In this thread I want to tell you about my problems and to hear about your problems.
Note: I have an HDA-Intel/HDA ATI Realtek ALC888 onboard sound card on my FOXCONN A7GM-S 2.0 mainboard. My current alsa-info.sh information is available at http://www.alsa-project.org/db/?f=62a33 ... 52f802162c
I use my ffmpeg-based capwin script to record videos (and then convert them using my ffmpeg-based vid2webm script).
capwin lets you click on a window and then calculates its position and size using xwininfo, grep and sed to then automatically start recording. The core command of the script is
- {l Code}: {l Select All Code}
ffmpeg -f alsa -i hw:0,0 -f x11grab -acodec pcm_s16le \
-s $CAPWIN_DIM -i :0.0+$CAPWIN_XPOS,$CAPWIN_YPOS \
-vcodec libx264 -crf 0 -preset ultrafast -threads 0 capwin-$DATE.mkv
Issue 0: Many Ffmpeg users don't have non-free codecs
This command might be an issue for systems that do not have non-free codecs. This might be easy to solve by replacing -vcodec libx264 -crf 0 -preset ultrafast with -vcodec huffyuv, a lossless codec which I assume is free. About 15 seconds of 800x600 Trigger Rally gamplay will prduce a ~90M libx264 file (video) and a ~340M huffyuv file (video). Converted to webm both are 18M. I don't know if a bigger space requirement could be a source of lagging because of bottlenecks or journaling during writing to disk (this is pure speculation) or if there might be other issues with using huffyuv.
Issue 1: Ffmpeg can't record ALSA desktop audio
My sound card's default ALSA configuration apparently makes it impossible for me to record desktop audio and my brain rejects to try to understand how ALSA works, its configuration files and consequently the instructions that I find.
I can solve this by closing all sound-using software, running pulsaudio and enabling software monitor as recording device in pavucontrol and replacing -i hw:0,0 with -i pulse.
I would much prefer to not have to use pulseaudio just for this of course.
Issue 2a: Ffmpeg video "freezing", even though game is not
Either of the codecs used above will have the issue of the video freezing in more or less regular intervals (video, freezing at 0:22)
I have not tested whether the issue is more prevalent with one of the two codecs mentioned above.
Issue 2b: Ffmpeg video jumping, audio-video out of synchronization
The video freezing issue can be 'fixed' by adding -r 30, which apparently sets a fixed frame rate of 30, which I believe makes the video pretend that there is no delay between image frames during these freezes, causing a jump (video, see first jump at 0:26), which I prefer over freezing, but this leads to audio-video not being synchronized any more, which is extremely annoying.
Issue 3: GLC video quality low
videos seem washed out and too bright (video - ffmpeg comparison). I haven't tried finding out the reason yet.
Issue 4: GLC can't record audio
See issue 1. Probably due to lack of a loopback device (speculation), GLC can't record game audio. I have not tried glc-pulseaudio-git yet.
What issues do you share? Got any solutions?