H.264 / Advanced Video Coding (AVC)
H.264 remains the most widely supported video codec. Distinguish codec (H.264 bitstream) from container (MP4/WebM) when debugging playback, transcoding, and MSE SourceBuffer codec strings.
What It Defines
Video compression codec (not a container): NAL units, SPS/PPS parameter sets, profiles and levels. Typically muxed into MP4 (`avc1`) or MPEG-TS for HLS. MIME codec string: `avc1.42E01E`.
Canonical (Normative)
Convenient (Practical)
Related References
The international standards body for telecommunications under the UN umbrella. Publishes Recommendations in series (E, G, H, Q, T, X…): E.164 phone numbering, G.711/G.722 audio codecs, H.323 VoIP framework, and G.9959 (Z-Wave). Free access to most Recommendations.
Related Specs
MP4 is the dominant video container on the web and in MSE players. Box hierarchy, codec vs container distinction, and fragmenting (fMP4 for HLS/DASH) are essential for media engineering.
WebM is the default output of browser MediaRecorder and a common delivery format for open web video. EBML element structure differs from MP4 boxes.
Video players (YouTube, Netflix, Twitch) use MSE for adaptive streaming. Required if you build a custom media player or do in-browser video processing.