[theora] Indexing Ogg files for faster seeking

Chris Pearce chris at pearce.org.nz
Wed Sep 23 15:32:59 PDT 2009

On 24/09/09 05:20, Michael Dale wrote:
> The only minor down side I see is sending the extra delta encoded byte 
> offset track and the second round trip.

For HTML5 web video, we need to download enough of the start of the 
video to get metadata (streams' header packets, frame size, duration, 
first video frame in the absense of poster, figure out if we can 
actually play it or not, etc) so downloading the index with the other 
header stuff as well isn't a big deal. The index is usually a very small 
fraction of a percent of the total file size anyway.

If media fragments is implemented client side as "download, initialize 
and seek", including the index at the start is a clear win.

If media fragments is implemented server-side, the index may help 
improve the server's chop accuracy and will reduce the number of 
disk-hits required.

> To make indexing Ogg happen I think we would need:
> 1) index per track as described later in the thread
> 2) Mozilla to quickly push out the patch as a "critical" update to 
> encourage adoption and to not have a large percentage of users 
> avoiding its usage because of lack of seeking for existing Firefox 
> clients. (as I understand present version of Firefox does not let you 
> do normal seeking on the indexed file because of a bug with liboggplay? )

We will do this. Firefox3.5 is probably the most widely deployed Ogg 
player out there currently.

All the best,
Chris P.

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