[FFmpeg-devel] [PATCH] avcodec/nvenc: Add support for H.265 encoding

[Philip Langdale]

On 2015-03-26 04:30, Ali KIZIL wrote:
> 
> It works fine now Phil. One more comment:
> 
> I have a GTX 980. It can encode upto 30-33 fps for 4K 60fps YUV Raw
> input file using nvenc_h265 avcodec with FFmpeg. First a side, It 
> looked
> to me like lack of performance of card. However; after I split the 
> video
> with crop filter into 2:
> 
> /opt/ffmpeghw/bin/ffmpeg -video_size 3840x2160 -framerate 50 -i
> /Projects/YUV/soccer.yuv -vcodec nvenc_h265 -an -filter:v
> "crop=in_w:in_h/2:0:0" -r 50 -g 50 -preset hp -f hevc top.hevc
> 
> /opt/ffmpeghw/bin/ffmpeg -video_size 3840x2160 -framerate 50 -i
> /Projects/YUV/soccer.yuv -vcodec nvenc_h265 -an -filter:v
> "crop=in_w:in_h/2:0:in_h/2" -r 50 -g 50 -preset hp -f hevc bottom.hevc
> 
> When I run them at the same time, both can be encoded with 50 fps. I
> tried to joing output files with padding but FFmpeg needs re-encoding
> and it makes no sense.
> 
> Do you have any comment or idea to use full performance of the card 
> over
> a single ffmpeg nvenc_h265 instance ?
> 
> Additional note: GTX cards can suport up to 2 HEVC encoding at the same
> time (as limitation.).

I honestly don't know. The hardware performance may not scale linearly 
with
frame size, so you might see a disproportionate slowdown past a certain 
size,
perhaps reflecting the need to use multiple buffers, etc.

Do you see any evidence that you're CPU bound? That might happen if our 
buffer
management is too inefficient, but I'd be surprised.

--phil