mxf files are randomly incorrectly playing
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#247 mxf files are randomly incorrectly playing
When playing a .MXF video in melt 6.3.0, it is played incorrectly. When I jump to any time of the video, another part is playing. Audio and video is desynchronized and when jumping to the beginning, video is often freezed.
In old 0.9 series, this didn't happen. When I convert the clip to another format, everything is ok.
I'm really sorry to bother you, but this seems like a serious problem. It affects not only MXF, but AAC as well. Just play any AAC song with Melt and seek forward and backwards – nothing happens. The bug makes working with these formats with Kdenlive impossible, which is very confusing.
Using Ubuntu 16.04 with MLT 6.3.0.
I have MPEG-2 Video MXF files that play just fine using Shotcut 16.10, which uses latest MLT and FFmpeg 3.0.2. Your bug report is very ambiguous. What kind of MXF or how can I make one like it? You should know this depends heavily on the version of FFmpeg or Libav, which is not provided. And what is "AAC song" exactly? .aac or .m4a?
What I have noticed while testing this is that some MXF files do not properly support seeking, while others do. Also .aac does not support seeking whereas .m4a (from which I made the .aac) does and works as expected. In Shotcut, I make a fairly strong test for seeking, and open files that do not support seeking in a "live" stream mode. I suspect the problem is that your files suffer the same problem, but Kdenlive lets you try to use them as seekable clips anyways. I am not going to try to workaround libavformat's inabilty to seek correctly on these files. I recommend you test with Shotcut (using the binary build we provide) to provide feedback about its behavior on these files.
Tried git master head, the bug persists.
(I haven't read your response before posting my own, now trying with Shotcut)
Last edit: Aslanex 2016-10-30
Ok, I see it is an audio bug somehow solved in Shotcut but not in MLT. The .aac song is not accepted in Shotcut at all, while .mxf (mpeg2video/pcm_s16le) is processed correctly, but the same file is seeked incorrectly when playing just with melt (even the executable inside Shotcut files). Both files work with ffplay, using ffmpeg 2.8.8-0ubuntu0.16.04.1.
What? Shotcut USES MLT. In any case, I don't see the problem. I am not volunteering to change MLT's FFmpeg seeking code to accomodate your files that seek poorly in MLT. It takes a very long time to develop andd test it, and the current code has evolved and been tested for 12 years. I simply don't have time, and I do not trust anyone else yet.