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Re: again about compression

Subject: Re: again about compression
From: "richpeet" <>
Date: Mon, 01 Apr 2002 22:10:25 -0000
Sony has made a large effort to make unavailable computer emulation 
of atrac.  If you want to test a few specific files I would be happy 
to convert a wave file to atrac and back to PC wave and send it back 
to you to look at.  I would make the transfer from wave to atrac all 
digital but I only have an ablility to make the atrac back to wave 
via line level analog. It would still be pretty clean but you may 
want to use someone with a digital out on their Minidisc. The limit 
on email to me for the conversion is 5 megs per message. please note 
that the first 3 secs may be cut on a digital record. If you want 
address it to richpeet(at) and note at=@.

--- In  Gianni Pavan <> wrote:
> I think the effect of compression on sound quality it is still a 
> question. It is very important to know which sound features may be 
> by compression and how the acoustic context may affect the 
> algorithm's behaviour. I made some tests with MP3 encoding/decoding 
> several effects can be easily detected by hearing or by 
> analysis. Of course, with MP3 the compression is scalable and 
> increase with increasing the compression factor (which corresponds 
> reducing the bit rate).
> The MP3 works both in frequency and in time; by using algorithms 
based on 
> both frequency and time masking, it can cut a short segment of a 
signal if 
> it is just after a strong sound. This happens with sperm whale 
clicks: if 
> they are very loud, after each click the spectrogram shows a short 
> of silence (it is not noticeable by hearing, but it may cut some 
> features we measure in the 10 ms after a click!).
> I don't know how ATRAC behaves. As I can't afford the buy of an MD 
> only for this testing, I would like to know if there is some 
software able 
> to perform ATRAC coding/decoding I could use for doing some tests.
> Any information will be appreciated,
> regards,
> Gianni
> --------------------------------------------------------------
> Gianni Pavan
> Email 
> Centro Interdisciplinare di Bioacustica e Ricerche Ambientali
> Universita' degli Studi di Pavia
> Via Taramelli 24, 27100 PAVIA, ITALIA
> Tel/Fax   +39-0382-525234 Laboratori
> Tel/Fax   +39-0382-526208 Segreteria
> Web


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