[FFmpeg-user] How to set video size when using -f dshow?

[Roger Pack]

> When running the command line below, I get "Option video_size not found."
> I've tried -video_size hd720, with no effect.
>
> How do you set the video size when using dshow? Thanks for any help you can
> provide.
>
> ffmpeg -rtbufsize 100000000 -f dshow -s hd720 -i video="Microsoft LifeCam
> Cinema" -vframes 1 test%06d.tif

You can't yet it's not implemented, I believe (just looking at it, I
think maybe it's using DirectConnect to connect the pins, which just
always choose some default).

My current work around is to (are you ready for this?) create a
graphviz file with one box as your LifeCam, then add a "Tee" box and
connect the two.  Then right click on your output pin coming from the
LifeCam, and set the resolution. Save the graphviz file.
Now create an avisynth file like:

DirectShowSource("tee.grf", fps=2.0, audio=False, framecount=1000000)
(from https://github.com/rdp/dirt-simple-usb-surveillance/blob/master/tee.avs
)
Then use ffmpeg on that file as input. (you have to install avisynth
as well, obviously).
Phew!

I'd be willing to offer a bounty for somebody to implement it so that
you can select the size and the fps though, that would be sweet and
avoid this work around.

-roger-