Greetings,

Kdenlive is a cool software that suits all my needs, but it has a major drawback : render time.

For example:
- Input file 2560x1440 60fps 45 min length, H264
- Resize/Crop to 1920x1080 60 fps (using the "Position and Zoom" effect)
- Render time to HEVC 01h10 (AMD Ryzen 3700X 8c/16t)

The same operation takes only 15 minutes on a famous proprietary and expansive software, thanks to GPU encoding (NVENC on a RTX 3070).

After reading MLT and ffmpeg documentation, I tried to tweak Kdenlive render profiles to use NVENC :
- NVENC H264 CQP : f=mp4 vcodec=h264_nvenc rc=constqp qp=20 profile=mlt_profile preset=quality acodec=aac ab=192k
- NVENC H265 CQP : f=mp4 vcodec=hevc_nvenc rc=constqp qp=20 profile=mlt_profile preset=quality acodec=aac ab=192k

Unfortunately, it's not faster than CPU rendering. Windows task manager shows that GPU encoding is working at ~20%, CPU at ~50%.

Without kdenlive I managed to top 100% GPU encoding speed with ffmpeg, witch does not apply the crop effect but demonstrates that it's possible to speed up things :

Code: Select all

ffmpeg.exe -hwaccel cuda -hwaccel_output_format cuda -i input.mp4 -preset 0 -profile 0 -rc 0 -qp 20 -c:v hevc_nvenc -c:a copy output.mp4

I'm still trying to figure out why kdenlive does not fully use the GPU for render. Is it related to MLT framework which does not have option for CUDA ?

Any help would be appreciated.

Xavier

EDIT: I managed to top 100% GPU encoding speed in kdenlive, just remove the "Position and zoom" effect. It seems like this effect can be processed only by the CPU. The reason why I'm using it is because I have a 2560x1440 screen but I record old games in 4:3. I will try to tweak OBS instead in order to get 4:3 input video file and avoid using effects is Kdenlive.

src386 wrote:EDIT: I managed to top 100% GPU encoding speed in kdenlive, just remove the "Position and zoom" effect. It seems like this effect can be processed only by the CPU.

I noticed this too..
Even basic operations (like transforming position and scaling) are VERY slow (in particular if you have, like me, a very old PC/CPU.. ) while using GPU for these kind of operations and (a dream) all the filters/effect would make it possible to use KDENLive for serious, complex editing jobs..
That's a pity, since the interface and the workflow are so great with KDENLive, better than all open-source alternatives.
But sadly.. at the moment...

You have to upgrade your laptop. Go with high-end GPU laptop like RTX 4050 laptop, RTX 4060 laptop, RTX 4070 laptop, RTX 4080 laptop or RTX 4090 laptop.

Also look for high-end CPU Intel Core i7-13800H laptop or Intel Core i9-13980HX laptop.

Thanks.

susanmiller wrote: RTX 3050 laptop, RTX 3060 laptop, RTX 3070 laptop, or RTX 3080 laptop.

What is that difficult to understand? VGA CARDS CAN'T BE USED FOR RENDERING RIGHT NOW. before buying an high end graphic card is necessary to wait that KDENLIVE can use it.