[FFmpeg-devel] [PATCH]lavd/decklink_dec: Do not claim to output transparency information

Marton Balint cus at passwd.hu
Fri Sep 29 23:54:28 EEST 2017

On Fri, 29 Sep 2017, Carl Eugen Hoyos wrote:

> 2017-09-29 17:35 GMT+02:00 Maksym Veremeyenko <verem at m1stereo.tv>:
>> 29.09.2017 0:20, Carl Eugen Hoyos пише:
>>> I don't have decklink hardware but I assume it never outputs actual
>>> transparency.
>>> Or does it?
>> dual link SDI could provide fill/key, some boards could support this
> (Do they or don't they?)

For output, there is definitely hardware support. For capture - I am not 
sure. I have not heard of a decklink device capturing key/fill.

Unfortunately the decklink SDK uses the same constants for both capture 
and output, and if we want to follow the SDK, we can't drop alpha channel, 
because for both RGBA and ARGB modes it explicitly mentions that the alpha 
channel might be valid. It does not differentiate between input and 
output however.

Maybe somebody should ask BlackMagic.


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