[whatwg] Video element and duration attribute

Chris Double chris.double at double.co.nz
Fri Oct 31 13:18:33 PDT 2008

Some video formats don't make it easy to get the duration.

For example, Ogg files can be concatenated to form a single playable
file. To compute the duration you need to do multiple seeks to find
the chains and total the durations of each chain. Even in the
unchained case a seek is required to go to the end of the file and
work backwards finding a packet with a timestamp. While this is not
difficult to implement it can be expensive over HTTP, requiring
multiple byte range requests.

The most common player for Ogg files on the web is probably the
Cortado Java applet, and it has an applet parameter to specify the
duration. There have been requests in #theora from people wishing that
<video> supported a duration attribute that could be set in the HTML.

Would such an attribute be useful? It seems to be a commonly used in
current Ogg web solutions. Are there any other video formats that
could benefit from this?


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