Mysterious failure to auto sync Timecode both audio clips to

Very simple test yesterday to verify Tentacle sync running for over two hours. Recorded one mic on BMPCC4K (24bit) and two mics on MixPre-6 II (32bit). The MixPre file size is split after 4GB so I have two files (call them AC1 and AC2) to add to the media pool with the video clip (VC1) and it’s embedded audio (BRAW Q0 24 fps).

Auto sync everything in the Video Bin using Timecode with Append. Create Timeline. The AC1 4GB file syncs properly on the Timeline but the content of the AC2 1GB file doesn’t!

Have tried a dozen different ways of doing this. If I only have the VC1 and AC2 in the Media pool, the auto sync works perfectly placing AC2 in the last part of the Timeline. But anytime AC1 and AC2 are both included in the sync, AC2 isn’t written to the timeline.

Mystery deepens. When I tried to auto sync by waveform, Resolve told me basically there wasn’t anything to sync for AC2, but if AC2 was the only file in the Media pool, auto sync by waveform worked perfectly as well.

Something that should work fine in a second of work is taking hours to analyze but I’m stumped!

I’m going to redo my two hour test but appreciate any insight you may have.

I don't use autosync, but it's been remarked upon before that the system will only sync one audio file to a given video clip. Despite the fact that the files are sequential in this case, that's what seems to be happening to you . Is there any way to append the second file to the first, with utilities which came with the recorder?

Oh! Thanks, John.

Must have missed that memo. That would explain the weird behaviour if that’s normal. I need to look at the manual because of course in a real production there would be several mics on isolated channels and so on. I’ve so far been doing those syncs manually without issue, but liked what auto sync can do.

Used Reaper to join the audio files and convert 32bit audio to one 24bit audio file. Unfortunately Timecode was stripped and I don’t know if that’s just a matter of a Reaper setting. I can look at that another time. Auto sync by waveform did not give good results.

I quickly synced it manually though and it proved a good test anyway in that it demonstrated no dropped audio frame and no drift using the Tentacle on the BMPCC4K after jamming the MixPre-6 II during a take that exceeded two hours. Very good news.

This is why we need the following...

viewtopic.php?f=33&t=96353

Problem resolved with a workaround. If the vaunted Resolve auto sync only syncs one audio file to one video clip, I cut my video clip using Mark In and Out to create two video clios in the Media pool based on the duration of the first audio clip. Now auto sync worked with both audio clips, one for each video clip.

I need to remember anytime MixPre creates an extended file, that I must cut that video to match the extensions (or learn how to rejoin the extensions into one file while retaining Timecode, which would be better)!

Rick, if I understand correctly, you have a really long take on VC1 that straddles more than 4GB of continuous audio from the audio recorder (AC1,AC2). Resolve fails to auto-synch more than one audio file to VC1, which sucks. But could you synchronize AC1 to VC1, and then append AC2 to the AC1 tracks in the timeline?


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I could but that is treated differently in Resolve. When you use the auto sync, the external tracks lose their identity and become audio attached to the video, including file name changed. That makes it easier to keel things straight in a complex project.

You could also use the free utility Wave Agent to stitch together the two files to one big file:

https://www.sounddevices.com/product/wa ... -software/

I believe there is a way in the prefs to allow creating single files bigger than 4GB. However, from my perspective I would say stop shooting takes that long. Give the talent and crew a break every 10 minutes or so.

Marc, this was a test to see how well the MixPre maintained and accurate clock after being jammed to a Tentacle.

In real life I don’t do two hour clips! But when I record theatrical performances those acts are usually over an hour with continuous shooting. I don’t even stop between scenes because the music is still going. The camera and the actors rest at the intermission.

Totally forgot Wave Agent. Surely that software will maintain Timecode! Ah, yes, now I remember it doesn’t support 32bit audio and may be a problem with Catalina that I’m using. I might try it later but not a good time now as I’m supposed to be editing this next ten days.