digitalFAQ.com Forum - Audio desync in Hybrid encoding with ffmpeg?

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Audio desync in Hybrid encoding with ffmpeg?

I guess its a question right away to Selur but maybe someone did deal with that.
Now with my workflow created in Hybrid the only problem that appears is bad audio sync with larger files after processing in hybrid. For example - 10-20 min video sample can work flawlessly, but when it comes to processing the whole tape - 1 hour .avi to prores with the spectre of filtering its just doesnt work well. i cant upload samples because the files are too large. I guess its due to a slight frames loss but mediadata doesnt show that. Maybe the solution would be to cut to shorter clips but i dont know how do i do this loselessly - Vdub directly? I dont wanna capture again. Thanks in advance.

Try, whether it helps to enable:

Config->Input->Decoding->CFR output
if you have a vfw decoder for your source try AviSource (Filtering->Vapoursynth->Misc->Source->Prefer AviSource for .avi input) as source filter (also try other source filters)
'Config->Internals->Automation->Always extract timecodes from input' + disable 'only some'

You could also enable 'Config->Containers->General->Keep intermediate files' this way you can check whether the extracted audio has the correct length. You might also want to check the Vapoursynth Preview to see whether everything gets decoded propers.

Cu Selur

used avisynth for everything. length is same, the preview code looks ok, will attach it later. thank u

Quote:

used avisynth for everything

Why?

Quote:

the preview code looks ok

Does the preview too?

Quote:

will attach it later.

don't bother for me, since I will not look at the script (since it doesn't hold all the additional info a debug output holds)

Cu Selur

tried again, seems to be not that bad but there are still problems with sync. its not about the length - but frame dropping i believe. attaching the debug output now. (Im using avysynth since one part of the process cant be done with vps)

In the past, my H.264 (mp4) files have an audio skew over time. But when I switched to ProRes (mov) the problem disappeared. It was a few versions ago, so I don't think I get this issue anymore. But in general, I like outputing to ProRes as I sometimes import the video into DaVince Resolve for color work before outputing to H.264.

About out of order or missing frames with avi(lagaright): try using AviSource, assuming you have a 64bit vfw decoder in your system.

About the not possible in Vapoursynth:

Your Avisynth code:

Code:

last=clp

U = UtoY() # separate U channel (should be: 360x288)

V = VtoY() # seprate V channel (should be: 360x288)



V = Crop(V,0,0,-16,-0) #remove discolore portion and black border  (should be: 344x288)

extra=FlipHorizontal(V).Crop(0,0,12,-0) # the last 12 pixels of the V channel reflected   (should be: 332x288)

V=StackHorizontal(V,extra).AddBorders(0,0,4,0,$808080) # add the extra, pad to 720 with grey (should be: 668x288)



YtoUV(U, V, last) # mix the separate U and V with the original

return last

can be straight forward ported to Vapoursynth:

Code:

# Separate U and V channels

U = core.std.ShufflePlanes(clip, planes=1, colorfamily=vs.GRAY)  # Extract U plane

V = core.std.ShufflePlanes(clip, planes=2, colorfamily=vs.GRAY)  # Extract V plane



# Process the V channel

V_cropped = core.std.CropRel(V, right=8)  # Remove discolored portion and border

extra = core.std.FlipHorizontal(V_cropped).std.CropRel(left=V_cropped.width - 6)  # Reflect last 6 pixels

V_extended = core.std.StackHorizontal([V_cropped, extra])  # Stack the reflected pixels

V_padded = core.std.AddBorders(V_extended, right=2, color=[128])  # Pad with grey to original width



# Combine U, V, and the original luma

return core.std.ShufflePlanes(clips=[clip, U, V_padded], planes=[0, 0, 0], colorfamily=vs.YUV)

in Vapoursynth.

Cu Selur

Hi I have problem when trying do deinterlace video with bwdif audio is going out of sync. AVI file is ok. I am usung current Hybrid and ProRes format.

Without any proper details: no clue.
Wild guess: some problem with the used source filter and the source or some vfr issues.

What details should I provide?

https://www.selur.de/support <- most importantly a debug output and ideally a sample file which allows reproducing the problem.

Cu Selur

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