H264H265

H264H265 is not a single codec but a shorthand that can refer to the two related ITU-T video compression standards ITU-T H.264 (AVC) and ITU-T H.265 (HEVC). Both specify methods for compressing video data for storage and transmission and have become foundational for digital video, from streaming to broadcast.

H.264, developed by the Joint Video Team (a collaboration of ITU-T VCEG and ISO/IEC MPEG) and published in 2003–2004, dramatically improved compression efficiency over earlier standards. It introduced features such as advanced intra-prediction, improved motion-compensation, and flexible block sizes, along with enhanced entropy coding (CABAC in many profiles). H.264 enabled high-quality video at lower bitrates and has seen widespread adoption across online streaming, broadcast, Blu-ray, video conferencing, and mobile video.

HEVC, or H.265, was developed by the Joint Collaborative Team on Video Coding (JCT-VC) and published in 2013. It doubles down on efficiency by using larger coding units (CTUs up to 64x64), refined motion compensation, and improved parallel processing support (tiles and wavefront parallel processing). HEVC delivers roughly another halving of bitrate at similar quality and supports resolutions up to 8K, making it prevalent for 4K and UHD Blu-ray, streaming, and high-end broadcast. Hardware and software decoders became common through the late 2010s.

Licensing and adoption have shaped their use. AVC has a well-established licensing framework, contributing to broad ecosystem support. HEVC involves multiple patent pools and more complex licensing, which in some cases affected uptake and spurred interest in alternatives such as AV1. Today, both standards remain in active use, with HEVC favored for high-resolution content and later codecs continuing to emerge beside them.