CN100455020C - Screen coding method under low code rate - Google Patents
Screen coding method under low code rate Download PDFInfo
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- CN100455020C CN100455020C CNB2006100271719A CN200610027171A CN100455020C CN 100455020 C CN100455020 C CN 100455020C CN B2006100271719 A CNB2006100271719 A CN B2006100271719A CN 200610027171 A CN200610027171 A CN 200610027171A CN 100455020 C CN100455020 C CN 100455020C
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Abstract
The present invention relates to a screen coding method under low code rate, which belongs to the technical field of video encoding and decoding. The present invention has steps as follows: a computer screen image is collected, and the screen image is evenly divide into a plurality of image blocks and is compared with corresponding blocks of a previous frame screen image. According to a comparative result, the present determines whether the current frame carries out spatial domain resolution ratio reduction and encoding. If the current frame is encoded, by using the method of self adaptation key frame interval on time domain, the present invention determines that the encoding is a key frame or a non-key frame, and mouse information and image data are respectively processed. By using the encoding method combined by lossy encoding and lossless encoding, the image data is processed. The present invention is suitable for videoconference under low code rate, remote teaching, remote control, etc., and has the advantages of low code rate, strong real time and low system resource occupying rate.
Description
Technical field
The present invention relates to the method in a kind of video coding and decoding technology field, specifically, what relate to is a kind of screen coding method under low code rate.
Background technology
In video conference, the telecommunication network teaching, all many-sides such as computer remote monitoring, the image of computer screen transmits the link that is absolutely necessary.One of topmost factor that influences the screen transmission quality is exactly the method for screen coding, especially under low code check, screen coding is had higher requirement.At present, at screen coding, following several method is arranged:
Method one: the collection on-screen data is a video data, utilizes conventional video encoder to encode.Traditional video encoder, comprise MPEG4 (dynamic image expert group formulate an ISO/IEC video encoding and decoding standard) and H.264 (video encoding and decoding standard that video joint working group formulates) and WME (video encoding and decoding standard of Microsoft's formulation) carry out encoding and decoding to video sequence good effect can be arranged, but screen is encoded, especially for the screen coding under the low code check, effect is not fine, above-mentioned video encoding and decoding standard complexity is than higher simultaneously, and CPU usage is than higher when realizing.
Method two: screen is regarded as static images, utilize existing static images coding techniques to encode.This method implements fairly simple, directly the on-screen data that collects as a width of cloth static images, adopt the coding techniques of static images, as JPEG, JPEG2000 etc. encode and are transferred to client.In this case, but client is received direct decoding after the data, does not rely on other view data.But the data volume that JPEG, JPEG2000 encode out is all bigger, so be not suitable for carrying out screen coding under low code check.
Method three: utilize the Windows Media Screen codec of Microsoft that screen is encoded.This method can to screen picture (as mouse move, dialog box and drop-down menu etc.) carry out the excellent reproduction of effect, its data rate can hang down and reach 15kbps, and screen resolution can be up to 1024 * 768.Yet following screen capture activity is difficult to compression: (1) dragged desktop with window; (2) scroll-up/down webpage; (3) the bigger image of Show Color change in depth.
Find through literature search prior art, United States Patent (USP) title: Adaptive entropy encoding/decoding for screen capture content (to the adaptive entropy encoding/decoding of screen capture content), the patent No. is: 7,016,547, this patent has proposed a kind of adaptive entropy coding that is used for screen coding, entropy decoding method.These patent characteristics are that coding side can adaptively selected coding mode (coding that counts, Run-Length Coding and Huffman coding), how to describe adaptively selected coding mode in detail, the coding that how to count, and Run-Length Coding and Huffman encode.But this patent does not have the complexity of considering screen content, factors such as the severe degree of adjacent screen change, and factors such as the severe degree of adjacent screen change, the data volume behind the coding is bigger, and occupied bandwidth is than higher.
Summary of the invention
The present invention is directed to the deficiencies in the prior art and defective, proposed a kind of screen coding method under low code rate, make it solve screen coding occupied bandwidth height in the past, the problem that the system resource occupancy is high.
The present invention is achieved by the following technical solutions, may further comprise the steps:
The screen picture of A, collecting computer;
B, present image evenly is divided into a plurality of image blocks, and compares with previous frame image corresponding blocks;
C, adopt spatial domain epigraph resolution dwindle and time-domain on self adaptation key frame method at interval, realize low code check sub-screen coding.According to the comparative result of step B, whether decision is carried out the spatial domain image resolution ratio to present frame and is dwindled and encode, if encode, adopts self adaptation key frame method at interval to determine that being encoded to key frame still is non-key frame;
D, the method that adopts lossy coding and lossless coding to combine to on-screen data are encoded;
E, mouse message is encoded separately;
In the steps A, to catch the running orbit of mouse.
In the steps A, the colour bits of the view data that collects are transferred to the low level look and preserve from high-order look.
Among the described step C, according to the comparative result of step B, whether decision is carried out the spatial domain image resolution ratio to present frame and is dwindled and encode, if encode, adopting self adaptation key frame method decision at interval to be encoded to key frame still is non-key frame, and concrete grammar is as follows:
(1) if the picture block of present frame is compared with the corresponding blocks of previous frame, do not change, then present frame is not encoded.If the time of not encoding surpasses one minute continuously, then key frame of forced coding.
(2) if the picture block of present frame is compared with the corresponding blocks of previous frame, have one or two pieces to change, it is smaller to be judged to be the image change amplitude, then present frame is carried out being encoded to non-key frame after spatial domain epigraph resolution is dwindled.
(3) if the picture block of present frame compare with the corresponding blocks of previous frame, there is the piece more than three or three to change, it is normal to be judged to be the image change amplitude, then earlier view data being carried out on the spatial domain resolution dwindles, then according to the residing moment point of present frame, this is compiled and just compiles for key frame is key frame, and this is compiled and just compiles for non-key frame is non-key frame.
(4) under the normal condition, every key frame of 20 seconds codings, if still image change satisfies situation (2) always, the non-key frame of continuous programming code surpasses 30 seconds, then key frame of forced coding as situation (3).
Among the step D, the method that adopts lossy coding and lossless coding to combine is encoded to on-screen data.At first view data is carried out motion prediction, reduce the inter frame image redundant information, find motion vector, at simple image such as window and literal, adopt the lossless coding mode then, both preserved picture original, the very high compression ratio of having got back.At images such as coloury scenery, personages, adopt lossy coding, significantly reduce data volume.Coding side is selected suitable coding method automatically according to the complexity of screen picture content, thereby obtains higher compression ratio and compression quality.
In the step e,, obtain mouse shape and mouse position respectively, note then and encode for mouse message.Owing to only when mouse changes, just write down the mouse shape, when moving, only writes down mouse mouse position, and therefore, the relative screen picture of mouse message can be ignored, but can reach good movement effects.The mouse absolute coding can improve the sample frequency of mouse to greatest extent, makes the operation of mouse look more smooth.
The present invention is primarily aimed at low code check screen coding down, according to the severe degree of screen change adopt spatial domain epigraph resolution dwindle and time-domain on self adaptation key frame method at interval, realize that low code check sub-screen encodes.If screen does not change, encoder is not just encoded so, if change very little then image resolution ratio is dwindled back coding, the method that adopts lossy compression method and lossless compress to combine is simultaneously encoded to on-screen data, mouse message is independent of on-screen data encodes.The present invention can save bandwidth, is convenient to low code check transmission, and can reduces the system resource occupancy.
Description of drawings
Fig. 1 is a flow chart of steps of the present invention.
Fig. 2 is a screen compression algorithm flow chart of the present invention.
Embodiment
Provide example with content of the present invention in conjunction with the accompanying drawings:
As shown in Figure 1, concrete implementation step is as follows:
At first, collecting computer screen picture data transfer the colour bits of the view data that collects the low level look to and preserve from high-order look.
Secondly, the even cutting of screen picture is a plurality of, and be that the corresponding blocks of unit and previous frame image compares with the piece, variation has taken place in total total several of record, according to the severe degree that changes, respectively in a different manner, adopt spatial domain epigraph resolution dwindle and time-domain on self adaptation key frame method at interval, carry out encoding process:
(1) if do not change, do not encode so, if but time of not encoding surpassed 1 minute, key frame of forced coding then.
(2), then present frame is carried out being encoded to non-key frame after the spatial domain image resolution ratio is dwindled if the piece that changes has only one or two image blocks.Even the residing moment point of present frame also will force to be encoded to non-key frame for compiling key frame time, to save bandwidth.Step (4) can be handled this situation of continuous appearance (2).
(3) if there is the piece more than three or three that variation has taken place, at first present frame being carried out the spatial domain image resolution ratio dwindles, decide according to the residing moment point of present frame then, if to this be encoded to the moment of key frame, so just be encoded to key frame, if to this be encoded to the moment of non-key frame, just be encoded to non-key frame.
(4) under normal image change situation, promptly as situation (3), encoder can be every key frame of 20 seconds codings, if but screen change is always very little, satisfy situation (2) always, so can be after 30 seconds at the non-key frame of continuous programming code, key frame of forced coding.
At last, according to above method, the method that adopts mouse message and screen picture data to handle respectively makes the motion of mouse can not increase the data volume of screen picture.Screen compression algorithm flow chart is seen Fig. 2.For on-screen data, the mode that adopts lossy coding to combine with lossless coding is encoded.At first adopt motion estimation technique efficiently, reduce the interframe redundant data, find motion vector, to simple image such as window and literal, adopt the lossless coding mode then, so both kept picture original, the very high compression ratio of having got back.To images such as coloury scenery, personages, adopt the lossy compression method coding, significantly reduce data volume.For mouse message, obtain mouse shape and mouse position respectively, note then and encode.Owing to only when mouse changes, just write down the mouse shape, only write down mouse position when mouse moves.Therefore, the relative screen picture of mouse message can be ignored, but can reach good movement effects.The mouse absolute coding can improve the sample frequency of mouse to greatest extent, makes the operation of mouse look more smooth.
The invention provides a kind of screen coding method under low code rate, coding back data volume is low, and occupied bandwidth is little, is easy to Network Transmission, and the picture quality height is low to the system resource occupancy simultaneously.
Claims (3)
1. a screen coding method under low code rate is characterized in that, may further comprise the steps:
The screen picture of A, collecting computer;
B, present image evenly is divided into a plurality of image blocks, and compares with previous frame image corresponding blocks;
C, adopt spatial domain epigraph resolution dwindle and time-domain on self adaptation key frame method at interval, realize low code check sub-screen coding, described self adaptation key frame method at interval, be meant: if the picture block of present frame is compared with the corresponding blocks of previous frame, there is the piece more than three or three to change, then earlier present frame being carried out spatial domain epigraph resolution dwindles, then according to the residing moment point of present frame, this is compiled and just compiles for key frame is key frame, and this is compiled and just compiles for non-key frame is non-key frame;
D, the method that screen picture The data lossy coding and lossless coding are combined are encoded;
E, mouse message is encoded separately.
2. a kind of screen coding method under low code rate as claimed in claim 1 is characterized in that, in the steps A, will catch the running orbit and the shape of mouse.
3. a kind of screen coding method under low code rate as claimed in claim 1 is characterized in that, among the described step D, lossy coding is at coloury personage, landscape image, and lossless coding is at the image of window and literal.
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| CNB2006100271719A CN100455020C (en) | 2006-06-01 | 2006-06-01 | Screen coding method under low code rate |
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| CNB2006100271719A CN100455020C (en) | 2006-06-01 | 2006-06-01 | Screen coding method under low code rate |
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Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101651827B (en) * | 2009-07-16 | 2012-06-13 | 上海交通大学 | Code rate control method of screen coding |
| CN103533356A (en) * | 2013-10-10 | 2014-01-22 | 深圳市智美达科技有限公司 | Video data transmission method and device |
| CN106303534B (en) * | 2015-06-08 | 2022-05-31 | 上海天荷电子信息有限公司 | Image compression method and device for multiple index string and pixel string fusion copy modes |
| CN106686384B (en) * | 2016-11-29 | 2019-05-24 | 西安万像电子科技有限公司 | The compression method and device and method for compressing image and device of character block |
| CN108810610B (en) * | 2017-05-05 | 2021-05-25 | 腾讯科技（深圳）有限公司 | Screen sharing method and device |
| CN107172376B (en) * | 2017-06-26 | 2020-04-21 | 北京奇艺世纪科技有限公司 | Video coding method and device based on screen sharing |
| CN107181928A (en) * | 2017-07-21 | 2017-09-19 | 苏睿 | Conference system and data transmission method |
| CN107480437B (en) * | 2017-08-01 | 2020-09-18 | 西安万像电子科技有限公司 | Data transmission method and device |
| CN108462878B (en) * | 2018-04-09 | 2020-10-09 | 公安海警学院 | Teaching video compression algorithm based on key frame and indicator motion model |
| CN113810639B (en) * | 2021-09-28 | 2023-09-29 | 深圳万兴软件有限公司 | Method, device and related medium for recording mouse information and re-editing |
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| US20020005909A1 (en) * | 2000-06-28 | 2002-01-17 | Junichi Sato | Image processing apparatus, image processing method, digital camera, and program |
| US20060104530A1 (en) * | 2002-06-28 | 2006-05-18 | Microsoft Corporation | Adaptive entropy encoding/decoding for screen capture content |
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