downscale 1080p to 720p with good quality using NVIDIA CUDA

[SmurfRecorder]

Hello. I found this ffmpeg code to downscale 1080p to 720p:

for %%f in (*.mkv) do (
    echo Processing %%f...
    ffmpeg -i "%%f" -c:v libx264 -crf 21 -level 3.1 -preset slow -tune film  -filter:v scale=-1:720 -sws_flags lanczos -c:a copy -c:s copy "output\%%f.mkv"
)

It should have good quality in small size. It use better scaling method than default.

But I have not powerful CPU and good GPU.

So, how to modify this command to use NVIDIA CUDA instead?

I found something like that but not sure how to add tune film and sws_flags lanczos

ffmpeg -hwaccel cuda -hwaccel_output_format cuda -i "%%f" " -c:a copy -c:s copy -vf "scale_cuda=-1:720" -c:v h264_nvenc "output_file.mp4"

[videoAI]

Try This Instead:
Best-Video-Converter

[dietboby]

Hello. I found this ffmpeg code to downscale 1080p to 720p:

for %%f in (*.mkv) do (
    echo Processing %%f...
    ffmpeg -i "%%f" -c:v libx264 -crf 21 -level 3.1 -preset slow -tune film  -filter:v scale=-1:720 -sws_flags lanczos -c:a copy -c:s copy "output\%%f.mkv"
)

It should have good quality in small size. It use better scaling method than default.

But I have not powerful CPU and good GPU.

So, how to modify this command to use NVIDIA CUDA instead?

I found something like that but not sure how to add tune film and sws_flags lanczos

ffmpeg -hwaccel cuda -hwaccel_output_format cuda -i "%%f" " -c:a copy -c:s copy -vf "scale_cuda=-1:720" -c:v h264_nvenc "output_file.mp4"

Can I ask which OS and 32 or 64bit you use and which Nvidia GPU?

[SmurfRecorder]

Win10 64bit
FFMPEG from here https://www.gyan.dev/ffmpeg/builds/

With this command:

  ffmpeg -y -hwaccel cuda -hwaccel_output_format cuda -i "%%f" -c:v h264_nvenc -profile:v high -level 4.0 -tune hq -preset p7 -vf "scale_cuda=-1:720" -b:v 0 -sws_flags lanczos -cq 27 -c:a copy -c:s copy  "output\%%f.mkv"

I have about 200fps with Nvidia 1050Ti while with CPU i have under 20fps

I found that nvenc is ignoring crf 19
and I should use cq to set quality (crf 19 = cq from 23 to 25)

And I can't find anything what is is "-tune hq" if I use "-tune film" I get error

And I don't know -sws_flags lanczos is used because I have no fps drop when using that

Edit:
Also tried that:

  ffmpeg -y -i "%%f" -c:v h264_nvenc -cq 25 -level 3.1 -preset slow -tune hq  -filter:v scale=-1:720 -sws_flags lanczos -c:a copy -c:s copy "output\%%f.mkv"

It's encoding with about 150fps

[pandy]

try to follow https://docs.nvidia.com/video-technologies/video-codec-sdk/12.2/ffmpeg-with-nvidia-gpu/index.html

Based on above NVidia guide seem ffmpeg commandline should look like this:

ffmpeg -y -vsync 0 -hwaccel cuda -hwaccel_output_format cuda -i input.mp4 -vf scale_cuda=1280:720 -vf scale_npp=1280:720 -c:a copy -c:v h264_nvenc -preset p7 -tune hq -b:v 5M -bufsize 5M -maxrate 10M -qmin 0 -g 250 -bf 3 -b_ref_mode middle -temporal-aq 1 -rc-lookahead 32 -i_qfactor 0.75 -b_qfactor 1.1 output.mp4

Use one (NVidia seem to accept both) of bellow HW accelerated resizers:


either

-vf scale_cuda=1280:720

or

-vf scale_npp=1280:720

[jagabo]

Pandy's command line encodes at about 550 fps on my RTX 4060 (1080p to 720p). Just use -qp N instead of -b:v 5M if you want "quality" based encoding.

[pandy]

Of course there is possibility to tweak both resizers (default resize algorithm seem to be bicubic) also there is possibility to use libplacebo with very high quality resize filters and/or custom shaders - how this impact performance is unknown to me - my last NVidia card was ancient Geforce 4 440MX (over 20 years ago).