Re: Questions about WAV Files

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On Tue, 06 Jun 2006 11:06:54 -0400, Scott McPhillips [MVP] wrote:

Luc wrote:
Hi, I was wondering if someone could provide me with some information on WAV
file volume levels.

For one thing, is there a way to record a WAV File so that it plays with a
specific output voltage level at max volume? If so, is there an application
that can set this?
Also, is there a way to increase this max volume so that I can force it to
clip on the sound card?


The WAV file samples should be thought of as a percentage of full scale,
not a specific voltage. +/- 32K (for 16 bit encoding) is full scale.

Since the sound card is designed to play up to full scale, you can't
force the sound card to clip on playback unless you clip (amplify) the
data before it goes to the card. But if you record it clipped it will
certainly play back clipped :(

With certain sound cards it may be possible to overdrive the output by
maxing out both the wave device volume and the master volume when playing a
full range sample. But Scott is absolutely correct, you can't overdrive
the output with data as it is not possible to get a sample out of bounds.
The only exception might be if a device driver was badly behaved and it
supported out-of-range values in IEEE-float data, but basically it ain't
gonna happen.

And as output level is not calibrated according to any scale, it's
impossible to match sample values to output levels. You can account for
change however. A 6dB change in the sample values will result in a 6dB
change in the output voltage (audio dB scale this is a doubling) provided
that no mixer volumes are adjusted.

--
http://www.chrisnet.net/code.htm
http://www.avdevforum.com/AV
.

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