Audio from a digital recorder

Odaroff wrote on 10/30/2009, 2:17 PM
Is there a good way - or will audio tracks automatically line up properly if the track settings are set for both, 48 and 44 respectivly - to work with a Video file that has audio grouped at 48khz with another audio file - of the same event - recorded at 44.1?

I.E. Camcorder records at 48, digital recorder records at 44.1, both running at the same time capturing the same audio.

If they do line up properly when I render out can I then set it for 48 (using some audio from both)?

Comments

musicvid10 wrote on 10/30/2009, 2:29 PM
1) Drop your camera tracks and external audio tracks on the timeline.
2) Set your project properties for the camera tracks
3) Render audio same as the camera (i.e., 48kHz

Vegas does the rest for you.

Now, as far as syncing the two tracks on the timeline, that is up to you and has nothing to do with the respective sample rates.

Since your portable was not genlocked to the camera, some clock drift will occur. The usual methods of dealing with this are time stretch, splitting the audio segments, or both.
Odaroff wrote on 10/30/2009, 2:34 PM
That's what I was hoping for, I know they'll drift a little but I have seen other methods for correcting that.

Thanks!
farss wrote on 10/30/2009, 3:18 PM
Make certain in the Audio tab of your project properties that Resampling quality is set to Best. At least for the final render.
If possible try to record all audio at the same sample rate as final delivery or at an even multiple of it.

Bob.
musicvid10 wrote on 10/30/2009, 3:51 PM
Big "yes" to each of Bob's points.

I have inadvertently done my external recording at 44, even though the Zoom clearly has a switch for 48. Many (most?) of the desktop mixer / recorders still only record at 44.

Vegas does fine with 44khz mixed with 48, however having them both the same is of course preferable.
farss wrote on 10/30/2009, 4:43 PM
Resampling audio, especially at Best uses a lot of CPU.
When I do have to handle audio from CDs on a heavy timeline resampling it to 48KHz before I start editing can make the experience sweeter.

Bob.
RalphM wrote on 11/1/2009, 10:45 AM
Assuming your recording methods are both digital, you will most likely see llittle or no relative drift for at least 30 minutes, probably longer.
Laurence wrote on 11/1/2009, 10:53 AM
Maybe you could do the sync automatically with this new http://www.sonycreativesoftware.com/forums/ShowMessage.asp?ForumID=4&MessageID=679774PluralEyes[/link] plugin. It is designed for syncing multiple video clips via the audio, but it may well work for syncing video to audio tracks as well.
jcloninger wrote on 11/1/2009, 10:55 AM
Plural Eyes works great. I used to have to do some "time stretching" to iRiver and H4 audio, but somehow in its magic processing, I think PE fixes the issue because I now notice ZERO drifting on those audio sources to the camera's audio... A nice sideline benefit I guess of PE.
Laurence wrote on 11/1/2009, 2:26 PM
Has anyone tried using PluralEyes to sync up audio from a lav/pocket recorder yet? It seems like it might work well for this as well.
bsuratt wrote on 11/1/2009, 3:44 PM
Works great... real time saver. I use it on a 2 camera with external Zoom H2 recorder audio track. Lay out each video track with video clips (and their associated audio) in chronological order... put external audio track underneath and PE will sync everything perfectly. Then to cutting.

musicvid10 wrote on 11/1/2009, 8:09 PM
Tried PluralEyes on a recent 2-1/2 hr stage production -- two 3-CCD SD cameras, not synced, and an H4.

First attempt was bad; since the plugin doesn't do any time stretch / compress, the H4 track was in sync in the middle, but quite a bit out at the beginning and end (150 ms).

Went back to the original project, this time chopped the H4 track into 10 minute chunks, which I'm used to doing anyway, ran the plugin, and this time it worked perfectly; I can't hear even a bit of flanging or phasing between the Zoom and the primary camera track. There are inaudible 20-30 ms crossfades at the cut points, which I positioned at relatively quiet points in the program.

We were running seven lavs, two pit mics, an on-camera stereo reference, and the Zoom.

If I split the stationary cam track similarly, the audio is even tighter with the reference, and it even crossfades one video frame for about an hour of work, bringing the video into closer sync at the end of each act than it was.

Going to get critical with it this week. So far it looks like a very useful plugin, and could trim a full day off my production workflow. I may even go back and run it on some past projects where the H4 was clear in the back of the theater (for 5.1 rear channel) and see how it works in that situation.
Steve Mann wrote on 11/1/2009, 8:47 PM
What most people forget, or forgot, if the recording equipment is not genlocked, then everything runs async to their own clock. "Voice Recorders" are the worst at keeping good time. Which is why you have to stretch or chop up the audio from the cheap recorder. Prosumer cameras are the best - which is why we can easily synch them on the timeline.
farss wrote on 11/1/2009, 10:54 PM
From my research and meagre understanding of this topic it's not even that simple. Some audio gear will take TC in and record it. That does not mean it's locked to TC. To make use of the recorded timecode you need an app that will chase TC, Vegas does not do this. Even then it's not all that precise.
What's really needed is a master clock that generates TC for the cameras and word clock for the audio gear. Then everything should be sample accurate. This is neither cheap or simple to setup.

Thankfully my EX1 and R4 hold sync extremely well and almost every concert that I record has drum hits in that cannot be mistaken so getting and keeping sync is a piece of cake. It's still not sample accurate and at times the offset between the various camera's shutters can be a right PIA when editing.

Bob.