[Canyoneagle]

I'm in the process of converting my iTunes library to the Apple lossless format (I import CD's with lossless, but downloaded music is mainly 128kb AAC format).  Can someone shed some light on the process?
My assumption is that the computer interpolates between the sampled points to 'smooth the curve'.  Is this correct?

Thanks!

Michael

[tomjtx]

ALAC (apple lossless) and FLAC are  truly lossless when decompressed. Some people have compared an ALAC bit file to the full CD file and the bits were identical. At least this is the way it was explained to me. However you should know I am a digital illiterate

I am sure someone else on the forum can go into much greater depth.

[LightFire]

I'm in the process of converting my iTunes library to the Apple lossless format (I import CD's with lossless, but downloaded music is mainly 128kb AAC format).  Can someone shed some light on the process?
My assumption is that the computer interpolates between the sampled points to 'smooth the curve'.  Is this correct?

Thanks!

Michael

I am not quite sure I understood your question. But, here it goes anyways:


There is no point in converting your 128 kbps AAC files to lossless. You will not "re-gain" quality. They will be as good (or bad) as before but will have a larger size.


Computers do not "smooth the curves" at this point. That occurs only at the sound output, at the DAC. It doesn't depend of file type used and occurs in almost all digital devices audio outputs (computers, CD, DVD, SACD players, etc.)

[tomjtx]

Yes, you shouldn't convert your AAC files to ALAC. All that will do is take up more space without increasing quality.
If you originally imported your CDs with ALAC then they already are ALAC and you don't need to convert. If you imported your CDs with AAC then you need to delete all those files and re-import the CDs at ALAC.

[Steve Eddy]

If the source files have already been compressed with a lossy compression schemes such as AAC, there's no getting them back to the original. That's the penalty paid for lossy compression schemes in exchange for higher compression ratios than can be achieved with lossless compression schemes. Data is thrown away and you're not going to get it back with simple interpolation.

So just keep your 128k AAC files as they are.

se

[Canyoneagle]

Thanks - good to know!

I guess that's the inherent downside to downloading music verus buying CD's.....

[tomjtx]

Michael,
One other thing I recently learned. If you burn your aac itunes music to a cd it will strip the drm. But when you re-import you shouldn't reimport it as aac because it will even FURTHER degrade the quality. eg. 128kbps becomes 96kbps or even less. The only way to keep it at 128kbps is to re-import as ALAC.
So, you use up ALAC space for crappy aac quality.
Yet more reasons never to buy from itunes.  eg. DRM, 128kbps, cant stream to SB.

I never download for these reasons and I've almost convinced my kid not to:
"Wait, son, I'll take you to the CD store"   

[Canyoneagle]

Very good to know.
I'd say I've downloaded 20 CD's worth so far from iTunes.

Looks like CD's will be the favored format until the downloads are comparable.

Thanks!

[Steve Eddy]

Looks like CD's will be the favored format until the downloads are comparable.

I wouldn't look for that to happen any time soon. But I could be wrong.

se