stuttering

[Nicolas Dufresne]

Le vendredi 21 janvier 2022 à 14:48 +0800, James via gstreamer-devel a écrit :
> Hi
> I'm making progress and wonder if someone can guide me:
> 
> I have a (coded in C, but looks like this) pipeline 
> 
> #! /bin/bash
> 
> IP=192.168.5.150
> 
> gst-launch-1.0 -e -v v4l2src device=/dev/video2 ! \
> 	video/x-h264,width=1920,height=1080,framerate=30/1 ! \
> 	tee name=vt \
> 	at. ! queue ! avenc_aac ! hl.audio \
> 	vt. ! h264parse ! queue ! avdec_h264 ! xvimagesink \
> 	vt. ! h264parse ! queue ! avdec_h264 ! xvimagesink \
> 	vt. ! avdec_h264 ! x264enc tune=zerolatency bitrate=1000 ! \

If I look a the transcoding branch:

  v4l2src ! tee ! avec_h264 ! x264enc ...

This is all running on the same thread, there is likely tones of interblocking
going on. Rule of thumb, always add queues right after tee, and avoid any
processing that would flow down other branches. This applies to you parser being
placed before their queues. You may also split the decoder and the encode on
their own stream threads.

> 	h264parse ! hlssink2 max-files=15 name=hl \
> 	playlist-root=http://$IP playlist-location=/dev/shm/ch1.m3u8 location=/dev/shm/ch1_%05d.ts \
> 	vt. ! h264parse ! queue max-size-buffers=0 max-size-bytes=0 max-size-time=1000000000 ! \
> 	mux. \
> 	pulsesrc device=0 ! queue ! audioconvert ! \
> 	tee name=at \
> 	at. ! audioresample ! audio/x-raw, rate=48000 ! \
> 	queue ! avenc_aac ! queue ! \
> 	mux. mp4mux name=mux ! \
> 	filesink location=try6.mp4
> 
> If I set the camera bitrate to 3Mb/s then everything is good. Files have no dropped frames.
> If I set the camera bitrate to 10 Mb/s then playback stutters and frames are dropped.
> I each case htop shows cpu usage around 50% on a 4core intel i7.
> nmon shows nothing glaringly wrong.
> 
> Logic says 'turn the record rate down" as per hlssink2 but I can just turn the camera rate down.
> If I record at 10 Mb/s using audiotestsrc then recording is fine.
> The error messages from pulsesrc are confusing saying "Down stream can't keep up"
> 
> What might I do to pulsesrc to be like audiotestsrc so that 10 Mb/s recording is OK
> 
> Thanks
> James