[FFmpeg-trac] #8377(undetermined:new): Using kmsgrab + h264_vaapi with audio causes stutter

[FFmpeg]

#8377: Using kmsgrab + h264_vaapi with audio causes stutter
-------------------------------------+-------------------------------------
             Reporter:  asineth      |                    Owner:
                 Type:  defect       |                   Status:  new
             Priority:  normal       |                Component:
                                     |  undetermined
              Version:  unspecified  |               Resolution:
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------

Comment (by asineth):

 Here's my cmdline for where I started.

 ffmpeg -y -framerate 60 -vsync 0 -device /dev/dri/card0 -vaapi_device
 /dev/dri/renderD128 -f kmsgrab -i - -vf 'hwmap,scale_vaapi=format=nv12'
 -c:v h264_vaapi -profile:v constrained_baseline -bf 0 output.mp4 -loglevel
 debug -report

 This produces a smooth recording. I've attached the output and log as
 output1.mp4 and output1.log

 I added in audio with "-f alsa -i default -c:a aac" and this is my new
 cmdline.

 ffmpeg -y -framerate 60 -vsync 0 -device /dev/dri/card0 -vaapi_device
 /dev/dri/renderD128 -f kmsgrab -i - -f alsa -i default -c:a aac -vf
 'hwmap,scale_vaapi=format=nv12' -c:v h264_vaapi -profile:v
 constrained_baseline -bf 0 output_waudio.mp4 -loglevel debug -report

 This produces a stuttery and unuseable recording. I've attached the output
 and log as output2.mp4 and output2.log

 What I don't understand is: why does the video become stuttery and
 unuseable when I add in audio? Am I missing something or doing something
 wrong?

 Files (too large, ~20MB for the videos):
 output1.mp4: https://anonfile.com/Z4Mf4aA2n2/output1_mp4
 output1.log: https://anonfile.com/Q5M442A0n0/output1_log
 output2.mp4: https://anonfile.com/WbMf4eA2n3/output2_mp4
 output2.log: https://anonfile.com/O1M943A4n4/output2_log

--
Ticket URL: <https://trac.ffmpeg.org/ticket/8377#comment:4>
FFmpeg <https://ffmpeg.org>
FFmpeg issue tracker