[Cin] Cinelerra & GPU

Sam cinelerra at posteo.de
Fri Apr 26 07:31:28 CEST 2019

On 26.04.19 06:12, Phyllis Smith wrote:
> Pierre: just some commentary here.
>     I wish it had worked better....
> That is what I was afraid of.
>     I did a lot of tests with the same.xml file that contains 4
>     mixers. Each
>     time I checked both with mpeg proxies and original DNxHD sources.
> When I load DNxHD sources, it falls back to using software as seen on 
> the startup window:
> Decoder dnxhd does not support device type vdpau.
> HW device init failed, using SW decode.
> file:/root/Downloads/DNx145_1080i_2997.gxf
>   err: Success
> FFmpeg apparently can not handle dnxhd with vdpau so that would be why 
> you see not speed up for those.
Here are some background information about hardware acceleration.

Hardware acceleration means that only the most common codecs, such as 
MPEG-2 and MPEG-4, are accelerated. The graphics card manufacturers have 
optimized the GPU to be able to play these certain video formats 
particularly efficiently. Conversely, this means that many other formats 
are not optimized and are played back normally unoptimized. These 
unoptimized formats do not provide any speed advantages. In this case, 
the CPU is normally used in the same way as if the hardware acceleration 
were deactivated.
The hardware acceleration only makes sense if you have a relatively 
strong graphics card. Very old graphics cards or non-performing graphics 
cards will probably bring only little speed advantage or no speed 
advantage at all.

But if you work for example with MPEG-2, MPEG-4 and H.264/MPEG-4 AVC 
encoded video material, you will see a significant speed advantage and 
performance increase. Depending on the graphics card, up to ten times 
higher processing speeds can be achieved.

Nvidia supports VDPAU. The following video formats are supported optimized:
MPEG-1, MPEG-2, MPEG-4 ASP (MPEG-4 Part 2), H.264/MPEG-4 AVC and VC-1, 

There are hundreds of different graphics cards, so the setting of one 
user does not necessarily have to be the same as the setting of another 
user. Here everyone has to test which setting is the best, otherwise if 
you only cut smaller videos from time to time and then use other codecs 
than the ones mentioned above, it is recommended to use the default 
settings without all the hardware tests.


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