ffmpeg or recordmydesktop bug?
 

I am using gtk-recordmydesktop and converting to asf using ffmpeg. I am finding the following very peculiar problem.

The script has a line

ffmpeg -i $f -vcodec wmv2 -sameq -acodec wmav2 -f asf $f.asf

(I get an .ogv.asf extension which is changed to .asf later)

The thing that is peculiar is this. On three out of four files, the conversion works. But on other occasions I get


Stream #0.0: Invalid Codec -1 (I get this for the files that do convert Ok as well)
Stream #0.1: Video: theora (and usual looking stuff)
Stream #0.2 Audio: vorbis (and usual looking stuff)

swScaler: Unknown format is not supported as input pixel format
Cannot get resampling context.

I have no idea whether recordmydesktop is giving bad output or ffmpeg is failing given good input. (The ogv files play fine.) I just get an asf file containing zero bytes.

Remember, it works on three files out of four. Anyone had this and found a work-around?
For instance, is there a way of hacking the ogv header?

It sure looks like something about the input format is making ffmpeg choke, but it's unknowable from the above output whether this is because gtk-recordmydesktop is creating corrupt files or whether ffmpeg is reading it wrong.

One thing you could do is replace ffmpeg with an equivalent mencoder command, say, and see if it can handle it better. This will at least give you a better idea of which program is at fault.