On Friday, October 7, 2016 5:25:10 PM CDT Matthias, Thomas wrote: > 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.
HDMI is limited to 8 channels. Sombody somewhere probably didn’t want to implement the logic required to make channel limits depend on the output interface used. > 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)? HDMI offers stereo mode, and 8 channel mode when using PCM streams. There is no a’la-carte audio mode. Dolby / DTS has things like 5.1, but that is an entirely differnt stream type separate from PCM. > 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? Probably. Depends on what the API supports. > 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? SDI is 20bit 48k audio only. There’s really no good reason for anything else. Technically SDI also supports 48048 and 47952 to allow for pull up/down, but I think that is done by manipulating the clock rather than explicitly changing the sample rate. -Reuben _______________________________________________ ffmpeg-user mailing list [email protected] http://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email [email protected] with subject "unsubscribe".
