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[BUG] Audio sync problem - Printable Version

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Audio sync problem - mykee - 11.05.2021

  • What Hybrid version did you use?(Windows 10 64 bit, Hybrid version is 2021.04.12.1)

  • What did happen? If an error message came up what did it exactly say? - No get error message, audio out of sync

  • What did you do to get to the bug?

Input video is:
- MPEG2, interlaced, top field first
- original size is 720x576 with 4:3 DAR (real is 16:9)
- audio: MP2

Target:
- I encode with NVENC to x264
- image resized to 720x576, input PAR: 64x45
- I use many filters with Vapoursynth

I have audio and tried these steps:
- passtrough all
- add first and encode to acc or ac3
- tried decode and demux with ffmpeg and used many options, but no helped, sound will out of sync. On audio tab see a preview, and there was synced.

Attached debug file.

RE: Audio sync problem - Selur - 11.05.2021

Quote:On audio tab see a preview, and there was synced.
That preview is meant to be able to listen to the original audio to know the language&co even when the streams are not flagged.
It has nothing to do with the processed output

Looking at the debug output, the Vapoursynth script contains:
....
# cutting from frame 22500 to 24000  - WARNING: This might cause synch issues
clip = core.std.Trim(clip=clip, first=22500, last=24000)
...
audio is cut using:
ffmpeg -y -ss 00:14:00.000 -threads 8 -i "F:\Be\!UPCBox\Torz\Broadway Szilveszter 2009 - 1.mpg" -map 0:1 -vn -sn -ss 00:01:00.000 -t 00:01:00.000 -acodec copy -map_metadata -1 -metadata encoding_tool="Hybrid 2021.04.12.1" "F:\Vidtemp\iId_6_aid_0_2021-05-11@19_08_12_9910_01.mp2"
Audio extraction&cutting doesn't show any errors and the audio length is reported as time=00:00:59.97.
NVEncC reports it encoded 1501 frames, which would be correct (+/- 1 frame can happen due to lots of reasons).

I can fix the problem that Vapoursynth produces one frame too much, but that probably won't fix the sync issue and I don't see a way to fix it.
(such strange things is why 'Cut Support' is *experimental*)

I'll create a dev version which will lower the 'last' frame in the Trim call by one and send you a link, but like I wrote I don't think this will fix the issue.

Cu Selur

Ps.: send link via pm.