Explain the significance of H.264/MPEG-4 standard.
1 Answer
  • High Efficiency Video Coding (HEVC), also known as H.265, is a new video compression standard, developed by the Joint Collaborative Team on Video Coding (JCT-VC).

  • HEVC was developed with the goal of providing twice the compression efficiency of the previous standard, H.264 / AVC. Although compression efficiency results vary depending on the type of content and the encoder settings, at typical consumer video distribution bit rates HEVC is typically able to compress video twice as efficiently as AVC.

  • End-users can take advantage of improved compression efficiency in one of two ways (or some combination of both); HEVC promises a 50% storage reduction as its algorithm uses efficient coding by encoding video at the lowest possible bit rate while maintaining a high image quality level. With this new format, image resolutions around 8192×4320 become possible to display and stream.

  • HEVC/H.265 not only has a better visual quality at a low storage and bandwidth but also a dexterously coding algorithm by encoding motion vectors with much greater precision and minimal residual errors. HEVC/H.265 comes with the trade-off requiring almost 10x more computing power. This new technology is on standby until the hardware market adapts to it, as it happened already with H.264.

  • Most of the power of video compression standards comes from a technique known as motion compensated prediction. Blocks of pixels are encoded by making reference to another area in the same frame (intra-prediction), or in another frame (inter-prediction). Where H.264/AVC defines macroblocks up to 16×16 pixels, HEVC can describe a much larger range of block sizes, up to 64 x 64 pixels.

  • HEVC allows predicted blocks to be coded in different block sizes than the residual error. Each top level coding unit (or CTU) is first coded as a prediction quad-tree, where at each depth the encoder decides whether to encode with merge/skip, inter, or intra coding. The residual from those predictions is then coded with a second quad-tree which can optionally have greater depth than the prediction quad-tree.

Technical Specifications:

Sr. No. Parameters H.265
1. Bit Reduction 40-52% reduction at same quality compared to H.264
2. Specification Support upto 8192×4320
3. Bandwidth required to broadcast 4K 15 Mbps
4. Compression Model * Enhanced Hybrid spatial-temporal prediction model * Flexible partitioning, introduces Coding Tree Units (Coding, Prediction and Transform Units -CU, PU, TU) * 35 directional modes for intra prediction * Superior parallel processing architecture, enhancements in multi-view coding extension * CTU supporting larger block structure (64x64) with more variable sub partition structures * Entropy coding is only CABAC
5. Industry adoption * Implementation demonstration across NAB, IBC and other events starting 2012 from companies e.g. ATEME, Broadcom, Thomson , Harmonic (Cisco), Ericsson, Qualcomm etc. * Increased R&D across Encoder/Decoder /CE vendors for software and hardware based solutions
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