With no studying other than the ffmpeg man page I was able to do:
ffmpeg -f x11grab -s 938x663 -i :0.0+0+0 -s 528x320 test10.mp4

But: Audacity has to be running in the upper left screen corner at the
right size (938x663).  That gets resized to 528x320 in the output
file.  The mp4 file doesn't work in omxplayer but does in mpv.  Some
codecs only work for some sizes, I think it's one of those things.

What I had in mind was to make Audacity have a hook to call an
external program each time it updates the screen.   Then call
something like xwd from the hook and put the frames together later.
No sound that way though, you'd have to mix in the audio file that
Audacity is playing/displaying. xwd can do screen dumps of a specific
window id, which Audacity would have access to since it owns it.

On 9/25/20, Stuart Longland <stua...@longlandclan.id.au> wrote:
> On 25/9/20 11:59 pm, Alan Corey wrote:
>> I've never explicitly used gstreamer so I don't know anything about
>> it, just seen the name as a requirement.
> I was the same about 10 years ago: had to make a test suite for a video
> intercom and I found gstreamer had all the bits needed to make the audio
> and video hardware tick for the purpose of factory testing newly built
> boards.
> Thus I was using it to pull images from the camera and display them on
> screen to test the camera worked, put up static test images to test the
> display worked, playing sound out the speaker output through a dummy
> load into the microphone input to test those worked, etc.
> I'm definitely no expert in that, but when you mentioned the issue of
> wanting a visualisation of an audio stream, it was what first popped
> into my head.
> There might be friendlier tools than gst-launch out there, I haven't
> researched this.
> --
> Stuart Longland (aka Redhatter, VK4MSL)
> I haven't lost my mind...
>   ...it's backed up on a tape somewhere.

No, I won't  call it "climate change", do you have a "reality problem"? - AB1JX
Cities are cages built to contain excess people and keep them from
cluttering up nature.
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