speed effect causes corrupted frames

I'm using the most recent sunab-svn versions of kdenlive and mlt on Kubuntu 12.10, x86-64.

When I apply the speed effect to a clip and set the speed to 200% I observe corrupted frames. For instance, there are black regions or even color noise regions ... which look a lot like memory corruption.

In addition, the new length of a clip is not consistent with project preview, single frame stepping, and rendering. For instance, when playing the clip, the duration as calculated by kdenlive is to long and in consequence, the final game gets repeated several times.

When I play the clip in kdenlive and stop somewhere in between then the frame shown at stop does not match the frame I see when stepping fourth and back again a single frame.

Is there a temporary workaround for the broken speed effect?

Please see this example, where there are artefacts in two consecutive frames. The artefacts are on the same height as the bottom-most line of titling and extending across more or less the whole width.


Is this the rendered result or a sceen shot of the project monitor?

If rendered - what codec did you use?


This is a snapshot taken in VLC from the rendered .mp4/H.264 material. The same problem is also visible on my Android Samsung Note 10.1 with its integrated H.264 decoder.

Render profile definition is as follows:

f=mp4 hq=1 acodec=aac ab='128k' 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=%dar pass=%passes