1234567890123456789012345678901234567890123456789012345678901234567890 Hi,
when using scale_npp to scale a test video down from 1920x1080 to 1024x576 or lower with multiple processes in parallel, CPU usage is unusually high.For context, when scaling the same video down to 1280x720, CPU usage stays at about0.5% per FFmpeg instance. When scaling down too 1024x576 or lower, CPU usage per FFmpeg process rises to about 3.0%. The values listed here appear when starting 29 instances of FFmpeg in parallel. The effect is less pronounced but still visible at 10 instances in parallel. Hardware used for this is an AMD EPYC 7401P 24 Core + NVIDIA Quadro RTX 4000. To generate 100s of random noise in 1080p (which will be the test video): ffmpeg -y -hide_banner -f lavfi -i nullsrc=s=1920x1080 -filter_complex "geq=random(1)*255:128:128;aevalsrc=-2+random(0)" -vcodec rawvideo -acodec pcm_s16le -t 100 noise.mkv Now rescale the test video to 720p: ffmpeg -hide_banner -y -i noise.mkv -vf hwupload_cuda,scale_npp=w=1280:h=720:format=nv12 -vcodec h264_nvenc -an -f null NUL This should not cause very high CPU usage. Now rescale the same video to 576p: ffmpeg -hide_banner -y -i noise.mkv -vf hwupload_cuda,scale_npp=w=1024:h=576:format=nv12 -vcodec h264_nvenc -an -f null NUL This should cause about 5 or 6 times as much CPU usage. This might be caused by some NVIDIA optimizations, but it does not seem to be documented and I have yet to find a good place to ask more in-depth questions about NVIDIA encoding hardware. So, if anyone has encountered a similar issue or knows why this issue might occur, I would be grateful about any advice. Greetings, Valentin _______________________________________________ ffmpeg-user mailing list [email protected] https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email [email protected] with subject "unsubscribe".
