[FFmpeg-user] creating a grid like Zoom

[Moritz Barsnick]

Hi Michael,

On Tue, May 19, 2020 at 10:25:17 -0700, Michael Glenn Williams wrote:
> We tried following the examples of making grids when reading live streams
> liek this:
> https://www.reddit.com/r/ffmpeg/comments/aimdx9/ffserver_video_grid_source_ffserver_http_ts/
>
> With the example:

Using that example works fine for you, right? It does for me. (I would
probably simplify the example using the "scale2ref", "hstack" and
"vstack" filters, but that's not the point.)

> We wrote the output into a file output.mkv for testing. However when we
> playback the file it has a terrible flickering, see this output sample:
> https://www.dropbox.com/s/58gj99u0ezplscw/output.mkv?dl=0

Oh, indeed.

> Any thoughts on what we are doing wrong?

Yes, but first:

> The actual bash code is something like this:

Though I can read bash, could you kindly provide us the actual
resulting command line (perhaps extracted using "bash -x"), and
ffmpeg's complete, uncut console output?

I do have a suspicion: Your framerates (or image timings), and perhaps
your resolutions, don't align very well. We may see from the output
log. Perhaps we can recommend some additional options or filters to
add.

Cheers,
Moritz