I had this itch about GIMP screencasts in Ogg Theora, like the last week frustration was not enough. This time I got a "clever" idea for the credits screen: make a PNG with the license info and just show it inside GIMP and stop the recording only after that.
So far, so good. But, as usual, my own stupidity in my worst enemy: I made a typo on the text, "Creative Commons Attribution Sahre Alike" and noticed it only after I recorded all the screencasts. At such stage, of course I will not record them again, so I needed a solution to split the video and take out the last few seconds.
Back in Divx/AVI/mencoder land, the solution would be like this:
Where HH:MM:SS is the time where I want it to be cut (is possible to define also -startpos, to cut from the start).
mencoder -oac copy -ovc copy long_video.avi -endpos HH:MM:SS -o short_video.avi
But I didn't want to transcode twice, so I searched for an Ogg Theora only solution, the best I found so far was (it still need re-encoding):
Where SS is the time in seconds (i could use also -s for start time), -v 9 a high video quality and -S 0 a sharp image.
ffmpeg2theora -e SS -v 9 -S 0 -o short_video.ogg long_video.ogg
With all my efforts, the quality of the image is visibly poorer (and as a plus, the file size smaller), is a bad idea to re-encode, but my stupidity is so big...
For now, the videos are uploaded only on YouTube (some of them are quite big and I don't want that much traffic on my own server), so the conversion to Flash lowered the quality a lot more compared with my own stupidity.