[FFmpeg-trac] #7563(undetermined:new): hwaccel nvdec consumes much more VRAM when compared to hwaccel cuvid

FFmpeg trac at avcodec.org
Fri Nov 23 22:42:52 EET 2018


#7563: hwaccel nvdec consumes much more VRAM when compared to hwaccel cuvid
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             Reporter:  malakudi     |                    Owner:
                 Type:  defect       |                   Status:  new
             Priority:  normal       |                Component:
              Version:  git-master   |  undetermined
             Keywords:               |               Resolution:
             Blocking:               |               Blocked By:
Analyzed by developer:  0            |  Reproduced by developer:  0
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Comment (by malakudi):

 Replying to [comment:1 oromit]:
 > nvdec keeps more of a buffer, because it hands through the directly
 mapped frames from the driver. While cuvid makes a vram-internal copy, and
 thus can work with a minimal buffer and potentially zero copies all the
 way through nvenc.
 > There's not much that can be done about that difference, as the buffer
 is needed for decoder and filter chain to not run out of frames in the
 predicted worst case scenario.

 Maybe this buffer can be made configurable, worst case scenario  might be
 not needed at all for specific workloads so why loose so much VRAM? If it
 is user configurable (as with cuvid decoding surfaces for example) then it
 might be able to get to similar VRAM allocation levels. As it is, at least
 for the workloads I use, nvdec makes me loose 10-12 transcodes per card
 due to VRAM limit.

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Ticket URL: <https://trac.ffmpeg.org/ticket/7563#comment:2>
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