What happens when you reencode a 128kbs mp3 to 256kbs??

[chiwawa626]

What happens when you reencode a 128kbs mp3 to 256kbs?

Im not totaly sure but from what i remember KBS is the kilobits or something per frame...something like that so how do u take 128 and make it into 256 or even 320?

 

[Bulk Beef]

It skips every other kilobit.

 

[aswedc]

The file gets bigger. It doesn't sound better. Why?

 

[Bulk Beef]

The file gets bigger. It doesn't sound better. Why?

Mp3=lossy.

 

[Maverick]

when you go from an original source to mp3 you lose information. The kbs is just a measure of how much you lost. Once you lose that information, there's no way to get it back. You have to re-encode the mp3 from the original source.

 

[chiwawa626]

But im talking about what actauly "fills in" to make the 128 into 256....If you play an mp3 slow enough and its a low bitrate you will have turnication beacuase there isnt enough data to stretch to that long time....so what would the diffrence be if it wwas a file incoded from 128 to 256

 

[notfred]

imagine a red square pixel. imagine you double the resolution. You now have 4 red pixels. 4 times the file size. However, the picture looks exatly the same. It's a red square. Imagine the same thing with audio.

 

[notfred]

128 kbps waveform

256 kbps waveform

Notice that the actual waveform is the same, the 256 kbps file jsut has twice as many data bits on it.

 

[KokomoGST]

Originally posted by: aswedc
The file gets bigger. It doesn't sound better. Why?

Your quality can't surpass that of the original with audio. Well, that's excluding tricks like psychoacoustics and weird algorithms... but that's not exactly bettering the accuracy of the source.

 

[DaveSimmons]

If you like a piece of music enough to be re-encoding it, why not buy a real copy instead of keeping your "preview" copy? Ripping from a real CD to 256kb will sound much better than anything you'll find on the net. And the CD itself will sound even better

 

[rubix]

what happens? you end up with a mp3 about the same quality as you'd find on one of those lame p2p programs.

 

[TheBDB]

Another question on this subject. What is the bitrate of songs on a CD? In other words, what bitrate sampling would you need to have no data loss when ripping a mp3?

 

[fyleow]

I'm pretty sure that it's something ungodly like 1144kbps or at least thats the rough approximation I remembered when I saw it being displayed on Real player.

Anyway I rip and store all my CDs in wave format so I don't really have to bother with this

 

[Zenmervolt]

Songs on a CD are encoded using a 16 bit 44.1kHz waveform (equals a *.wav file). While 256 kbps MP3's are arguably audibly indistinguishable from the CD source and 360 kbps MP3's are almost certainly indistinguishable to the human ear, there will always be a data loss when converting from a waveform to an MP3. A 360 kbps MP3 file still contains less auditory data than the original CD source.

Actually, if you re-encode a 128 kbps MP3 to 256+ kpbs, the new (higher bitrate) file will sound worse than the 128 kbps file because some data is lost with each encoding pass.

ZV

EDIT: Regarding the first part of my post: I should point out that the encoding used for a CD is not directly related to MP3, and that due to the nature of the MP3 file type there will be data loss regardless of the bitrate.

 

[TheBDB]

16 bits * 44 kHz = 704 kbps

Is that the answer to my question?

 

[Thegonagle]

Originally posted by: Zenmervolt
Songs on a CD are encoded using a 16 bit 44.1kHz waveform (equals a *.wav file). While 256 kbps MP3's are arguably audibly indistinguishable from the CD source and 360 kbps MP3's are almost certainly indistinguishable to the human ear, there will always be a data loss when converting from a waveform to an MP3. A 360 kbps MP3 file still contains less auditory data than the original CD source.

Actually, if you re-encode a 128 kbps MP3 to 256+ kpbs, the new (higher bitrate) file will sound worse than the 128 kbps file because some data is lost with each encoding pass.

ZV

Welcome back, Zenmervolt.

(As usual, he is correct.)

 

[BD2003]

Originally posted by: TheBDB
16 bits * 44 kHz = 704 kbps Is that the answer to my question?

Almost, theres two channels, left and right, so double that, and your final answer is....

1408 kbps.

 

[Zenmervolt]

Originally posted by: TheBDB
16 bits * 44 kHz = 704 kbps

Is that the answer to my question?

See the edit in my previous post. The only way to get a lossless copy of a CD is to rip it to a *wav file (a little more than 9 megs per minute or 650/74 megs per minute). Any and all MP3's will be lossy.

ZV

EDIT: Thanks for the welcome back Garfang. Very good to be back, summer dial-up is gladly ending. If it seems that I'm usually right, it's only because I just pick off the easy questions and leave the hard ones for those who really know what they're doing like Russ, Harvey, RedDawn, Workin', and at least a dozen others to whom I must apologise for not recalling their names right now.

 

[silverpig]

Originally posted by: sward666

The file gets bigger. It doesn't sound better. Why?

Mp3=lossy.

I don't think he was asking "why does it sound worse?" but "why do you ask?"

Either way, you lose data with each encoding.

128 kbps sounds fine if you're not really paying attention.
256 kbps is good unless you're really listening.
320 kbps is so close that it's gonna take a good set of ears, a good set of speakers (or headphones), and a whole ton of listening and playback to distinguish.

 

[BD2003]

Originally posted by: Zenmervolt

Originally posted by: TheBDB 16 bits * 44 kHz = 704 kbps Is that the answer to my question?

See the edit in my previous post. The only way to get a lossless copy of a CD is to rip it to a *wav file (a little more than 9 megs per minute or 650/74 megs per minute). Any and all MP3's will be lossy. ZV

There are a few lossless codecs out there, such as WMA pro or monkey. Half the size, but a perfect copy.

 

[mithrandir2001]

Originally posted by: chiwawa626
But im talking about what actauly "fills in" to make the 128 into 256....If you play an mp3 slow enough and its a low bitrate you will have turnication beacuase there isnt enough data to stretch to that long time....so what would the diffrence be if it wwas a file incoded from 128 to 256

It doesn't stretch or truncate over the time domain.

When you convert a 128kbps MP3 to a 256kbps MP3 (senseless, BTW) you have to make an intermediary step: convert the original MP3 to WAV. The encoder that is charged with making the 256kbps MP3 sees this WAV as it does any other WAV. It doesn't know if the WAV was decoded from a MP3 or is a direct rip from CD. It just sees a 44.1KHz 16-bit digital stream and it encodes the stream like any other. Because lossy formats assume only one conversion from WAV, they often use aggressive psychoacoustic algorithms to remove perceptually unnecessary data. These algorithms leverage facilities like the absolute threshold of hearing and temporal masking to achieve steep bitrate reductions. For the first encode, these algorithms can work very well. However, when these algorithms are run twice the results suffer because they assume the inputted WAV is the original, not a decoded WAV from a lossy format.

 

[mithrandir2001]

Originally posted by: BD2003

Originally posted by: Zenmervolt

Originally posted by: TheBDB 16 bits * 44 kHz = 704 kbps Is that the answer to my question?

See the edit in my previous post. The only way to get a lossless copy of a CD is to rip it to a *wav file (a little more than 9 megs per minute or 650/74 megs per minute). Any and all MP3's will be lossy. ZV

There are a few lossless codecs out there, such as WMA pro or monkey. Half the size, but a perfect copy.

Perfect indeed but the bitrate varies fairly wildly. Half the size is a little hopeful. Realistically, lossless formats achieve 40-45% compression on average. For music like heavy metal, compression might only equal 30% but on classical material 60-70% compression is not unusual.

 

[Zenmervolt]

Originally posted by: BD2003

There are a few lossless codecs out there, such as WMA pro or monkey. Half the size, but a perfect copy.

If the file is physically smaller than the file on the CD, then the smaller file must logically have some information loss, right? Or am I completely screwed up in my thinking here? In any case, I should have thought of the fact that there would be other lossless codecs aside from *.wav out there. Oops

ZV

EDIT: Disregard my rambling about the smaller file size, I suddenly remembered that my good old *.zip files are both lossless and smaller. Brain fart. Sorry.

 

[mithrandir2001]

Originally posted by: Zenmervolt

Originally posted by: BD2003

There are a few lossless codecs out there, such as WMA pro or monkey. Half the size, but a perfect copy.

If the file is physically smaller than the file on the CD, then the smaller file must logically have some information loss, right? Or am I completely screwed up in my thinking here? In any case, I should have thought of the fact that there would be other lossless codecs aside from *.wav out there. Oops

ZV

WMA Pro or Monkey's Audio is like WinZIP for WAV. You can shrink the WAV to a format that can decompress back to an exact copy of the WAV.

And what's nice about these lossless formats is that you can play them in WinAMP and WMP without decompressing them back to WAV (the plug-in does it on the fly).

 

[Zenmervolt]

mithrandir2001 posts faster than I can edit.

ZV