H264HEVC

H264HEVC is not a single codec but a shorthand reference to the two main modern video compression standards used for digital video: H.264, also known as AVC, and H.265, known as HEVC. Both standards were developed by the joint efforts of ITU-T Video Coding Experts Group (VCEG) and ISO/IEC MPEG to improve compression efficiency for applications such as broadcast, streaming, and storage, while maintaining visual quality.

H.264/AVC appeared in the early 2000s and became the dominant video codec for many years due to its balance of compression efficiency, complexity, and broad hardware and software support. H.264 profiles (such as Baseline, Main, and High) allow a range of capabilities from low-cost consumer devices to high-end broadcast systems. HEVC/H.265, standardized around 2013–2014, was designed to deliver substantially better compression at comparable quality, particularly at higher resolutions, with aims of roughly 50 percent bitrate savings over H.264.

Technically, H.264 relies on inter-frame and intra-frame prediction, transform coding, and entropy coding, with a modular approach defined by profiles. HEVC builds on similar concepts but introduces a larger and more flexible framework, including coding tree units up to 64x64, more prediction directions and partitions, and enhanced motion compensation and transform coding, along with advanced entropy coding. These changes generally yield higher efficiency at the cost of greater computational demand and more complex licensing.

In practice, H.264 remains widely compatible and is often used for legacy content and devices, while HEVC is favored for new high-resolution and bandwidth-constrained applications. Content may be encoded in either format depending on device support, licensing considerations, and desired balance of quality, bitrate, and complexity.