[FFmpeg-user] Newbie needs help on capture video/audio using ffmpeg on RPI

Ram Shaffir ram at ram.sh
Tue May 12 00:05:39 EEST 2020


Hi Carl, thank you for your reply!

No, you are not missing anything, I had many many different tests and all were with poor results, for this discussion, I pulled one call (its choppy and audio out of sync) but I'll call it once with h264_omx and once with libx264:

ffmpeg -f alsa -ac 2 -i hw:1,0 -f v4l2 -i /dev/video0 -acodec ac3 -ab 128k -f matroska -s 1280x720 -vcodec libx264 -preset ultrafast -qp 16 /usr/ramDisk/testsize2.mkv

ffmpeg -f alsa -ac 2 -i hw:1,0 -f v4l2 -i /dev/video0 -acodec ac3 -ab 128k -f matroska -s 1280x720 -vcodec h264_omx -preset ultrafast -qp 16 /usr/ramDisk/testsize2.mkv

the results are here:
h264_omx output: https://dl.dropbox.com/s/sxy43vkmrw46a8u/h264_omx.mkv
libx264 output: https://dl.dropbox.com/s/e0zhkniw74inpza/libx264.mkv

Cheers,
RS.

-----Original Message-----
From: ffmpeg-user <ffmpeg-user-bounces at ffmpeg.org> On Behalf Of Carl Zwanzig
Sent: Monday, May 11, 2020 11:22 PM
To: ffmpeg-user at ffmpeg.org
Subject: Re: [FFmpeg-user] Newbie needs help on capture video/audio using ffmpeg on RPI

On 5/11/2020 5:12 AM, Ram Shaffir wrote:
> I tried some different ways to capture this. Still, my quality results 
> are poor, and no audio or the audio is out of sync and video is 
> choppy, another issue is that when I try to use the hardware 
> acceleration codec h264_omx I get very low quality comparing to libx264.

Unless I'm missing it, what is the exact command line you're using and its output. Also, how does it behave without using h/w acceleration?

z!
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