H.264 (AVC)

What is H.264?

H.264 is a video compression standard published in 2003 by the ITU and the ISO. It is also known as AVC (Advanced Video Coding) or MPEG-4 Part 10. It shrinks video by removing redundant information between frames and within each frame, so a film that would take hundreds of gigabytes uncompressed fits in a few.

What made it dominant was support as much as efficiency: almost every phone, computer and TV chip decodes H.264 in hardware, which plays video while using little battery. That is why it is the default for cameras, for OBS when it streams over RTMPRTMPThe protocol encoders such as OBS and vMix use to send a live signal to the platform. Viewers then watch over HLS.Open definition →, and for most MP4 files.

H.264 is not MP4

A common mix-up. MP4, MOV and MKV are containers: the file that holds video, audio and subtitles together. H.264 is the codecCodecThe algorithm that compresses and decompresses video — H.264, H.265 (HEVC) and AV1 are the most common in modern streaming.Open definition → that compresses the video track inside. A typical MP4 carries H.264 video and AAC audio, but it can also carry H.265 or AV1, which is why an MP4 sometimes opens on one device and not on another.

H.264 vs H.265 vs AV1

When the video has to play everywhere, H.264 is still the safe choice; newer codecs are added as a more efficient option, not a replacement.

Profiles and bitrate

H.264 defines profiles — sets of compression tools. For web video and streaming the standard is High Profile; Baseline and Main only make sense for very old devices. The other key setting is the bitrateBitrateThe amount of data used per second of video. Higher bitrate means more detail and a larger file; the core lever behind streaming quality.Open definition →. As a rough guide for moderate motion: 1–1.5 Mbps at 480p480pStandard-definition video, 480 pixels tall — 854×480 in 16:9. The fallback rung of the adaptive ladder for slow or metered connections.Open definition →, 2.5–4 Mbps at 720p720pHigh definition at 1280×720 — 921,600 pixels per frame. The entry point to HD and the fallback rung below Full HD.Open definition → and 5–8 Mbps at 1080p1080p (Full HD)Full HD at 1920×1080 — just over two million pixels. The default target for course, sales and web video.Open definition →. Sport and games need more; a slide-based lecture needs much less. Work out sizes with the video bitrate calculator.

Further reading

• ITU-T H.264 — the official recommendation.
• Video bitrate calculator — file size and bandwidth for any bitrate.

Written by

Denis Konnov Verified

CMO at Kinescope

Denis leads marketing and content at Kinescope, working closely with the platform's engineers. This glossary is reviewed and kept up to date by the team building Kinescope's streaming, encoding and CDN delivery infrastructure.