[vlc-devel] DXVA no CPU access design

Rémi Denis-Courmont remi at remlab.net
Wed Apr 22 14:06:16 CEST 2015

Le 2015-04-21 21:46, Julian Scheel a écrit :
> Where is this hwaccel_context coming from? And what prevents you from
> retrieving it in the vout and putting it into a picture_sys_t?

Desktop slice-based decoders need the hardware context at 
initialization (i.e. vlc_va_New()) to check hardware capabilities. There 
are no pictures to retrieve the hardware context from because the video 
output is not initialized yet. Some further changes to the libavcodec 
plugin would be required to solve this ordering problem.

That being said, fetching the device handle from a picture - as the 
vdpau_chroma filter does - is ugly. I would rather provide the device 
handle as an opaque chroma-specific pointer from the video output to the 
decoder (*). That would be tidier IMO; but it would require core 

(*) not in the opposite direction

Rémi Denis-Courmont

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