[theora] Join two theora video files

[Gregory Maxwell]

On Sun, Oct 18, 2009 at 9:30 AM,  <yorn at gmx.net> wrote:
>
>> I have a question which, maybe, could go to the Theora FAQ.
>>
>> How can I join two theora video files in one without recompressing them?
>> Can I just join them one after the other, like with Ogg/Vorbis?
>
> Yes, this is possible under some conditions:
> 1) Every part must begin with a keyframe
> 2) Every part must be equal in it's encoder configuration
>
> However you have to care for the process to mux the created video packet into an ogg stream/file.

You must then contend with the fact that the constant uncoordinated
restarts make effective rate control impossible... unless you use very
large segments you'll need to only run in constant quality mode.  And
that unless you use large segments the additional keyframes will
degrade compression efficiency.

Other than that, you just combine the results in an oggCat like manner
(removing the redundant headers and renumbering it all into one
stream).