Overview

video/mp4 is the media type for video in the MP4 (MPEG-4 Part 14) container, commonly wrapping H.264/H.265 video and AAC audio. With the broadest compatibility, it is the de facto standard video format across web, mobile, and broadcast.

Details

The heart of web video playback is the range request. For a `<video>` element to play and let users scrub the timeline, the server must advertise `Accept-Ranges: bytes` and answer `Range: bytes=...` requests with 206 Partial Content. Without it, the browser must download the whole file before playing or seeking, badly hurting the experience.

Another key point is the position of the 'moov atom' (metadata/index). If the encoder places this index at the end of the file, the browser must fetch most of the file before playback starts. The `faststart` option moves the moov atom to the front so playback begins immediately. In adaptive streaming (HLS/DASH), this MP4 is cut into segments to switch quality by bandwidth.

Syntax

e.g. Content-Type: video/mp4

File extensions

Notes

• Seeking and partial playback require Accept-Ranges: bytes and Range (206) support — confirm your static server provides it.
• For instant playback, place the moov atom at the front (faststart) during encoding; at the end it causes large startup delay.
• Already-compressed binary, so transport gzip is pointless. For codec compatibility, add a video/webm fallback in <source>.

Related types

Related headers