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Author Topic: Audacity "Mix And Render" (and scanning levels)  (Read 6702 times)

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Offline auto_pilot

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Audacity "Mix And Render" (and scanning levels)
« on: February 18, 2012, 03:13:00 PM »
I taped three bands at a small local venue last Sunday.
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The venue has a decent PA and I was recording centrally approx 6ft back from the stage. I've got some decent captures from this position in the past but this time there's a noticeable split between the left and right channels - for example, the first band are a three-piece and the left channel has more guitar and vocals, the right channel has more bass and drums.

Playing with a few functions in Audacity, the best mix I've managed to get out so far involved using the Compression function (I used the Audacity presets), limiting a small number of peaks and then using the Mix And Render function, which has produced a far better balance between the contents of the two channels but without creating two identical channels.

So - what does 'Mix And Render' actually do? Is its use regarded as some sort of cardinal sin?
Any suggestions on tweaks in what I've done which may produce better results?
I haven't done any EQ because I have absolutely no idea where to start with that.

Whilst we're on Audacity - I have an *ancient* copy of Soundforge which I still use primarily for the one thing I haven't managed to work out how to do in Audacity - scanning recordings to get guideline RMS figures. The Normalize function in Soundforge allows me to Scans Levels, returning Peak and RMS figures for the whole recording or each channel if selected. I find the RMS figures give me an effective guide in balancing the volumes of the two channels, but I can't work out how to get them out of Audacity. Anyone?

Offline rjp

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Re: Audacity "Mix And Render" (and scanning levels)
« Reply #1 on: February 18, 2012, 06:25:50 PM »
Mix and Render explicitly mixes all of your selected channels into a single track. Any selected tracks will be mixed, and the result replaces the source tracks.

The main thing I'd use it for would be when I want to further edit the mixed/rendered result as a single track.

One way you could find peak level is to select the desired region of audio, go to the Amplify effect, and take the negative of the "Amplification" value.

For RMS, I was going to suggest the Contrast analyzer, but it seems to analyze all tracks at once, making it useless for left/right comparison.
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Re: Audacity "Mix And Render" (and scanning levels)
« Reply #2 on: February 18, 2012, 06:32:06 PM »
Mix and Render explicitly mixes all of your selected channels into a single track. Any selected tracks will be mixed, and the result replaces the source tracks.

The main thing I'd use it for would be when I want to further edit the mixed/rendered result as a single track.

One way you could find peak level is to select the desired region of audio, go to the Amplify effect, and take the negative of the "Amplification" value.

For RMS, I was going to suggest the Contrast analyzer, but it seems to analyze all tracks at once, making it useless for left/right comparison.

Thanks for the reply.
Presumably the tracks could be split before the Contrast analyzer is run so that each track could be done separately?

Mix and Render has mixed the two channels but not to the degree that it's created two identical mixes, so there's still a stereo mix rather than dual mono. I wonder how much of each channel it's taken into the resulting mix?


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Re: Audacity "Mix And Render" (and scanning levels)
« Reply #3 on: February 18, 2012, 06:38:34 PM »
If you mix and render two or more stereo tracks, you get a single stereo track (mixing all of the source tracks together).

I haven't tried using it with mono tracks.

As for the contrast analyzer, I tried taking a stereo track, splitting it, and (de-)amplifying it by -3 dB. When I tried to compare the left and right tracks, I got identical results for both, so it doesn't seem to work right.  ::)
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Re: Audacity "Mix And Render" (and scanning levels)
« Reply #4 on: February 19, 2012, 03:57:41 AM »
As for the contrast analyzer, I tried taking a stereo track, splitting it, and (de-)amplifying it by -3 dB. When I tried to compare the left and right tracks, I got identical results for both, so it doesn't seem to work right.  ::)

Thanks for the update.
Seems strange that it's not possible to scan levels in Audacity - anyone else?

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Re: Audacity "Mix And Render" (and scanning levels)
« Reply #5 on: February 19, 2012, 08:11:18 AM »
I'd consider creating a second, duplicate, stereo trackset -  (So now you have 4 tracks in your editor.)

Then perform my signal processing/effects on the second trackset - and blend that with your original trackset.

This works particularly well with reverb...

When you "Export" - all the tracks are mixed down to 2 track stereo.

Another tip that might help here - on the left side of each stereo trackset - click the little black triangle for the dropdown - and select "Split Stereo Track"

This will split your stereo track set into 2 separate tracks so you can work on each channel separately and/or make better use of the PAN controls - which might help with getting your balance back.

Watch for overs - (red peaks in the meters) - when you combine sources.
« Last Edit: February 19, 2012, 08:14:40 AM by runonce »

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Re: Audacity "Mix And Render" (and scanning levels)
« Reply #6 on: February 19, 2012, 08:58:39 AM »
Thanks for the reply, runonce - all useful tips.

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Re: Audacity "Mix And Render" (and scanning levels)
« Reply #7 on: March 05, 2012, 06:43:16 PM »
One way you could find peak level is to select the desired region of audio, go to the Amplify effect, and take the negative of the "Amplification" value.
I don't know of any other way to do this in Audacity.  ???

And I don't know how to find RMS in Audacity either.  :(
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