[vlc-devel] Decoder/Display implementation selection

[Steve Lhomme]

On 2019-07-04 8:23, Steve Lhomme wrote:
> The default behavior should not be an issue. It could select the decoder 
> device based on the OS and if the implementation is available. It's bit 
> heavier than the current ffmpeg VLD flavor selection as we need to open 
> system resources to know if the HW acceleration is available (and yet we 
> don't know exactly the codec/profile needed). On the other hand right 
> now we open a whole display module and then check the VLD flavor works. 
> So it would probably be done faster anyway.

There's a slight difference with the current behaviour. Currently lavc 
proposes various VLD flavors and we go though each to pick the right 
decoder and end up with software decoding if none is found. If we always 
select the same "default" decoder device no matter the VLD flavor, we 
lose the possibility of trying different decoders. So the VLD flavor (or 
more likely the VLC FourCC) be passed to the decoder device creation so 
it can decide better if it's a good match or not ?

If the case of NVDec, it's a full on decoder. So it will be driving the 
decoder device creation, it can also iterate through possibilities like 
lavc until it finds a match.