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jono grant

Attention - Noel Borthwick

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I'm not sure I understand your workflow here. How are you exporting the audio from Cakewalk?

You mention "Audio Exported from MP4 within Sound Forge". What does this mean - are you exporting an MP4 from Soundforge or a wav file which is synced to an MP4 video file. Are you recording new audio synced to a video file and then exporting just the audio?

Can you describe the exact steps you are doing in Cakewalk and how it intersects with the MP4 video - I'm not sure at what stage the delay is introduced here.

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I think he opened some mp4 video in various DAW, and export the audio portion of the video as wav, then open the mp4 video in vegas and import the audio wav into vegas..

The result appears that audio which was exported from cakewalk somehow has delay (not synced) .

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But is the audio synced to the video file it came from within Cakewalk itself? i.e. is the delay problem was introduced at import time, the export step is irrelevant.

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@Noel Borthwick

Hi Noel, thanks for the reply.

When an MP4 or QuickTime file is inserted into Cakewalk, it adds silence before the start of the MP4/QT. Whereas other programs don't.

There is nothing wrong with the way Cakewalk is exporting audio, it's rock-solid. It's that the MP4/QT has the silence added to itself, so when you watch it and score to it in Cakewalk, everything looks fine. But when you export any audio and someone tries to marry the audio with the same video in another program, that program won't have the added silence issue, so the audio exported from Cakewalk will be late when brought into another program. 

Cakewalk is functioning properly except it adds the silence to the MP4/QT. So the video and video's audio track both play later than they should. My tests were done by exporting the MP4's original audio so the sync issue would be obvious as I was zooming in on the exact same audio. 

If you did the same test with an AVI or something, there's no padding added to the video file, so it wouldn't have the issue. Everything would look identical when brought into another program.

Another simple test would be: make an AVI and an MP4 of the exact same video. Bring the MP4 and it's audio into a cakewalk session, then replace that video with the AVI (keeping the MP4 audio in the session) - the newly imported AVI's audio would be out of sync with the audio from the MP4. The MP4's audio would be late by a frame or so. Even though they are the same footage. The padding is added when the MP4/QT is inserted into cakewalk, not on export.

I was able to test it, exporting from ProTools, Cubase, Sound Forge and then re-marrying the video and audio in Vegas and there was no sync issue. So those programs don't add any padding/silence to MP4s or QT files. This is a different issue than with MP3 files, which add the padding in any program.

PS. Someone here in the original post suggested trying "vidplayvst" which is a VST that you can use to  insert video into Cakewalk, but it did the same thing. That might offer a clue of some sort...

Hope I explained it a bit more clearly. 

If there's anything else I could supply to help any investigation, I'd be happy to!

Thanks

Jono

Edited by jono grant

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OK so if I'm summarizing correctly:

  • You import an MPEG4 video file into cakewalk and choose to import its audio.
  • The audio has padding applied at the beginning to line up with the video.
  • Within Cakewalk when you play the imported audio along with the video it plays perfectly in sync.
  • Now if you export just the audio from cakewalk it is out of sync with another app that plays the same video because of the padding.

If the above is correct this is related to the video engine that we're using for playback and transcoding. All the video support in Cakewalk is based on Microsoft's built in video support. We don't really have control over how it internally handles video playback and transcoding. In fact if the offset to the audio didn't get applied, then it would be out of sync with the video in Cakewalk itself. I think that would be a far worse problem.

I can pass on this information to Microsoft since its not something we can solve internally. If you are taking audio out of Cakewalk that originated from an MP4 your only solution right now is to manually trim the silence from the audio before exporting.

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35 minutes ago, Noel Borthwick said:

OK so if I'm summarizing correctly:

  • You import an MPEG4 video file into cakewalk and choose to import its audio.
  • The audio has padding applied at the beginning to line up with the video.
  • Within Cakewalk when you play the imported audio along with the video it plays perfectly in sync.
  • Now if you export just the audio from cakewalk it is out of sync with another app that plays the same video because of the padding.

If the above is correct this is related to the video engine that we're using for playback and transcoding. All the video support in Cakewalk is based on Microsoft's built in video support. We don't really have control over how it internally handles video playback and transcoding. In fact if the offset to the audio didn't get applied, then it would be out of sync with the video in Cakewalk itself. I think that would be a far worse problem.

I can pass on this information to Microsoft since its not something we can solve internally. If you are taking audio out of Cakewalk that originated from an MP4 your only solution right now is to manually trim the silence from the audio before exporting.

@Noel Borthwick

Yes, that's correct; but why don't the other programs have this problem? Aren't they using Microsoft's video support as well? Assuming that they are, it would be a cakewalk issue. Are they not using Microsoft video support? J     

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23 hours ago, Noel Borthwick said:

They are not

Well, whatever they're using seems to work. Hopefully Microsoft can do something about it if they become aware of it.

Thanks

Jono

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