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Subject: Re: low-fi mp3s
From: Neon John (johngd_at_bellsouth.net)
Date: 2004-02-29


I've noticed this of late too, when playing 32kb, 8khz sampled audio books.
The high frequency tone (probably 8-10khz) is of fairly low level, doesn't
appear to change with volume or other sound settings and comes and goes rather
randomly. It sometimes persists even when the playback is paused. I can't
say when I first noticed it but I think it was when I went from Ben's bookmark
version to the first CVS merged version of the bookmark code. It might have
been when I flashed the code, as I did both in close proximity.

I have a set of computer speakers on my bedside table and first started
noticing the tone when I'd pause a book to go to sleep. If I happened to
pause when the tone was present I'd have to turn the speakers off to eliminate
the noise.

I did go back to one of my backup Recorders that has Ben's next to last
pre-CVS release, non-flashed. The tone is not present.

John

On Sun, 29 Feb 2004 14:10:13 -0500 (EST), "John Donahue"
<john.donahue_at_excite.com> wrote:

>
>I've been recording some old 78rpm albums to .wavs(CDquality) and then converting those to low fi, 16kbps mp3s through MusicMatch. Examination in Mp3DirectCut shows them to be mpeg2.5,layer3, 16kbps, 11kHz Mono.
>Anyway, they sounded fine, no loss in quality since not much to begin with, and I get that nice 1/90 compression ratio :) 8kbps was just too much of a squeeze.. even for 78's.
>
>They sound great that is on software players, musicmatch, mediaplayer, directCut, but on the archos(i have FMrecorder) and on a CDmp3 player(AudioPhase) there's that high tone of constant pitch accompanying the intended sound. There's no other sound difference - otherwise it's just as clear as the software players except the tinny whine. The music's midrange frequencies seem to bring it out most.
>And the problem occurs for all bit rates from 8 to 32kbps.. 40kbps is where the high tone immediately disappears, so its a shame to have to increase the file size by more than three times in order to lose the squeak.

---
John De Armond
johngdDONTYOUDARE_at_bellsouth.net
http://bellsouthpwp.net/j/o/johngd/
Cleveland, Occupied TN
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