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Subject: Re: mp3-editor?
From: planet77 (planet77_at_gmx.net)
Date: 2003-03-27


Hello!
I think GOLDWAVE is a good one, you CAN load MP3 and save MP3 files on the
fly and it is really easy, good and free. I use it for three years now,
although I have Steinberg Clean/Wavelab.

Have a ROCK per Box today!
FRED

----- Original Message -----
From: "Chris Holt" <amiga2k_at_cox.net>
To: <rockbox_at_cool.haxx.se>
Sent: Thursday, March 27, 2003 2:18 AM
Subject: RE: mp3-editor?

> On Wed, 26 Mar 2003 12:20:52 -0500, Matthew P. OReilly wrote:
> >That's true - I had forgotten about that. (It's been a while since I
> did
> >any compressed editing.)
> >
> >What is it about re-compression that causes quality loss? If something
> >is
> >compressed, uncompressed, then compressed again, shouldn't it be a
> >function
> >of the quality of the recompression algorithm whether or not it loses
> any
> >quality? If one is going from, say, 16-bit to 24-bit and back to 16-bit
> >(uncompressed), all you're losing is the 8 least significant bits in the
> >24->16 conversion, which would be all zeroes anyway from the 16->24 bit
> >conversion. I know that compression adds more complexity to that mix,
> >but I
> >don't understand why it necessitates a loss of quality... if I compress
> >the
> >same uncompressed data twice, shouldn't it be the same as if I
> >compressed,
> >uncompressed, and compressed again?
> >
> >Thx
> >Matt
>
>
> There is no "scheme" commonly known as a recompression scheme, so the
> quality of such a scheme is irrelevant.
> MP3, like JPG is a lossy compression scheme. Where JPG tries to discard
> file information that is not easy to see, MP3 tries to discard file
> information that is not easy to hear. Each generation of compression is
> compressing a file with discarded information that cannot be retrieved
> and so quality is lost. Even worse with JPG is that file sizes can
> actually increase over the first generation of compression because
> complex artifacts introduced in the initial compression have to be
> analyzed and compressed. Of course MP3 filesize (for CBR files anyway)
> is dependant only on length and bitrate so this is not an issue.
>
> Lossless compression schemes, like Monkey for audio or PNG/TIFF for
> images, don't suffer from multiple generations of extraction and
> recompression, so your example of 16-24-16 would work out with no loss.
> (but I see no potential for gain in doing this either)
>
> Chris
>
>
>



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