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Old 15th May 2018, 21:21   #3090  |  Link
manolito
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Join Date: Sep 2003
Location: Berlin, Germany
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@ Sir Didymus

Yes, you are correct. I repeated my tests keeping all the temp files, and indeed it was AVStoDVD which removed the last (out of range) chapter from the conversion. BatchMux was called without this last chapter, so MuxMan had no problem. Still this is not the desired outcome, the chapters are not at the positions where they should be...


@ MrC

After some long hours of testing I do know why I had this feeling that implementing OGG chapter import would be a major task...

AVStoDVD is so advanced now, it offers many methods for FPS conversion, and all of these methods require a different handling of importing OGG chapters which are based on time codes.

From my understanding the goal must be:
When I import an OGG chapter file into A2D, then the chapters must appear at the same position of the video in the conversion result. If A2D does not speed up or slow down the video then the chapters must appear at the same point in time (which is also the same position in the video). But if A2D does speed up or slow down the video, then the chapters should still be at the same position of the video. But of course the time stamps for the chapter points should be different to reflect the now different length of the clip. Do we agree on this?


Alright, I tested most of the possible scenarios with the current Alpha, this is what I found so far:

Test environment:
Source file was a short 6min 9sec clip. I created an OGG chapter file with chapters at 2:00, 4:00 and 6:00 min. From this source clip I made different clips for the different use cases:

PAL progressive (interlaced was not needed, it made no difference)
NTSC with soft pulldown 25 -> 29.97 ("irregular" pulldown)
NTSC with soft pulldown 23.976 -> 29.97 ("regular" 3:2 pulldown)
NTSC without soft pulldown, either hard telecined or pure progressive)

I then loaded the desired source clip into A2D and imported the previously created OGG chapter file.


Results:

PAL to NTSC

Using the default soft pullown:
Chapters were way off. MuxMan did not crash though because A2D removed the out-of-range chapters.

Using hard FPS conversion (either hard telecine or ChangeFPS). Also applies to interlaced sources:
No problem


NTSC to PAL

Genuine 29.97 source without pulldown flags (progressive or interlaced):
A2D uses hard FPS conversion, no problem.

Soft telecined source:
A: Telecined 23.976 -> 29.97

A1: Using DGDecode
Pulldown flags are honored, A2D sees the source as 29.97 and uses hard FPS conversion. Chapter points are correct

A2: Using DSS2Mod with LAVFilters
MediaInfo recognizes the frame rate as 23.976, DSS2 removes the pulldown flags, and A2D will either use PAL speedup or 23.976 -> 25 pulldown. In both cases the chapter points are off (by about 4% with PAL speedup, much worse when using 23.976 -> 25 pulldown).

B: Telecined 25 -> 29.97
MediaInfo does not recognize the pulldown flags. A2D sees the source as 29.97 and will use hard FPS conversion. No problems with the chapter points.


Generally it looks like hard FPS conversions are handled correctly by the current implementation. When soft pulldown or speedup/slowdown gets used then the problems start. There are probably some more use cases which will need special attention, but right now I am not in the shape for more testing (my head is buzzing already...).


Cheers
manolito

Last edited by manolito; 16th May 2018 at 18:53.
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