I have this basic task: a screencast in Ogg Theora and a still PNG image, which I want to add at the end, for 5-10 seconds, like a credits screen (displaying the CC license, author name).
I create a PNG with the same resolution with the screencast and using ffmpeg and ffmpeg2theora from that PNG I do a short (6 seconds) clip in Ogg Theora.
Now the ugly part: join the two clips... I use the old tried and true method from avi (divx), some results after a Google search say it should work also with Ogg:
cat part1.ogg part2.ogg > full_video.ogg
It doesn't work: in both Totem and Mplayer the playback is aborted (with an error) right after the end of the first part (it does work OK with VLC).
Then I remember what I do after joining avi files:
mencoder -forceidx -oac copy -ovc copy full_video.ogg -o full_video_good.ogg
The result is a broken 5KB empty file.
I look for help and get a receipe:
mencoder -oac copy -ovc copy part1.ogg part2.ogg -o full_video_good.ogg
It doesn't work either, a result similar with what I get with "-forceidx".
The sad thing is, if I use divx encoded AVIs, all is good: the join work perfectly (either with cat and forceidx or with one step mencoder) but it is suboptimal: transcode from theora to divx > join the avis > transcode back to theora, two transcoding options and a huge quality loss.
I see two losing options: drop Ogg Theora and do everything as DivX AVI or drop the screencast at all. Frustrating. And don't get me started about the lack of a nice GUI for all this process... (PiTiVi)