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Topic: Lame 3.97, -q3 vs -q2 (Read 3937 times) previous topic - next topic
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Lame 3.97, -q3 vs -q2

I understand that now -q3 is used rather than -q2 in the default settings (used to be the alt presets).

Is -q3 used because it has shown to be better quality, or is it just used because it's deemed "as good as" -q2 but faster?

Lame 3.97, -q3 vs -q2

Reply #1 –
Quote
I understand that now -q3 is used rather than -q2 in the default settings (used to be the alt presets).

Is -q3 used because it has shown to be better quality, or is it just used because it's deemed "as good as" -q2 but faster?
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I encoded two files. One with "-V2 --vbr-new" and one with "-V2 --vbr-new -q2". Whilst LAME did report different Q values, they were bit for bit identical 

Quote
INFO (foo_bitcompare) : Comparing:
INFO (foo_bitcompare) : location: "file://C:\Home\Incoming\testnoqchange.mp3" (0)
INFO (foo_bitcompare) : location: "file://C:\Home\Incoming\testq2.mp3" (0)
INFO (foo_bitcompare) : No differences in decoded data found.
INFO (foo_bitcompare) : Finished successfully.

Lame 3.97, -q3 vs -q2

Reply #2 –
I believe --vbr-new only has 3 real -q values based on what Gabriel has said.

-q0 through -q4 are bit identical
-q5
-q6 through -q9 are bit identical

Now if I'm wrong I'm sure Gabriel or one of the other LAME devs will correct me, but I'm pretty sure I read what he posted once correctly.
Nero AAC 1.5.1.0: -q0.45

Lame 3.97, -q3 vs -q2

Reply #3 –
It was me [:
Anyway, NeoRenegade isn't explicitly asking about --vbr-new, and in old VBR mode there still are ten -q levels.
To answer his question, I'm not aware of any listening tests showing that lower -q values produce higher quality files (thogh of course it is designed to produce higher quality files), so I guess that -q3 being default is a choosen compromise between (unperceptably) higher quality & speed - LAME devs probably decided that -q value any lower than 3 would slow things down too much without giving noticably better quality.

Lame 3.97, -q3 vs -q2

Reply #4 –
Actually I believe current --vbr-old's -q3 is the same as the old -q2.  I believe the numbers were bumped down when the experimental and super slow -q0 was implemented at some point after the 3.90 branch.  Again I could be wrong but I'm sure I've read that here too.
Nero AAC 1.5.1.0: -q0.45

Lame 3.97, -q3 vs -q2

Reply #5 –
Thanks for the good replies so far.

To elaborate on my original post, I'm messing around with CBR. I'm guessing this is the same as --vbr-old, with reference to -q values and their application?
 

Lame 3.97, -q3 vs -q2

Reply #6 –
AFAIK -q values are the same for --vbr-old as for CBR.  --vbr-old reuses something from the CBR models that --vbr-new doesn't but I honestly can't remember what it was, something to do with the quantisation step I believe though I may be way off on this as I can't claim to understand the internals of the LAME source all that well.
Nero AAC 1.5.1.0: -q0.45