thanks for listing the info on the bitrates. its very helpful. les

Cd/Dvd Duplication & Custom Printing

Customer Service

Les Gordon
Phone: (267)329-8150
email: sa...@cdrdvdr.com
web: http://www.cdrdvdr.com




----- Original Message ----- From: "Kevin Lloyd" <kevin.llo...@sky.com>
To: "PC Audio Discussion List" <pc-audio@pc-audio.org>
Sent: Sunday, December 27, 2009 8:55 AM
Subject: Re: Pros and cons of varible bit rate


I wouldn't use joint stereo because it changes the original sound of the track by performing a psychoacoustic algorithm intended to make very poor low bit rate encoded music sound better. I've pasted some details of the lame settings below taken from the CDEx manual. I would use a minimum of 128kbps so as not to risk over working the encoder and ending up with some peculiar results. I've seen the arguments around file size but, to be honest, I don't have many tracks that are digital silence in my collection and figure I can cope with the extra few kb of disc space usage that I'd probably save by setting the floor lower.

Settings for Lame MP3/Blade DLL/Internal MP3 encoder:




This paragraph describes the options for the encoder mentioned above. However, not all options might be available for certain encoders.

Bitrate (default value 128 Kbits/s):

Determines the number of bits per second.

Mode (default value Stereo):

With the LAME encoder, you can specify how the file is encoded. The default stereo option is recommended, but at lower bit-rates, the Joint-stereo or Forced stereo can yield better sound quality.


Stereo: In this mode, the encoder makes no use of potential similarity between the two input channels. It can, however, negotiate the bit demand between both channels, i.e. give one channel more bits if the other contains silence.

Joint stereo: In this mode, the encoder will make use of a correlation between both channels. The signal will be matrixed into a sum ("mid") and difference ("side") signal. For quasi-mono signals, this will give a significant gain in encoding quality. This mode does not destroy phase information like IS stereo that may be used by other encoders. This setting can be used to encode DOLBY ProLogic surround signals.


force joint stereo: This mode will force MS joint stereo on all frames. It's faster and it uses some special mid and side masking threshold.

Mono: This option will forcibly generate a mono file; if the input file is a stereo file, the input stream will be read as a mono by averaging the left and right channels.



Quality (default value Normal):



With the LAME encoder, you can specify the output quality; thus you can trade off encoding time against sound quality. The default (normal) is recommended for the lower bitrates (<160 kbps), high quality for bitrates >160 kbps. The voice quality is more or less optimized to generate the >best quality for voice. Details of the R3Mix quality option can be found at http://www.r3mix.net.



MPEG-I/II setting (default value MPEG-I):



The difference between MPEG-I and MPEG-II are the sample frequencies of the input file. MPEG-I can handle input streams (WAV files) with a sample frequency of 48000, 44100 and 32000 Hz. MPEG-II on the other hand will support stream for 24000, 22050 160000 Hz. Basically, use MPEG-II when you want to encode with low bit rates (e.g. for voice files, or if you need small MP3 files with reduced quality). As you can see, the lowest bit-rate for MPEG-II is 8 Kbits/sec while for MPEG-I the lowest bit rate is 32 Kbits/s.



VBR Method Setting



The VBR method setting allows you the change the VBR algorithm which is used for the encoding (detailed information can be found in the LAME user documentation - see http://www.sulaco.org/mp3/doc/html/index.html). The following selections are available



 Disabled: Don't use VBR; instead encodie with a Constant Bit Rate (CBR)
 VBR-Default: Use the default VBR method (currently set to VBR-MTRH)
VBR-Old: LAME's first functional approach, based on masking, bisection in the bit domain. VBR-New: LAME's second approach, based on masking and direct noise allocation.
 VBR-MTRH: a combination of old and new (VBR) routines
VBR-ABR: The Average Bit Rate (ABR) setting, the encoding principle is similar to what AAC uses as VBR encoding, it is based on perceptual entropy, but more like CBR than VBR. When you select the ABR option in the VBR Settings box, the ABR edit box will be enabled. In this edit box you can specify the target average bit rate. Of course, a larger bit rate will yield generally better-sounding (but larger) MP3 files.



ABR Settings



VBR Quality Setting



This option allows you to set the Variable bit-rate option. Variable bit-rate encoding will enable dynamically determined bit-rates that depend on the music content of the current frame. This improves the overall quality of the encoded file without increasing the file size. This option sets the criteria used to determine when to increase the bit-rate for a frame. The lower the number, the lower the criteria will be. Thus VBR_0 will yield the best quality (but the largest file size) while VBR_9 will have less sound quality but the file size will be the smallest. The recommended variable bit-rate option is VBR_4. If you don't want VBR encoding, set this option to None.



Private



When enabled, it will set the private flag in the MP3 stream.



Original



When enabled, it will set the original flag in the MP3 stream.



Copyright



When enabled, it will set the copyright flag in the MP3 stream.



Checksum



When enabled, it will add a cyclic redundancy check (CRC) code in each frame, allowing [the decoding software] to detect transmission errors that could occur on the MP3 stream. However, it takes 16 bits per frame that would otherwise be used for encoding, and therefore will slightly (probably imperceptibly) reduce the sound quality.



stereo

Kevin Lloyd
E-mail: kevin.llo...@sky.com
----- Original Message ----- From: "Sunshine" <sunsh...@abe.midco.net>
To: "PC Audio Discussion List" <pc-audio@pc-audio.org>
Sent: Sunday, December 27, 2009 11:57 AM
Subject: Re: Pros and cons of varible bit rate


Dane, and others.
this is how i have my vbr method set in easy cd da extracter.
joint stereo.vbr method old.
min bit rate 8 kbps max bit rate 320 kbps.
let me know what you all think of this  set up also the quality setting i
have set to highest.

----- Original Message ----- From: "Dane Trethowan" <grtd...@internode.on.net>
To: "PC Audio Discussion List" <pc-audio@pc-audio.org>
Sent: Saturday, December 26, 2009 6:15 PM
Subject: Re: Pros and cons of varible bit rate


So there we are, the first audio players I've heard of that won't touch VBR
<smile>.


On 27/12/2009, at 11:03 AM, Tim Noonan wrote:

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

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