Media type / video
video/mp4
The MPEG-4 container, usually H.264 or H.265 video with AAC audio — the default for web delivery.
Served inline: Browsers display this in the tab without granting it script access to the page. Safe to serve inline, provided the bytes really are what the header claims.
Browser behaviour
Renders inertly
Charset
no charset
Compression
Already compressed
Send it like this
Content-Type: video/mp4A binary payload has no character encoding. A charset parameter here is meaningless and occasionally confuses strict parsers.
Handling verdict
Browsers display this in the tab without granting it script access to the page. Safe to serve inline, provided the bytes really are what the header claims.
A binary payload has no character encoding. A charset parameter here is meaningless and occasionally confuses strict parsers.
The format compresses internally. Another transport encoding costs CPU on both ends and typically changes the size by less than a percent — sometimes upward.
Registered with IANA through a public review process, so the name is stable and every implementation can rely on it meaning the same thing.
Anatomy of the name
RFC 6838Top-level type
video
Video
Subtype
mp4
Registered in the standards tree.
Structured syntax
none
No suffix, so the payload format is defined entirely by the subtype itself.
Parameters
codecs
Defined for this type in addition to any charset rule above.
What trips people up
2 notes- Progressive playback needs the moov atom at the front of the file ("faststart"); otherwise the browser must download everything before the first frame.
- Range request support is what makes seeking work — a server that ignores Range serves video that cannot be scrubbed.
Response headers
Content-Type: video/mp4
X-Content-Type-Options: nosniff
Content-Disposition: inlinenosniff stops the browser second-guessing the type you declared, which is what makes the rest of this reliable. Serving it inline is safe here because the browser renders it without granting it script access.
Server configuration
extension mappingnginx
types {
video/mp4 mp4 mp4v mpg4;
}Apache
AddType video/mp4 .mp4 .mp4v .mpg4Caddy
@type path *.mp4 *.mp4v *.mpg4
header @type Content-Type "video/mp4"Extensions and other spellings
with signatureFile extensions
File signature
?? ?? ?? ?? 66 74 79 70
Check these bytes rather than the client-supplied Content-Type when validating an upload. The header is a claim; the signature is evidence.