On 22/11/15 20:15, MrNice wrote: > Hi, > > I try to capture with the simplified command > ./ffmpeg -debug 1 -f pulse -thread_queue_size 1024 -i > alsa_input.pci-0000_00_14.2.analog-stereo -f v4l2 -channel 1 > -thread_queue_size 1024 -i /dev/video0 -c:v ffv1 -level 3 -g 1 -aspect > 4:3 -pix_fmt yuv422p -top 0 -c:a pcm_s16le -channel_layout stereo > /Store3/Test/t_`date +%Y%m%d_%H%M`.mkv > > I get audio out of sync late by 1.7 second. > If I add -itsoffset 0.70 to video input, I get audio just 1 second late. > But when I rise the value above 1.2, I get a lot of drops. I noticed as > well that above 1.0 the debug lines are output in burst with short > pauses between them. Pauses time increases with value. > > What is/does the limit of -itsoffset value? > > BTW, I tried with: > -af aresample=async=1 => Nothing better > -ts mono2abs/abs => Do nothing only start audio/video value closer > -Audio output before video output => Nothing > -vsync passthrough => Nothing > -ss 1.70: in video input => /dev/video0: could not seek to position > 34725.055 and a lot of drops > -ss 1.70 in audio input => alsa_input.pci-0000_00_14.2.analog-stereo: > could not seek to position 1448217795.270 > -ss 1.70: in output => Nothing > -threads 1 => Nothing > > Is there another way to sync audio/video? > Any suggestion welcome. > > Many thanks >
I'd like to add some more info. When I use sdl to preview while recording ./ffmpeg -debug 1 -f pulse -thread_queue_size 1024 -i alsa_input.pci-0000_00_14.2.analog-stereo -f v4l2 -channel 1 -thread_queue_size 1024 -i /dev/video0 -c:a pcm_s16le -channel_layout stereo -c:v ffv1 -level 3 -g 1 -aspect 4:3 -pix_fmt yuv422p -top 0 /Store3/Test/t_`date +%Y%m%d_%H%M`.mkv -aspect 4:3 -f sdl "Dazzle output" Preview audio/video is perfectly sync even with or without -itsoffset _______________________________________________ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user
