Such an easy question

[James]

> On 15 Aug 2021, at 2:41 pm, James via gstreamer-devel <gstreamer-devel at lists.freedesktop.org> wrote:
> 
> Utter frustration:
> 
> I have a script
> 
> #! /bin/bash
> 
> GST_DEBUG_DUMP_DOT_DIR=/home/jam/DOT gst-launch-1.0 $@ v4l2src device=/dev/video2 ! \
> 	video/x-h264,width=1920,height=1080,framerate=30/1 ! \
> 	h264parse ! \
> 	tee name=t \
> 	t. ! queue ! avdec_h264 ! xvimagesink sync=false \
> 	t. ! queue ! avdec_h264 ! xvimagesink sync=true \
> 	t. !  queue max-size-buffers=0 max-size-bytes=0 max-size-time=1000000000 ! \
> 	mux. pulsesrc device=0 ! \
> 	queue ! \
> 	audioconvert ! \
> 	audioresample ! audio/x-raw, rate=16000 ! \
> 	queue ! \
> 	avenc_aac ! \
> 	queue ! \
> 	mux. mp4mux name=mux ! \
> 	filesink location=try9.mp4
> 
> and a C version that behaves pretty much identically.
> 
> Running the script on its own I have never seen it fail.
> My app is a QT5 gui. Running my app AND the script OR the compiled version by QProcess sometimes fails with the dreaded pulsesrc underflow, downstream consuming too slowly message.
> If it fails, it always fails until reboot.
> 
> htop shows cpu usage of 10..30% 5..6G ram as cache and 0 swap being used.
> gnome-system-monitor shows no spikes in cpu usage.
> In desperation I swapped my 2 core i3 for a 4 core i7. Behaviour was the same.
> 
> At other times it works for hours, many times in a row.
> 
> What measurements might I make that may lead me to the problem.
> 
> Needless to say if I leave the tee multiplex (and hence pulsesrc) out of the pipline then it never fails.
> I've tried mp4mux, qtmux and (by accident) mpegtsmux without any change being visible. I tried matuska but that fails everytime.

This gets more outlandish:

App->record: error after 25sec
App->quit
Script->record: all ok
App->start
Script stop
App->record: all ok

Repeatable, tried lots of times !!!

Note
App->record: error
App->idle
Script->record: error every time.

cpu usage never goes over 40%

James