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Subject: Re: MPEG Audio format

Re: MPEG Audio format

From: David Bryant <dbryant_at_impulse.net>
Date: 2006-01-14

I just ran lame with no options on the first file I found and got the
following output:
---------------
LAME version 3.96.1 (http://lame.sourceforge.net/)
CPU features: MMX (ASM used), SSE, SSE2
Using polyphase lowpass filter, transition band: 17249 Hz - 17782 Hz
Encoding concat.wav to concat.mp3
Encoding as 44.1 kHz 128 kbps j-stereo MPEG-1 Layer III (11x) qval=3
    Frame | CPU time/estim | REAL time/estim | play/CPU | ETA
  2379/2381 (100%)| 0:09/ 0:09| 0:10/ 0:10| 6.2245x| 0:00
average: 128.0 kbps LR: 849 (35.64%) MS: 1533 (64.36%)

Writing LAME Tag...done
ReplayGain: -0.8dB
-----------------
As you can see on the line starting with "average" this particular sample
used joint-stereo on 64% of the frames.

If you don't have lame installed or can't find a track that produces both
kind of frames, I can easily put this file somewhere.

David

>
> >When it comes to sample rate, layer and version switching, I think you're
> >reasonably safe, though it is probably legal. Stereo mode I think you
will
> >find encoders may switch from frame to frame.
>
> Is anyone in a position to send me an example file please? Or seond-best,
> name an encoder with a required set of options.
>
> Difficult to test my app without test data - and quite a chore to
> manufacture such a file by hand. (...and that bit of the app is not yet
> written)
>
> BC
>
>
Received on Sat Jan 14 05:40:23 2006


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