MPEG-4 Part 2 (H.263) is a video compression technique developed by MPEG. It belongs to the ISO / IEC MPEG-4 standard. It is a compression standard based on the Discrete Cosine Transform (DCT), similar to previous standards such as MPEG-1 and MPEG-2.
The other video codec defined as part of the MPEG-4 standard, the MPEG-4 part 10, is also called H.264 or AVC and was jointly developed by the ITU-T and MPEG. Profiles
To specify the different ranges of application of the standard, from low quality, such as low resolution cameras, to high definition television and DVDs, the different coding tools of the standard are grouped, according to their characteristics, into profiles and levels. Part 2 of MPEG-4 has about 21 profiles, among which are: Simple, Advanced Simple, Main, Core, Advanced Coding Efficiency, Advanced Real Time Simple, etc. The most used profiles are Advanced Simple and Simple, which is a part of the previous one. Most video compression plans standardize the bit frame, and implicitly the decoder, leaving the encoder design to individual implementations. In this way, implementations for a particular profile (such as Xvid or DivX, which are implementations of the Advanced Simple profile) are all technically the same on the decoder side. A possible comparison to this is found in an MP3 file that can be played on any MP3 player, regardless of whether it has been created with iTunes, Windows Media Player, LAME or the most common encoder, Fraunhofer. Perfil Simple (SP)
The Simple Profile is designed for situations in which a low bitrate and a low resolution are necessary, imposed by the conditions in which the standard is applied, such as network bandwidth, storage space of the network, device, etc. Some examples are found in mobile phones, some videoconferencing systems, survival equipment. Advanced Simple Profile (ASP)
The most notable technical characteristics of the Advanced Simple Profile (ASP), similar to the H.263, compared to the Simple Profile, are:
MPEG quantization and interlacing support have been designed in the same way as Part 2 of MPEG-2. The support for B images, too, has been developed as in H. 263v2 and in Part 2 of MPEG-2. The fourth pixel motion compensation is an innovation, and has been included later in Part 10 of MPEG-4 and VC-1. Some implementations dispense with the use of this feature, because it has negative effects on speed and is not always beneficial for video quality. The global motion compensation feature is not implemented today in most applications, although the official standard requires that the decoder support it. Most encoders do not implement it either, and some experts believe that this add-on does not provide any compression benefit. The use of global motion compensation in the profile has a detrimental impact on speed and adds excessive complexity to the implementation.
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