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| 4N4 |
| Posted: Oct 9 2013, 02:09 AM |
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If I use Frame rate conversion to convert a source file from 25.0017 25.017 to 25 fps, the audio gradually goes more out-of-sync.
I'm assuming this is because the audio is not being adjusted, but I thought that the Frame rate conversion feature kept audio in-sync, but the Source rate adjustment feature did not.
If neither keep the audio in sync, then what's the difference between using Source rate adjustment and Frame rate conversion to change FPS to 25 ?
How can I use VirtualDub to change video frame rate and have the audio rate auto-adjusted so it keeps in sync ?
EDIT: Corrected the FPS to 25.017 in case it is a bug in VirtualDub and is relevant.
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| jpsdr |
| Posted: Oct 9 2013, 07:45 AM |
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I think it's not possible to do this with VDub only. VDub is video processing only. You have to process audio with another software, slowing it down with the ratio 25/25.0017. |
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| raffriff42 |
| Posted: Oct 9 2013, 09:48 AM |
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>I thought that the Frame rate conversion feature kept audio in-sync, but the Source rate adjustment feature did not.
I think you are right, but maybe not for such a subtle framerate change. You can adjust the audio with the timestretch filter...
(EDIT - malky - simul-posts!)
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| malky |
| Posted: Oct 9 2013, 09:48 AM |
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Could it not be done in the Audio menu using Full processing mode > Use advanced filtering > Filters.
'Input' > 'Time Stretch' > 'Output'.
Double click on 'Time Stretch' and enter '.999932' (which is 25/25.007). |
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| raffriff42 |
| Posted: Oct 9 2013, 10:12 AM |
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I am more comfortable using Avisynth for framerate conversions, as there are several methods available - AssumeFPS changes run time; ChangeFPS drops or repeats frames; ConvertFPS blends frames. I think I would go with ChangeFPS - dropping a few video frames to avoid having to resample the audio.
http://avisynth.nl/index.php/FPS |
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| -vdub- |
| Posted: Oct 9 2013, 11:11 PM |
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Did 4N4 mean when using Video > Frame Rate... sometimes we see difference for the audio for the option 'video and audio durations match'. A virtualdub bug maybe ! or the source video has an error audio sync cannot be maintained ! |
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| 4N4 |
| Posted: Oct 20 2013, 08:14 PM |
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Many thanks @raffriff42 and @malky! Time stretch worked perfectly, although I'm going to try with Avisynth so I don't have to manually calculate the ratio each time.
Would be great if some option could be added into VDub to handle this synchronisation when changing frame rate.
@-vdub- Yes, I'm talking about Video > Frame Rate. Don't think video or audio had an error as time stretch worked perfectly. |
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| meowmeow |
| Posted: Oct 20 2013, 10:33 PM |
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| QUOTE (4N4 @ Oct 20 2013, 08:14 PM) | | Would be great if some option could be added into VDub to handle this synchronisation when changing frame rate. |
Then you have to be sure VD is doing it best way possible or it'll just crew your audio.
Maybe something like that
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