IPB

Welcome Guest ( Log In | Register )

mp3 to wav to mp3 to wav same?
gts
post Feb 27 2003, 14:42
Post #1





Group: Members
Posts: 10
Joined: 27-February 03
Member No.: 5219



If a file is encoded to mp3, then coverted back to a wav, and then that wav is convered back to mp3, will the both mp3s be the same?
Go to the top of the page
+Quote Post
 
Start new topic
Replies
2Bdecided
post Aug 22 2003, 11:05
Post #2


ReplayGain developer


Group: Developer
Posts: 5142
Joined: 5-November 01
From: Yorkshire, UK
Member No.: 409



This reply is in response to no one in particular...

Be careful saying that things are "impossible".

50 years ago, there were a lot of old 78rpm discs around that people wanted to issue onto LPs. But they couldn't get the noise out of them. Or if they did, the results sounded horrible. And there's a problem: you have a valid signal, and added noise. And theory tells you that when the two are mixed together, you can no longer separate them. Where both are essentially unknown, you can't reconstruct either. It is not possible. You can't get back that nice clean audio signal from within all that noise.


And then Cedar came along, followed by many others, and built products that declick and denoise old records! How? Is theory wrong? No! But it doesn't matter if the result is mathematically identical to what was originally recorded - it just matters that, after cedar processing, it sounds significantly better than the noisy version.

Whether or not you can "un-decode" an mp3, I'm not sure. I'm 100% certain that you can't get from the mp3 back to the original .wav without loss. However, we often say "the information has been lost - it can't be put back". Not perfectly, no. But come 2050, when the only source of some recordings are 128kbps mp3s, I bet you some bright spark has a process which makes them sound a lot closer to the original than the surviving mp3 does.

So, my advice is to try to do the impossible. (Though please, don't jump out of your upstairs window thinking you can fly!). Because some people succeed, and they usually make a lot of money out of a product that is "good enough" - much more money than the theorists who say "it is theoretically impossible to do this perfectly".

Cheers,
David.
Go to the top of the page
+Quote Post

Posts in this topic
- gts   mp3 to wav to mp3 to wav same?   Feb 27 2003, 14:42
- - CiTay   No. MP3 encoding is a lossy process. The WAV that ...   Feb 27 2003, 14:46
- - gts   Well the first conversion from wav to mp3 removes ...   Feb 27 2003, 15:05
- - Xenion   QUOTE (gts @ Feb 27 2003 - 03:05 PM)Well the ...   Feb 27 2003, 15:15
- - X-Fixer   QUOTE (gts @ Feb 27 2003 - 09:05 PM)Well the ...   Feb 27 2003, 15:26
- - gts   QUOTE theoretically this could work this way. (sec...   Feb 27 2003, 23:30
- - gts   QUOTE original wav => mp3 =lossy agreed QUOTE m...   Feb 27 2003, 23:33
- - Messer   Codec does not remove anything. It rounds some val...   Feb 27 2003, 23:39
- - gts   Thank you. What search words will find the topic? ...   Feb 27 2003, 23:43
- - Mac   I'll chip in because it took me a few goes of ...   Feb 27 2003, 23:46
- - Messer   I'd try "reencoding". This is for e...   Feb 27 2003, 23:49
- - gts   Thank you!   Feb 28 2003, 00:01
- - CiTay   QUOTE Codec does not remove anything. It rounds so...   Feb 28 2003, 00:21
- - gts   QUOTE It doesn't care if the WAV was previousl...   Feb 28 2003, 00:30
- - Messer   QUOTE (CiTay @ Feb 28 2003 - 01:21 AM)QUOTE C...   Feb 28 2003, 00:35
- - gts   QUOTE that essential process in lossy compression ...   Feb 28 2003, 00:37
- - fewtch   There's a simple way to test this. Encode a ....   Feb 28 2003, 00:42
- - Artemis3   If you record a CD into a cassette tape, then use ...   Feb 28 2003, 02:14
- - gts   QUOTE If you record a CD into a cassette tape, the...   Feb 28 2003, 02:29
- - rjamorim   QUOTE (gts @ Feb 27 2003 - 08:30 PM)In the jp...   Feb 28 2003, 02:39
- - gts   QUOTE But reducing the amount of colors is only ON...   Feb 28 2003, 02:44
- - rjamorim   QUOTE (gts @ Feb 27 2003 - 10:44 PM)but the p...   Feb 28 2003, 03:05
- - andrew3199   I think we can all agree that there is some loss w...   Feb 28 2003, 04:29
- - rjamorim   QUOTE (andrew3199 @ Feb 28 2003 - 12:29 AM)fo...   Feb 28 2003, 04:36
- - dreamliner77   QUOTE I perceived the decay of plucked notes on an...   Feb 28 2003, 05:19
|- - makarov   An analogy to JPEG lossy image compression was mad...   Jan 30 2005, 07:33
- - NeoRenegade   gts, with regards to your JPEG analogy... you refe...   Mar 2 2003, 23:14
- - kdo   QUOTE (rjamorim @ Feb 28 2003 - 03:05 AM)Code...   Mar 3 2003, 00:37
- - aggies11   Not to resurrect a dead thread or anything, but it...   Aug 21 2003, 02:13
- - Doctor   aggies: no. Lossy sound encoding is not like you ...   Aug 21 2003, 02:54
- - phong   An interesting thought, but probably academic. MP...   Aug 21 2003, 02:58
- - AtaqueEG   QUOTE (dreamliner77 @ Feb 27 2003, 11:19 PM)R...   Aug 21 2003, 03:18
- - 2Bdecided   QUOTE (aggies11 @ Aug 21 2003, 01:13 AM)Could...   Aug 21 2003, 10:33
- - 2Bdecided   In reply to the original question, the simplistic ...   Aug 21 2003, 10:39
- - sld   (Redundant post, sorry)   Aug 21 2003, 10:40
- - Vietwoojagig   I remember long time ago, there was a technology c...   Aug 21 2003, 12:53
- - 2Bdecided   DCC used (what would become) MPEG-1 layer I. You ...   Aug 21 2003, 13:24
- - aggies11   Thanks for the quick replies. Very informative ind...   Aug 21 2003, 17:06
- - phong   The answer to the first question is "no...   Aug 21 2003, 19:29
- - Doctor   Yawn. phong: I think you are wrong on both counts...   Aug 22 2003, 03:29
- - phong   I think I mis-specified which questions I was answ...   Aug 22 2003, 03:46
- - Canar   QUOTE (2Bdecided @ Aug 21 2003, 01:33 AM)I do...   Aug 22 2003, 04:08
- - bexx   Isn't wavpacklossy/hybrid whatever its called ...   Aug 22 2003, 04:29
- - sublimelouie   easiest way to think of it, its like xeroxing a xe...   Aug 22 2003, 04:51
- - aggies11   Sublime: easiest way to think of it, its like xero...   Aug 22 2003, 05:26
- - 2Bdecided   This reply is in response to no one in particular....   Aug 22 2003, 11:05
- - Gabriel   QUOTE IIRC FhG looked at this. You could call it a...   Aug 22 2003, 11:23
- - smg   QUOTE (2Bdecided @ Aug 22 2003, 06:05 AM)This...   Aug 22 2003, 14:46
- - phong   QUOTE Do it enough, you can reduce the complexity ...   Aug 22 2003, 16:13
- - ErikS   QUOTE (Gabriel @ Aug 22 2003, 11:23 AM)Now, t...   Aug 22 2003, 16:50
- - Zilva   Cosine transformation is NOT LOSSY. After transofm...   Sep 10 2003, 10:06
- - tigre   QUOTE (Zilva @ Sep 10 2003, 01:06 AM)Cosine t...   Sep 10 2003, 10:35
- - 2Bdecided   QUOTE (Zilva @ Sep 10 2003, 09:06 AM)Cosine t...   Sep 10 2003, 11:11
- - MugFunky   wow.. old post. ("holy thread resurrection, b...   Jan 31 2005, 04:06
- - h.tuehn   I don't want to correct anything MugFunky or m...   Jan 31 2005, 07:16


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: 22nd September 2014 - 15:14