[vlc-devel] [PATCH] access module for BlackMagic SDI cards

Laurent Aimar fenrir at elivagar.org
Sat Oct 2 21:18:27 CEST 2010


On Sat, Oct 02, 2010 at 06:51:50PM +0300, Rémi Denis-Courmont wrote:
> Als a few general questions... I guess this plugin copies entire video frames 
> from the SDK into VLC block_t. The rawvideo codec will again copy those entire 
> frames into VLC pictures_t. Is this intended?
 With the current vlc API, rawvideo 'decoder' needs to do a copy.
 Now, depending on the blackmagic SDK, it may or may not possible to avoid a copy
in the demuxer. The copy could be avoided if:
 - the blackmagic pictures have a stride equals to the width (in pixels
   not numerical value)
 - the SDK allows to keep a reference to its buffer.
If yes, then we could hijack the release callback of a block_t.

> And does Demux() not get stuck if we never get an image? Is that possible at 
> all? Do you really need the mutex and condition variable?
 That's why I requested the code to be changed to not need Demux() at all. No
polling and no deadlock.


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