Re: Question on 'quality' ... VBR .vs. ABR. vs. VBR w/minimum

[Simon Howson]

Hi Linda,

The VBR routines in LAME are very heavily optimised and thus produce very
good quality. Setting an arbitrary minimum bitrate will most likely just
increase the file size without increasing quality. It is best just to let
the VBR routines do their job without any restriction.

It is best just to stick to the -Vx quality settings. For the highest
quality VBR, use -V0. It will average around 245 Kbps VBR. If that still
isn't good enough for your purpose, then you could either use an average
bitrate setting greater than 245 (e.g. -abr 250), or maybe you should just
use 320 Kbps CBR (-b 320).

I strongly recommend sticking with the -Vx settings, because they have been
tested and tuned the most, and are rarely beaten by alternate encoder
settings.

LAME doesn't support slicing the files to increase encoding speed. On
multi-core or multi-processor systems you can run multiple instances of LAME
simultaneously so that batch encoding can encode multiple files at a time.
Four Core systems (Intel Core 2 Quad, AMD Phenom X4) can encode four files
at once, with the only limiting factor being the speed of the discs
providing the encoder with files.

Foobar2000 and dBPowerAMP Music Converter both support encoding using
multiple cores, but for dBPowerAMP it is only in the paid version, or the 30
day trial of the paid version.

I hope this helps,

Simon



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[Linda W-6]

> It is best just to stick to the -Vx quality settings. For the highest
> quality VBR, use -V0. It will average around 245 Kbps VBR.
---
        That's what I usually use.


> If that still
> isn't good enough for your purpose, then you could either use an average
> bitrate setting greater than 245 (e.g. -abr 250), or maybe you should just
> use 320 Kbps CBR (-b 320).
---
        I don't know how variable "variable rate" (or V0) is.  Does V0
have 320 as an upper bound?  I'd assume it would drop to some minimal rate
if, say, there were extended 'simple' sections (ex. a section of 'quiet').


> I strongly recommend sticking with the -Vx settings, because they have been
> tested and tuned the most, and are rarely beaten by alternate encoder
> settings.
---
        Any measurable benefit for a -q0 over a -q1?


>
> LAME doesn't support slicing the files to increase encoding speed.
---
        I know it doesn't support it now, but was thinking of a parallel version of
bzip2 that did speedup by N-cpu's, but the resulting file
was maybe a couple hundred bytes, or so, more/processor than the
standard version.


> I hope this helps,
---
        Yeah -- at least I won't waste space w/useless settings...

...with space becoming so cheap I'm beginning to wish for a lossless MP3 setting
(alot of things do MP3, only MP3 or that and some other standard or proprietary
format).

thanks...
Linda

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[Rogério Brito-2]

On Mar 30 2008, Linda W wrote:
> Yeah -- at least I won't waste space w/useless settings...
>
> ...with space becoming so cheap I'm beginning to wish for a lossless
> MP3 setting (alot of things do MP3, only MP3 or that and some other
> standard or proprietary format).

Actually, modern encoders can give you a headache to discern between
them if you perform an ABX-HR test. With 64kbps it is hard enough, as
the listening tests on Hydrogenaudio has shown us.

Of course, you can always have some artifact that you won't be able to
listen now, but will be aware of in the future, but lame with "-V 5"
already gives people a hard time in ABX tests. I guess that the closer
to "lossless" that you can get is to encode with "--preset insane",
which will give you 320kbps files.

You could encode with a free-format MP3 file with higher bitrates,
though, but the file may not be playable with standard players.

BTW #1, is there any difference between "--preset insane" and "-b 320",
people?

BTW #2, if I am not mistaken, the sound files on most DVDs is encoded
(with AC-3, most frequently), but with a maximum bitrate of 448kbps and
people don't usually complain about the sound of DVDs. (Ah!  Found it here:
http://en.wikipedia.org/wiki/Dolby_Digital)


Regards, Rogério Brito.

--
Rogério Brito : rbrito@{mackenzie,ime.usp}.br : GPG key 1024D/7C2CAEB8
http://www.ime.usp.br/~rbrito : http://meusite.mackenzie.com.br/rbrito
Projects: algorithms.berlios.de : lame.sf.net : vrms.alioth.debian.org

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[Gabriel Bouvigne]

Rogério Brito a écrit :

> BTW #1, is there any difference between "--preset insane" and "-b 320",
> people?

In current version, they are identical


--
Gabriel Bouvigne
www.mp3-tech.org
personal page: http://gabriel.mp3-tech.org

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