Pointless guessing contest!

[iago]

In an attempt to save room on my ipod, and because I notice no difference between 320kbps and 192kbps (except for the file size), I'm converting everything on my ipod to 192kbps.  I'm even re-encoding the files that ARE 192kbps, because it was easier. 

The facts are:
- 7279 songs (38gb)
- 500mhz cpu

Nothing else really matters.  The computer is exclusively converting and doing nothing else while it's converting. 

Now, there are two questions:
1. How much room will 7279 192kbps songs take up when it's done, in kilobytes?  Remember, some are 128, some are 320, and most are 192. 
2. How long will it take, in days/hours/minutes/seconds/milliseconds?

On each question, the closest answer without going over will win nothing, but everybody who participates has a chance of winning it!

[Newby]

Re-encoding is gonna make the song quality worse. It's like constantly compressing and decomrpessing something. It's gonna lose original value even moreso than when it was ripped from the CD.

'tard

[Sidoh]

Re-encoding is gonna make the song quality worse. It's like constantly compressing and decomrpessing something. It's gonna lose original value even moreso than when it was ripped from the CD.

'tard

I think it's blatantly obvious that the songs are going to lose some quality.  He's decreasing the bit rate; there's no sense in assuming that he's thinking the songs are going to gain quality.  If you read what he said, he says he notices no difference between 320 and 192 bit rate MP3's.  Lowering the bit rate is obviously going to decrease the quality of the MP3, but like iago said, it's hardly noticeable.

[Super_X]

I'll guess.. 3.5 days going 24 hours/day.  And I'll say.. 17 gb.

[deadly7]

22gb space
And I'll guess 48 hours max.

[igimo1]

24gb

[Newby]

30gb, 1.5 days tops.

And you're still going to lose quality decompressing and recompressing it, no matter what bitrate you're going to and what bitrate you originated at.

[Sidoh]

30gb, 1.5 days tops.

And you're still going to lose quality decompressing and recompressing it, no matter what bitrate you're going to and what bitrate you originated at.

That's assuming there is unrecoverable data in an MP3.  I don't know enough about MP3's to argue that this isn't always the case, but I really don't think it is.

[Newby]

It's a lossy compression format. You're always going to lose something from what I've seen in lossy compressions on audio/video.

[Sidoh]

It's a lossy compression format. You're always going to lose something from what I've seen in lossy compressions on audio/video.

From my understanding, the loss caused by this is either: a) non-existant b) humanly indifferent.  If you think differently, tell me why.

[Newby]

It's a lossy compression format. You're always going to lose something from what I've seen in lossy compressions on audio/video.

From my understanding, the loss caused by this is either: a) non-existant b) humanly indifferent.  If you think differently, tell me why.

http://en.wikipedia.org/wiki/Lossy_data_compression

The image at totally shit compression, decompressed, will look just like that. If you re-compress it, the only way to retain 100% of that image is to retain with a compression that includes everything. If you make a more compressed/less data compression of the already-compressed image, it's going to look even worse.

That's how it works with images, and it doesn't seem to be much farther off for audio.

Of course, the sound difference is miniscule unless you have a really really good speaker system and/or are an audiophile.

[Sidoh]

http://en.wikipedia.org/wiki/Lossy_data_compression

The image at totally shit compression, decompressed, will look just like that. If you re-compress it, the only way to retain 100% of that image is to retain with a compression that includes everything. If you make a more compressed/less data compression of the already-compressed image, it's going to look even worse.

That's how it works with images, and it doesn't seem to be much farther off for audio.

Of course, the sound difference is miniscule unless you have a really really good speaker system and/or are an audiophile.

Cool article.

I still don't think you loose any additional data decompressing, then recompressing to a more compressed state.  iago is consciously sacrificing quality (not much, obviously) for space.  I don't think he'll mind.

[iago]

I have re-encoded plenty of songs already and they lose no discernable quality.  Perhaps what they lose is outside the hearing range of a human.. I'll have to ask my cat if it sounds different to her.  Also, there were a lot of songs (Most of your Grave Digger albums come to mind) that wouldn't play at all on my iPod, I guess they use a weird encoding or bitrate or something that my iPod couldn't understand.  Reingold wouldn't play for sure until I re-encodeded it.  So there is a definite advantage to re-encoding there, and that's the other major reason (besides making the 320kbps take less space). 

I also realize that re-encoding from 128 to 192 will make absolutely no difference.  The only reason I'm doing it is for consistency and because I just have a loop that runs lame (I didn't feel like checking the current bitrate). 

<edit>
Also, to quote the Wikipedia article on mp3, "[the mp3 format] provides [...] audio data in a much smaller size by discarding portions that are considered less important to human hearing."  Based on that, I'd say that un- and re-encoding them a few times won't make much difference because the losses fall outside the human hearing range. 

[Newby]

I have re-encoded plenty of songs already and they lose no discernable quality.  Perhaps what they lose is outside the hearing range of a human.. I'll have to ask my cat if it sounds different to her.  Also, there were a lot of songs (Most of your Grave Digger albums come to mind) that wouldn't play at all on my iPod, I guess they use a weird encoding or bitrate or something that my iPod couldn't understand.  Reingold wouldn't play for sure until I re-encodeded it.  So there is a definite advantage to re-encoding there, and that's the other major reason (besides making the 320kbps take less space).

newby@impaler:~$ file music/Grave\ Digger/Grave\ Digger\ -\ 2003\ -\ Rheingold/*.*
music/Grave Digger/Grave Digger - 2003 - Rheingold/01-The Ring.mp3:             
        MP3 file with ID3 version 2.3.0 tag
music/Grave Digger/Grave Digger - 2003 - Rheingold/02-Rheingold.mp3:           
        MP3 file with ID3 version 2.3.0 tag
music/Grave Digger/Grave Digger - 2003 - Rheingold/03-Valhalla.mp3:             
        MP3 file with ID3 version 2.3.0 tag
music/Grave Digger/Grave Digger - 2003 - Rheingold/04-Giants.mp3:               
        MP3 file with ID3 version 2.3.0 tag
music/Grave Digger/Grave Digger - 2003 - Rheingold/05-Maidens Of War.mp3:       
        MP3 file with ID3 version 2.3.0 tag
music/Grave Digger/Grave Digger - 2003 - Rheingold/06-Sword.mp3:               
        MP3 file with ID3 version 2.3.0 tag
music/Grave Digger/Grave Digger - 2003 - Rheingold/07-Dragon.mp3:               
        MP3 file with ID3 version 2.3.0 tag
music/Grave Digger/Grave Digger - 2003 - Rheingold/08-Liar.mp3:                 
        MP3 file with ID3 version 2.3.0 tag
music/Grave Digger/Grave Digger - 2003 - Rheingold/09-Murderer.mp3:             
        MP3 file with ID3 version 2.3.0 tag
music/Grave Digger/Grave Digger - 2003 - Rheingold/10-Twilight Of The Gods.mp3:
        MP3 file with ID3 version 2.3.0 tag

Interesting.. I had a similar problem where all of my Slayer @ 320kbps sounded TERRIBLE on my iPod. It was all staticy but sounded perfect on my computer.

Then my iPod died. (And I got my dad's old one, and it sounds perfectly fine...)

[Quik]

Like video, audio reencoding at the same bitrate will lose such little quality that it will not be percievable.