JP2011155474A - Encoding apparatus and system using thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an encoding apparatus which prevents the occurrence of remarkable quality differences between frames and a system using thereof. <P>SOLUTION: An amount-of-code calculating part 13 calculates the amount of codes for data encoding for each frame, and a bit rate management part 14 calculates and manages the difference value between a target value and the amount of codes, which is calculated by the amount-of-code calculating part 13 to assign the total storage value to a specified number of frames. Then, an encoding apparatus 15 encodes the specified number of frames to be the target value assigned by the bit rate management part 14. Thereby, the occurrence of remarkable quality differences between frames can be prevented. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a technique for encoding audio, video, and the like, and more particularly, to an encoding apparatus that prevents a difference in quality between frames and a system using the same.

  In recent years, various apparatuses for encoding audio and video have been developed. VBR (Variable Bit Rate) is used in coding schemes such as MPEG (Moving Picture Experts Group) -AUDIO and MPEG-VIDEO used in such apparatuses.

  In the VBR, a difference value obtained by subtracting the actual bit rate (calculated code amount) from the planned bit rate (target value) of the current frame is calculated and stored. If the difference value is larger than “0”, that is, if there is a surplus in the bit rate, the surplus is added to the planned bit rate of the next frame to add the advantage for each frame. To do. As technologies related to this, there are inventions disclosed in the following Patent Documents 1 to 3.

  Patent Document 1 aims to provide an encoding method that suppresses image quality deterioration due to scene characteristics, and suppresses variations in image quality in the entire image, with respect to an input image. A step of calculating encoding difficulty level information representing the difficulty level of encoding of the frame group; a step of calculating encoding difficulty level information indicating the encoding difficulty level of each frame constituting the frame group; and A step of calculating a target code amount; a step of calculating a target code amount of each frame constituting the frame group; and encoding in each frame by controlling the generated code amount to be equal to or less than the calculated target code amount. Encoding step for outputting encoded data. As a result, it is possible to suppress variations in image quality due to scene differences such as scenes with intense motion, scenes with scene changes, and scenes with little motion, and it is possible to suppress significant image quality degradation such as scene transitions.

  Patent Document 2 aims to suppress quantization distortion and keep the bit rate at an average value. The increase bit amount determination unit determines an increase bit amount to be used for quantization when the processing block type from the block type determination unit is a short type. The bit control unit adds the average bit allocation amount to the determined increase bit amount, outputs an allowable bit amount usable for quantization to the bit amount / error amount control unit, and also obtains the previous code obtained from the multiplexing unit. The difference between the used bit amount and the average bit allocation amount when processing a frame is obtained. Then, addition with the bit amount accumulated so far is performed, and when the value exceeds a predetermined upper limit value, the accumulated bit release amount is output to the multiplexing unit.

  Patent Document 3 aims to provide an image encoding device and the like that can prevent deterioration in image quality due to a drastic decrease in the number of assignable bits and a sudden change in frame rate when scenes that are difficult to encode are continuous. . The frame group target bit number deriving unit reads out the total number of bits in frame group units that can be allocated to the remaining frames from the storage unit, updates the subframe by subtracting the generated bit number used in the previous frame encoding, and Sent to the number derivation unit. The next frame target bit number deriving unit calculates a target value of the number of bits to be allocated to the next frame based on the received total number of bits and the remaining number of frames considering the frame rate value Rf. The average frame bit number deriving unit calculates an average value of the number of bits allocated to the past frame. The calculation unit multiplies the average value of the calculated number of bits by a predetermined coefficient, compares this with the target value of the number of bits, selects the larger value, and transmits it to the quantization step deriving unit.

JP 7-288810 A JP 2003-066998 A JP 2004-007619 A

  In the above-described VBR, unless the surplus is accumulated until the current frame, the advantage is not added in the current frame, so it cannot be said that the bit rate increase / decrease control is performed efficiently. There is a problem that it cannot be assured in an embedded device that strictly guarantees.

  In addition, when data with a small total number of frames is encoded, there is a high possibility that a significant difference in quality between frames will occur. For example, it is possible that the encoding of the frame is finished without using the surplus bit rate.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an encoding apparatus and a system using the same that prevent a significant difference in quality between frames. is there.

  According to an embodiment of the present invention, an encoding device is provided. The code amount calculation unit calculates the code amount when data is encoded for each frame. The bit rate management unit calculates and manages a difference value from the target value and the code amount calculated by the code amount calculation unit, and assigns the accumulated total value to a predetermined number of frames. Then, the encoding unit encodes a predetermined number of frames so as to be the target value after being assigned by the bit rate management unit.

  According to another embodiment of the present invention, a system for encoding and storing music or video data and decoding and reproducing the encoded music or video data is provided. The hard disk stores encoded data. The data processing unit encodes music or video data and stores it in the hard disk. The data processing unit decodes and reproduces the encoded music or video data stored in the hard disk. The display processing unit displays display data related to music or video data reproduced by the data processing unit. The encoding device calculates a difference value from a code amount calculation unit that calculates a code amount when encoding music or video data for each frame and a code amount calculated by the target value and the code amount calculation unit. A bit rate management unit that manages and allocates the accumulated total value to a predetermined number of frames, and an encoding unit that encodes the predetermined number of frames so as to be a target value after being allocated by the bit rate management unit.

  According to this embodiment, the encoding unit encodes a predetermined number of frames so as to be the target value after being assigned by the bit rate management unit, so that there is a significant difference in quality between frames. It becomes possible to prevent.

It is a block diagram which shows the structural example of the encoding apparatus in the 1st Embodiment of this invention. 3 is a block diagram for explaining the configuration of a bit rate management unit 14 in more detail. FIG. It is a flowchart for demonstrating the process sequence of the encoding apparatus in the 1st Embodiment of this invention. It is a flowchart for demonstrating the process sequence of the encoding apparatus in the 2nd Embodiment of this invention. It is a block diagram which shows the structural example of the portable music player system in the 3rd Embodiment of this invention.

(First embodiment)
FIG. 1 is a block diagram showing a configuration example of an encoding apparatus according to the first embodiment of the present invention. This encoding apparatus includes an SDRAM (Synchronous Dynamic Random Access Memory) 11 used as an input buffer, a data acquisition control unit 12, a code amount calculation unit 13, a bit rate management unit 14, and an encoding unit 15. And SDRAM 16 used as an output buffer.

  The SDRAM 11 is a buffer that temporarily stores data to be encoded, for example, music data. The SDRAM 16 is a buffer that temporarily holds the encoded data. SDRAMs 11 and 16 may be composed of different semiconductor memories, or may be composed of the same semiconductor memory, and the area may be divided into an input buffer and an output buffer.

  In response to the capture request signal from the bit rate management unit 14, the data acquisition control unit 12 acquires the data held in the SDRAM 11 for one frame and outputs it to the code amount calculation unit 13. The code amount calculation unit 13 calculates the code amount when the data for one frame received from the data acquisition control unit 12 is encoded.

  The bit rate management unit 14 calculates a surplus of the bit rate (code amount) based on the code amount calculated by the code amount calculation unit 13 and the target value, and distributes the surplus to a plurality of frames. Manage the assigned total value. Note that the target value is stored in advance in the SDRAM 11 or the like.

  Also, the bit rate management unit 14 outputs a capture request signal to the data acquisition control unit 12 when acquiring the next frame. Further, the bit rate management unit 14 receives the code amount when it is actually encoded by the encoding unit 15, manages the surplus bit rate (code amount) as a carry-over amount, and assigns it to the subsequent frame groups It also has a function.

  The encoding unit 15 encodes the frame data so as to be the target value (code amount) after the surplus is allocated by the bit rate management unit 14, and writes the encoded data to the SDRAM 16.

  FIG. 2 is a block diagram for explaining the configuration of the bit rate management unit 14 in more detail. The bit rate management unit 14 includes a threshold determination unit 21 and a planned bit rate management unit 22.

  The threshold determination unit 21 calculates the surplus of the bit rate (code amount) by subtracting the code amount calculated by the code amount calculation unit 13 from the target value of the frame, and accumulates it as a difference value. Then, when the accumulated difference value (accumulated total value) is equal to or smaller than the threshold value, the threshold determination unit 21 acquires the capture request signal so as to acquire the data of the next frame and output it to the code amount calculation unit 13. Output to the control unit 12. The threshold determination unit 21 may hold the threshold in advance, or the threshold determination unit 21 may read the threshold stored in the SDRAM 11 or the like.

  The planned bit rate management unit 22 manages the accumulated total value output from the threshold value determination unit 21. When the surplus bit rate (code amount) is accumulated, the plan bit rate management unit 22 stores the accumulated value in one or more frames. Allocate the surplus.

  FIG. 3 is a flowchart for explaining the processing procedure of the coding apparatus according to the first embodiment of the present invention. First, the data acquisition control unit 12 acquires data for one frame from the data stored in the SDRAM 11 and outputs the data to the code amount calculation unit 13 (S11). Then, the data acquisition control unit 12 counts the number of acquired frames by incrementing the acquired frame number F by “1” (S12).

  Next, the code amount calculation unit 13 calculates the code amount (B) of the data for one frame acquired by the data acquisition control unit 12, and outputs the code amount (B) to the threshold determination unit 21 (S13). ).

  The threshold determination unit 21 calculates the difference value (C) by subtracting the code amount (B) calculated by the code amount calculation unit 13 from the target value (A) of the frame. Then, the threshold determination unit 21 adds the difference value (C) to the accumulated total value (D) (S14).

  Next, the threshold determination unit 21 determines whether or not the acquired frame number F matches the acquireable frame number N (S15). Note that the number N of frames that can be acquired is obtained based on the capacity of the SDRAM 11 that is an input buffer. For example, the number of frames that can be stored in the SDRAM 11 may be N, or a value that is smaller than the number of frames that can be stored in the SDRAM 11 may be set in consideration of the processing load due to the distribution processing of the excess code amount.

  If the acquired frame number F matches the acquireable frame number N (S15, Yes), the process proceeds to step S18. If they do not match (S15, No), it is determined whether there is next input data (S16). If there is no next input data (S16, No), the process proceeds to step S18.

  When there is next input data (S16, Yes), the threshold determination unit 21 outputs a capture request signal to the data acquisition control unit 12 so as to acquire the data of the next frame and output it to the code amount calculation unit 13. Then, the threshold determination unit 21 determines whether or not the accumulated total value (D) is larger than the threshold (S17). An arbitrary value is set as the threshold value. For example, when the accumulated total value (D) is allocated to F frames, an upper limit value that cannot be allocated may be set.

  If the accumulated total value (D) is smaller than the threshold (S17, No), the process returns to step S11 and the subsequent processing is repeated. If the accumulated total value (D) is larger than the threshold (S17, Yes), the threshold determination unit 21 determines whether the accumulated total value (D) is larger than “0” (S18).

  If the accumulated total value (D) is “0” or less (S18, No), the process proceeds to step S20 as it is. If the accumulated total value (D) is greater than “0” (S18, Yes), the planned bit rate management unit 22 assigns the accumulated total value (D) evenly to all the acquired F frames. (S19), the process proceeds to step S20.

  In step S <b> 20, the encoding unit 15 encodes F frames so that the accumulated value (D) is evenly assigned by the planned bit rate management unit 22 to a target value (code amount).

  Note that evenly allocated as described herein is a method of allocating the accumulated total value (D) to F frames strictly evenly. Also, for example, if there is an accumulated total value (D) of 5F + 1 for F frames, it is substantially uniform by assigning 5 to F frames and assigning the rest to any one frame. May be assigned. That is, the equality of the present embodiment does not mean in a narrow sense but has a broad meaning including a substantially equal allocation method.

  Then, the threshold determination unit 21 calculates a difference value (C) obtained by subtracting the actual code amount (B) from the target value (A) for the F frames, and sums them. Then, the difference value (C) is added to the accumulated total value (D) (S21). Finally, the acquisition frame counter F is reset (S22), and the process ends.

  As described above, according to the coding apparatus in the present embodiment, the planned bit rate management unit 22 assigns the accumulated total value (D) evenly to the F frames, so that the quality between frames is improved. A significant difference can be prevented from occurring, and the bit rate increase / decrease control can be efficiently performed.

(Second Embodiment)
The configuration of the encoding apparatus according to the second embodiment of the present invention is the same as the configuration of the encoding apparatus according to the first embodiment shown in FIGS. Therefore, detailed description of overlapping configurations and functions will not be repeated.

  FIG. 4 is a flowchart for explaining the processing procedure of the encoding apparatus according to the second embodiment of the present invention. First, the data acquisition control unit 12 acquires data for one frame from the data stored in the SDRAM 11, and outputs the data to the code amount calculation unit 13 (S31). Then, the data acquisition control unit 12 counts the number of acquired frames by incrementing the acquired frame number F by “1” (S32).

  Next, the code amount calculation unit 13 calculates the code amount (B) of the data for one frame acquired by the data acquisition control unit 12, and outputs the code amount (B) to the threshold determination unit 21 (S33). ).

  The threshold determination unit 21 calculates the difference value (C) by subtracting the code amount (B) calculated by the code amount calculation unit 13 from the target value (A) of the frame. Then, the threshold determination unit 21 adds the difference value (C) to the accumulated total value (D) (S34).

  Next, the threshold determination unit 21 determines whether or not the acquired frame number F matches the acquireable frame number N (S35). If the acquired frame number F matches the acquireable frame number N (S35, Yes), the process proceeds to step S38. If they do not match (S35, No), it is determined whether there is next input data (S36). If there is no next input data (S36, No), the process proceeds to step S38.

  When there is next input data (S 36, Yes), the threshold determination unit 21 outputs a capture request signal to the data acquisition control unit 12 so as to acquire data of the next frame and output it to the code amount calculation unit 12. Then, the threshold determination unit 21 determines whether or not the accumulated total value (D) is larger than the threshold (S37).

  If the accumulated total value (D) is smaller than the threshold value (S37, No), the process returns to step S31 and the subsequent processing is repeated. If the accumulated total value (D) is larger than the threshold value (S37, Yes), the threshold value determination unit 21 determines whether there is a frame in which the difference value (C) is negative (S38).

  If there is no frame in which the difference value (C) is negative (S38, No), the planned bit rate management unit 22 evenly assigns the accumulated total value (D) to all the acquired F frames (S39). The process proceeds to step S41.

  In addition, if there is a frame in which the difference value (C) is negative (S38, Yes), the planned bit rate management unit 22 applies only to a frame in which the difference value (C) is negative among the acquired F frames. Thus, the accumulated total value (D) is equally allocated (S40), and the process proceeds to step S41.

  In step S <b> 41, the encoding unit 15 encodes the F frames so that the target value (code amount) after the accumulated total value (D) is assigned by the planned bit rate management unit 22.

  Then, the threshold determination unit 21 calculates a difference value (C) obtained by subtracting the actual code amount (B) from the target value (A) for the F frames, and sums them. Then, the difference value (C) is added to the accumulated total value (D) (S42). Finally, the acquisition frame counter F is reset (S43), and the process ends.

  As described above, according to the encoding apparatus in the present embodiment, the planned bit rate management unit 22 assigns the accumulated total value (D) evenly to frames in which the difference value (C) is negative. In addition to the effects described in the first embodiment, it is possible to preferentially allocate a surplus code amount to a frame in which the actual code amount is larger than the target value.

(Third embodiment)
The third embodiment relates to a portable music player system using the encoding device described in the first and second embodiments.

  FIG. 5 is a block diagram showing a configuration example of a portable music player system according to the third embodiment of the present invention. This portable music player system includes a central processing unit (CPU) 41, a read only memory (ROM) 42, a RAM 43, a hard disk (HDD) 44, an input processing unit 45, and an external IF 46 that control the entire system. A data processing unit 47, a speaker 48, a display processing unit 49, a display 50, and a media drive 51.

  The CPU 41 reads out various programs stored in the ROM 42 via the internal bus, transfers them to the RAM 43, and executes the programs to control the entire portable music player system. In addition, the CPU 41 performs a process according to a command received from the input processing unit 45 by performing a predetermined arithmetic process.

  The external IF 46 detects the operation of the operation button by the user, and outputs an operation input signal corresponding to the operation to the input processing unit 45. The input processing unit 45 performs predetermined processing according to the operation input signal received from the external IF 46 to convert the operation input signal into a command, and transfers the command to the CPU 41 via the internal bus.

  The data processing unit 47 compresses and encodes the music data given from the media drive 51 and stores it in the hard disk 44. In addition, the data processing unit 47 performs music data reproduction processing in accordance with a user operation.

  When playing music data in response to a user's operation, the CPU 41 outputs a music data playing command to the data processing unit 47 and reads designated music data in the hard disk 44 and transfers it to the data processing unit 47. To do. The data processing unit 47 decodes the music data transferred from the hard disk 44 to reproduce the music data, and causes the speaker 48 to output it. The encoding device described in the first and second embodiments is arranged in the data processing unit 47.

  Further, the CPU 41 generates display data by executing various programs stored in the RAM 43 and transfers the display data to the display processing unit 49, or reads out music-related information (music title) stored in the hard disk 44 for display processing. Forward to the unit 49. The display processing unit 49 causes the display 50 to display music related information and the like according to the display data received from the CPU 41.

  As described above, according to the portable music player system in the present embodiment, the encoding device described in the first and second embodiments is arranged in the data processing unit 47. It is also possible to construct a system that achieves the effects described in the second embodiment.

  In the present embodiment, the music player system (encoding of music data) has been described. However, the encoding apparatus described in the first and second embodiments is also used in the video reproduction system (encoding of video data). It is possible to apply similarly.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  11, 16 SDRAM, 12 Data acquisition control unit, 13 Code amount calculation unit, 14 Bit rate management unit, 15 Coding unit, 21 Threshold determination unit, 22 Planned bit rate management unit, 41 CPU, 42 ROM, 43 RAM, 44 HDD, 45 input processing unit, 46 external IF, 47 data processing unit, 48 speaker, 49 display processing unit, 50 display, 51 media drive.

Claims (6)

A calculation means for calculating a code amount when data is encoded for each frame;
Managing means for calculating and managing a difference value from the target value and the code amount calculated by the calculating means, and assigning the accumulated total value to a predetermined number of frames;
An encoding device including encoding means for encoding the predetermined number of frames so as to be a target value after being assigned by the management means.   The encoding apparatus according to claim 1, wherein the management unit assigns the accumulated total value evenly to all frames for which difference values have been calculated.   The said management means calculates | requires the number of frames when the said accumulation total value becomes larger than a predetermined threshold value, and allocates the said accumulation total value equally with respect to all the frames corresponding to this frame number. Encoding device.   The encoding apparatus according to claim 1, wherein the management unit assigns the accumulated total value evenly to only frames having a negative difference value.   The management means obtains the number of frames when the accumulated total value is larger than a predetermined threshold value, and calculates the accumulated total value only for a frame in which a difference value in a frame corresponding to the frame number is negative. The encoding device according to claim 4, wherein the encoding device is equally allocated. A system for encoding and storing music or video data, decoding and reproducing the encoded music or video data,
Storage means for storing encoded data;
An encoding device that encodes the music or video data and stores the encoded data in the storage unit;
Playback means for decoding and playing back the encoded music or video data stored in the storage means;
Display means for displaying display data related to music or video data reproduced by the reproduction means,
The encoding device includes: a calculating unit that calculates a code amount for each frame when the music or video data is encoded;
Managing means for calculating and managing a difference value from the target value and the code amount calculated by the calculating means, and assigning the accumulated total value to a predetermined number of frames;
Encoding means for encoding the predetermined number of frames so as to be a target value after being assigned by the management means.

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