CN104135662A - Improved H.264 compressed encoding method for video file under limited bandwidth and emission rate condition - Google Patents
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Abstract
The invention discloses an improved H.264 compressed encoding method for a video file under the limited bandwidth and transmission rate condition, and relates to the field of digital image processing. The improved H.264 compressed encoding method aims at solving the problem that adaptive network resources of a video downloading transmission method in an existing wireless mobile communication network are limited, and the high-speed and high-definition transmission requirement is met. The improved H.264 compressed encoding method includes the steps that in the initial phase, each frame of image is compressed in advance, characteristics of the images in different directions are extracted through plural wavelet transformation, and meanwhile information redundancies are reduced; in the inter-frame prediction phase, according to the directive characteristics obtained through the wavelet transformation, the spatial correlation between inter-frame images is judged, the complexity and the dimensionality of motion vector calculation are reduced, and a P frame and a B frame are obtained; in the intra-frame prediction phase, detail characteristics are eliminated, prediction and integer cosine transformation are only carried out on the overall characteristics, and an I frame is obtained. The improved H.264 compressed encoding method is suitable for improved H.264 compressed encoding on the video file under the limited bandwidth and transmission rate condition.
Description
Technical field
The present invention relates to digital image processing field, be specifically related to H.264 compression coding technology.
Background technology
The object of Video coding is the compression in order to realize video.According to the viewpoint of Shannon information theory, carry out the information of characterization data by comentropy, all the other information are redundancy.The redundancy of a large amount of fragment types is still present in video information, therefore, remove redundancy and also become the core content in video coding technique, to reach the object of compression, video coding technique mainly for redundancy have following a few class:
(1), the time redundancy between frame and frame.People's vision is to have a brief stay effect, and the scene of flashing can not disappear immediately, therefore frequency is higher than this value of the mankind if picture flashes, human eye just can not felt the pause between frame and frame, and general video council adopts above frame sampling rate 25 frame/seconds.So the time interval between two successive frames will be less than 1/25=0.04 second, so unlikely when too fast when the speed of moving objects in video, the degree of correlation between adjacent two frames will be very high, forms redundancy.
(2), the spatial redundancy of each frame inside.One sub-picture is exactly a frame, and spatial redundancy is also present in frame of video.
(3), ubiquitous statistical redundancy.Signal in our daily life, the probability of the rule of the value order in its respective signal space is very little, and conventionally can get maximum value or minimum value at one or several particular point.So, can be by distributing compared with short code word for the larger data point of probability, for the less distribution of probability is compared with long code word, improve like this compression efficiency.
(4), the visual redundancy based on human eye.Source video sequence is extremely wide, abundant in content colorful, and wanting wherein all information all to be received this by human eye is the thing that may accomplish hardly.Therefore, can, for the blind area of Human Perception, it suitably be simplified, carry out cancellation visual redundancy.
In sum, technology of video compressing encoding should have following feature:
1), algorithm is simple: the resolution of video image is high, and frame rate is fast, and therefore, the data volume of processing is very big, for the processing time that makes algorithm reduces, need to reduce its complexity;
2), practical: should be able to extensively to support the application scenarios of most, as high-resolution Digital Television of needs etc.;
3), various dimensions processing: utilize image in the redundancy of time, space and frequency space, image to be compressed.
Existing scheme and pluses and minuses thereof: digital video decoding industry is rapidly grown up like the mushrooms after rain, consider compatible and problem interoperability, and different coding and decoding video producers have all made huge contribution.The standardization issue of video coding and decoding technology seems and becomes more and more important, and the Ge great world is organized in digital video decoding standardization aspect and has launched much work and formulated a series of video encoding and decoding standards.
When MPEG-X series standard, MPEG tissue is since the video compression algorithm that nineteen ninety has defined, and adopted the technology such as motion compensation, discrete cosine transform (DCT), quantification of block mode.Speed is from the 1.5Mbps of MPEG-1, the dynamic code rate of 3～100Mbit/s of MPEG-2.Within 1999, MPEG-4 is pushed out, be intended to the mpeg standard for real-time Transmission sound, vision signal are formulated on Internet or mobile communication equipment, numerous multimedia application are integrated in a complete frame, for multimedia communication and applied environment provide canonical algorithm and instrument, thereby set up a kind of Uniform data format that can generally be adopted by applications such as multimedia transmission, storage, retrievals.
MPEG-4 adopts and compresses based on object mode,, standard compression is than greatly improving, compression multiple is 450 times (still image can reach 800 times), and resolution input can be from 320X240 to 1280X1204, and this is MPEG-1 and more than 10 times of MJEPG of homogenous quantities.
H.26X series standard is the another kind of Video coding mode being proposed by ITU-T, and H.264 what application was the most ripe at present is exactly.H.264 be a new digital video coding standard of joint video team (the JVT:joint video team) exploitation of the VCEG (Video coding expert group) of ITU-T and the MPEG (Motion Picture Expert Group) of ISO/IEC, it be ITU-T H.264, be again the 10th part of the MPEG-4 of ISO/IEC, formally issue in March, 2003.H.264 strengthened the adaptive capacity to various channels, Adoption Network close friend's structure and grammer, be conducive to the processing to the error rate and packet loss, under identical reconstructed image quality, and can be than the code check of H.263 saving half left and right.The network adaptability of code flow structure is H.264 strong, has increased error resilience, can adapt to well IP and wireless network.
But, any video encoding and decoding standard is pursuing higher compression ratio and respectively in rate, the complexity of its algorithm has produced restriction to real-time application, is difficult to meet under wireless channel environment, and channel is obtained and holding time, the requirement of access delay at random.Meanwhile, the transmission requirement code stream of wireless channel itself has very strong error recovery capabilities.Radio communication requires the compressed encoding of video to support auto-adaptive parameter setting, can be the in the situation that of channel capacity or power limited, and by sacrificial section image quality, and the reduction that does not bring obvious user to experience.
Summary of the invention
The present invention is that the video download transmission method adaptation Internet resources in order to solve existing mobile radio networks are limited, and in order to adapt at a high speed, the demand of the transmission of high image quality, thereby provide a kind of under finite bandwidth and emission rate condition to H.264 compaction coding method of the modified model of video file.
For under finite bandwidth and emission rate condition to H.264 compaction coding method of the modified model of video file, under the limited wireless channel environment of frequency range, for the compressed encoding of the video of each two field picture, include following steps:
Step 1, initialization: judge whether current frame image is start frame, that is: judge whether current frame image is the first frame of video flowing or the first frame of encoding stream, if judged result is yes, execution step one by one; If judged result is no, perform step one or two;
Step one by one, current frame image is carried out to Complex wavelet variation, obtains the level of present frame, vertical and 45° angle directional information, and performs step four;
Step 1 two, current frame image is carried out to Complex wavelet variation, obtain present frame level, vertical and 45° angle directional information, execution step two;
Step 2, prediction mode are selected: according to the direction character correlation of current frame image and reference frame image, the prediction mode that judgement adopts, if employing is inter prediction mode, performs step three; If what adopt is infra-frame prediction mode, perform step four; Described reference frame image is that former frame image is passed through to block elimination effect filter, rebuilds the image obtaining after the characteristic information of original image and all directions;
Step 3, in level, vertical direction, respectively present frame is carried out to offset dependence operation, and judge the motion principal direction of current frame image with respect to reference frame image according to peak value, calculation of motion vectors, and perform step four;
If what step 4 current frame image adopted is inter prediction, perform step 41; If what current frame image adopted is infra-frame prediction, execution step four or two;
Step 4 one, according to motion vector and reference frame image, be residual signals by the principal component image compression after wavelet transformation, remove minutia, that is: remove the information to angular direction, and perform step five;
Step 4 two, principal component image is carried out to Intra prediction mode selection H.264, remove minutia simultaneously, that is: remove the information to angular direction, execution step five;
Step 5, to prediction after current frame image do integer cosine transformation and quantification, execution step six;
Step 6, judge whether current frame image is the last frame of video flowing or encoding stream, if judge that judged result is no, performs step 61; If judged result is yes, carry out six or two;
Step 6 one, current frame image is carried out to re-quantization and inverse transformation, current frame image is carried out to entropy coding simultaneously, and packing sends under different host-host protocols, complete the compressed encoding of current frame image;
Step 6 two, directly carry out entropy coding, packing sends, and completes the compressed encoding of current frame image.
It also comprises: step 7, after completing steps 61, by block elimination effect filter, rebuild the characteristic information of original image and all directions, as the reference frame of next frame.
Prediction mode selection course in step 2 is specially:
The relative operation that carries out respectively segmentation in horizontal and vertical direction, operation is in the horizontal direction specially:
Step 2 one, according to the resolution of horizontal direction characteristic image, horizontal direction characteristic image is carried out to N decile in the horizontal direction, and performs step two or two; N is positive integer;
Step 2 two, on the subimage of the by stages such as n, carry out the skew of n-1 unit, carry out relative operation with the image in the corresponding interval of reference frame, calculate cross correlation value, obtain N cross correlation value;
Step 2 three, the N of an acquisition cross correlation value is done to normalization operation, judge whether that more than 50% cross correlation value is greater than 0.5, if judged result is yes, perform step two or four; If judged result is no, perform step two or five;
Step 2 four, determine and carry out inter prediction, calculate initial level motion excursion amount and equal the weighted sum form that N interval side-play amount and cross correlation value multiply each other;
Step 2 five, definite infra-frame prediction of carrying out.
The Complex wavelet changing method that step is used one by one or in step 1 two is specially: require and application scenarios according to the image quality of video image, use dissimilar small echo to extract directional pattern picture.
Step one by one or the Complex wavelet using in step 1 two changes employing Haar or dbN small echo is realized.
The present invention be a kind of under finite bandwidth and emission rate condition to H.264 compaction coding method of the modified model of video file, the video that has solved existing mobile radio networks is downloaded transmission plan and is adapted to Internet resources limited problems.Adapted at a high speed, the demand of the transmission of high image quality.
Brief description of the drawings
Fig. 1 is the H.264 video compression coding hierarchy schematic diagram that the present invention uses;
Fig. 2 be the present invention under finite bandwidth and emission rate condition to H.264 compressed encoding structural representation of the modified model of video file;
Fig. 3 is the CABAC entropy coding schematic flow sheet using in the present invention;
Fig. 4 is the complete video transmission plan schematic flow sheet in the present invention;
Embodiment
Embodiment one, under finite bandwidth and emission rate condition to H.264 compaction coding method of the modified model of video file, it is realized by following steps:
Step 1, initialization: whether present frame is start frame, if the first frame of the first frame of video flowing or encoding stream performs step one by one, if not, execution step one or two;
Step one by one, image is carried out to Complex wavelet variation, obtains level, vertical and 45° angle directional information, execution step four;
Step 1 two, image is carried out to Complex wavelet variation, obtain level, vertical and 45° angle directional information, execution step two;
Step 2, prediction behavior are selected: according to the direction character correlation of present frame and reference frame, and the prediction mode that judgement adopts, if select inter prediction, execution step three, if select infra-frame prediction, execution step four;
Step 2 one, according to the resolution of horizontal direction characteristic image, carry out in the horizontal direction N decile, execution step two or two;
Step 2 two, on the subimage of the by stages such as n, carry out the skew of n-1 unit, carry out relative operation with the image in the corresponding interval of reference picture, calculate cross correlation value;
Step 2 three, obtain N cross correlation value, do normalization operation, if there is more than 50% cross correlation value to be greater than 0.5, execution step two or four, if do not had, performs step two or five;
Step 2 four, determine and carry out inter prediction, calculate initial level motion excursion amount and equal the weighted sum form that N interval side-play amount and cross correlation value multiply each other;
Step 2 five, definite infra-frame prediction of carrying out;
Step 3, in level, vertical direction, carry out respectively offset dependence operation, judge that according to peak value present frame is equivalent to the motion principal direction of reference frame, calculation of motion vectors, execution step four;
If what step 4 present frame adopted is inter prediction, execution step 41, if adopt infra-frame prediction, execution step four or two;
Step 4 one, according to motion vector and reference frame, be residual signals by the principal component image compression after wavelet transformation, remove minutia, i.e. the information to angular direction, execution step five;
Step 4 two, principal component image is carried out to Intra prediction mode selection process H.264, remove minutia simultaneously, execution step five;
Step 5, to prediction after present frame do integer cosine transformation and quantification, execution step six;
If step 6 present frame is not the last frame of video flowing or encoding stream, carry out six or two if carry out 61;
Step 6 one, the process of present frame being carried out to re-quantization and inverse transformation are carried out entropy coding to it simultaneously, send execution step seven according to different host-host protocol packings;
Step 6 two, directly carry out entropy coding, packing sends, and completes the compressed encoding work of video.
Step 7, by block elimination effect filter, rebuild the characteristic information of original image and all directions, use as the reference frame of next frame.
The present invention, in the starting stage, carries out precommpression to the image of each frame, extracts the feature of image at different directions by Complex Wavelet Transform, reduces the redundancy of information simultaneously; In the inter prediction stage, according to changing through small echo the direction characteristic obtaining, judge the spatial coherence between inter frame image, reduces complexity and the dimension of motion vector calculation, obtains P frame and B frame; In the infra-frame prediction stage, weed out minutia, only global feature predicted and integer cosine transformation, obtains I frame.
Compaction coding method complexity of the present invention is significantly reduced, and transmission speed is greatly improved.And allow to transmit according to different transmission requirements, the video that has solved existing mobile radio networks is downloaded the limited problem of transmission plan adaptation Internet resources.
Claims (5)
- For under finite bandwidth and emission rate condition to H.264 compaction coding method of the modified model of video file, it is characterized in that: under the limited wireless channel environment of frequency range, for the compressed encoding of the video of each two field picture, include following steps:Step 1, initialization: judge whether current frame image is start frame, that is: judge whether present frame is the first frame of video flowing or the first frame of encoding stream, if judged result is yes, execution step one by one; If judged result is no, perform step one or two;Step one by one, current frame image is carried out to Complex wavelet variation, obtains the level of current frame image, vertical and 45° angle directional information, and performs step four;Step 1 two, current frame image is carried out to Complex wavelet variation, obtain the level of current frame image, vertical and 45° angle directional information, execution step two;Step 2, prediction mode are selected: according to the direction character correlation of current frame image and reference frame image, the prediction mode that judgement adopts, if employing is inter prediction mode, performs step three; If what adopt is infra-frame prediction mode, perform step four; Described reference frame image is that former frame image is passed through to block elimination effect filter, rebuilds the image obtaining after the characteristic information of original image and all directions;Step 3, in level, vertical direction, respectively current frame image is carried out to offset dependence operation, and judge the motion principal direction of current frame image with respect to reference frame image according to peak value, calculation of motion vectors, and perform step four;If what step 4 current frame image adopted is inter prediction, perform step 41; If what current frame image adopted is infra-frame prediction, execution step four or two;Step 4 one, according to motion vector and reference frame image, be residual signals by the principal component image compression after wavelet transformation, remove minutia, that is: remove the information to angular direction, and perform step five;Step 4 two, principal component image is carried out to Intra prediction mode selection H.264, remove minutia simultaneously, that is: remove the information to angular direction, execution step five;Step 5, to prediction after present frame do integer cosine transformation and quantification, execution step six;Step 6, judge whether current frame image is the last frame of video flowing or encoding stream, if judge that judged result is no, performs step 61; If judged result is yes, carry out six or two;Step 6 one, current frame image is carried out to re-quantization and inverse transformation, current frame image is carried out to entropy coding simultaneously, and packing sends under different host-host protocols, complete the compressed encoding of current frame image;Step 6 two, directly carry out entropy coding, packing sends, and completes the compressed encoding of current frame image.
- According to claim 1 under finite bandwidth and emission rate condition to H.264 compaction coding method of the modified model of video file, it is characterized in that it also comprises:Step 7, after completing steps 61, by block elimination effect filter, rebuild the characteristic information of original image and all directions, as the reference frame of next frame.
- According to claim 1 under finite bandwidth and emission rate condition to H.264 compaction coding method of the modified model of video file, it is characterized in that the prediction mode selection course in step 2 is specially:The relative operation that carries out respectively segmentation in horizontal and vertical direction, operation is in the horizontal direction specially:Step 2 one, according to the resolution of horizontal direction characteristic image, horizontal direction characteristic image is carried out to N decile in the horizontal direction, and performs step two or two; N is positive integer;Step 2 two, on the subimage of the by stages such as n, carry out the skew of n-1 unit, carry out relative operation with the image in the corresponding interval of reference frame, calculate cross correlation value, obtain N cross correlation value;Step 2 three, the N of an acquisition cross correlation value is done to normalization operation, judge whether that more than 50% cross correlation value is greater than 0.5, if judged result is yes, perform step two or four; If judged result is no, perform step two or five;Step 2 four, determine and carry out inter prediction, calculate initial level motion excursion amount and equal the weighted sum form that N interval side-play amount and cross correlation value multiply each other;Step 2 five, definite infra-frame prediction of carrying out.
- According to claim 1 under finite bandwidth and emission rate condition to H.264 compaction coding method of the modified model of video file, the Complex wavelet changing method that it is characterized in that step and use one by one or in step 1 two is specially: require and application scenarios according to the image quality of video image, use dissimilar small echo to extract directional pattern picture.
- According to claim 1 under finite bandwidth and emission rate condition to H.264 compaction coding method of the modified model of video file, it is characterized in that step one by one or step 1 two in the Complex wavelet that uses change and adopt Haar or dbN small echo to realize.
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