#3192: Dropped Frames With Overlay Filter
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Reporter: ian_m | Owner:
Type: defect | Status: new
Priority: normal | Component:
Version: git-master | undetermined
Keywords: x11grab | Resolution:
Blocking: | Blocked By:
Analyzed by developer: 0 | Reproduced by developer: 0
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Comment (by jnvsor):
I can confirm it occurs when both streams are passed through
filter_complex, even if they are null filters that shouldn't effect
performance at all.
Low fps:
{{{
ffmpeg -f x11grab -framerate 30 -s hd1080 -i :0.0 -f v4l2 -framerate 30 -i
/dev/video0 -filter_complex '[0]null[cap];[1]null[webcam]' -map '[cap]'
-map '[webcam]' -c:v libx264 -pix_fmt yuv444p -preset ultrafast -qp 0
-threads 2 -y out.avi
}}}
Remove either of the null filters and it will work at full framerate:
{{{
- '[0]null[cap];[1]null[webcam]'
- -map '[cap]'
+ '[1]null[webcam]'
+ -map 0
OR
+ '[0]null[cap]'
+ -map 1
}}}
Add the v4l2 input first and it will work at full framerate:
{{{
- -f x11grab -framerate 30 -s hd1080 -i :0.0 -f v4l2 -framerate 30 -i
/dev/video0
+ -f v4l2 -framerate 30 -i /dev/video0 -f x11grab -framerate 30 -s hd1080
-i :0.0
}}}
It only occurs if that filter output is actually used, piping one to a
nullsink also makes it work at full framerate:
{{{
- '[0]null[cap];[1]null[webcam]'
- -map '[cap]'
+ '[0]null[cap];[cap]nullsink;[1]null[webcam]'
+ -map 0
}}}
--
Ticket URL: <https://trac.ffmpeg.org/ticket/3192#comment:11>
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