base info: ppa openshot 1.42 running mlt 0.7.7 (reported by melt) on 32bit Ubuntu 12.04 and on 32bit Ubuntu 11.10
enabled repositories: ubuntu universe & multiverse, openshot ppa and medibuntu (non free as well).
I selected the mlt++ category but please change when tagged incorrectly.
When adding some avc based clips on the timeline and then adding a set of images with transitions, some of the transitions are not played correctly. When the transition starts it first shows extremely briefly in a split second the image to transition to and then start the transition itself. The transition itself is not relevant. I tried it with all transitions (by now).
Also: when checking the properties from within openshot, where mlt is used, it displays video clip lenghts that are not always the same as "ffmpeg -i" or "ffprobe" reports. What's more: mlt reports clip lengths that are not correct for the <number of frames>/ <fps> calculation.
With some of the avc clips come the transitions are distorted, but not all. It doesn't happen with other video codecs like mpeg4 asp, theora, mepg2.
The issue is also extensively described in the openshot forum at <http://openshotusers.com/forum/viewtopic.php?f=24&t=1250>
I tried to add a tar.bz with a couple of clips to this ticket but that didn't work. The tar.bz can also be found at <http://www.mediafire.com/?wdlbiy3pc1ox3d1>.
The clips are rendered from an "animated title" which uses blender to create an imageset of 250 pngs (in this case). The clip length of the imageset of 250 pngs is reported correctly as 9.96 seconds by mlt/openshot.
The clips are 100% copies apart from the video codec and container. Different clip lenghts and number of frames are reported by both ffmpeg and mlt.
As mentioned: the mpeg4 AVC (h.264) clips distort some of the transitions. The other video codecs, no matter the container and no matter the slightly incorrect clip length and frame numbers, work correctly.
Note that not all avc encoded videos generate the error, but the ones that do generate "distorted" transitions do this always (100% reproducable).
If you require more info please ask.