WO2008007436A1 - Dispositif et procédé de commande de codage d'images - Google Patents

Dispositif et procédé de commande de codage d'images Download PDF

Info

Publication number
WO2008007436A1
WO2008007436A1 PCT/JP2006/314036 JP2006314036W WO2008007436A1 WO 2008007436 A1 WO2008007436 A1 WO 2008007436A1 JP 2006314036 W JP2006314036 W JP 2006314036W WO 2008007436 A1 WO2008007436 A1 WO 2008007436A1
Authority
WO
WIPO (PCT)
Prior art keywords
code amount
bit rate
frame
code
image
Prior art date
Application number
PCT/JP2006/314036
Other languages
English (en)
Japanese (ja)
Inventor
Masato Ohkawa
Original Assignee
Panasonic Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Panasonic Corporation filed Critical Panasonic Corporation
Priority to PCT/JP2006/314036 priority Critical patent/WO2008007436A1/fr
Publication of WO2008007436A1 publication Critical patent/WO2008007436A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
    • H04N19/124—Quantisation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/134—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or criterion affecting or controlling the adaptive coding
    • H04N19/146—Data rate or code amount at the encoder output
    • H04N19/149—Data rate or code amount at the encoder output by estimating the code amount by means of a model, e.g. mathematical model or statistical model
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/134—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or criterion affecting or controlling the adaptive coding
    • H04N19/146—Data rate or code amount at the encoder output
    • H04N19/15—Data rate or code amount at the encoder output by monitoring actual compressed data size at the memory before deciding storage at the transmission buffer
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
    • H04N19/17—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object
    • H04N19/172—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object the region being a picture, frame or field
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/60—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding

Definitions

  • the present invention relates to an image coding control apparatus and an image coding control method, and more specifically
  • the present invention relates to an image code control device and an image code control method capable of controlling the bit rate to a predetermined value or less even when a large amount of code occurs during compression encoding of moving image data It is.
  • the compression code method for moving images uses an intra-frame code method that uses a spatial correlation in one frame, and a frame that uses a temporal correlation between consecutive frames.
  • the amount of code generated when compressing a moving image according to continuously input image data may increase or decrease on the order of several hundred times, so the bit rate of the moving image data that has been compression encoded It is relatively difficult to control the value below a certain value.
  • the variable bit rate can be allocated more effectively than the fixed bit rate method in which the code amount is fixed to a fixed value. The system is said to be advantageous in terms of image quality.
  • variable bit rate when used, it is necessary to pay attention to the following points.
  • the peak bit rate must not exceed the range of the standard specified by each device.
  • the maximum code amount per frame must not exceed the standard range defined by each device.
  • the code bit rate must not exceed the possible recording rate of recording media such as SD memory cards.
  • bit rate and the amount of code may increase drastically when there is a sudden scene change, white noise and! / is assumed.
  • the bit rate of compression-coded moving images is generally controlled by quantization parameters.
  • the amount of code is also suppressed by control using quantization parameters. Since it is difficult to do this, a method of forcibly suppressing the amount of code by using the uncoded information as described above is often employed.
  • This first conventional image compression apparatus performs discrete cosine transform (hereinafter simply referred to as “DCT”) processing on the input digital data of block-unit moving images to obtain time.
  • DCT unit 600 that converts domain data into frequency domain coefficient data (hereinafter referred to as “DCT coefficient”), and a quantum that quantizes the DCT coefficient converted by DCT unit 600 with a predetermined quantum step width.
  • the zigzag scanning unit 602 that rearranges the DCT coefficients quantized by the quantization unit 601 (hereinafter, “quantization coefficient” t ⁇ ⁇ .) In the zigzag scanning order, and the zigzag scanning unit 602 Run-length on the quantum coefficient VLC unit 603 that performs variable length coding (hereinafter referred to simply as “VLC”) processing and outputs the compressed bit stream thus obtained to an output canoffer (not shown).
  • VLC variable length coding
  • the first conventional image compression apparatus further includes an adjustment value determination unit 604 that determines a reduction level of the quantization coefficient corresponding to the frequency component from the quantization coefficients rearranged by the zigzag scanning unit 602, and an adjustment value determination unit 604.
  • the coefficient adjustment unit 605 forcibly reduces the code amount by changing the quantization coefficient after zigzag scanning from the highest corresponding frequency component to 0 according to the reduction level of the quantization coefficient corresponding to the frequency component determined by
  • the adjustment value determination unit 604 suppresses the code amount of one frame to a predetermined value based on the free capacity of the output canoffer that inputs the compressed bit stream output from the VLC unit 603. As described above, the reduction level of the quantization coefficient corresponding to the frequency component is determined, and the overflow of the encoding buffer is prevented.
  • FIG. 8 there is also known an image compression apparatus that suppresses the code amount by reducing the quantization coefficient in accordance with the complexity of the image (see, for example, Patent Document 2).
  • the same reference numerals as those of the first image compression device shown in FIG. 7 are used for the configurations similar to the configurations of the first image compression device. Detailed description will be omitted.
  • This second conventional image compression apparatus includes a DCT unit 600, a quantization unit 601, a zigzag scanning unit 602, a VLC unit 603, an adjustment value determination unit 604, and a coefficient adjustment unit 605.
  • a distribution value calculation unit 706 that calculates the image complexity by calculating the pixel dispersion value in each block in the frame from the input digital data
  • the adjustment value determination unit 604 includes the distribution value calculation unit 604.
  • the reduction level of the quantization coefficient corresponding to the frequency component is determined. The larger the variance value calculated by the variance value calculation unit 706, the more complex the image, and the more the code amount that is generated tends to increase.
  • the reduction level of the quantization coefficient corresponding to the frequency component determined by the unit 604 increases.
  • Patent Document 1 Japanese Patent Laid-Open No. 9-23427
  • Patent Document 2 Japanese Patent Laid-Open No. 2003-259376
  • the technique of reducing the high-frequency component power of the quantization coefficient corresponding to the frequency component based on the free capacity of the output buffer is very effective.
  • the first conventional image compression apparatus can suppress the maximum code amount within a predetermined standard range and avoid buffer overflow, but has only means for suppressing the code amount of the frame. For this reason, there has been a problem that the bit rate cannot be appropriately suppressed when the code amount changes abruptly at the time of compression encoding.
  • the second conventional image compression apparatus a method of reducing the quantization coefficient corresponding to the frequency component from the high frequency component according to the complexity of the digital data of the input moving image is very effective.
  • the second image compression apparatus has a large amount of processing to calculate the complexity of the image, so that it is difficult to apply it to compression encoding processing of moving images that require high-speed processing.
  • the present invention has been made to solve such a problem, predicts a code amount generated from the processing frame, predicts a bit rate using a past code amount, By reducing the quantization coefficient corresponding to the frequency component when it is predicted to exceed the value, an image code controller and image code that realizes bit rate suppression with a simple configuration and a small amount of computation.
  • An object is to provide a dredge control method.
  • An image coding control apparatus for compressing and coding a moving image includes a code amount storage unit for storing a code amount generated in a past frame and a frame being processed, and a frame being processed.
  • a predictive code amount calculating means for calculating a predictive code amount that is finally expected to be generated in the frame being processed based on the generated code amount; and a past code amount stored in the code amount storage unit.
  • a bit rate calculating unit that calculates a bit rate based on a code amount generated in the frame and a predicted code amount predicted to be generated in a currently processed frame calculated by the predicted code amount calculating unit; Bit The bit rate calculated by the rate calculation means is compared with a predetermined threshold value, and the reduction code amount determination means for determining the reduction amount of the quantization coefficient corresponding to the frequency component and the reduction code amount determination means A code amount adjusting means for reducing a quantum coefficient corresponding to a frequency component based on the determined reduction amount is provided.
  • the image code controller of the present invention predicts the code amount generated from the processing frame, predicts the bit rate using the past code amount, and exceeds a predetermined value. If the quantization coefficient corresponding to the frequency component is reduced, the bit rate can be suppressed with a simple configuration and a small amount of calculation.
  • the image coding control apparatus of the present invention may further include a configuration including a reduction code amount adjusting means for adjusting the predetermined threshold.
  • the image code control device of the present invention adjusts the predetermined threshold so as to accelerate the convergence of the bit rate when a change in the code amount is predicted abruptly, and conversely
  • the predetermined threshold can be adjusted so that the control of the code amount is not suddenly controlled by the method of the present invention, so that the code amount changes abruptly during compression encoding.
  • the bit rate can be appropriately suppressed.
  • the prediction code amount calculation means refers to the code amount generated in a predetermined number of past frames stored in the code amount storage unit.
  • the code amount may be calculated, and the image coding control device may further include a reference frame number adjusting unit that adjusts the predetermined number.
  • the image coding control apparatus of the present invention can suppress deterioration of image quality stably and adaptively by performing bit rate control more accurately and more appropriately for the situation.
  • the prediction code amount calculation means includes a macroblock that exceeds a predetermined number of code amounts predicted to be generated in a currently processed frame. Further, the image coding control apparatus may be configured to include a reference macroblock number adjusting unit that adjusts the predetermined number.
  • the image code control device of the present invention can suppress deterioration of image quality stably and adaptively by performing bit rate control more accurately and more suitable for the situation.
  • the predicted code amount calculation means calculates a code amount predicted to occur in a currently processed frame by skipping a predetermined number of macroblocks. Furthermore, the image coding control apparatus may have a configuration including skipped macroblock number adjusting means for adjusting the predetermined number.
  • the reduction code amount determination means can calculate the reduction level of the quantization coefficient corresponding to the frequency component more quickly and with a load.
  • the image code key control device of the present invention can suppress the deterioration of the image quality stably and adaptively by performing the bit rate control more accurately and more suitable for the situation.
  • the reduction code amount determination means determines a reduction amount of the quantization coefficient corresponding to the frequency component based on a predetermined increase / decrease amount, and further, the image code
  • the key control device may have a configuration including an increase / decrease amount determining means for adjusting the predetermined number.
  • the image code control device of the present invention adjusts the predetermined increase / decrease amount so as to accelerate the convergence of the bit rate when a change in the code amount is predicted suddenly, and reversely
  • the predetermined increase / decrease amount can be adjusted so that the control of the code amount is not suddenly controlled. Even in this case, the bit rate can be appropriately suppressed.
  • the image coding control method of the present invention includes a code amount storage step for storing the code amount generated in the past frame and the frame being processed, and a code amount storing step in the frame being processed. Based on the generated code amount! /, A predicted code amount calculating step for calculating a predicted code amount that is expected to occur finally in the frame being processed, and a past frame stored in the code amount storing step A bit rate calculating step for calculating a bit rate based on the generated code amount and a predicted code amount predicted to be generated in the currently processed frame calculated in the predicted code amount calculating step; and the bit rate calculating step.
  • the bit rate calculated in step (b) is compared with a predetermined threshold value to determine a reduction amount of a quantization coefficient corresponding to a frequency component, and a reduction code amount determination step determined by the reduction code amount determination step. It has a configuration including a code amount adjustment step for reducing the quantization coefficient corresponding to the frequency component based on the reduction amount.
  • the image coding control method of the present invention predicts the code amount generated from the processing frame, predicts the bit rate using the past code amount, and exceeds a predetermined value.
  • the bit rate can be suppressed with a simple configuration and a small amount of calculation.
  • the image code key control method of the present invention may further include a configuration including a reduction code amount adjustment step for adjusting the predetermined threshold value.
  • the image coding control method of the present invention adjusts the predetermined threshold so as to accelerate the convergence of the bit rate when a change in the code amount is predicted abruptly.
  • the predetermined threshold value can be adjusted by the method of the present invention so that the control of the code amount suppression is not abruptly applied. Even in this case, the bit rate can be appropriately suppressed.
  • the image code key control method of the present invention in the prediction code amount calculation step, the code amount generated in a predetermined number of past frames stored in the code amount storage unit is referred to The prediction code amount is calculated, and the image coding control method may further include a reference frame number adjustment step of adjusting the predetermined number.
  • the image code key control device of the present invention can control the deterioration of image quality stably and adaptively by performing the bit rate control more accurately and more suitable for the situation. Togashi.
  • the prediction code amount calculation step A code amount predicted to occur in a frame being processed is calculated based on a code amount generated in a macro block exceeding a predetermined number, and the image encoding control method further includes a reference macro for adjusting the predetermined number. You may have the structure provided with the block number adjustment step.
  • the image coding control method of the present invention suppresses deterioration of image quality stably and adaptively by performing bit rate control more accurately and more appropriately for the situation. It is out.
  • the predictive code amount calculation step a code amount predicted to occur in a currently processed frame is calculated by skipping a predetermined number of macroblocks. Furthermore, the image coding control method may include a skipped macroblock number adjustment step for adjusting the predetermined number.
  • the image coding control method of the present invention suppresses deterioration of image quality stably and adaptively by performing bit rate control more accurately and more appropriately for the situation. It is out.
  • the reduction code amount determination step determines a reduction amount of a quantization coefficient corresponding to a frequency component based on a predetermined increase / decrease amount, and further, the image The sign control method may have a configuration including an increase / decrease amount determining step for adjusting the predetermined number.
  • the image coding control method of the present invention adjusts the predetermined increase / decrease amount so as to accelerate the convergence of the bit rate when a change in the code amount is predicted abruptly, and conversely If the change in code amount is small, the predetermined increase / decrease amount can be adjusted so that the control of the code amount suppression is not performed suddenly, so that the code amount changes rapidly during compression encoding. In addition, the bit rate can be appropriately suppressed.
  • the recording medium of the present invention has a configuration in which an image code key control program for causing a computer to execute the processing procedure of the image code key control method described above is stored.
  • the recording medium storing the image coding control program of the present invention predicts the code amount generated by the processing frame force, and uses the past code amount to change the bit rate.
  • the bit rate can be suppressed with a simple configuration and a small amount of calculation.
  • a mobile communication system of the present invention has a configuration in which the image code key control device described above is provided.
  • the mobile communication system of the present invention predicts the code amount generated from the processing frame, predicts the bit rate using the past code amount, and is predicted to exceed a predetermined value.
  • the bit rate can be suppressed with a simple configuration and a small amount of calculation.
  • the present invention can provide an image coding control apparatus and an image coding control method that can suppress the bit rate with a simple configuration and a simple configuration with a simple configuration.
  • FIG. 1 shows an image code key control apparatus according to a first embodiment of the present invention.
  • the image coding control apparatus performs discrete cosine transform (hereinafter simply referred to as “DCT”) on input digital data of block-unit moving images. ) Performs processing and converts the time domain data into frequency domain coefficient data (hereinafter referred to as “DCT coefficient”), and the DCT coefficient converted by the DCT section 100 has a predetermined quantization step width.
  • DCT discrete cosine transform
  • quantization coefficients t ⁇ ⁇ .
  • VLC Variable length coding
  • the code amount memory unit 104 constituting the code amount storage unit of the present invention for saving the signal amount, and the current processing based on the accumulated generated code amount generated in the currently processed frame saved in the code amount memory unit 104
  • Predictive code amount calculation means 105 that predicts the final code amount that is predicted to be finally generated in the middle frame, and the code amount and predictive code amount calculation means that were generated in the past frame saved
  • the DCT unit 100 performs DCT conversion that is performed in a generally known moving image encoding process such as MPEG, and converts the input digital data of the moving image in the spatial domain to the DCT coefficient in the frequency domain. Convert.
  • the encoding process is performed in units of a plurality of blocks called macroblocks for one frame image. For example, in MPEG-4, processing is performed in units of 16 ⁇ 16 pixel macroblocks.
  • MPEG-4 processing is performed in units of 16 ⁇ 16 pixel macroblocks.
  • the DCT processing and the processing such as quantization, zigzag scanning, and VLC described later are basically performed in units of macroblocks.
  • Quantization section 101 divides each DCT coefficient in the macroblock transformed by DCT section 100 by the quantization parameter. Since the specific method follows a general encoding method, detailed description is omitted. Since the compression rate, that is, the amount of code after quantization, is determined by the large quantization parameter, it is one of the important processes in bit rate control. However, depending on the input data, it may not be possible to suppress the amount of code by using only the quantization parameter. In this case, generally, skipping of frames, reduction of the quantization coefficient corresponding to the frequency component, non-signed data When the data with the smallest amount of code called (NotCoded) is output, the method is adopted.
  • the zigzag scanning unit 102 quantizes the quantized quantized coefficients in order from the quantized coefficient corresponding to the DC component to the quantized coefficient corresponding to the higher frequency component, in order of decreasing corresponding frequency components. This is a process of rearranging the coefficients.
  • the specific method follows the general coding method, and after quantization, a lot of high-frequency components remain, so the subsequent run-length coding is performed to increase the compression efficiency.
  • quantization coefficient prediction processing corresponding to frequency components may be performed to further increase the compression efficiency. In such a case, special horizontal and vertical priority scans (reordering) are performed. Do.
  • the VLC unit 103 performs variable-length coding processing by run length that assigns a short code to frequently-occurring coefficient data for the quantized coefficient group rearranged by the zigzag scan unit 102.
  • variable length code encoding processing by run length may be forced to assign a long code to coefficient data that occurs less frequently. For this reason, depending on the input coefficient data, there is a power S that can reduce the compression efficiency. Generally, when the input moving image data is complex, the compression efficiency tends to decrease.
  • the code amount memory unit 104 saves the data amount after VLC processing currently being processed, for example, the cumulative generated code amount of the currently processed frame and the code amount of the past frame.
  • the accumulated code amount of the frame currently being processed and the code amount of the past frame are used to calculate the bit rate.
  • the data configuration of the code amount memory unit 104 is facilitated in order to facilitate data management and bit rate calculation.
  • a ring buffer data structure is preferable.
  • the present invention is not limited to this.
  • the code amount memory unit 104 may be used as a rate control code amount buffer based on a quantum parameter, or may be provided independently.
  • the predicted code amount calculation means 105 predicts the final code amount of the frame currently being processed.
  • the following formula is used as a specific prediction method.
  • PB is the predicted code amount
  • CB is the cumulative code amount generated up to the current processing macroblock
  • NM is the total number of macroblocks in one frame
  • CM is the macroblock number currently being processed, That is, it represents the number of processed macroblocks of the frame.
  • the predicted code amount PB Since the predicted code amount PB is used to calculate the instantaneous bit rate, it may be saved in the code amount memory unit 104.
  • One or more macro blocks may be skipped and calculated at an appropriate timing. In addition, this timing may be determined and determined independently according to the system. As the number of macroblocks to be skipped increases, the adjustment value determining unit 107 can calculate the reduction level quickly with a reduced load.
  • the method for calculating the prediction code amount is not limited to Equation 1 described above, and the prediction code amount may be calculated using another generally known prediction method. Yes.
  • the bit rate calculation means 106 is based on the code amount PB of the past frame stored in the code quantity memory unit 104 and the prediction code quantity PB calculated by the prediction code quantity calculation means 105. Is calculated.
  • the instantaneous bit rate is calculated based on a predetermined number saved in the code amount memory unit 104, that is, the code amount of the past frame of the reference frame number and the current predicted code amount. Specifically, it is calculated as follows.
  • MR represents the instantaneous bit rate, that is, the number of bits per second, where n is the number of frames from the past of the bit rate calculation target to the currently processed frame, and BF is the reference number of frames for bit rate calculation.
  • FR represents the frame rate, ie the number of frames per second,
  • the bit rate calculation reference frame number BF increases as the value of BF increases, and the calculated instantaneous bit rate MR becomes closer to the average bit rate, that is, the target bit rate, and a sudden change in the bit rate is reflected. Also, the smaller the bit rate calculation reference frame number, BF, the smaller the calculated instantaneous bit rate MR will tend to reflect a sudden change in the bit rate, but conversely the control of the amount of code to be reduced may become unstable. There is sex. From this, it is necessary to set the bit rate calculation reference frame number BF to a value suitable for the system. BF may be determined according to the system to be applied.
  • the adjustment value determination unit 107 determines the reduction level of the quantization coefficient corresponding to the frequency component according to the instantaneous bit rate MR calculated by the bit rate calculation means 106. Specifically, it is determined whether or not the instantaneous bit rate MR calculated by the bit rate calculating means 106 exceeds a specific bit rate, that is, a reference threshold value. When it is determined that the instantaneous bit rate MR calculated by the bit rate calculation means 106 exceeds a predetermined threshold, the reduction amount of the quantization coefficient corresponding to the frequency component is increased. Specifically, the quantization coefficient reduction level parameter corresponding to the frequency component is increased.
  • the quantization coefficient output by the zigzag scan unit 102 is only the quantization coefficient corresponding to the direct current component, for example, if there is no reduction coefficient, the current level is maintained. To do. On the contrary, when the instantaneous bit rate MR is smaller than the threshold value, the reduction amount of the quantization coefficient corresponding to the frequency component is reduced. Specifically, the quantization coefficient reduction level parameter corresponding to the frequency component is reduced. If the quantization coefficient corresponding to the frequency component is reduced! / ⁇ ⁇ , that is, if the quantization coefficient reduction level power SO corresponding to the frequency component is SO, the current level is maintained and nothing is done.
  • FIG. 2 shows an image of quantization coefficient reduction corresponding to the frequency component. Fig.
  • the increase / decrease amount of the quantization coefficient reduction level corresponding to the frequency component determined by the adjustment value determination unit 107 is
  • the amount of increase / decrease may be increased in order to accelerate the convergence rate determined according to the system.
  • the coefficient adjustment unit 108 according to the reduction level of the quantization coefficient corresponding to the frequency component determined by the adjustment value determination unit 107, the quantization coefficient corresponding to the frequency component in descending order of the corresponding frequency component Set to 0.
  • the quantization coefficient corresponding to the frequency component in descending order of the corresponding frequency component By reducing the quantization coefficient corresponding to the frequency component in descending order of the corresponding frequency component, the amount of code after VLC processing can be suppressed.
  • the present invention is not limited to setting the quantization coefficient value to be reduced to 0.
  • the code capacity allocated at the time of VLC processing by the VLC unit 103 may be set to any value other than 0 as long as the value can be reduced efficiently.
  • the predicted code amount is not calculated until the currently processed macro block number CM reaches a predetermined start macro block number. Further, in order to facilitate understanding, in the following description, it is assumed that the number of past frames satisfying the bit rate calculation reference frame number BF is already stored in the code amount memory unit 104.
  • step ST300 various initializations are performed at the beginning of the sequence (step ST300). Specifically, the code amount memory unit 104 is initialized and various system variables are initialized. Next Initialize and update the cycle processing for each frame (ST301). Here, necessary initialization is performed for each frame. For example, when the adjustment value determination unit 107 changes the reduction level of the quantization coefficient corresponding to the frequency component, the increase / decrease amount is initialized or updated, and the start macroblock number is initialized or updated. Next, initialization and updating of the process in units of macroblocks are performed (ST302). For example, initialization or updating of the macro block number, initialization or updating of the accumulated code amount (CB) up to the currently processed macro block, and one when the prediction code amount calculation means 105 calculates the prediction code amount. When skipping the above macroblocks, initialize or update the number of macroblocks to skip.
  • CB accumulated code amount
  • the currently processed macroblock is a macroblock to be subjected to code amount prediction (ST303). Specifically, it is determined whether or not the macro block number CM currently being processed is greater than or equal to a predetermined start macro block number, and if the macro block number CM currently being processed is greater than or equal to the start macro block number. If it is determined, the macro block currently being processed is assumed to be a macro block subject to code amount prediction. Furthermore, if the code amount prediction is set to be performed by skipping one or more macroblocks, the current processing is also performed based on the number of macroblocks to be skipped that are initialized or updated in step ST302. It is determined whether or not the macroblock is the target macroblock for code amount prediction.
  • step ST303 When it is determined in step ST303 that the currently processed macroblock is not a macroblock subject to code amount prediction, that is, the currently processed macroblock number CM is less than the start macroblock number.
  • Step ST303 If it is determined in step ST303 that the currently processed macroblock is a macroblock to be subjected to code amount prediction, the current process saved in the code amount memory unit 104 by the prediction code amount calculation unit 105 Prediction code amount calculation processing is performed for predicting the final code amount PB of the currently processed frame based on the accumulated generated code amount CB generated up to the currently processed macroblock of the current frame (ST304). Next, based on the code amount of the past frame saved in the code amount memory unit 104 by the bit rate calculation unit 106 and the final prediction code amount PB of the currently processed frame calculated by the prediction code amount calculation unit 105. Moment A trait is calculated (ST305).
  • the instantaneous bit rate MB power adjustment value thus calculated is determined by the determination unit 107 to determine whether or not the reference threshold is exceeded (ST306), and it is determined that the instantaneous bit rate MB exceeds the reference threshold. In this case, the reduction level of the quantum coefficient corresponding to the frequency component is increased (ST307). Conversely, if it is determined that the instantaneous bit rate MB is less than the reference threshold, the quantization corresponding to the frequency component is performed. Reduce the coefficient reduction level (ST308). Next, normal macroblock processing by the DCT unit 100, the quantization unit 101, and the zigzag scanning unit 102 is executed.
  • the quantization coefficient corresponding to the frequency component in descending order of the corresponding frequency component by the coefficient adjustment unit 108 Is set to 0, and the sign key processing is executed by the VLC unit 103 (ST 309).
  • step ST310 it is determined whether or not processing of one frame is completed. If it is determined that the processing is not completed, the number of the currently processed macroblock is determined. After the increment, step ST303 is returned again to perform macro block periodic processing. If it is determined in step ST310 that the processing of one frame has been completed, the code amount is saved in the code amount memory unit 104 (ST311), and then the process returns to step ST300 and the above processing is performed again until the sequence is completed. continue.
  • the graph shown in FIG. 4 shows the instantaneous bit rate measured by the image coding control apparatus of the present embodiment and the conventional image coding apparatus when the target bit rate is 384 kbps. This is a comparison with the series, and shows the effect of bit rate suppression by the image code key control apparatus of the present embodiment.
  • FIG. 5 shows a comparison between the input image and the image re-decoded after compression encoding in the image encoding control device of this embodiment and the image encoding device of the conventional method. This shows the effect of improving the image quality of a moving image in the image code control device of the present embodiment.
  • the conventional image coding apparatus reduces the quantization coefficient corresponding to the frequency component in particular and performs rate control only on the ⁇ quantization parameter, and when the code amount is extremely increased.
  • the use of uncoded data is assumed.
  • the input image is extremely severe when the first few frames of the black image shown in Fig. 5-A are continuous and the white noise image shown in Fig. 5-B is displayed from the middle.
  • the simulation is performed in the case.
  • Fig. 5-C shows an image that is decoded when using uncoded data, that is, NotCoded, in order to keep the code size of one frame at a specified value. The lower part of the frame leaves uncoded data, that is, a black image that is the previous frame due to NotCoded, which is an unnatural result.
  • the graph shown by the solid line in FIG. 4 shows the instantaneous bit rate measured at the time of compression coding in the image coding control device of the present embodiment.
  • the bit rate is suppressed near the target bit rate even in the case of a white noise image scene where almost no code amount is generated. Recognize.
  • An image decoded again after compression coding by the image code controller of this embodiment is shown in Fig. 5-D. Blurred parts can be seen due to the quantization coefficient reduction corresponding to the frequency components (high frequency component reduction), but there is also a little movement due to frame skipping, and there is no influence of forced code amount suppression due to uncoded data. It can be seen that the impression given to the user has been improved. In actual use, however, the simulation is more severe than the simulation using a human image, and the effect of image quality deterioration is less when the natural image is a target with fewer cases.
  • the present embodiment has been described as the configuration in which the coefficient adjustment unit 108 reduces the quantization coefficient corresponding to the frequency component for the data after the zigzag scan by the zigzag scan unit 102,
  • the present invention is not limited to this.
  • the coefficient adjustment unit reduces the quantization coefficient corresponding to the frequency component with respect to the quantization coefficient quantized by the quantization unit 101, and then the zigzag scanning unit performs zigzag scanning. The same effect can be obtained.
  • the adjustment value determination unit 107 performs quantization corresponding to the frequency component. Initialization or updating of the increase / decrease amount when changing the coefficient reduction level, initialization or updating of the start macroblock number, etc. are performed in step ST301, and the cumulative amount of code generated up to the currently processed macroblock (CB) Initialization or updating of the code, the code amount calculation unit 105 adjusts the start macroblock number for starting the code amount calculation process, or skips one or more macroblocks when calculating the code amount to be predicted.
  • the ability to initialize or update the number of macroblocks to be performed in step ST302 is not limited to this.
  • step ST302 performs initialization or update of the increase / decrease amount when the adjustment value determining unit 107 changes the reduction level of the quantization coefficient corresponding to the frequency component, and initialization or update of the Z or start macroblock number.
  • the increase / decrease in the reduction level and the start block number can be changed in the macro block processing cycle, not the frame processing cycle, so the bit rate control can be performed quickly in response to the input video data. Can be performed.
  • initialization or updating of the accumulated code amount (CB) up to the currently processed macroblock, and one or more macroblocks are calculated when the Z or predictive code amount calculation means 105 calculates the predictive code amount.
  • the number of macroblocks to be skipped may be initialized or updated in step ST301. In this case, the system stably controls the bit rate.
  • the image coding control apparatus predicts the code amount of the frame from the code amount up to the currently processed macroblock, and calculates the instantaneous bit rate from the past code amount and the current code amount. If it exceeds the reference value, it suppresses the amount of code generated by increasing the reduction amount of the quantization coefficient corresponding to the frequency component after quantization, and conversely if it falls below the reference value, the frequency The amount of generated code is increased by reducing the amount of reduction of the quantization coefficient corresponding to the component, so a rapid increase in bit rate is suppressed and the bit rate is controlled so that it falls within the rate specified by the standard. Is possible. If the moving image data exceeds the bit rate and cannot be played back by another device, it is possible to avoid problems such as a malfunction or exceeding the recording rate of the media.
  • the image coding control apparatus of the present embodiment can keep the quantization coefficient range corresponding to the frequency component to be reduced to a minimum by constantly monitoring the instantaneous bit rate, and the bit rate. If there is a margin, reducing the coefficient will minimize image quality degradation. Therefore, frame skipping, which has been used to reduce the bit rate, has a great merit for users with less image quality degradation compared to the case of outputting unsigned data.
  • the code amount is predicted and rate control is performed early, it is possible to prevent a frame with a large code amount from being output suddenly and to stabilize the rate control.
  • the present invention can provide a large effect with a very simple configuration and calculation amount, can provide a low-cost image code control device, and is used in combination with rate control by a general quantization parameter. It is also possible to do.
  • the image code key control device can be incorporated as a mobile terminal, for example, and can be realized as a mobile communication system including the mobile terminal device, for example.
  • the image coding control apparatus can also be realized as a method by software, and the image medium key control according to the present embodiment is read out by reading the recording medium force storing this software. It is also possible to realize an image code key control method executed by the apparatus.
  • the configuration of the image coding control apparatus according to the present embodiment is substantially the same as the configuration of the image coding control apparatus according to the first embodiment, and therefore the first embodiment shown in FIG.
  • the detailed description will be omitted by using the same reference numerals as those of the configuration of the image code control device of the embodiment.
  • the operation of the image coding control apparatus according to the present embodiment is almost the same as the operation of the image coding control apparatus according to the first embodiment, and therefore the image of the first embodiment shown in FIG.
  • the detailed description will be omitted by using the same reference numerals as the steps of the sign control device.
  • the configuration of the image coding control device of the present embodiment is such that the image coding control device of the first embodiment uses the reference frame number adjusting means, the reference macro of the present invention, and the like.
  • the configuration is the same as that provided with a parameter adjustment unit 509 that constitutes a block number adjustment unit, a skipped macroblock number adjustment unit, and an increase / decrease amount determination unit.
  • the parameter adjustment unit 509 refers to the information saved in the code amount memory unit 104 and the like, and operates the predictive code amount calculation unit 105, the bit rate calculation unit 106, and the adjustment value determination unit 107.
  • the prediction code amount calculation means 105 adjusts the position of the macroblock where the prediction code amount calculation processing starts, that is, the adjustment of the start macroblock number, or calculates the prediction code amount.
  • skipping one or more macroblocks adjustment of the number of macroblocks to be skipped, adjustment of the bit rate calculation reference frame number BF in the bit rate calculation means 106, and the quantum value corresponding to the frequency component in the adjustment value determination unit 107
  • the threshold value for reducing the quantization factor and the amount of increase / decrease in the quantization factor reduction level are adjusted! By adjusting these parameters, the optimal quality for the system can be obtained.
  • the parameter adjustment unit 509 observes the transition of the past code amount saved in the code amount memory unit 104, and if a change in the code amount is predicted suddenly, the bit rate convergence The parameter is adjusted so that the amount of code changes little, and conversely, if the change in the amount of code is small, the parameter is adjusted so that the control of the amount of code is not suddenly controlled by the method of the present invention.
  • a difference value is taken every predetermined time with respect to the past code amount saved in the code amount memory unit 104, and when it is determined that the difference value exceeds a predetermined threshold, the bit rate MR
  • the adjustment value determination unit 107 may adjust the threshold value and the reduction level that are used as a reference for reducing the quantization coefficient corresponding to the frequency component so as to accelerate the convergence.
  • bit rate calculation reference frame number BF is simply set to 0.
  • the bit rate calculation means 106 may calculate the instantaneous bit rate MR smaller than the actual bit rate.
  • the parameter adjustment unit 509 performs correction by adjusting the bit rate calculation reference frame number BF.
  • the parameter adjustment unit 509 can stabilize the bit rate control by adjusting the start macroblock number, the number of macroblocks to be skipped, and the like. Even in environments where bit rate control is essential at the expense of image quality due to hardware limitations, it is possible to execute precise bit rate control at any time and focus on the target value in a short time. .
  • the prediction code amount calculation unit 105 uses the prediction code.
  • adjusting the position of the macroblock where the amount calculation process is started that is, adjusting the start macroblock number, or when skipping one or more macroblocks when calculating the prediction code amount, adjusting the number of macroblocks to be skipped
  • Parameter adjustment for adjusting the number of bit rate calculation reference frames BF in the bit rate calculation means 106 and adjusting the threshold value and the reduction level of the quantization coefficient corresponding to the frequency coefficient reduction reference in the adjustment value determination unit 107 By providing the unit 509, in addition to the effect of the image coding control device of the first embodiment, the bit rate control more accurately and more suitable for the situation is performed, so that the image quality can be adaptively adjusted. Can be prevented.
  • the image code control device of the present invention predicts the code amount generated from the processing frame, predicts the bit rate using the past code amount, and determines a predetermined value.
  • the bit rate can be suppressed with a simple configuration and a small amount of calculation.
  • the image coding control apparatus of the present invention can control the bit rate so as not to exceed the level defined in the standard, this maintains compatibility with other devices.
  • the recording rate of SD media can be protected, it is possible to avoid problems as a system, and the bit rate is reduced by reducing the quantization coefficient corresponding to the frequency component. Degradation can be minimized.
  • the image code key control device of the present invention can be incorporated as a mobile terminal, for example, and can also be realized as a mobile communication system including the mobile terminal device, for example.
  • the image coding control apparatus of the present invention can be realized as a method by software, and the image coding key control apparatus according to the present embodiment reads out the recording medium force storing this software. It is also possible to implement an image code key control method to be executed.
  • the present invention predicts the amount of code generated by the processing frame force with a simple configuration and the amount of calculation, predicts the bit rate using the past amount of code, and determines the predetermined amount.
  • an image coding control apparatus and a picture control device that realizes bit rate suppression with a simple configuration by reducing the quantization coefficient corresponding to the frequency component.
  • An image code key control method can be provided and can be applied to various devices such as a digital camera and a portable terminal camera.
  • FIG. 1 is a block diagram showing a configuration of an image coding control apparatus according to a first embodiment of the present invention.
  • FIG. 2 is a frequency executed by the image coding key control apparatus according to the first embodiment. Explanatory drawing showing an image of the quantization coefficient reduction processing corresponding to the component
  • FIG. 3 is a flowchart showing an image code key control method executed by the image code key control device of the first embodiment.
  • FIG. 4 is a graph showing the effect of bit rate suppression in the image code control device of the first embodiment.
  • FIG. 5 is a diagram showing the effect of improving the image quality of a moving image decoded after compression code input by the image code key control device of the first embodiment.
  • FIG. 6 is a block diagram showing a configuration of an image code key control device according to a second embodiment of the present invention.
  • FIG. 7 is a block diagram of a first conventional image compression device.
  • FIG. 8 is a block diagram of a second conventional image compression apparatus.
  • Code amount memory unit (Code amount storage unit)
  • Adjustment value determination unit (reduction code amount determination means)
  • Parameter adjustment unit (reference frame number adjustment means, reference macroblock number adjustment means, skipped macroblock number adjustment means, increase / decrease amount determination means)

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Algebra (AREA)
  • General Physics & Mathematics (AREA)
  • Mathematical Analysis (AREA)
  • Mathematical Optimization (AREA)
  • Pure & Applied Mathematics (AREA)
  • Compression Or Coding Systems Of Tv Signals (AREA)

Abstract

L'invention concerne un dispositif de commande de codage d'images permettant d'obtenir un débit binaire réduit avec une configuration simple et une faible complexité de calcul. Le dispositif de commande de codage d'images, conçu pour assurer le codage de compression d'un film, comprend une partie de mémorisation de nombre de bits (104) destinée à mémoriser le nombre de bits présents dans les images précédentes et l'image en cours de traitement; un moyen de calcul de nombre de bits estimés (105) destiné à calculer un nombre de bits estimés qui seront finalement présents dans l'image en cours de traitement à partir du nombre de bits actuellement présents dans cette même image; un moyen de calcul de débit binaire (106) destiné à calculer le débit binaire instantané à partir du nombre de bits présents dans les images précédentes et du nombre de bits estimés qui seront présents dans l'image en cours de traitement; une partie de détermination de valeur de correction (107) destinée à comparer le débit binaire instantané à un seuil prédéterminé et à déterminer la réduction du coefficient de quantification correspondant à la composante fréquentielle; et une partie de correction de coefficient (108) destinée à réduire le coefficient de quantification correspondant à la composante fréquentielle, en fonction de la réduction déterminée.
PCT/JP2006/314036 2006-07-14 2006-07-14 Dispositif et procédé de commande de codage d'images WO2008007436A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/JP2006/314036 WO2008007436A1 (fr) 2006-07-14 2006-07-14 Dispositif et procédé de commande de codage d'images

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/JP2006/314036 WO2008007436A1 (fr) 2006-07-14 2006-07-14 Dispositif et procédé de commande de codage d'images

Publications (1)

Publication Number Publication Date
WO2008007436A1 true WO2008007436A1 (fr) 2008-01-17

Family

ID=38923008

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2006/314036 WO2008007436A1 (fr) 2006-07-14 2006-07-14 Dispositif et procédé de commande de codage d'images

Country Status (1)

Country Link
WO (1) WO2008007436A1 (fr)

Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62272790A (ja) * 1986-05-21 1987-11-26 Mitsubishi Electric Corp 符号化制御回路
JPH0418857A (ja) * 1990-04-23 1992-01-23 Ricoh Co Ltd 画像データ圧縮方式
JPH0479587A (ja) * 1990-07-20 1992-03-12 Kokusai Denshin Denwa Co Ltd <Kdd> 可変レートビデオ符号化制御方式
JPH06205393A (ja) * 1993-01-08 1994-07-22 Nippon Steel Corp 動画像符号化情報発生量制御装置
JPH06296274A (ja) * 1993-04-09 1994-10-21 Matsushita Electric Ind Co Ltd 画像符号化装置
JPH0730889A (ja) * 1993-06-28 1995-01-31 Ricoh Co Ltd 画像データ符号化装置
JPH07322254A (ja) * 1994-05-25 1995-12-08 Sony Corp 符号化装置
JPH0923427A (ja) * 1995-07-06 1997-01-21 Sony Corp 画像圧縮方法及び装置
JPH11215497A (ja) * 1998-01-29 1999-08-06 Hitachi Ltd 可変ビットレート符号化方式画像データ圧縮システム
JP2000032449A (ja) * 1998-07-09 2000-01-28 Sony Corp 画像情報処理装置および方法、並びに提供媒体
JP2000134617A (ja) * 1998-10-22 2000-05-12 Matsushita Electric Ind Co Ltd 画像符号化装置
JP2004336103A (ja) * 2003-04-30 2004-11-25 Texas Instr Japan Ltd 画像情報圧縮装置
JP2006148502A (ja) * 2004-11-19 2006-06-08 Matsushita Electric Ind Co Ltd 符号量抑制方法および符号化装置

Patent Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62272790A (ja) * 1986-05-21 1987-11-26 Mitsubishi Electric Corp 符号化制御回路
JPH0418857A (ja) * 1990-04-23 1992-01-23 Ricoh Co Ltd 画像データ圧縮方式
JPH0479587A (ja) * 1990-07-20 1992-03-12 Kokusai Denshin Denwa Co Ltd <Kdd> 可変レートビデオ符号化制御方式
JPH06205393A (ja) * 1993-01-08 1994-07-22 Nippon Steel Corp 動画像符号化情報発生量制御装置
JPH06296274A (ja) * 1993-04-09 1994-10-21 Matsushita Electric Ind Co Ltd 画像符号化装置
JPH0730889A (ja) * 1993-06-28 1995-01-31 Ricoh Co Ltd 画像データ符号化装置
JPH07322254A (ja) * 1994-05-25 1995-12-08 Sony Corp 符号化装置
JPH0923427A (ja) * 1995-07-06 1997-01-21 Sony Corp 画像圧縮方法及び装置
JPH11215497A (ja) * 1998-01-29 1999-08-06 Hitachi Ltd 可変ビットレート符号化方式画像データ圧縮システム
JP2000032449A (ja) * 1998-07-09 2000-01-28 Sony Corp 画像情報処理装置および方法、並びに提供媒体
JP2000134617A (ja) * 1998-10-22 2000-05-12 Matsushita Electric Ind Co Ltd 画像符号化装置
JP2004336103A (ja) * 2003-04-30 2004-11-25 Texas Instr Japan Ltd 画像情報圧縮装置
JP2006148502A (ja) * 2004-11-19 2006-06-08 Matsushita Electric Ind Co Ltd 符号量抑制方法および符号化装置

Similar Documents

Publication Publication Date Title
JP4256574B2 (ja) 画像信号符号化方法および画像信号符号化装置
KR100850705B1 (ko) 시공간적 복잡도를 고려한 적응적 동영상 부호화 방법 및그 장치
US7653129B2 (en) Method and apparatus for providing intra coding frame bit budget
US8031769B2 (en) Method and device for controlling quantization scales of a video encoding bit stream
KR100850706B1 (ko) 적응적 동영상 부호화 및 복호화 방법과 그 장치
US9077968B2 (en) Image processing apparatus and method, and program
US20100098169A1 (en) Method and apparatus for motion estimation using compressed reference frame
JP2001169281A (ja) 動画像符号化装置、および動画像符号化方法
JP2001501429A (ja) 可変ビットレートビデオ符号化方法及び対応するビデオ符号化装置
JPH07184196A (ja) 画像符号化装置
JP4221655B2 (ja) 符号化装置および符号化方法、プログラム、並びに記録媒体
EP1350394A2 (fr) Procede d&#39;execution de commande de vitesse de codage video utilisant un budget de bits
JP2005328183A (ja) 動画像符号化装置及び方法、並びにコンピュータプログラム及びコンピュータ可読記憶媒体
JP2000197049A (ja) 動画像可変ビットレート符号化装置および方法
EP1077000A1 (fr) Masquage conditionnel pour codeur video
JP4736619B2 (ja) 画像処理装置および画像処理方法
KR100708182B1 (ko) 동영상 부호화기의 비트율 제어 장치 및 방법
JP4407249B2 (ja) データ処理装置およびその方法と符号化装置、その方法及びプログラム
WO2008007436A1 (fr) Dispositif et procédé de commande de codage d&#39;images
JP3425130B2 (ja) 符号化装置及び符号化方法
JP2002354484A (ja) 符号化画像のレート変換方法、及び符号化画像レート変換装置
KR100949755B1 (ko) 비디오 시퀀스의 레이트를 제어하는 방법 및 장치, 비디오부호화 장치
WO2005104561A1 (fr) Dispositif de traitement de données, procédé pour celui-ci, et dispositif de codage
JP2002232894A (ja) データレート変換装置
KR20040046055A (ko) 동영상 전송 비트율 조절방법

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 06781110

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

NENP Non-entry into the national phase

Ref country code: RU

122 Ep: pct application non-entry in european phase

Ref document number: 06781110

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: JP