VBR and Apple Lossles Question

[anamorphic96]

I was wondering if someone could help clear something up for me.

Please keep in mind im new to downloading music and just started about 4 months ago so im not up on all the MP3 codecs out there just yet or all things you can do with the files.

But my question stems around my downloads from Emusic.com. They encode everything using a VBR MP3. The files end up around 190ish to over 200 kbps. But once I have them in Itunes I can then convert them to Apple Lossles. So in doing this am improving the sound with this format. Didnt think you could do this with purchased MP3's.

Sounds stupid but I was under the impression that you could only do this with CD's that are imported.

Thanks for any input. Just a bit lost here.

 

[MDS]

But my question stems around my downloads from Emusic.com. They encode everything using a VBR MP3. The files end up around 190ish to over 200 kbps. But once I have them in Itunes I can then convert them to Apple Lossles. So in doing this am improving the sound with this format. Didnt think you could do this with purchased MP3's.

No, you would not be improving the sound.

A quick primer on lossy vs lossless codecs:

Lossy codecs (mp3, wma, aac, etc) use 'perceptual coding'; in layman's terms what they do is examine the uncompressed data and compare it to a model of human hearing to determine which parts we can hear and which parts we would not (eg. a soft sound that immediately precedes or follows a loud sound is 'masked' by the loud sound and would not be heard - so it is discarded). That is how they achieve a reduction in file size.

You can decompress a lossy format file back to an uncompressed format, like WAV (essentially PCM with a header preceding it that contains details about the file like number of channels, sampling frequency, bit depth, etc) but the decompressed file is NOT the same as the original from which it was made.

So for your question, if emusic ripped a track from a CD and then transcoded it to MP3 and you were to convert it back to WAV, the result would NOT be identical to the original track. [The theory is that it would sound the same, but I don't want to debate that.]

Lossless codecs on the other hand, simply compress the data to a smaller size - nothing is discarded. It is analogous to using WinZip to compress a file to make it smaller (although the algorithm is different). When you decompress a lossless file, the result is bit for bit identical to the original.

 

[jeffsg4mac]

If you downloaded something in mp3 then you want to keep it in mp3. There would be no advantage in converting to something else. Apple lossless is for reducing the space taken up by your existing CD collection. In theory it is supposed to sound identical to the original but at about half the file size. I have never tested this myself though.

 

[wilkenboy]

...my question stems around my downloads from Emusic.com. They encode everything using a VBR MP3. The files end up around 190ish to over 200 kbps. But once I have them in Itunes I can then convert them to Apple Lossles. So in doing this am improving the sound with this format. Didnt think you could do this with purchased MP3's.

The quick answer is no. Once you lose the data in compression (which is what MP3s do, VBR or not), you've lost the data and there's nothing you can do to get it back. Just like converting all of your old dubbed cassette tapes to CDs does not improve the sound quality.

For those interested in the technology of MP3 encoding, lossy and lossless codecs, here's a very well written article that also covers the best encoders / decoders out there. A good place to start before you spend too much time ripping those CDs to your harddrive.

http://arstechnica.com/guides/tweaks/encoding.ars/1

Enjoy!

~Josh

 

[anamorphic96]

Thanks For the help everyone.

Wilkenboy thanks for the link. It helped a good bit. Easy to understand.