[FFmpeg-user] Blackmagic DeckLink Quad 2

Moritz Barsnick barsnick at gmx.net
Thu Jun 7 16:07:23 EEST 2018

On Wed, Jun 06, 2018 at 15:52:48 -0600, Robert Frazier wrote:

> *ffmpeg -video_size 1280x720 -pixel_format uyvy422 -framerate 60 -vsync
> > drop -f dshow -rtbufsize 150M -i video="Decklink Video Capture (5)" -i
> > video="Decklink Video Capture" -i video="Decklink Video Capture (5)" -i
> > video="Decklink Video Capture" -an -filter_complex "[0:v][1:v]hstack[t];
> > [2:v][3:v]hstack[b]; [t][b]vstack" -c:v libx264 -preset ultrafast -f mpegts
> > pipe: | ffplay pipe: -vf scale=1280:720 \ pause*
> > video=Decklink Video Capture: No such file or directory

I don't use Decklink, but what you did is to provide the input options
"-pixel_format uyvy422 -framerate 60 -f dshow" only to the first input
"-i". The three others ffmpeg doesn't realize are DShow devices. You
need to provide your input option before *every* input.

> So my optimistic concern is just that I'm using the wrong naming
> scheme;

Wrong syntax, actually.

> my only other idea is that I can't read two streams from the DeckLink
> card simultaneously (though I feel like I've read I can).

I have no idea, but my guess is that it will work.

> streams does not run with frame rate set to 60fps, I need to set it to
> 59.94fps to work, otherwise it is a black screen.

That may be a Decklink limitation, or have to do with the actual input.
BTW. 59.94 is also wrong or at least inprecise, you should probably
write it as "60000/1001", as ffmpeg accepts rationals.


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