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What is H.264/MPEG-4 AVC


H.264 or MPEG-4 Part 10, is a highly compressed digital video encode format standard developed by the ITU-T Video Coding Experts Group (VCEG) along with the ISO/IEC JTC1 Moving Picture Experts Group (MPEG), which is normally known as H.264/AVC or H.264/MPEG-4 AVC, or MPEG-4/H.264 AVC to clearly explain its developers of both sides. H.264 is perhaps best known as being one of the video encoding standards for Blu-ray discs. And H.264 is capable of using in all Blu-ray disc players. Besides, it is widely used by streaming websites, such as Vimeo, YouTube, and the iTunes Store. And supported software like the Adobe Flash Player and Microsoft Silverlight or various HDTV broadcasts over terrestrial (Advanced Television Systems Committee standards, ISDB-T, DVB-T or DVB-T2), cable (DVB-C), and satellite (DVB-S and DVB-S2).

The main parts of H264 standard are included Access Unit delimiter, SEI, primary coded picture, Redundant Coded Picture, Instantaneous Decoding Refresh(IDR), Hypothetical Reference Decoder(HRD), and Hypothetical Stream Scheduler(HSS).


1. Low Bit Rate: With the same compression technology and equal visual quality, the data which used H.264 for compression are only 1/8 of MPEG2's or 1/3 of MPEG4's that compared with MPEG2 and MPEG4 ASP.

2.High visual quality: H.264 provides fast and high definition image.

3. Bug fixes: H.264 provides tools for fixing some bug like packet loss when the network is poor.

4. Adaptable to network: H.264 provides Network Abstraction Layer, which makes its files all available to transfer to different websites such as CDMA, GPRS, WCDMA and CDMA2000.

The biggest advantage of H.264 is that it has high compression rate when compressing data. In an equal visual quality condition, the compression rate of H.264 is twice more than that of MPEG-2 and 1.5-2 times of MPEG-4. That is to say, with an original 88GB file, it turns into 3.5GB with MPEG-2 compression standard while with H.264, the file is compressed into 879MB. And the marvelous compression rate of H.264 is reached to 102 to 1. Low Bit Rate plays an significant role in high compression rate. Also compared with MPEG-2 and MPEG-4 ASP, H.264 is capable of greatly saving download time and payment of data usage. In particular, H.264 provides best visual quality with high compression rate. And that's why the video data are more economic and with less bandwidth if used H.264 compression standard.

Visit our: how to convert MPEG to MP4 (h.264) on a Mac computer


As its former standard, H.264 is also a mixed coding mode that adds DPCM and transformed coding. What makes it more superior is its concise design with higher compression rate than H.263++. It fosters a greater adaptability by using "Internet friendly" structure and syntax which is good for dealing with error rate and packet loss.

Being an excellent format with wider application, it aims at meeting requirements of different velocities, resolutions and data transmitting situations. Technically, H.264 included ll advantages of older versions and accumulated experiences of standardization. Compared with H.263 v2(H.263+) or MPEG-4(Simple Profile), H.264 may save 50% rate when using the foregoing encoding method under most situations. H.264 provides high quality video constantly with any rate, also adapts to real time telecommunication in a low latency mode, such as storing videos and the applications of streaming video based on server. Certainly, H.264 furnishes required tools that can be used to deal with problem like packet loss while transferring the data online and error code existed in wireless network.

At a system level, there is a new concept of H.264 in which it split into Video Coding Layer(VCL) and Network Abstraction Layer(NAL). The former is about the core content of the video and latter is about sending users a specific kind of network. With this structure, it is more convenient to package and make better control of the date.

Derived formats

  • AVCHD, designed by Sony and Panasonic, is a high-definition recording format that uses H.264. If you'd like to convert a AVCHD files to something more acceptable on computer, see how can you convert AVCHD .mts to MOV format.
  • AVC-Intra, also developed by Panasonic, is compression format that allows intraframe only.
  • XAVC is a recoding format which uses the highest level of 5.2 of H.264/mpeg-4 AVC. XAVC can support 4K resolution (4096 × 2160 and 3840 × 2160), which may achieve 60 frames per second (fps). Sony declares that the camera can support two CineAlta cameras, that is the Sony PMW-F55 and Sony PMW-F5. Sony PMW-F55 is capable of recording XAVC with 4K resolution at 30 fps at 300 Mbit/s. While with 2K resolution, it can achieve 30 fps at 300 Mbit/s.

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