Subject: Re: [linux-audio-dev] AC3 encoder for Linux? AAC vs MP3 vs MP2 quality :-)
From: Benno Senoner (sbenno_AT_gardena.net)
Date: ke tammi 12 2000 - 05:23:38 EST
On Wed, 12 Jan 2000, David Olofson wrote:
> On Mon, 10 Jan 2000, Juhana Sadeharju wrote:
> > My idea is to store sample databases with 320 kbps but because plenty of
> > the samples may be something like square wave, I wonder if this is
> > a good idea.
>
> "If it sounds good, it IS good!" However, keep in mind that some
> sorts of signal processing may emphasize the errors, so the
> requirements are higher than for the final output.
>
> > I have compared visually the graphs of the original wave and decoded mp3.
> > They look pretty the same with 320 kbps but maximum error in sample-to-sample
> > comparison is nearly 8 bits. This made me think that the bytes are in wrong
> > order but the mp3 audio is crystal clear and not noisy. Hmm...
>
> 8 bits aren't much if the frequencies are high, and the error is in
> the time domain... :-)
I can only say you one thing:
use 384kbit MP2 instead of 320Kbit MP3,
it uses 20% more space, but you get:
- much faster compression and decompression times
- much better behaviour on weird signals like 50Hz square waves etc.
With a fast MP2 implementation you ( commercial = qdesign or philips ),
you get 4x - 5x realtime on a PII400.
With the ISO MP2 reference encoder you get about 1.5x - 2x realtime I think
but it cuts away most audio material above the 16kHz.
Benno.
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