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AIFF vs ALAC for AirPlay, Which one would yield the best-sounding end result?
Rodzilla
post May 15 2013, 08:32
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Hey guys, this is a copy my first post on these forums (since the first post was done on the wrong section), and I have a question that I don't believe has been asked here yet.

I'll start with my question:
Will an AIFF file played over AirPlay to an AirPort Express sound any better than an ALAC file played over AirPlay to an AirPort Express?

I know that iTunes converts all files that are streamed via AirPlay into ALAC, and then the AE reconverts them back to their original file (at most 16, 44.1). This means that an ALAC file would not be converted, and would probably be the most direct way to play a file over AirTunes. An AIFF file that is sent over AirPlay would first be converted to ALAC by iTunes, transmitted, and then reconverted to AIFF by the AE unit.

I'm wondering if this upconversion of ALAC to AIFF by the AirPort Express would really leave a finalized version of the AIFF file just like the one that is in the iTunes library. I know that some will say that lossless is lossless, but there are people who claim that AIFF may sound better due to the fact that it doesn't require CPU to decompress. I am worried that the fact that an AIFF file sent though AirPlay would have to be compressed, then decompressed, and that this would have a negative effect on it's quality due to processing going on "on-the-fly".

Are there any other reasons why the upconversion from ALAC to AIFF within the Airport Express may not yield the same high quality AIFF as in the original iTunes library?

I would much prefer to have AIFF files, just to have peace of mind, but not if the compressing and decompressing (or just upconversion) will affect it's final sound quality. Anyone out there experimented how these files sound? I plan to use the AirPort Express' optical out to an Audioengine D1 DAC, then to my amp. Also, I just plan to listen to my mainstream music, which is all recorded at 16 bits, 44.1. This is why I decided to go the AirTunes route, due to it's ease of music navigation, and the fact that I have both an iPhone and and iPad which I can use to control my music library.

Thanks!
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Nessuno
post May 15 2013, 09:21
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QUOTE (Rodzilla @ May 15 2013, 09:32) *
Will an AIFF file played over AirPlay to an AirPort Express sound any better than an ALAC file played over AirPlay to an AirPort Express?

Short answer: no differencies.

For what is known from Apple (and some reverse engineering) about AE, whichever codec for a given source file is transcoded to ALAC and sent to AE, which in turn decodes ALAC to PCM and sends this latter stream to its internal D/A and to its digital output. Nothing more, nothing less.

About 16/44.1 downsampling of HD sources, I've never found a clear answer: yes the internal D/A is a 16/44.1 only, but I don't know (and actually don't care... wink.gif) if the digital output has the same limitation. In other word, if it's an hardware or a protocol limit.

QUOTE
I know that iTunes converts all files that are streamed via AirPlay into ALAC, and then the AE reconverts them back to their original file (at most 16, 44.1). This means that an ALAC file would not be converted, and would probably be the most direct way to play a file over AirTunes. An AIFF file that is sent over AirPlay would first be converted to ALAC by iTunes, transmitted, and then reconverted to AIFF by the AE unit.

Where have you got this information about the (supposed) reconvertion? Never heard before and don't see any point in it!



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Rodzilla
post May 15 2013, 10:22
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QUOTE
Where have you got this information about the (supposed) reconvertion? Never heard before and don't see any point in it!

Exactly! I don't see a point in upconverting the ALAC file into AIFF, since supposedly it is supposed to end up sounding the same as the AIFF. I can't find any official sources to either prove or disprove this!
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db1989
post May 15 2013, 12:03
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QUOTE (Rodzilla @ May 15 2013, 08:32) *
I'm wondering if this upconversion of ALAC to AIFF by the AirPort Express would really leave a finalized version of the AIFF file just like the one that is in the iTunes library. I know that some will say that lossless is lossless, but there are people who claim that AIFF may sound better due to the fact that it doesn't require CPU to decompress.
There are people who claim lots of things. We are not very interested in seeing those claims repeated here unless they are supported by the objective evidence they are lacking everywhere else. I am not discounting your ability to question such claims, but exercising more scepticism in advance would be useful. It may not apply to you, but too many people come here thinking that the fact they have read something in some unspecified other location means that it has a fighting chance of being true.

QUOTE
I am worried that the fact that an AIFF file sent though AirPlay would have to be compressed, then decompressed, and that this would have a negative effect on it's quality due to processing going on "on-the-fly".
Why would this matter? Decompressing lossless is a relatively trivial process with the right algorithm, and even though I have a lot of issues with Apple, I highly doubt that they would stock their device with a CPU that was so sluggish as to be incapable of decompressing in time. Even then, the result would be not subtle degradations in quality but rather stuttering, etc.

QUOTE
Are there any other reasons why the upconversion from ALAC to AIFF within the Airport Express may not yield the same high quality AIFF as in the original iTunes library?
Are there any reasons why they would? Are they supported by anything other than, apparently, misunderstandings by other people who do not understand digital audio and its compression and choose to convert their ignorance into fear, uncertainty, and doubt? Personally, I think proceeding from a position of disbelief is much more productive in cases like this.
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Nessuno
post May 15 2013, 17:26
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QUOTE (db1989 @ May 15 2013, 13:03) *
Decompressing lossless is a relatively trivial process with the right algorithm, and even though I have a lot of issues with Apple, I highly doubt that they would stock their device with a CPU that was so sluggish as to be incapable of decompressing in time. Even then, the result would be not subtle degradations in quality but rather stuttering, etc.

For example: http://www.hydrogenaudio.org/forums/index....st&p=777105


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Wombat
post May 15 2013, 18:48
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QUOTE (Rodzilla @ May 15 2013, 11:22) *
Exactly! I don't see a point in upconverting the ALAC file into AIFF, since supposedly it is supposed to end up sounding the same as the AIFF. I can't find any official sources to either prove or disprove this!

This may sound smart-arse but when talking about going from ALAC to aiff this is not upconverting. The only thing that goes up is filesize.
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