Updating your MP3 procedures - P2P-Zone

Snarkridden · 07-06-02, 06:48 AM

MP3 technology is improving all the time, for the best results you need to keep up to date with developments.

There is a new version of LAME out now since April (3.92)

http://www.mp3dev.org/mp3/

Which means that if you use DBPowerAmp which uses the LAME
codec you will probably be using an out of date codec, same applys to DbPowerAmp music converter..

http://www.dbpoweramp.com/dmc.htm

With the standard installation of the converter, the codec .DLL
should be in the path depicted in the attached JPG file.

Just download the new LAME version, install, and move a copy of the LAME .DLL into your DbPoweramp LAME folder, rename the old DLL just in case you have a problem.

Latest start of the art in MP3 ripping (quality before convenience) seems to be Exact Audio copy (EAC) to create the track wave files and Razorlame (frontend) using LAME 3.92 with Variable Bit rate mode (VBR) to do the encoding.

Doing a dummy run with various VBR minimum/maximum settings using the historgram to check bit-rate demand, if you set 160 mini mum and 320 maximum, run the encode, and the 320k bar NEVER comes up, then your material does not need the highest bit rate encode option, so set it down a bit, I find a good general setting for most CD rips is 128 min 256 max.

If you use vinyl, and your setup is top notch, you might find that also needs the higher setting of 256 to 320k, as the high frequencies from a good analogue disc player often exceed those from a CD which is bound by Nyquist rules to encoding frequency divided by 2 (usually 22k max).

If your albums are older, and your cartridge just average, then set the minimum bit rate to 96k and the maximum to 160k this will reduce the size of the MP3 file considerably.

All the above applies to MP3 pure & simple, NOT MP3PRO or any other lesser quality encode method.

Snark..

assorted · 07-06-02, 09:02 AM

i have a question; if VBR encoding why not just set the minimum bitrate as low as possible (say 32kbs) - since you are actually setting quality through the vbr # setting.

Snarkridden · 07-06-02, 02:02 PM

The minimum setting really depends on the material being encoded, it is true to say that LAME adjusts the bit rate to that which required, so in theory you could set 32k as the minimum, though with most music, I doubt that the 32k minimum would ever be reached, except at the fade in/fade out points of the track, so you are unlikely to actually see very much actually encoded at that level, however a lot of P-2-P applications seem to use the first few frames to determine the actual bit rate to report, which of course would be wildly wrong on material with a un-demanding start.

So setting a practical lower rate just below the actual minimum required, does help with this aspect of file detail reporting.

If your material is really hi quality, i.e tracks from a SACD disc ot a hi-sample DAT recording (96k) then using VBR will throw away too much of the fine detail in the High frequency regions, so best to use a fixed bit rate anyway.

If you can do a spectral analysis of your WAV file from a CD, then encode it VBR, decode it to a WAV file again, do a spectral check on this second WAV file, you will easily see the limitations of VBR
on high quality material.

Do the same tests with LAME 3.92 at fixed bit rate 320k, and you will find the decoded WAV file will have almost an identical spectra to the original probably up to about 21.5 kHz a perfect match with the original.

I am still playing with this SACD player at the moment, material to test with is hard to come by, most being slightly tarted up original CD material, so true tests will have to wait for a while.

By the way, NEVER use Joint Stereo on high quality material, the quality reduction, is just to much for the small drop in file size.

Snark..

Snark..

pod · 07-06-02, 02:08 PM

People are getting worked up over comparing the before and after wave forms way too much. The point of mp3 encoding is not to preserve the wave form, it is to throw away as much as possible without affecting the perceived sound quality. Unless the wave forms are exactly identical, the pretty picture tells you nothing.

(Well, ok, if you see important frequencies getting chopped right off that's bad.)

If you want a high quality compressed sound file, you don't use mp3.

AweShucks · 07-06-02, 02:47 PM

Quote:

Originally posted by pod

If you want a high quality compressed sound file, you don't use mp3.

Thats why I added a 3rd harddrive to hold all my lossless encodes.

IMHO I don't care for any preset settings in most encoders when using Lame Vbr. 9 times out of 10 they are outdated in a month, and stay that way for much longer. For best quality command lines and a frontend encoder are the way to go. Reasoning is most presets in encoders have only a few settings "low/med/high" etc. And a Min and Max bitrate option is far to vague even with a nominal setting.
Command lines give you so much more options and configuration while letting Lame decide how much is needed and where.

http://www.hydrogenaudio.org/ is probably one of the best audio related sites out there for all types of audio encoding.

assorted · 08-06-02, 03:18 AM

Quote:

Originally posted by Snarkridden
So setting a practical lower rate just below the actual minimum required, does help with this aspect of file detail reporting.

ah... it's just a file trading fart then.... i like keeping it at 32kbs cuz i like to give my machine all the control; hehe. i'm encoding 30-60 minute "mix tapes" that have lots of drops so i like to save all the memory i can.

btw; i always set joint stereo since it's simply the default... what SHOULD i be setting it as?

AweShucks · 08-06-02, 06:46 AM

Quote:

Originally posted by assorted

btw; i always set joint stereo since it's simply the default... what SHOULD i be setting it as?

Always use J-stereo when VBR is used

07-06-02, 06:48 AM	#1
Snarkridden OpenNap Server Operator Join Date: Jan 2002 Location: U.K Posts: 401	Updating your MP3 procedures MP3 technology is improving all the time, for the best results you need to keep up to date with developments. There is a new version of LAME out now since April (3.92) http://www.mp3dev.org/mp3/ Which means that if you use DBPowerAmp which uses the LAME codec you will probably be using an out of date codec, same applys to DbPowerAmp music converter.. http://www.dbpoweramp.com/dmc.htm With the standard installation of the converter, the codec .DLL should be in the path depicted in the attached JPG file. Just download the new LAME version, install, and move a copy of the LAME .DLL into your DbPoweramp LAME folder, rename the old DLL just in case you have a problem. Latest start of the art in MP3 ripping (quality before convenience) seems to be Exact Audio copy (EAC) to create the track wave files and Razorlame (frontend) using LAME 3.92 with Variable Bit rate mode (VBR) to do the encoding. Doing a dummy run with various VBR minimum/maximum settings using the historgram to check bit-rate demand, if you set 160 mini mum and 320 maximum, run the encode, and the 320k bar NEVER comes up, then your material does not need the highest bit rate encode option, so set it down a bit, I find a good general setting for most CD rips is 128 min 256 max. If you use vinyl, and your setup is top notch, you might find that also needs the higher setting of 256 to 320k, as the high frequencies from a good analogue disc player often exceed those from a CD which is bound by Nyquist rules to encoding frequency divided by 2 (usually 22k max). If your albums are older, and your cartridge just average, then set the minimum bit rate to 96k and the maximum to 160k this will reduce the size of the MP3 file considerably. All the above applies to MP3 pure & simple, NOT MP3PRO or any other lesser quality encode method. Snark.. Attached Images

07-06-02, 09:02 AM	#2
assorted WAH! Join Date: Apr 2001 Posts: 725	i have a question; if VBR encoding why not just set the minimum bitrate as low as possible (say 32kbs) - since you are actually setting quality through the vbr # setting. __________________ I hate hate haters

07-06-02, 02:02 PM	#3
Snarkridden OpenNap Server Operator Join Date: Jan 2002 Location: U.K Posts: 401	Why Indeed? The minimum setting really depends on the material being encoded, it is true to say that LAME adjusts the bit rate to that which required, so in theory you could set 32k as the minimum, though with most music, I doubt that the 32k minimum would ever be reached, except at the fade in/fade out points of the track, so you are unlikely to actually see very much actually encoded at that level, however a lot of P-2-P applications seem to use the first few frames to determine the actual bit rate to report, which of course would be wildly wrong on material with a un-demanding start. So setting a practical lower rate just below the actual minimum required, does help with this aspect of file detail reporting. If your material is really hi quality, i.e tracks from a SACD disc ot a hi-sample DAT recording (96k) then using VBR will throw away too much of the fine detail in the High frequency regions, so best to use a fixed bit rate anyway. If you can do a spectral analysis of your WAV file from a CD, then encode it VBR, decode it to a WAV file again, do a spectral check on this second WAV file, you will easily see the limitations of VBR on high quality material. Do the same tests with LAME 3.92 at fixed bit rate 320k, and you will find the decoded WAV file will have almost an identical spectra to the original probably up to about 21.5 kHz a perfect match with the original. I am still playing with this SACD player at the moment, material to test with is hard to come by, most being slightly tarted up original CD material, so true tests will have to wait for a while. By the way, NEVER use Joint Stereo on high quality material, the quality reduction, is just to much for the small drop in file size. Snark.. Snark..

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07-06-02, 02:08 PM	#4
pod Bumbling idiot Join Date: Feb 2002 Location: Vancouver, CA Posts: 787	People are getting worked up over comparing the before and after wave forms way too much. The point of mp3 encoding is not to preserve the wave form, it is to throw away as much as possible without affecting the perceived sound quality. Unless the wave forms are exactly identical, the pretty picture tells you nothing. (Well, ok, if you see important frequencies getting chopped right off that's bad.) If you want a high quality compressed sound file, you don't use mp3.