I have read several postings that suggest converting a 256 kbps AAC audo file purchased from iTunes to Apple Lossless does nothing but increase the file size - i.e. there is no improvement in sound quality.
If that is the case, I wonder:
- Why iTunes has functionality to allow that (it can't just be a ploy for Apple to sell more hard disk capacity).
- What is the extra file size filled with if it is not better sound?
The conversion from AAC to Apple Lossless does in fact not
improve anything.
There is a case for the conversion though. You can convert
an AAC to lossless and then use audio enhancement software
on it to "improve it" or just simply make it sound like you want
that simple playback adjustments cannot do. Then, if you
keep it in lossless, none of changes will get thrown out.
I have not known many situations where things were absolutely prevented just because they were not a good idea. 🙂 I'm at a loss to think of a situation where you would want to go AAC to ALE but probably there is one.
I haven't tried AAC to ALE and I don't know the details of how the codecs work. One thing for certain though is you cannot recover lost information. Let's say the AIFF to AAC encoder says, "Let's toss out this quiet guitar playing a C note because there's a loud drum roll right here. Nobody is going to hear it and we can save a bit of data encoding to cut down file size." When you convert to ALE there's no way it is going to know there was originally a C being played quietly in that section.
But I can't imagine that going from AAC to ALE drops anything. AAC is lossy and ALE is lossless. Apple lossless file sizes are over three times larger than the same AAC song.
Converting from AAC to Lossless does not drop anything, but that's not what Limnos said. He said that converting cannot recover anything that was discarded during the compression to AAC.
iTunes has the capability of converting any of the formats it can use to any of the other formats. That doesn't mean that doing so makes sense, just that Apple's programmers didn't see any point in locking out any conversion. Someone may have a good reason why they want all their tracks in Lossless format, even if they don't gain sound quality in having it so.
Regards.
I just used a sound generator to creat a pure 30s 1kHz signal. I saved it as 128k .m4a, a lossless format, and as AIFF.
AIFF 5.1 MB
lossless 0.92 MB
.m4a 0.36 MB
As I said before, I don't know the details of the codecs. Typically a lossless format file will be about 60% the size of an AIFF file and the 128k .m4a about 10%. My examples are much smaller so both probably reflect the minimal descriptive encoding required because of the purity of the sound. Still, the lossless file is 3x the .m4a version which I suppose has something to do with the coding structure since both are very simple in terms of waveform. You would have to check on on an audiophile web site to find an explanation.
Thanks. I understand Limnos's point.
I'm new to researching various music file types. A guy at a stereo shop suggested that I should convert my iTunes AAC downloads to Apple Lossless and I did. Maybe it was all in my mind, but with a listening comparison, the losseless music does seem to sound better than the AAC file for the same music.
Now I am trying to better understand if there is truly a techincal reason for this or is it really all in my perception and all I've really accomplished from this exercise is using up three times the disk space.
The stereo guy wasted your time. There will be no benefit in doing making such a conversion, at least none that makes it worth the time and effort. Based on testing I've seen done on Apple's Lossless format in the past, any improvement you hear is most probably the "placebo effect" and not any real difference in the waveform, though I can't say with absolute certainty that there is no difference in the decoders in iTunes that might account for some small difference in playback.
Regards.
Well you know what they say. Perception is reality.
Converting to lossless is no real effort - one click in iTunes and less than 30 seconds. I'm still interested in understanding the technical distinction between an AAC file and a lossless file converted from that same AAC song.
I'm still interested in understanding the technical distinction between an AAC file and a lossless file converted from that same AAC song.
There is none. The conversion to ALE, because it is lossless, gives you an ALE file that has exactly the same sonic content as the AAC that you started with. That is what "lossless" means.
Thanks for the clarification. So I guess it's kind of like filling the additional space in the bigger box lossless file size with styrofoam.
rjgrichmond wrote:
Thanks for the clarification. So I guess it's kind of like filling the additional space in the bigger box lossless file size with styrofoam.
Yes, that is a good analogy.
If you rip a track from CD with Apple Lossless, you get the full sonic detail that was on the CD.
If you then compress it to AAC and then expand it back to Apple Lossless, it will expand but will not recapture the detail that was lost. Kind of like the bird at the bottom.
If you stream to a good hi-fi system, where you can actually hear music, try converting from whatever you have to Apple Lossless Audio Codec (ALAC). It only takes a moment and and does not destroy your original file, whatever it is.
I know actual missing data can't be recovered or even invented but it is possible to better interpolate lines of best fit between samples and it may be possible to do more with the dynamics and ambiance data.
If you convert a file you can try listening to a part of one version and then the same part of the other version a few times and make your own mind up.
I stream into around £8000 of hi-fi and I find that ALAC files give; a larger sound stage, increased dynamics, more definition overall, and generally more musicality. Putting it another way – simply better.
I've had the same question (and am still looking).
Could it be - The 256 ACC file is a compressed file, and that converting this file to a lossless file uncompresses the file for conversion to Apple Lossless. This saves the same data but now without the compression. Ergo - which increases the file size .... i.e. now LossLess.
My Apologies to those that have said the same thing, but maybe a bit more Techy.
Very simplified - The Size of the ACC 256 compressed file = X and when uncompressed to Apple Lossless the file size is now 3X (arbitrary ratio)
No new data - Just uncompressed.
The conundrum:
I too "believe", the ACC file converted to ALAC Apple Lossless file, sounds better when played. Wether real or not I prefer to convert the compressed file to a lossless file because my ears thinks it hears a LARGE difference and the difference in perceived quality pleases me i.e. sounds better to me..
I prefer to convert the compressed file to a lossless file because my ears thinks it hears a LARGE difference and the difference in perceived quality pleases me i.e. sounds better to me..
Good, then go for it.
Bud74 wrote:
I've had the same question (and am still looking).
Could it be - The 256 ACC file is a compressed file,
It is compressed but mainly it is smaller because bits are discarded, i.e.. no longer present in the file. They cannot be restored by converting it to anything.
and that converting this file to a lossless file uncompresses the file for conversion to Apple Lossless. This saves the same data but now without the compression.
Apple Lossless (ALAC) is compressed. That how ALAC file size is ~50%-60% of the original size with no loss of data.
No new data - Just uncompressed.
You cannot uncompress what is not there. AAC is missing large chunck of the original data.
Apple Lossless vs AAC
