[theora] Add an intro to a theora file without re-encoding?

Conrad Parker conrad at metadecks.org
Thu Jul 16 15:23:15 PDT 2009

2009/7/17 Michael Opdenacker <michael at free-electrons.com>:
> Hello,
> I would like to add a introduction video (typically a title with fade-in
> / fade-out) at the beginning of an Ogg/Theora video. I generated this
> intro video in Ogg/Theora from a sequence of png files.
> I would need to do this in an automatic script, because I have many such
> videos to process, and without doing any re-encoding step (which would
> be very costly because my videos are huge).
> I tried to use oggCat:
> oggCat final.ogv intro.ogv video.ogv
> Unfortunately, this doesn't work well because my intro video has no
> sound track to be concatenated with the one in the real video. As a
> consequence, the concatenated video only has a video track.
> It tried to add a silent track to my introduction video (same bitrate)
> with oggzmerge, but oggCat doesn't like the result:
> Warning: found unknown stream, this stream will be ignored
> Warning: found unknown stream, this stream will be ignored
> StreamSerializer::fillStreams: we got a real problem with the stream

what was the silent track? What encoder did you use, and was it the
same version as was used for the audio track of the main video?


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