[FFmpeg-devel] [PATCH] libavcodec/nvenc.c: copy incoming hwaccel frames instead of ref count increase

[Roman Arzumanyan]

Hello,

This patch makes nvenc copy incoming hwaccel frames instead of ref count increase.
It fixes the bug which may happen when on-GPU transcoding is done and encoder is set to use B frames.

How to reproduce the bug:
./ffmpeg \
  -hwaccel cuda -hwaccel_output_format cuda \
  -i input.mkv \
  -c:v h264_nvenc -preset p4 -tune hq -bf 3 \
  -y output.mkv

Expected output:
[h264 @ 0x55b14da4b4c0] No decoder surfaces left
[h264 @ 0x55b14da682c0] No decoder surfaces left
[h264 @ 0x55b14da850c0] No decoder surfaces left
[h264 @ 0x55b14daa1ec0] No decoder surfaces left
Error while decoding stream #0:0: Invalid data found when processing input
[h264 @ 0x55b14da2e6c0] No decoder surfaces left
Error while decoding stream #0:0: Invalid data found when processing input
    Last message repeated 1 times


Although fix adds extra CUDA DtoD memcopy, our internal testing results didn't show any noticeable difference in transcoding performance.
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