[FFmpeg-user] DeckLink Output Controls

[Matthias, Thomas]

Hi There,

I’m looking into using FFMPEG for its DeckLink device control.  The capture part of the API seems fairly fully featured, however the output/playback controls seems to have some strange limitations.  Specifically, on output, there is a hard-coded limit of only 8 channels of audio.  What’s strange, is that the capture partition can handle up to 16, which makes sense considering most DeckLink cards have SDI input/output, and 16 channels is a standard workflow for SDI.  Also, is there a reason why only 2 and 8 channels are supported, instead of just “n” channels (4 or 6 channels, for example)?

Would it be possible to output 16 channels of audio?  Is there a better way to do this (via the command line?)?  Could a custom version of the decklink_enc files be built to handle 16 channels or is there some other limitation I’m not aware of?

Thanks in advance, I really appreciate any advice/ideas here.  Also, is there a specific reason that input/output are limited to only 48khz for audio?  I’m guessing this is specific to DeckLink cards, but I haven’t found a specific reason yet.

~Thomas Matthias