The H.264 standard
H.264 is an industry standard for video compression. Video compression can be defined as the process of converting digital video into a format that reduces the file size for when it is stored or transmitted.
An H.264 video encoder carries out prediction and encoding processes to produce a compressed H.264 bitstream.
Video compression (or video coding) is an essential technology for applications such as digital television, DVD-Video, mobile TV, videoconferencing and internet streaming video. Standardizing video compression makes it possible for products from different manufacturers (e.g. encoders, decoders and storage media) to inter-operate. An encoder converts video into a compressed format and a decoder converts compressed video back into an uncompressed format.
The H.264 standard reduces the amount of information required to reproduce a video. Encoders process each frame by subdividing the picture into a grid of blocks and searching previous or future frames for each block for matching texture. This technique is known as motion estimation. When a suitable match is found, a decoder can reproduce the texture of the block in the current frame using only a vector pointing to the matching reference texture along with some information to correct any small texture differences.
The H.264 standard offers substantial performance improvements over its predecessors. For example: A standard DVD can hold one two-hour movie compressed using the MPEG-2 (the popular standard for DVD movies) codec and four hours of movies using an H.264 codec.
The biggest advantage of H.264 over previous standards is its compression performance. Compared with standards such as MPEG-2 and MPEG-4, H.264 can deliver better image quality at the same compressed bitrate or a lower compressed bitrate for the same image quality.
Here are some samples to see the difference:
The reduced image size offered by H.264 utilizes dramatically less Bandwidth that either MPEG-2 or MPEG-4.
H.264 is getting so much attention because it can encode video with approximately 3 times fewer bits than comparable MPEG-2 encoders.
Because H.264 is up to twice as efficient as MPEG-4 Part 2 (natural video) encoding, it has recently been welcomed into the MPEG-4 standard as Part 10 – Advanced Video Coding. Many established encoder and decoder vendors are moving directly to H.264 and skipping the intermediate step of MPEG-4 Part 2.