Audio TC Burn from Aux Track

We have a musical coming up and will need a working Playback TC burn. Currently I can choose a Aux Burn but there is no way to feed it time code.

We had originally planned this feature, but it’s never made it to the top of the list due to lack of demand. I think we will need some sample files in order to scope the work required as well… do you have any yet for this project?

Not sure I will be able to get any before it starts, It turns out the file I had before was something else. We have about 3 weeks before the episode rolls around.

Going to be tough to make much progress on this without files… Is there a time during the day you would be available to discuss this further with me and @JDV?

Yeah maybe via cell.

We have also had this request in the past. I agree it could be very useful.

I have a sample file - should be similar to what @idolfun will be using. It’s a WAV file. Ch1-3 are production sound, Ch4 is the playback, Ch5 is the TC of the playback (LTC). When playback starts, the TC also starts - so ch5 is silent for part of the file.

I’ve uploaded the file to the MTI FTP. I have a few other sample files if you need them.

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@24pdailies - do you happen to know what the expected Aux TC is at some corresponding master timecode in that file?

At WAV timecode 03:27:47:14, the playback timecode on ch5 should be 01:59:53:17

Also, at WAV timecode 03:27:57:07, the playback timecode should be 02:00:03:10

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I imported that file into an Avid and then used their Read Audio Timecode feature. I end up with almost the same relationship, but its off by 1 second:

Wav timecode: 03:27:47:14
Aux timecode: 01:59:54:17

Wav timecode: 03:27:57:07
Aux timecode: 02:00:04:10

Weird - I used the same Read Audio Timecode feature to get those numbers. Let me double check. Is your Avid project set up for 23.976?

Just experienced some weirdness with Avid. I used the full audio file and had Avid use its Read Audio TC tool. The aux TC came out the same as Dave’s numbers. But when I made a subclip from the audio and ran it through Read Audio TC, the timecode was one second advanced (like the numbers I first posted).

I made subclips because the aux TC on channel 5 does break. And with Avid media, you can’t have any kind of TC break or you’ll have problems.

Since the aux TC is just LTC, would something like LibLTC over at Github help?

Yep, 23.976… if I import the audio file and change the timecode interpretation, I end up with much bigger delta for the wave timecode…

We had this feature in Control Dailies, so we know how to decode LTC timecode from an audio track. But we need to dust it off, integrate it into Cortex and sort out the UI.

Having no sample files to verify the implementation was another blocking issue, but with the file you provided we should be able to do this at some point.

Its not an enormous amount of work, but its sizeable. We’ll get to it eventually, just not sure we’ll be able to schedule it to turn it around in time for @idolfun’s project.

We are starting to look closer into what will be involved to implement this, but right now we just have the one sample file from @24pdailies. Do you have any other examples now that you could share for testing and development purposes @idolfun?

Yeah i probably do they just started the musical i will see what i can do

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We’ve made some progress on this. We are getting consistent results now for the example file we have but they don’t match the Avid. Hard to say which is right. Would be great to see some other examples…

Found this - might help. One-N BWF Timecoder - takes a folder of BWF (WAV) files and generates LTC audio from the BWF timecode. If you know what the timecode should be (based on BWF header info) then it should be easy to determine which app is reading LTC correctly.

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OK, we have this feature implemented in v1.5.4 beta b5430.

To use:

  1. Right-click on wav clips, or clips sync’d to wave files, and choose ‘Edit Timecode’
  2. Choose ‘Update Manually’ or ‘Update Automatically’
  3. If Update Automatcally is chosen, choose which Audio Channel to read for decoding the timecode
  4. Click OK
    (It will take a while if updating automatically)

Afterwards, the timecode will be available as a burn-in, and any reel that includes clips with non-zero Aux timecodes will also have them listed in the ALE in the column Auxiliary TC 3


Note: we get close, but different results than Avid in the sample that @24pdailies originally provided, but we get the expected results for everything BWF Timecoder creates.

As mentioned in an earlier comment, I think there might be something weird in the way Avid’s Read Audio TC tool is reading these files. See my comments. It may be your and BWF Timecoder’s implementation is correct and Avid is having the problem? Can’t comment too much more though - could just be our version of Avid (MC 5).