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[Andy Finch <503112@xxxxxxxxxxxxxxxxxx>]

I spent some time looking at this bug tonight. I haven't been able to
fix it, but did notice a couple of things which might be pointers to the
problem.

Cutting the same video in Kdenlive does not result in white output.
Comparing the xml files between Kdenlive & Openshot, there is a
difference of 2 frames in the in & out points & overall length of the
clip (the length in frames is reported as 1705 in melt, 1707 in
Openshot). This may or may not be relevant.

While working with the clip, the line:

[mpeg1video @ 0xaf0a5640]Missing picture start code

was output occasionally, which may indicate that we are cutting in a
segment that doesn't contain an I Frame - I'm not sure under what
conditions ffmpeg throws out that error. Mpeg video contains I frames
(key frames), P frames (predicted frames) & B frames (bi-directional
predicted frames), it is not possible to playback a segment of video
before the first I frame in the segment, so if we are cutting out the I
frame, this would explain the white output.

I'm not sure how we can ensure the cut segment includes an I frame, or
even if that is desirable, as that would result in the cut being a
number of frames away from where it was intended to be (there are
usually 12-15 reference frames per I frame).

More research required.

-- 
White video output on some mpeg files
https://bugs.launchpad.net/bugs/503112
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Status in OpenShot Video Editor: Confirmed

Bug description:
Some mpeg files display a white screen after they have been cut with the razor tool. This issue was originally reported on the forum as white output when the video is muted, however I have found that just cutting a clip is enough to display the white output.

http://openshotusers.com/forum/viewtopic.php?f=11&t=121

Steps to reproduce:

1. Drop the attached mpeg file on to the time line.
2. Cut the file into 3 roughly equal portions.
3. Set to play - when the playhead reaches the 2nd clip the video output is white.

The only other mpeg file I had (from a different source) wasn't affected by this, but it was only 11 seconds long, so not sure if it is related to length or some other property of the file.

Reproduced on bzr version 181, Jaunty 32 bit, MLT version 0.4.4 (from TJ's old repository).