Tag: H.264 encoding HD video VC-1 encoding This article refers to the address: http:// When it comes to watching TV at home, I always want to see the famous name. It’s not simply watching the cable TV show. The big tablet in the house is used to see the analog signal. Is there some “killing the chicken knife� Feeling, yes, we have to watch HD, we have to enjoy the effect of video and audio at home, high-definition movies have become the target of many friends in the petty bourgeoisie life, this time the answer is to friends who care about HD A comprehensive interpretation of our interpretation of the HD video format. What is HD? Many people will not hesitate to tell me "1080P", ask in depth, what is the format of HD? For high-definition video, mainstream technologies currently mainly include MPEG-2, Divx, Xvid, H.264, and VC-1. Among them, MPEG-2, H.264 and VC-1 are the three encoding formats selected by HDDVD and Blu-ray DVD, and are therefore the most popular. Because of the technical specifications and the cost of licensing, the range of these encoding formats is different. First, a household name: H.264/X264 Most audiovisual players are not unfamiliar with H.264 encoding. The H.264 encoding is distinguished by ITU-T (International Telecommunication Union - Video Coding Experts Group) and ISO/IEC (International Organization for Standardization - Motion Picture Experts). Group) A new generation of digital video coding standards promoted by the JVT (Joint Video Group), also known as MPEG-4/AVC encoding. H.264 encoding relies on a strong background and is unique in technology and is far ahead of other encoding algorithms. Below, the author tries to explain the four technical features of H.264 encoding in a more popular way. 1. Hierarchical design: H.264 encoding algorithm is divided into two levels: video coding and network extraction, which are responsible for high coding efficiency and network friendliness respectively. That is, the two teams independently complete two tasks of video processing and network transmission to ensure the whole process. The task is flexible, efficient and professional. 2. High-precision, multi-mode motion estimation: H.264 supports motion vectors with 1/4 or 1/8 pixel precision. In motion estimation, the encoder can select an enhanced interpolation filter to improve the prediction effect, ie: H. 264 accurately and delicately reduces noise on video pixels, and predicts and corrects adjacent video frames (pictures) according to the encoded video frames (pictures) to maximize the clarity and accuracy of the video. 3, 4 × 4 block integer transform: block-based transform coding for residuals, allowing the same precision transform and inverse transform in the encoder and decoder, using a smaller quantization step size for the chrominance coefficient, namely: More accurately identify moving objects in the video, reduce edge distortion and color blocks of moving objects, and make the video color more realistic. 4. Uniform VLC symbol coding. There are two methods for entropy coding in H.264. The decoder can easily identify the codeword prefix. UVLC can quickly obtain resynchronization when bit errors occur, that is, the error correction and fault tolerance of the coding algorithm are better. it is good. Comparison of H.264 and MPEG-2/MPEG-4, H.263 compression performance Supported by the four technical characteristics, the H.264 encoding algorithm has a very high coding efficiency. Under the same image quality conditions, it can save about 50% of the code rate than H.263/MPEG-2, that is, the file volume is reduced. 50% smaller, and H.264's error correction capability is increased, and network adaptability is stronger. X264 encoding is an open source branch of H.264 encoding. It conforms to the H.264 standard. Its function is encoding (encoding), not as a decoder. The biggest feature of X264 encoding is that it is practical, it is not Under the premise of significantly reducing the coding performance, efforts to reduce the computational complexity of coding, X264 has made a compromise for some complex coding features in H.264 coding, and its compressed video volume is smaller than Xvid (MPEG4) encoded video, with small size and high The characteristics of the picture quality have been recognized by many netizens. Most of H.264 and X264 currently use the MKV package format, which is an emerging multimedia package format/container that can package various types of video coding, 16 or more different formats of audio and language subtitles in one file. It has the advantages of open source code, rich audio and video coding, and good network affinity. It has been supported by many video suppression groups and players, and is gradually becoming the mainstream video format for HD video. Second, mature framework: MPEG-2/MPEG-4 The MPEG-2/MPEG-4 encoding standard is an international standard for video and audio compression published by the Moving Picture Experts Group. MPEG-2 encoding was released in 1994, and is often used for video and audio encoding of broadcast signals (satellite TV, cable TV). After continuous modification, it has not only become the core technology of DVD, but also applied to HDTV HDTV transmission. The characteristics of MPEG-2 encoding compression technology are as follows: 1. Remove space redundancy, that is, identify important elements in the video picture, remove elements that are duplicated, have no influence, and are easily overlooked by the human eye; 2. remove space redundancy, ie : Using the visual persistence phenomenon, removing the redundancy of similar video pictures on the time axis, and performing video compression; 3. Variable bit rate, that is, according to the complexity of the dynamic picture, timely adjusting the data transmission rate/bit rate to achieve uniformity The encoding effect and smooth and balanced video effects, in DVD applications, the maximum bit rate of up to 10.4Mbit / S. Due to the low compression ratio of MPEG-2 encoding, it is mainly used for DVD source standard (720*480 resolution/NTSC system, 720*576/PAL system). Under the DVD standard, MPEG-2 encoded video files are mainly Adopt MPG, MPE, MPEG, M2V and VOB formats. For 720P/1080P HD video, MPEG-2 encoded compressed files are large (120 minutes long, 20GB or more). Under the HDTV standard, MPEG-2 encoded video files mainly use TP and TS encapsulation formats. Among them, TS format is a more advanced package format, BD Blu-ray original disk is TS package, it provides time stamp in video and audio packaging, guarantees synchronization of audio and video in any time period (separate), TS package supports almost All encoded HD video and audio track encoding, including MPEG2, H.264/MPEG4-AVC, VC-1, audio encoding including Dolby AC3, TrueHD, DTS, DTS-HD and more. TS package format supports DTS-HD HD audio coding MPEG-4 encoding was released in 1998. It inherits the advantages of MPEG-2 encoding, further optimizes the compression ratio, improves network transmission, strengthens copyright protection and support for subtitles and audio tracks, and greatly expands and extends. The application framework of the domain, which is not only applied to voice transmission (video telephony), network video, optical disc storage and television broadcasting, but also developed a series of sub-standards. Among them, the MPEG-4 Part2 standard is very common Divx, Xvid encoding, they (especially the newer Xvid encoding) are mostly used to suppress video files in DVDRip, AVI or MP4 format, and the MPEG-4 Part10 standard is mentioned above. The technical characteristics of H.264/AVC encoding are not repeated here. Now, MPEG-4 has been revised to the Part20 standard and is still being improved. Third, rising star: VC-1 WMV (Windows Media Video) has been continuously improved as a long-lasting video encoding. In 2003, Microsoft officially proposed the VC-1 encoding standard based on WMV Ninth Edition (WMV9) encoding technology, and officially launched in 2006. Become an international standard. WMV is the core of Microsoft's multimedia technology As a later high-definition encoding algorithm, VC-1 encoding naturally absorbs the advantages of MPEG-2 and H.264 encoding. Its compression ratio is between MPEG2 and H.264, and the codec complexity is only H.264. Half, that is, the compression time is shorter and the decoding calculation is smaller. Under the strong promotion of Microsoft, VC-1 encoding has been supported by the BD Blu-ray Disc, Film and Television Society (SMPTE). In recent years, in order to better promote the WMV9/VC-1 coding standard, Microsoft has spared no effort to establish a WMV-HD HD resource site, and released a large number of 720P, 1080P promotional videos and demos (WMV-HD) suppressed by VC-1 encoding. Video format), trying to create momentum and attract users' attention. At the same time, in the field of BD Blu-ray Disc, the cooperation between VC-1 encoding and movies/drama has become increasingly fierce. The cooperation with computer hardware manufacturers is also accelerating the promotion of VC-1 encoding. It can be seen that Microsoft is accelerating VC- 1 coded enclosure movement. VC-1 encoding and Blu-ray disc speeding marriage However, the modest technology (compared to H.264, no obvious coding advantage), closed platform (limited to Windows system), latecomer disadvantages (passed in 2006, become an international standard) still apply to Microsoft VC-1 encoding The prospects have brought about greater uncertainty. Whether it is possible to overthrow the mountain of H.264 still needs to be tested.
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iPad mini 5th: A2124/A2125/A2126/A2133
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