[Libav-user] DeckLink libavdevice

Nicolas George nicolas.george at normalesup.org
Fri Feb 24 00:08:43 CET 2012

Le quintidi 5 ventôse, an CCXX, Deron a écrit :
> Taking Nicolas George's suggestion, I have created a basic
> libavdevice for Blackmagic's DeckLink HD-SDI cards. I'm thrilled to
> have it working to any degree (much easier than I expected), but
> still have several issues to work out. Where is the proper place to
> ask questions for a new libavdevice? ffmpeg-dev or here or ?

I believe ffmpeg-devel is the best place.

> The most important is that the normal use of the device will be to
> output a specific frame size/fps and the audio is _always_ 48k s16le
> 2, 8 or 16 channels.
> The issues I'm not sure about are:
> 1) Automatically converting audio to 48k, s16le, 2/4/8 channels.
> 2) Automatically scale/crop video to output.

The usual way is not to convert anything: if the provided data is not in the
required format, fail with a clear error message and let the user (or the
application) fix it the way they see fit:

$ ffmpeg -f s16le -ar 47000 -i /dev/zero -f alsa hw:1
[alsa @ 0x1c84de0] cannot set channel count to 1 (Invalid argument)
[alsa @ 0x1c84de0] sample rate 47000 not available, nearest is 48000

> 3) Proper configure detection of installed DeckLink includes.

The configure script has plenty of support, this should be easy.


  Nicolas George
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