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Subject: Re: mp3 features

Re: mp3 features

From: David McIntyre <>
Date: Wed, 10 Sep 2003 17:14:48 -0700
Shows that the automatic volume adjustment feature is built into the MAS chip.
Why bother re-writing it?

On Wed, Sep 10, 2003 at 05:40:18PM -0500, LoveLearn wrote:
> The current automatic volume alteration discussion raised questions.
> MusicMatch JukeBox includes a volume leveling option. Select which mp3
> files to process. Processed files are replaced by slightly larger
> volume leveled copies. On MusicMatch playback formerly frustratingly
> quiet files seem normally loud. Is this processing equivelant or
> identical to the volume leveling proposed RockBox?
> MusicMatch volume leveling processing appears CPU intensive on PCs.
> Similar processing might be very slow on Archos hardware.
> I ran Peavey CS800 professional sound reinforcement amplifiers years ago
> which included a quick acting volume peak limiting option. When driving
> one of these 800 watt units to very high levels, audience members never
> heard these spike reductions nor did they hear the recovery period
> because it was so fast acting in both directions. When playing really
> loudly, switching off this spike limiting circuitry instantly revealed
> clearly recognizable clipping distortion while reducing apparent average
> sound pressure level. After we discovered those two perceived
> performance enhancements, we always left the spike reduction circuit
> switched on.
> I've played with RockBox "Auto Volume" spike limiting. I don't use it
> because its shortest recovery time is distressingly long and obvious to
> me. I've experienced volume spike limiting that functions so fast
> audience members can't perceive it's occurring. Would it be possible to
> duplicate that circuit's effects with RockBox software?

David McIntyre
PGP Key fingerprint = CAB5 A73A 43FA 19E3 449D  20B8 25D7 FA84 8847 D6A7 for geek code, pgp key, etc. 
Received on 2003-09-11

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