Hi all, I have a problem which I think is something to do with avconv, one or more codecs, and possibly related to the way I'm using them.
I capture my screen (with audio) using this command: avconv -f alsa -i pulse -f x11grab -r 30 -s 1280x720 -i :0.0+100,125 -acodec ac3 -vcodec libx264 -pre:0 lossless_ultrafast -threads 0 video-$(date +%F-%H-%M-%S).mkv and during recording, it spits out some warnings about non monotonous ... and tells me that this may result in incorrect timestamps in the output file. Possibly noteworthy is that the values is prints seem to suggest that somehow this count went "backwards" relative to it's earlier number (e.g.: previous: 9138, current: 9123; changing to 9139) Now, I wasn't too bothered by this, as it seemed to create a usable file... That is, until now. I'm trying to edit this in a video editor (cinelerra) and I find that with these files, I get really strange behavior. Specifically, if I select a point in the timeline, and start playing, then go back to a couple of seconds before that point, and hit play, then as the playback passes the original point, it's playing a significantly different part of the video. This, as you will clearly understand if I've successfully conveyed the effect, makes editing the video essentially impossible. It's like selecting a paragraph in a word processor, hitting delete, and discovering that you deleted the next paragraph instead. Clearly, something of a deal breaker. By the way, I'm effectively certain that the problem isn't intrinsic in Cinelerra, since it works just fine with files from a Canon video camera. I have tried to re-code these videos into other formats, but that seems to create even more warnings about "non monotonous" (I think it means non monotonic, but whatever :) That said, I'm pretty ignorant of the various codecs I might try converting it to and the parameters that control them. (I need a lossless video, or darn close to it; my end users must read text from the video that shows the computer screen :) Can anyone help? Or can anyone point me in a useful direction? I need to end up with video that I can edit successfully, preferably without having to buy a Mac and a bunch of expensive Adobe software! Thanks, Simon -- Simon Roberts Certified Professional Photographer http://dancingcloudphotography.com (303) 249 3613
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