Render Speed Up? 7 hours or more for render MTS to MP4... (Ubuntu Studio 12.10)


I'm trying to reduce the time that my videos are created. There are a method to speed up renders???
My current profile:

"/usr/bin/melt" "/tmp/kde-jordiMFuSFg/kdenlivefB2247.mlt -profile atsc_1080p_50 -consumer avformat:/home/jordi/Dià progress=1 f=mp4 hq=1 acodec=aac ab=192k ar=48000 pix_fmt=yuv420p vcodec=libx264 minrate=0 vb=6000k g=250 bf=3 b_strategy=1 subcmp=2 cmp=2 coder=1 flags=+loop flags2=dct8x8 qmax=51 subq=7 qmin=10 qcomp=0.6 qdiff=4 trellis=1 aspect=@16/9 threads=1 real_time=-1"

Is a Project with MTS files (Canon HF G10), Titles, Flac Audio file... But the Speed is slowwww...

I'm catalan. Sorry for my english! :)


We just edited a 1 hour video and had the same slow render. In fact, it was so slow that we aborted it and pondered our fate.
Our video is 1920 x 1080 DNxHD 145Mb/s 30fps no proxy.
Kdenlive is 0.9.5 from GIT
MLT is 0.8.8 from GIT
OS is OpenSuse 12.1 64-bit

On a guess, we pondered converting the Affine transitions to Composite. Then we did a render test of a 1 minute segment that was entirely either Affine or Composite.

RESULTS for 1 minute render:
Affine - 8 minutes to render
Composite - 1 minute to render

Our 1 hour project rendered in 3 hours once we converted from Affine to Composite.

We understand that Affine is the new improved and preferred method, but all we were doing was hard cuts from one camera to the other. I wonder if anyone else has noticed this.

@kukat, what processor do you have and have you tried setting encoder threads equal to cores? So a four core processor, 4 encoder threads? It halves render times for me.

@Stevej, interesting results, I have a bug report open regarding other matters between Affine and Composite, in that Affine appears to skew colors in the rendered output, greys go greenish, Project Monitor vs Affine output differs. Where as Composite looks wrong in Project Monitor but encodes correct colors in render.

Thanks for the answer.

I have a Intel Core i3 - 370M Processor, and 4GB DDr3. and Ati HD Radeon 5470.

.mmmm...if I put a "4" on Encoder Threads I have more speed??? :D

My Kdenlive Project:

7 hours for rendering!! with 3 encoder threats to H264 mp4... 1 time only encode, with 8000 video audio 256..

Your MTS files are from the Canon HF G10?

Does it have a 50P 1920x1080 shooting mode to match your 1080 50P project?

Or is the camera 50i shooting mode? 1080_50i project?

If MLT is adjusting the frame rate of your source from 50i to match your project 50p then that might be part of the reason for such a long render time for a 30mins duration?

Thanks for the tips everyone. I just converted some of my affine transitions to composite transitions--we'll see how that change manifests itself.

What is your intended output? I'm posting some video to YouTube--I want it to look nice but YT doesn't exactly have the nicest video quality. Perhaps some pre-processing may be useful.


I suggest that you consider yourself fortunate to have got so far.

Kdenlive is unstable to the point of being not useable. Assuming that you can get beyond the crashing points of which there are many, stabilisation and rendering are unacceptably slow.

I have Sony Vegas running on Windows 7, and that stabilises and renders faster than real time.

I have Ubuntu on my laptop Lenovo T400, and that is fast for most software, but Kdenlive is slow and unstable.

If you've managed to produce the video clips, try Openshot. That will render much faster, but it won't stabilise.

Best of luck with Kdenlive - be positive, you are probably well ahead of the field.


Typically when kdenlive is horribly unstable for me there are permissions issues on hand. Search for any config files in your profile (.kde/) and then delete them. You'll have to go through the profile wizard again, but it beats an unstable Kdenlive.