Also,
There are devices, even modern ones, which don't reliably, or indeed at
all,
cope with VBR.
The Olympus machines, even the DM-520 are a case in point - so use VBR
with
care if you want to guarantee everyone and everything can play your MP3
files.
Regards
Tim
Tim Noonan
Director, Vocal Branding Australia
Transforming products, brands and experiences so they Sound as great as
they
look and feel!
Phone: +61 419 779 669
Web: www.vocalbranding.com.au/blog
Email: t...@vocalbranding.com.au
Twitter: www.twitter.com/VocalEssence
Skype: TimNoonan
-----Original Message-----
From: pc-audio-boun...@pc-audio.org
[mailto:pc-audio-boun...@pc-audio.org]
On Behalf Of Dane Trethowan
Sent: Sunday, December 27, 2009 9:05 AM
To: PC Audio Discussion List
Subject: Re: Pros and cons of varible bit rate
Okay, I just consulted an audio engineer abut what you wrote about
minimum
bit rates for VBR encoding and here's his response, it also talks about
setting VBR quality and I'll have a few words to say about this after
his
quotation which follows:
Well, basically it depends on what you're trying to do. There are
several
factors that contribute to VBR quality (apart from encoding quality
settings
of course). Most immediately noticeable is the over-all VBR quality
setting, which `weights' the VBR result between the minimum and maximum
you
set. Imagine VBR as a set of scales swinging everywhere between min. and
max. depending on what's going into the encode. VBR quality simply
determines how the scales are weighted, either more towards minimum or
maximum depending on what you set. The higher VBR Quality, the less the
encoder will `throw away', and so the more it will weight the encode
towards
the higher end of the scale. If the quality is set high enough, you
won't
achieve *anything* by increasing the minimum; all you'll do is make your
file larger for no benefit, since the encoder will waste a load of
bandwidth
encoding things (such as silence or low frequencies) that don't need it.
Conversely, if your VBR Quality setting is too low, the encoder will
throw
away so much that everything will get pushed towards the lower end, and
so
the Minimum setting will make a great deal more difference. But even
then,
all it will do is make your file bigger, and probably it won't help the
encode quality, since you shouldn't have set the quality so low in the
first
place.
So, basically, for normal operation, it's a complete waste of time
pushing
up the minimum. The exception is if you have a hardware player that
can't
cope with very low bitrates (our Omni DVD players were hopeless with
anything below 64KbPS), unless, _perhaps_ if the source is *very* noisy
(an
old dodgy cassette) where you don't want noise causing a load of
artifacts,
but you still want the file as small as possible. But under those
circumstances, you'd be far better off processing the original source
and
removing as much noise as possible without damaging the audio _before_
encoding.
The only other reason you might want to push up the minimum is if the
encoder has a dodgy VBR algorithm that tends to push too much towards
the
bottom of the scale, even when the VBR Quality setting is high. LAME's
`--vbr-old' algorithm is excellent, but `--vbr-New' still has problems.
Unfortunately, other encoders (such as Fraunhofer) are a *hell* of a lot
worse, so if you're forced to use them, it might be worth it.
Anyway, hope this explains things; basically, unless you have a very
specific need, don't play with Min/Max bitrates - you're likely only to
get
worse encodes and bigger files.
Thank you kind Sir for your time and trouble <smile> so now to my
additional
notation about VBR quality and this can add to confusion. When setting
VBR
quality it works in the reverse as it looks, in other words the lower
the
number the higher the VBR quality, 3 or 4 may be a good setting for
music,
for mono audio or talking books, audio documentaries etc try say between
4
and 6.
On 27/12/2009, at 6:38 AM, Kevin Lloyd wrote:
The only point I'd add to Dane's notes is that I have read advice
around
not setting your variable floor too low. I'd suggest for music that you
set
the floor to 128kbps rather than the suggestion below of 16kbps.
Regards.
Kevin
E-mail: kevin.llo...@sky.com
----- Original Message ----- From: "Dane Trethowan"
<grtd...@internode.on.net>
To: "PC Audio Discussion List" <pc-audio@pc-audio.org>
Sent: Saturday, December 26, 2009 7:33 PM
Subject: Re: Pros and cons of varible bit rate
I suppose it comes down once again to personal preference, I've been
using varriable bit rates for youears.
As I understand it, encoding with a varriable bit rate takes a lot
longer
as the encoder looks at every sample of the song thus deciding what bit
rate
it should be encoded at, silence for example is encoded at a lower bit
rate
than a full sample of orchestra sound, minimum and maximum bit rates for
variable encoding are set up with your encoding engine such as LAME so
for
the best and accurate results you're better off doing this sort of thing
manually with a command line so use an app which supports this, Exact
Audio
Copy is an excellent choice here.
Their are several methods of VBR encoding, "Old" and "new", "new" is
quicker for those jobs you want out the door fast but quality isn't
quite
as
good if you're picky, with today's flying processor speeds you may as
well
use "Old".
Also note that some older players may not handle VBR playback though I
haven't struck one that doesn't yet.
Suggested minimum and maximum bit rates for VBR? Well just use the
minimum and maximum rates available or if you're configuring from a
command
line or a piece of software that takes full advantage of the
LAME-ENC.dll
library then 16 bits for the minimum and 320KBPS for the maximum, there
are
2 quality settings you have to be aware of here, one is VBR quality and
you
may wish to change this for certain audio material you're encoding, say
music and talking books. The other quality setting leave at maximum,
will
take longer but far better results.
On 27/12/2009, at 6:21 AM, Jamie Pauls wrote:
The subject is a question, not a statement. I have been uploading
Main
Menu archives as a 128KBPS MP3 file. I see that many people recommend
192KBPS, but there a parts of the show that really don't need that high
a
bit rate. In fact, I have also read that encoding at too high a bit rate
can
cause unwanted artifacts just as much as encoding at too low a bit rate.
Variable bit rate seems a good choice for me to use, but I would like
some
thoughts from audio experts. Thanks.
Jamie Pauls
MSN: jamiepa...@hotmail.com
Skype: jamie.pauls
To unsubscribe from this list, send a blank email to:
pc-audio-unsubscr...@pc-audio.org
******************************
Dane Trethowan
From Melton Victoria Australia
mailto:"grtd...@internode.on.net
Twitter: http://twitter.com/grtdane
blog: http://www.grtdane.wordpress.com
Phone United Kingdom
02032874641
Phone Australia
0390058589
Phone United States
8159261869
Fax:
+61 3 9743 7954x
MSN grtd...@dane-trethowan.net
skype:grtdane12
******************************
To unsubscribe from this list, send a blank email to:
pc-audio-unsubscr...@pc-audio.org
To unsubscribe from this list, send a blank email to:
pc-audio-unsubscr...@pc-audio.org
******************************
Dane Trethowan
From Melton Victoria Australia
mailto:"grtd...@internode.on.net
Twitter: http://twitter.com/grtdane
blog: http://www.grtdane.wordpress.com
Phone United Kingdom
02032874641
Phone Australia
0390058589
Phone United States
8159261869
Fax:
+61 3 9743 7954x
MSN grtd...@dane-trethowan.net
skype:grtdane12
******************************
To unsubscribe from this list, send a blank email to:
pc-audio-unsubscr...@pc-audio.org
To unsubscribe from this list, send a blank email to:
pc-audio-unsubscr...@pc-audio.org
