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Add timecode to audio tracks???

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Michael McCune
Add timecode to audio tracks???
on Nov 30, 2017 at 7:21:49 am

Frame sequence codecs do not of course include audio tracks. But frame sequences are sometimes desirable and can easily be created in the Delivery page in various flavors.

But of course the audio is left behind.

Eventually one needs to restore audio. To be sure, there is always the manual method of slipping sliding, trying to align various waveform peaks with visual references. A better way???

And there are tools which can attempt to align existing audio tracks--still linked and in sync with the original video--with separately recorded "double system" audio tracks, usually to get better quality. But that isn't our specific problem.

And, yes, there is the Broadcast Wave recording option which tries to address this audiio-with-timecode problem but Broadcast Wave is not widely used nor available on many audio recorders.

Our problem is video that is separated from its source audio and we want to re-sync it perfectly after editing or transcoding.

Is there a way to add timecode to the audio track, perhaps when the audio and video are not yet separated and still in sync???

This would allow much quicker and more confident re-syncing.

Yeah, I know: I haven't heard of anything like this, either. But perhaps someone has a clever solution to this issue which must be a daily chore for professionals.

Thanks, Mike


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Brent Marginet
Re: Add timecode to audio tracks???
on Nov 30, 2017 at 3:54:17 pm

The easiest and most common solution to syncing audio to video is to always have a 2 Pop at the beginning and end of both the audio and video. You can then cut them out once everything is aligned and export your final delivery.

"MY MEDIA/PROJECT MOTTO: If you think three copies of your Media or Projects are enough. Take a moment to place a value on them and then maybe add two more.
Hard Drives are now stupidly cheap. A RE-SHOOT AND YOUR TIME AREN'T."


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Michael Gissing
Re: Add timecode to audio tracks???
on Dec 1, 2017 at 12:04:17 am

[Michael McCune] "And, yes, there is the Broadcast Wave recording option which tries to address this audiio-with-timecode problem but Broadcast Wave is not widely used nor available on many audio recorders.

I'm not sure this is accurate. Location sound recording devices mostly record with timecode. Unless you are using cheap domestic recorders, all pro devices have embedded timecode on location recording. What frame sequence codecs are you shooting that require syncing? I sometimes shoot cDNG on my Ursa Mini 4.6 and can record with my Sound Devices 788t. Both those devices are timecode capable and the camera can jam sync the 788t timecode.

Can you describe your workflow and where timecode relationships disappear? If it is deliverables then 2 pip as mentioned or just note that both files start with first frame.


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Marc Wielage
Re: Add timecode to audio tracks???
on Dec 1, 2017 at 5:06:19 am

Michael Gissing above is correct: the best workflow for any dual-system (camera/sound recorder) project is to make sure that both camera and sound have the identical timecode 100% of the time. Frequently, this requires putting a "jam box," like a Denecke SB-T or an Ambient Lockit, on the camera and letting the camera run in continuous jam all day long.

If you do this, the sound will never drift. It's been proven to be a rock-solid workflow for many, many decades. Recording audio without embedded timecode is fraught with problems. I strongly recommend that you don't do this. One reason why is you will run into long-take situations where the sound will slowly drift out of sync, requiring hours and hours of work to manually slide it back in sync.


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Michael McCune
Re: Add timecode to audio tracks???
on Dec 1, 2017 at 6:37:52 am

Yes, you both are quite right: I did not mention professional recorders with time code.

This is from B&H, showing eight portable recorders with time code:


True, an original recording with double system sound with time code solves this problem.

But my situation is different: I have to sync audio --actually re-syncing audio--which began life as an otherwise acceptable original video with audio track (such as an Atomos Shogun with outboard Sennheiser). But the audio lost its pairing with the timecoded video due to transcoding the video into a frame sequence format which of course has no audio channels.

I guess one could re-record the audio: that is, play original video+audio, taking the timecode out of the playback device and feed that timecode and the audio into another audio recorder which does lay down timecode.

Probably too much work. But you all have at least help cover the waterfront on this issue.

Thanks, Mike


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Bouke Vahl
Re: Add timecode to audio tracks???
on Dec 1, 2017 at 10:47:54 am

This is quite easy.
If the image sequence carry the same TC as the AV files, you can extract BWF audio from the AV and have audio with TC. (Actually, broadcast Wave has no tc, but a timestamp in samples that can be calculated to TC.)

My QTchange app. can do this for you, but is a bit old, and limited to two channels.
If you want more, let me know and I can make something custom.

Now, if the AV files are no longer available, but there is 'something' that matches the image sequence to the audio, it's also possible to 'upgrade' Wave files to BWF.

So, what exactly do you have now?

Bouke
http://www.videotoolshed.com


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Michael Gissing
Re: Add timecode to audio tracks???
on Dec 1, 2017 at 11:57:33 pm

[Michael McCune]" But the audio lost its pairing with the timecoded video due to transcoding the video into a frame sequence format which of course has no audio channels."

When the video was transcoded to a frame sequence, the then paired audio needed to be also output as a broadcast wav. And the transcode should have maintained the original timecode of the original. How was the transcode done? Did it break the timecode relationship between the original and the new transcode?

If the timecode relationship was not broken, then the audio can be extracted as broadcast wav files which will resync with the transcoded video. It would help to tell us where the relationship broke in your workflow. Indeed your workflow is not really described including the software you are using so we are guessing, hence the constant questions.


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Michael McCune
Re: Add timecode to audio tracks???
on Dec 2, 2017 at 4:48:56 pm

Thank you, Michael. Using Resolve 14.1.1 Studio and also Adobe Media Encoder for this work.

You said, "... the audio can be extracted as broadcast wav files... "

That is news to me but welcome indeed. I see there are programs to export BW metadata from existing BW files.

But, with the exception of Steinberg CUBASE software (https://steinberg.help/cubase_pro_artist/v9/en/cubase_nuendo/topics/export_...), I do not see a method to re-encode audio in a BW format.

And in the CUBASE manual there seems to be little info on exactly how this works, referring only generally to: "...the embedding of additional file information..." by which presumably they mean timecode. How this is done is not mentioned.

FWIW, interesting factoids in the Broadcast Wave standard here: https://tech.ebu.ch/docs/tech/tech3285.pdf.

Thanks, Mike


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Bouke Vahl
Re: Add timecode to audio tracks???
on Dec 2, 2017 at 4:56:45 pm

Dude,
You do NOT provide any info we've asked, and you seem to be lost.
If you work on image sequences, that indicates a high end workflow.
You seem to be totally clueless.

We can help, but not this way.

Bouke
http://www.videotoolshed.com


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