a TV function for reproducing and recording broadcast program data such as a digital TV broadcast program. When the TV activation button 15A is pressed by the user, an application program for executing the TV function is automatically activated. The DVD start button 15B is a button for playing back video content recorded on a DVD. When the DVD activation button 15B is pressed by the user, an application program for reproducing video content is automatically activated.

  Next, the system configuration of the computer 10 will be described with reference to FIG.

  As shown in FIG. 2, the computer 10 includes a CPU 111, a north bridge 112, a main memory 113, a graphics controller 114, a south bridge 119, a BIOS-ROM 120, a hard disk drive (HDD) 121, and an optical disk drive (ODD) 122. , A digital TV broadcast tuner 123, an embedded controller / keyboard controller IC (EC / KBC) 124, a network controller 125, and the like.

  The CPU 111 is a processor provided to control the operation of the computer 10, and various types such as an operating system (OS) and a video playback application program 201 loaded from the hard disk drive (HDD) 121 to the main memory 113. Run the application program.

  The video reproduction application program 201 is software for decoding and reproducing the compression-coded moving image data. This video playback application program 201 is an H.264 file. This is a software decoder corresponding to the H.264 / AVC standard. The video playback application program 201 is an H.264 file. A moving image stream (for example, a digital TV broadcast program received by the digital TV broadcast tuner 123, an HD (High) read out from the optical disc drive (ODD) 122) that is compressed and encoded by the encoding method defined in the H.264 / AVC standard. Definition) standard video content, etc.).

  As shown in FIG. 3, the video playback application program 201 includes a load detection module 211, a decode control module 212, and a decode execution module 213.

  The decode execution module 213 is an H.264 implementation. It is a decoder that executes a decoding process defined in the H.264 / AVC standard. The load detection module 211 is a module that detects the load of the computer 10. For example, the load detection module 211 detects the current load amount of the computer 10 by inquiring the current load of the computer 10 to the operating system (OS) 200. The load amount of the computer 10 is determined based on the usage rate of the CPU 111, for example.

  Further, the load amount of the computer 10 can be determined by a combination of the usage rate of the CPU 111 and the usage rate of the memory 113. Usually, in order to smoothly execute the software decoder, a memory having a certain size or more is required. As the memory usage rate of the system increases, the decoding performance of the software decoder decreases due to paging of the OS. Therefore, by detecting the load amount of the computer 10 based on the combination of the usage rate of the CPU 111 and the usage rate of the memory 113, the current load amount of the computer 10 interferes with the execution of the software decoder (high load state). ) Can be more accurately determined.

  The decode control module 212 controls the content of the decoding process executed by the decode execution module 213 according to the load on the computer 10 detected by the load detection module 211.

  Specifically, when the load amount of the computer 10 is equal to or less than a predetermined reference value, the decode control module 212 determines the H.264 standard. The contents of the decoding process to be executed by the decoding execution module 213 are controlled so that the decoding process defined by the H.264 / AVC standard is executed by the CPU 111. On the other hand, when the load amount of the computer 10 is larger than the reference value (high load state), the decode control module 212 determines that the H.264 is in the H.264 standard. The content of the decoding process to be executed by the decoding execution module 213 is controlled so that a part of the decoding process defined in the H.264 / AVC standard is replaced with a process that is omitted or simplified.

  The moving image data decoded by the video playback application program 201 is sequentially written into the video memory 114A of the graphics controller 114 via the display driver 202. As a result, the decoded moving image data is displayed on the LCD 17. The display driver 202 is software for controlling the graphics controller 114.

  The CPU 111 also executes a system BIOS (Basic Input Output System) stored in the BIOS-ROM 120. The system BIOS is a program for hardware control.

  The north bridge 112 is a bridge device that connects the local bus of the CPU 111 and the south bridge 119. The north bridge 112 also includes a memory controller that controls access to the main memory 113. The north bridge 112 also has a function of executing communication with the graphics controller 114 via an AGP (Accelerated Graphics Port) bus or the like.

  The graphics controller 114 is a display controller that controls the LCD 17 used as a display monitor of the computer 10. The graphics controller 114 generates a display signal to be sent to the LCD 17 from the image data written in the video memory (VRAM) 114A.

  The south bridge 119 controls each device on an LPC (Low Pin Count) bus and each device on a PCI (Peripheral Component Interconnect) bus. The south bridge 119 incorporates an IDE (Integrated Drive Electronics) controller for controlling the HDD 121 and the ODD 122. Further, the south bridge 119 has a function of controlling the digital TV broadcast tuner 123 and a function of controlling access to the BIOS-ROM 120.

  The HDD 121 is a storage device that stores various software and data. The optical disk drive (ODD) 123 is a drive unit for driving a storage medium such as a DVD in which video content is stored. The digital TV broadcast tuner 123 is a receiving device for receiving broadcast program data such as a digital TV broadcast program from the outside.

  The embedded controller / keyboard controller IC (EC / KBC) 124 is a one-chip microcomputer in which an embedded controller for power management and a keyboard controller for controlling the keyboard (KB) 13 and the touch pad 16 are integrated. . The embedded controller / keyboard controller IC (EC / KBC) 124 has a function of powering on / off the computer 10 in accordance with the operation of the power button 14 by the user. Furthermore, the embedded controller / keyboard controller IC (EC / KBC) 124 can also power on the computer 10 in accordance with the operation of the TV start button 15A and the DVD start button 15B by the user. The network controller 125 is a communication device that executes communication with an external network such as the Internet.

  Next, the functional configuration of the software decoder realized by the video playback application program 201 will be described with reference to FIG.

  The decode execution module 213 of the video playback application program 201 is an H.264 file. As shown in the figure, the entropy decoding unit 301, the inverse quantization unit 302, the inverse DCT unit (DCT: Discrete Cosine Transform) 303, the addition unit 304, the deblocking filter unit 305, the frame memory 306, a motion vector prediction unit 307, an interpolation prediction unit 308, a weighted prediction unit 309, an intra prediction unit 310, and a mode changeover switch unit 311. H. The H.264 orthogonal transform has integer precision and is different from the conventional DCT, but is referred to as DCT here.

  Each screen (picture) is encoded in units of macroblocks of 16 × 16 pixels, for example. For each macroblock, either the intraframe coding mode (intra coding mode) or the motion compensated interframe prediction coding mode (inter coding mode) is selected.

  In motion-compensated interframe predictive coding mode, motion-predicted interframe prediction signals corresponding to the current picture are generated in a defined shape unit by estimating the motion from the already coded picture (picture). Is done. A prediction error signal obtained by subtracting the motion compensation inter-frame prediction signal from the encoding target screen (picture) is encoded by orthogonal transform (DCT), quantization, and entropy encoding. Further, in the intra coding mode, a prediction signal is generated from a coding target screen (picture), and the prediction signal is encoded by orthogonal transform (DCT), quantization, and entropy coding.

H. In order to further increase the compression rate, the codec corresponding to the H.264 / AVC standard
(1) Motion compensation with higher pixel accuracy (1/4 pixel accuracy) than conventional MPEG (2) Intraframe prediction for efficient intraframe coding (3) Deblocking to reduce block distortion Filter (4) 4x4 pixel integer DCT
(5) A technique such as multi-reference frame (6) weighted prediction that can use a plurality of screens (pictures) at arbitrary positions as a reference screen is used.

  Hereinafter, the operation of the software decoder of FIG. 4 will be described.

  H. A moving image stream compression-encoded according to the H.264 / AVC standard is first input to the entropy decoding unit 301. In addition to encoded image information, motion vector information used in motion-compensated interframe prediction encoding (inter-prediction encoding), intra-frame prediction encoding (intra prediction encoding) Intraframe prediction information used in (encoding), mode information indicating a prediction mode (inter prediction encoding / intra prediction encoding), and the like are included.

  The decoding process is executed in units of macro blocks of 16 × 16 pixels, for example. The entropy decoding unit 301 performs entropy decoding processing such as variable length decoding on the moving image stream, and from the moving image stream, the quantized DCT coefficient, motion vector information (motion vector difference information), intra-frame prediction information, and Separate mode information. In this case, for example, each macroblock in the decoding target screen (picture) is subjected to entropy decoding processing for each block of 4 × 4 pixels (or 8 × 8 pixels), and each block is converted into 4 × 4 (or 8 × 8 pixels) quantized DCT coefficients. The In the following, it is assumed that each block is 4 × 4.

  The motion vector information is sent to the motion vector prediction unit 307. The intra-frame prediction information is sent to the intra prediction unit 310. The mode information is sent to the mode changeover switch unit 311.

  The 4 × 4 quantized DCT coefficients of each decoding target block are converted into 4 × 4 DCT coefficients (orthogonal transform coefficients) by the inverse quantization process by the inverse quantization unit 302. The 4 × 4 DCT coefficients are converted from frequency information into 4 × 4 pixel values by an inverse integer DCT (inverse orthogonal transform) process by the inverse DCT unit 303. This 4 × 4 pixel value is a prediction error signal corresponding to the decoding target block. This prediction error signal is sent to the adding unit 304, where a prediction signal (motion compensation inter-frame prediction signal or intra-frame prediction signal) corresponding to the decoding target block is added, and thereby a 4 × 4 pixel value corresponding to the decoding target block. Is decoded.

  In the intra prediction mode, the intra prediction unit 310 is selected by the mode changeover switch unit 311, and thereby the intraframe prediction signal from the intra prediction unit 310 is added to the prediction error signal. In the inter prediction mode, the weighted prediction unit 309 is selected by the mode changeover switch unit 311, and thereby the motion compensation interframe prediction signal obtained by the motion vector prediction unit 307, the interpolation prediction unit 308, and the weighted prediction unit 309. Is added to the prediction error signal.

  As described above, the process of adding the prediction signal (motion-compensated inter-frame prediction signal or intra-frame prediction signal) to the prediction error signal corresponding to the decoding target screen and decoding the decoding target screen is executed in predetermined block units.

  Each decoded screen (picture) is subjected to deblocking filter processing by the deblocking filter unit 305 and then stored in the frame memory 306. The deblocking filter unit 305 performs a deblocking filter process for reducing block noise on each decoded screen, for example, in units of 4 × 4 pixel blocks. This deblocking filter processing prevents block distortion from being included in the reference image, and thereby block distortion propagates to the decoded image. The amount of processing for the deblocking filter processing is enormous and may occupy 50% of the total processing amount of the software decoder. The deblocking filter process is adaptively executed such that a stronger filtering is performed on a portion where block distortion is likely to occur, and a weak filtering is performed on a portion where block distortion is less likely to occur. The deblocking filter process is realized by a loop filter process.

  Each screen subjected to the deblocking filter processing is read out from the frame memory 306 as an output image frame (or output image field). Each screen (reference screen) to be used as a reference image for motion compensation inter-frame prediction is held in the frame memory 306 for a certain period. H. In motion compensation interframe predictive coding according to the H.264 / AVC standard, a plurality of screens can be used as reference screens. For this reason, the frame memory 306 includes a plurality of frame memory units for storing images for a plurality of screens.

  The motion vector prediction unit 307 generates motion vector information based on the motion vector difference information corresponding to the decoding target block. The interpolation prediction unit 308 generates a motion compensation inter-frame prediction signal from the integer precision pixel group and the quarter pixel precision prediction interpolation pixel group in the reference screen based on the motion vector information corresponding to the decoding target block. To do. A 6-tap filter (six inputs, one output) is used in the generation of the prediction interpolation pixel with 1/4 pixel accuracy. For this reason, it is possible to execute highly accurate predictive interpolation processing considering even high frequency components. However, a large amount of processing is required for motion compensation.

The weighted prediction unit 309 performs weighted motion compensation interframe prediction signals (weighted prediction signals) by executing a process of multiplying the motion compensation interframe prediction signals by a weighting coefficient in units of motion compensation blocks (macroblocks). Is generated. This weighted prediction is a process for predicting the brightness of the decoding target screen. FIG. 5 shows an example of weighted prediction. FIG. 5 shows a case where the macroblock to be decoded uses two images as reference images. The weighted prediction signal is generated by adaptively multiplying the motion compensation prediction signals Y ₀ and Y ₁ by weight coefficients W ₀ and W ₁ . The weighted prediction is performed as follows.

(1) Inter-frame prediction of P (predictive) slice
Assuming that the L0 motion compensated prediction signal is Y ₀ and the weighting coefficient is W ₀ , the weighted prediction unit 309 generates a weighted prediction signal W ₀ Y ₀ . The weight coefficient W ₀ is included in the moving image stream (H.264 stream) from the encoder.

(2) In the case of prediction using only one reference image in a B slice
When the L0 (or L1) motion compensated prediction signal is Y ₀ (or Y ₁ ) and the weighting coefficient is W ₀ (or W ₁ ), the weighted prediction unit 309 performs the weighted prediction signal W ₀ Y ₀ (or W ₁ Y). ₁ ) is generated. The weighting factor W ₀ (or W ₁ ) is included in the H.264 stream.

(3) Bi-predictive prediction of B slice using two reference images
(3-1) Explicit mode
If the L0 and L1 motion compensated prediction signals are Y0 and Y1, the weighting coefficients are W0 and W1, and the offset is D, the weighted prediction unit 309 generates a weighted prediction signal W ₀ Y ₀ + W ₁ Y ₁ + D. The weighting factors W0 and W1 and the offset D are included in the H.264 stream.

(3-2) Implicit mode In the implicit mode, the weighting factors W ₀ , W ₁ and offset D are not included in the H.264 stream from the encoder. When the time distance to the reference image 0 is tb and the time distance to the reference image 1 is td, the weighted prediction unit 309 calculates the weighting factors W0 and W1 and the offset D with the following calculation formula, and weights A prediction signal W ₀ Y ₀ + W ₁ Y ₁ + D is generated.

W1 = tb / td
W0 = 1-W1
D = 0
Such weighted prediction processing can improve the image quality of an image whose brightness changes with time, such as fade-in and fade-out. However, the amount of processing required for software decoding increases accordingly.

  The intra-prediction unit 310 performs intra-screen prediction processing according to the intra-frame prediction information described above, and the pixels in other blocks that are present in the same screen as the decoding target block and are already decoded close to the decoding target block An intra-frame prediction signal is generated from the value. This intra-frame prediction (intra prediction) is a technique for increasing the compression rate using pixel correlation between blocks. In this intraframe prediction, four types including vertical prediction (prediction mode 0), horizontal prediction (prediction mode 1), average value prediction (prediction mode 3), and plane prediction (prediction mode 4) are determined according to the intraframe prediction information. One of the prediction modes is selected in units of intra-frame prediction blocks (for example, 16 × 16 pixels). The frequency with which plane prediction is selected is lower than in other intra-frame prediction modes, but the amount of processing required for plane prediction is greater than the processing amount in any other intra-frame prediction mode.

  In the present embodiment, in order to be able to decode a moving image stream in real time within a time constraint even if the load on the computer 10 increases, all the decoding described with reference to FIG. Processing (hereinafter referred to as normal decoding processing) and special decoding processing are selectively executed. The special decoding process is a decoding process that simplifies the process related to weighted prediction. In the special decoding process, when the value of the weight coefficient is zero or in the vicinity thereof, a process of generating a decoded image from only the prediction error signal with the weighted prediction signal as zero is executed.

  Hereinafter, the procedure of the decoding process executed by the video playback application program 201 will be described with reference to the flowchart of FIG.

  During the execution of the decoding process, the video playback application program 201 periodically and repeatedly executes a process for detecting the current load on the computer 10 by inquiring about the current load on the computer 10 from the OS (step S101). In this step S101, the video playback application program 201 acquires the current usage rate (processor usage rate) of the CPU 111 and the current usage rate (memory usage rate) of the main memory 113 from the OS.

  Then, the video reproduction application program 201 determines whether or not the computer 10 is in a high load state depending on whether or not the current load amount of the computer 10 is larger than a predetermined reference value (step S102). In step S102, for example, the video playback application program 201 determines whether or not the current processor usage rate is larger than a predetermined processor reference usage rate, and the current memory usage rate is a predetermined memory. It is determined whether it is larger than the reference usage rate. If any one of the current processor usage rate and the current memory usage rate is larger than the corresponding reference usage rate, the video playback application program 201 determines that the computer 10 is in a high load state. If both the current processor usage rate and the current memory usage rate are equal to or lower than the corresponding reference usage rate, the video playback application program 201 determines that the computer 10 is not in a high load state.

  If the computer 10 is not in a high load state (NO in step S102), the video playback application program 201 selects the above-described normal decoding process as the decoding process to be executed by the CPU 111, and thereby the series of processes described in FIG. Processing is executed on the CPU 111 (step S103). Unless the computer 10 is in a high load state, that is, unless the decoding performance is deteriorated, the moving image stream is normally decoded by the decoding process.

On the other hand, if the computer 10 is in a high load state (YES in step S102), the video playback application program 201 selects the above-described special decoding process as a decoding process to be executed by the CPU 111, thereby performing a process related to weighted prediction. The simplified decoding process is executed on the CPU 111 (step S104). In the special decoding process of step S104, the video playback application program 201 omits the calculation process of the prediction signal when the weighting factors W ₀ and W ₁ are 0 or near 0. That is, when the weight coefficients W ₀ and W ₁ are 0 or near 0, the video playback application program 201 outputs the weighted prediction signal as zero.

  By simplifying the processing related to weighted prediction, the reproduced image does not exactly match the encoded image, but the processing amount required for software decoding per screen can be greatly reduced. Therefore, even if another program is executed during execution of software decoding and the computer 10 is in a high load state, the moving image data does not cause a problem such as dropped frames or extremely slow movement of the object. Can be smoothly and continuously executed.

  Until the decoding of all the moving image streams is completed, the processes in steps S101 to S104 described above are repeatedly executed (step S105). When the load on the computer 10 decreases due to termination of execution of other programs, the decoding process is switched again from the special decoding process to the normal decoding process.

  Next, the procedure of special decoding processing executed by the video playback application program 201 will be described with reference to the flowchart of FIG.

The video reproduction application program 201 first determines whether or not the weighting factors W ₀ and W ₁ are 0 or near 0 (step S201). In step S201, the video reproduction application program 201, depending on whether Bunch falling within the scope of the weighting factors W _0, W _1, for example -5 to 5, the weighting factor W _0, W _1, 0, or near zero It is determined whether or not. When the weighting factors W ₀ and W ₁ belong to the range from -5 to 5, that is, when the weighting factors W ₀ and W ₁ are 0 or near 0 (YES in step S201), the video playback application program 201 outputs a zero weighted prediction signal without executing the weighted prediction processing (step S202). Then, the video reproduction application program 201 outputs the prediction error signal as a decoded image of the decoding target block without synthesizing (adding) the prediction error signal and the weighted prediction signal (step S203).

On the other hand, if the weighting factors W ₀ and W ₁ are not 0 or not near 0, that is, if the weighting factors W ₀ and W ₁ do not belong to the range from -5 to 5 (NO in step S204), the video The playback application program 201 executes the same weighted prediction process as the normal decoding process to generate a weighted prediction signal (step S204). Then, the video playback application program 201 combines (adds) the prediction error signal and the weighted prediction signal to generate a decoded image of the decoding target block (step S203).

  As described above, according to the present embodiment, when the system is in a heavy load state, the weighted prediction process that requires a large amount of processing is simplified to reduce the load on the system. Smooth video playback can be realized without causing problems such as extremely slow movement of the object.

  Since all the decoding control processes described above are realized by a computer program, the same effect as that of the present embodiment can be easily realized simply by introducing this computer program into a normal computer through a computer-readable storage medium. be able to.

  Further, the software decoder of the present embodiment can be applied not only to a personal computer but also to a PDA, a mobile phone, and the like.

  Further, the present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine a component suitably in different embodiment.

The perspective view showing the general view of the computer concerning one embodiment of the present invention. The block diagram which shows the system configuration | structure of the computer of FIG. The block diagram which shows the function structure of the video reproduction application program used with the computer of FIG. The block diagram which shows the structure of the software decoder implement | achieved by the video reproduction application program of FIG. The figure for demonstrating the weighted prediction performed by the video reproduction application program of FIG. FIG. 4 is a flowchart showing a procedure of decoding processing executed by the video playback application program of FIG. 3. FIG. 4 is a flowchart showing a procedure of special decoding processing executed by the video playback application program of FIG. 3.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Computer, 111 ... CPU, 113 ... Memory, 114 ... Graphics controller, 201 ... Load detection module, 212 ... Decode control module, 213 ... Decode execution module, 301 ... Entropy decoding part, 302 ... Inverse quantization part, 303 ... Inverse DCT unit, 304 ... adding unit, 305 ... deblocking filter unit, 306 ... frame memory, 307 ... motion vector prediction unit, 308 ... interpolation prediction unit, 309 ... weighted prediction unit, 310 ... intra prediction unit, 311 ... mode Changeover switch part.

Claims (9)

In an information processing apparatus for decoding a compression-coded moving image stream,
Motion compensation means for generating an inter-frame prediction signal corresponding to a decoding target screen from one or more decoded reference screens;
Weighted prediction means for performing weighted prediction processing for generating a weighted prediction signal by multiplying the interframe prediction signal by a weighting factor;
Means for adding the weighted prediction signal corresponding to the decoding target screen to the prediction error signal corresponding to the decoding target screen and decoding the decoding target screen;
Load detecting means for detecting a load of the information processing apparatus;
Control means for executing a process of setting the weighted prediction signal to zero according to the value of the weighting coefficient when the load detected by the load detecting means is larger than a predetermined reference value. Information processing apparatus.   The control means determines whether the weight coefficient value belongs to a range from a first reference value smaller than zero to a second reference value larger than zero, and the weight coefficient value is Means for executing the processing for setting the weighted prediction signal to zero when belonging to the range, and means for executing the weighted prediction processing by the weighted prediction means when the value of the weighting coefficient does not belong to the range The information processing apparatus according to claim 1, further comprising:   The information processing apparatus according to claim 1, wherein the weighting factor is included in the moving image stream. The moving image stream includes information indicating a time distance between the decoding target screen and the reference screen,
The information processing apparatus according to claim 1, further comprising means for calculating the weighting factor based on the information.   2. The information processing apparatus according to claim 1, wherein the load detecting means includes means for inquiring of an operating system executed on the information processing apparatus about a load of the information processing apparatus.   The information processing apparatus according to claim 1, wherein the load detection unit includes a unit that detects a load of the information processing apparatus based on a usage rate of a processor provided in the information processing apparatus.   The load detecting means includes means for detecting a load on the information processing device based on a usage rate of a processor provided in the information processing device and a usage rate of a memory provided in the information processing device. The information processing apparatus according to claim 1. A program for causing a computer to execute a decoding process for decoding a moving image stream,
A procedure for causing the computer to execute motion compensation processing for generating an inter-frame prediction signal corresponding to a decoding target screen from one or more decoded reference screens;
A procedure for causing the computer to execute a weighted prediction process for generating a weighted prediction signal by multiplying the interframe prediction signal by a weighting factor;
A procedure for causing the computer to execute a process of decoding the decoding target screen by adding a weighted prediction signal corresponding to the decoding target screen to a prediction error signal corresponding to the decoding target screen;
A procedure for causing the computer to execute a process of detecting a load on the computer;
A procedure for causing the computer to execute a control process for executing the process of setting the weighted prediction signal to zero according to the value of the weighting coefficient when the detected load is greater than a predetermined reference value. The program characterized by doing.   The procedure for causing the computer to execute the control process includes a process of determining whether or not the value of the weight coefficient belongs to a range from a first reference value smaller than zero to a second reference value larger than zero. A procedure for causing the computer to execute, a procedure for causing the computer to execute processing for setting the weighted prediction signal to zero when the value of the weighting factor belongs to the range, and a value of the weighting factor not belonging to the range The program according to claim 8, further comprising: a step for causing the computer to execute the weighted prediction process.

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