I've narrowed this rendering problem down to DNxHD files so I am starting a new thread with a more specific and appropriate title.

If I open a project, place a DNxHD file (dnxhd video + pcm audio) created by ffmpeg, and render the project (to another DNxHD file in this case), the project will not render. The render progress immediately jumps to 100% and an empty output file is created.

If I place the same clip, but the original MTS file from the camcorder, the project renders properly.

NOTE: The DNxHD file loads and behaves properly *inside* kdenlive, the timeline can be scrubbed and edited normally and the monitor window works fine.

If I place the DNxHD file, and create a script and run the sciprt from the command line, everything looks normal, there are no error messages, and MLT thinks it has successfully rendered the file, even though it finished immediately and generates an empty file.

I see this behavior on both Mint and Opensuse, so I don't think it has to do with the OS.

Kdenlive - 0.8.2.1
MLT - 0.7.6
libavcodec53 - 4:0.9.1
libavformat53 - 4:0.9.1

since there are a lot of posts about rendering crashes, I would like to clarify that this doesn't appear to be a crash, the render process completes without any error messages and the progress reaches 100%, it's just that it doesn't do anything, almost as if the source clip was a zero length clip.

This seems to be fixed with MLT 0.7.8