[App_rpt-users] uLaw playback

[Ken]

I have read where uLaw produces 14 bit audio (-8159 to +8158
numerically-speaking)  - see Wikipedia on this, for example.

I am guessing this is the range of numbers used by app_rpt. 

Your 16-bit WAV format is going to produce +/- 32768 (numerically-speaking
again).

So - you need to divide the WAV output by a factor of 4 to get into the
range that uLaw supports.

The tutorial on using Audacity for app_rpt:
http://images.ohnosec.org/app-rpt-audacity.pdf  says to normalize at -6dB.

You really need to follow that advice to get clean audio.

"Normalize" will set the loudest sound to the amplitude you select.  If
there are a lot of sound "spikes" in the audio track, you can end up with a
pretty low average sound level.  I have found the best way to fix this is
some judicious use of the Audacity "hard limiter" function. It really does
not damage the sound quality, when used within reason.

73

Ken