[studiorecorder] Re: MP3 tests
- From: "ROB MEREDITH" <rmeredith@xxxxxxx>
- To: <studiorecorder@xxxxxxxxxxxxx>
- Date: Fri, 16 Jun 2006 14:23:12 -0400
Neal:
Joint Stereo is not necessary in files of 192 KBPS or higher (in my
opinion.) If you pick <Default> for our Mode box, you will get Stereo if
the bit rate is 192 or higher. Joint stereo can mess things up in some
situations, but it really does help at the lower bit rates, like 128
KBPS.
I will probably leave VHQ in there because it is only used to instruct
the encoder. Different versions of the LAME encoder may act differently,
and some day, they really may have a VHQ mode that is useful. Perhaps
they do now; I haven't felt like messing with the newer LAME versions
lately. 3.96 was too much of a let-down.
By the way, it isn't always necessary to select high quality. In some
situations, like for 48 KBPS spoken word files, i prefer low quality,
because it is very fast and almost sounds better.
>>> neal.ewers@xxxxxxxxxxxxxx 06/16/06 02:08PM >>>
Well, I have certainly learned some interesting things today.
Results.
Studio recorder on a 1 hour file with white noise and various other
high
quality sounds. No VBR high quality, and in simple stereo and not
joint
stereo. Converted all files at 192 KBPS.
Time taken. 3 minutes 40 seconds.
Sound Forge with the same file, and the same settings except that I
had
stereo set to joint.
Are you ready for this? 20 minutes and 23 seconds. I then discovered
the error of my ways and set Sound Forge to simple stereo. It still
took 20 minutes and 23 seconds.
The SF and SR files were within 3 KB of being the same size and I
could
tell no difference in quality between them.
I then read Rob's message about very high quality MP3 conversion. It
was way down at the bottom of the list and I didn't see it the first
time. So, I cheated. I used the same file in SR but only 10 minutes
of
it and multiplied it by 6 to get 60 minutes. When I got to 7 minutes
on
the 10 minute file, times 6 or 42 minutes, I canceled the operation.
Rob, I think you're right. If there is no significant difference, I
would remove it. The question is, is there a difference. Even if
there
is, it ain't worth that long a time to convert in my opinion.
One question though. Here is the definition of Joint stereo that
Sound
Forge uses. Rob, tell me if this is your understanding of this and if
it is needed on a file that is converted at 192 KBPS. Sound forge
does
some other additional processing as you will see in their description.
if
Joint stereo
Select this radio button if you want the encoder to be able to
take advantage of the similarity between the two channels of
a stereo file. Joint stereo encoding is useful when you want
to create a stereo file but require a relatively low bit rate.
When the radio button is selected, select or clear the
Intensity stereo or MS (mid/side) stereo check boxes to
indicate which encoding methods will be used.
Intensity stereo
In this mode, the encoder can take advantage of the fact that
the human ear does not distinguish location information for
low frequencies as well as it does for higher frequencies.
For high frequencies, magnitude and spatial information is
encoded. For low frequencies, only magnitude and phase are
encoded.
These check boxes are not available in SF in normal stereo mode.
So, there you have it friends.
Neal Ewers
Ravenswood Productions
Local phone: 608-277-1995
Toll Free: 888-544-8332
Email: <mailto:Neal.ewers@xxxxxxxxxxxxxx> Neal.ewers@xxxxxxxxxxxxxx
<http://www.ravenswood.org/> http://www.ravenswood.org
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