how to find max & min samples

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Grey Swan
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how to find max & min samples

Post by Grey Swan » Tue Mar 30, 2010 6:25 am

'ello all!
I've been searching the manual for how to locate max and min samples in a project track.
Any clues would be appreciated.

David

whomper
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Re: how to find max & min samples

Post by whomper » Tue Mar 30, 2010 11:50 pm

you can find out how tall the max is by using amplify
it will tell you how far you can go until you clip so you are that many db down from FS. i see no easy way to tell how to find the min. or where the max was located. i guess if you expanded the wave form enough that you could *slowly* scroll through it and find those points though. maybe if you used the find silence feature it could find the min if you used a narrow enough gap but it could depend on the noise level so would not be really useful.

Grey Swan
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Re: how to find max & min samples

Post by Grey Swan » Wed Mar 31, 2010 3:17 am

Thanks for your suggestion Womper.
I just realised that by min. val. sample, I should have said "maximally negative."
They can't be hard to find. I wonder whether anyone else has a use for such info...
I'm interested in finding them to make some editing decisions prior to normalising the track, so as to achieve an overall higher mean amplitude.
I'm not really interested in doing it by hand/sight as that can't be batched.

Does the dev. team read any of this or should I email them specifically?

cheers,

David

steve
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Re: how to find max & min samples

Post by steve » Wed Mar 31, 2010 4:21 am

The Amplify effect will indicate the max OR min of a selection.
The default amplification is to bring the peak level to 0dB ... that's +/- 1.0

If you use Audacity 1.3 and you set "View menu > Show Clipping", and then amplify to 0dB, the place(s) where the waveform touches +/- 0dB will be indicated by a red vertical line.
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kozikowski
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Re: how to find max & min samples

Post by kozikowski » Wed Mar 31, 2010 5:45 am

<<<If you use Audacity 1.3 and you set "View menu > Show Clipping", and then amplify to 0dB, the place(s) where the waveform touches +/- 0dB will be indicated by a red vertical line.>>>

Since "0" is a valid number, I thought they turned red if the samples exceeded 0.

Koz

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Re: how to find max & min samples

Post by steve » Wed Mar 31, 2010 8:09 am

Unless you are using 32 bit, then it can't exceed +/- 1.0
That's what makes digital clipping so nasty. 1 bit over +1 and you are suddenly at -1

Audacity therefore triggers the clip indicator at 0dB.
In the case of one or two single lines, it's no problem. Where the audio attempts to exceed 0dB (or for 32 bit, if it does exceed 0dB, then there will be a whole wodge of red lines with the appearance of thick red lines and that indicates there is a problem.
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Re: how to find max & min samples

Post by whomper » Wed Mar 31, 2010 3:34 pm

stevethefiddle wrote:
If you use Audacity 1.3 and you set "View menu > Show Clipping", and then amplify to 0dB, the place(s) where the waveform touches +/- 0dB will be indicated by a red vertical line.
tried that in 1.3.9 and did not get the red line.
it shows during recording. did not see it when i allowed clipping and overamplified the signal to force clipping.

steve
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Re: how to find max & min samples

Post by steve » Wed Mar 31, 2010 3:55 pm

You've broken it :(

Post a full description of the problem including repeatable steps of how to reproduce the issue in a new topic.
Don't forget all the usual information that is required in a good error report.
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whomper
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Re: how to find max & min samples

Post by whomper » Wed Mar 31, 2010 5:08 pm

is there a template for a good error report?

this one did work after all .
it was hidden temporarily.
it started out as max at the very beginning so the line got pushed off display. had to scroll back to see it. and at 0.1 db over clipping it was very thin.

feature request? optionally be able to put fatter yellow line around the thin red lines to help spot the very short clipping spots.
and maybe a spot with a fixed flag that turns on when there is clippign anywhere to alert the fact that it happened.

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Re: how to find max & min samples

Post by steve » Wed Mar 31, 2010 5:38 pm

whomper wrote:is there a template for a good error report?
Here: http://www.catb.org/~esr/faqs/smart-questions.html
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