Subject: Re: [linux-audio-dev] AC3 encoder for Linux? AAC vs MP3 vs MP2 quality :-)
From: Juhana Sadeharju (kouhia_AT_nic.funet.fi)
Date: su tammi 09 2000 - 21:12:14 EST
>From: Benno Senoner <sbenno_AT_gardena.net>
>
> AAC is not AC3 !
Hello.
Is AC3 used in DVDs? Is AC3 made by Dolby?
>The ISO reference encoder doesn't sound very good,
I use Lame patch against the example implementation.
Look at them homepage for some graphs (through Phillip's pages).
>I think Fraunhofer & friends will not give us a free high-quality AAC encoder,
Ha! F.'s behaviour on their patents on mp3 shows what to expect from AAC.
>In a few special cases you can cheat the mp3 encoders (square waves
>for example), producing very bad S/N ratio.
>MP2 is much more stable in these cases.
Hmm.. I have use mp3 with 320 kbps (stereo). What do you think about
performance at that rate? Note, Lame is equivalent with the example
implementation at this rate (in case you know only about it).
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.
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...
If you now rush to implement a mp3 sample database program, please
notice that example implementation adds silence (1000 samples?) to the
begin of the sample and drops off samples (700 samples?) from the end.
Not good for synth samples and sample loops.
Yours,
Juhana
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