IPB

Welcome Guest ( Log In | Register )

 
Reply to this topicStart new topic
Increasing / Decreasing MP3 Compression, 192 to 128 and 128 to 192
FXtrader
post Aug 26 2005, 04:55
Post #1





Group: Members
Posts: 9
Joined: 19-August 05
Member No.: 24003



I need confirmation that I've got this right please......Look, If you rip an original CD track to MP3 @ 192 kbps, and then for whatever reason, decide to compress that MP3 even further - say to 128, that would result in an MP3 sounding pretty much similar to one that was ripped directly to 128....Am I Right ?

But, if you rip a CD track to MP3 @128, and then decide to increase that same MP3 to 192 kbps, you're not really going to get any improvement - or at least very little - as whilst the sound would be spread out further, there's no 'new data' to read as it's been discarded.....Am I Right ?

I Suspect this to be the simplest question ever asked but....well I need comfirmation !.....Thanks !
Go to the top of the page
+Quote Post
boojum
post Aug 26 2005, 04:58
Post #2





Group: Members (Donating)
Posts: 819
Joined: 8-November 02
From: Astoria, OR
Member No.: 3727



1) Once it is compressed it cannot be made better.
2) Recompressing at a different rate will almost always degrade the resulting file.
3) So, always start from the original WAV file if you want a different rate MP3.

L8R

cool.gif


--------------------
Nov schmoz kapop.
Go to the top of the page
+Quote Post
Jebus
post Aug 26 2005, 05:54
Post #3





Group: Developer
Posts: 1294
Joined: 17-March 03
From: Calgary, AB
Member No.: 5541



As boojum said, you're not quite right... every compression session throws stuff away. 128kbps will throw away more stuff of course, but then recompressing to 192kbps will throw away more stuff again so the second-gen 192kbps file will actually have LESS of the original audio data in it than the 1st generation 128kbps file.

Every time you compress at 128 you are essentially throwing out 91% of the original data (128/1440 kbps for uncompressed wave) Compressing at 192 throws out about 87% of the original data. Compressing at 128, then at 192 will result in even more data loss, of course.

Hope this makes sense. Don't transcode, essentially.
Go to the top of the page
+Quote Post
Defsac
post Aug 26 2005, 06:00
Post #4





Group: Members
Posts: 347
Joined: 17-May 05
Member No.: 22107



I tried some blind tests comparing transcoded and directly encoded MP3s using LAME 3.96.1. I found it did a fairly reasonable job at transcoding (though all the samples I tested were ABXable on the equipment in my signiture).

If you're not listening in critical listening conditions (if you're in a car or using a portable for example) you'll probably find transcoded MP3s encoded with LAME to be acceptable quality.

This post has been edited by Defsac: Aug 26 2005, 07:33
Go to the top of the page
+Quote Post
FXtrader
post Aug 26 2005, 06:23
Post #5





Group: Members
Posts: 9
Joined: 19-August 05
Member No.: 24003



OK, Thanks for replies....I get the 'jist'of it - I won't do that - I was more curious than seriously going to do that....Answers usually lead to more questions unfortunately....

As data is thrown out and permanently deleted from an MP3, why call it 'Compression'..... afterall, you can't 'Decompress' it then can you....a better term might be 'cannibalize'...!
Thanks...
Go to the top of the page
+Quote Post
Benjamin Lebsanf...
post Aug 26 2005, 07:27
Post #6





Group: Members
Posts: 761
Joined: 29-September 01
Member No.: 40



easy, when you make something smaller it's called compression. It does not yet say anything about being lossy or lossless smile.gif
Go to the top of the page
+Quote Post
Jens Rex
post Aug 26 2005, 07:47
Post #7





Group: Super Moderator
Posts: 605
Joined: 18-December 01
Member No.: 680



QUOTE (FXtrader @ Aug 26 2005, 07:23 AM)
As data is thrown out and permanently deleted from an MP3, why call it 'Compression'
*

That's why we differentiate between lossy and lossless compression.
Go to the top of the page
+Quote Post
Sunhillow
post Aug 26 2005, 07:57
Post #8





Group: Members (Donating)
Posts: 483
Joined: 13-October 01
From: Stuttgart
Member No.: 286



QUOTE (FXtrader @ Aug 26 2005, 07:23 AM)
As data is thrown out and permanently deleted from an MP3, why call it 'Compression'..... afterall, you can't 'Decompress' it then can you....a better term might be 'cannibalize'...!
Thanks...
*


"Cannibalize" is good biggrin.gif

When MP2 and MP3 still were young, they were called "data reduction" which IMO is the right term for what it does
Go to the top of the page
+Quote Post

Reply to this topicStart new topic
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:

 



RSS Lo-Fi Version Time is now: 21st September 2014 - 15:58