Hello everybody,

This topic seems to deserve a bigger attention then it have. I
downloaded test files, and can fully confirm all claims by sikahr - it
seems there is a serious bug in Squezebox mp3 decoder.

I also made some new tests, some analyze, and my conclusons are:

1. Effect is related to most common mp3 formats, not only a some
strange cases

Sikahr tested low-volume mono sine file and low-volume music, which may
cause false idea that effect is related only to that specific cases. I
made a new series of tests, with a normal music, 44100/16bit stereo, at
the (almost) normal listening levels.

Result is the same - squeeze decoder produces clearly audibile
artefacts. More details in the following post.

2. Effect is not subtle

As shown in my examples, the artefacts introduced by SqueezeBox are
easily recognized after the music is lowered only 20dB from the normal
level.

It seems that the same thing is also audible at the normal listening
level, but that should be additionally verified by a serious tests.

My claim is, if it is easily recognizable at -20dB, then it may, at
least occasionally, cause the audibile deterioration at the normal
musical levels.

3. Effect is not a regular mp3 artefact
4. Effect is not caused by DAC or analog circutry

Comparing mp3 (lame compressed from original cd) with wav (lame
decompressed from the former mp3), it become obvious that quality
deterioration was not the property of the compressed file, but the
squeeze decompressing process.

Actually, that may be the very reason why some people are using
loseless instead of mp3.


-- 
damir
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damir's Profile: http://forums.slimdevices.com/member.php?userid=14119
View this thread: http://forums.slimdevices.com/showthread.php?t=40409

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