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November 13, 2010 - 9:23am

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dhs0403

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Kudos to John Marks

Kudos to John Marks for his recent editorials -- one on the importance of data density and a second raising concerns about spectator sports.

I took John's advice and constructed my own demonstration disk using PCM 24/96 downloads from ITRAX and compressed mp3 downloads from ITRAX and from ITUNES. I selected tracks that I already own on an original, hard copy DVD-Audio disk.

So I was able to compare:

--- PCM 24/96 from a hard copy DVD-A disk
--- PCM 24/96 from an ITRAX download and transfer to CD-R
--- mp3 from an ITUNES download and transfer to CD-R

On point 1, John's right -- the difference between 24/96 and mp3 is obvious and remarkable. We all expected that to be the case, but it's nice to hear the difference demonstrated.

On point 2, however, I discovered something new. The ITUNES that I run on my Macbook has a Toolbar Command that converts compressed downloads to Apple's lossless format. Simple, free, takes about 3 seconds per track! What a pleasant surprise.

Which just goes to show, sometimes we may have the ability to help ourselves -- as long as we take the time to do a little research.

John's editorials remind me of the time I discovered Macbooks can send 5-channel Dolby Digital directly to a receiver using the mini-jack that appears -- at least to our casual spectators -- to be just an earphone jack.

Keep up the good work, John. Some things in life really are free if only we do the homework.

Dave

November 13, 2010 - 10:07am

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Editor

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Re: Kudos to John Marks

Quote:
The ITUNES that I run on my Macbook has a Toolbar Command that converts compressed downloads to Apple's lossless format. Simple, free, takes about 3 seconds per track! What a pleasant surprise.

I am not sure what the point is that you are making. Once an audio file has been compressed with a lossy codec like MP3 or AAC, the damage is done. Transcoding to Lossless doesn't restore the musical information that has been discarded, I am afraid.

John Atkinson
Editor, Stereophile

November 13, 2010 - 8:32pm

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dhs0403

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Re: Kudos to John Marks

I wrote separately to JA asking why the ITUNES description of my downloaded MP3 file changed from "compressed" to "lossless" -- and now shows the Red Book sample rate = 44 kHz and sample size = 16 bit.

John's patient reply is shown below -- ITUNES is only stating that the envelop is now 16/44 -- not that the information stored in the envelop is 16/44.

So, I stand corrected on my second point -- but I stand pat on John Mark's suggestion that we create demo disks comparing PCM 24/96 downloads from ITRAX with the corresponding MP3 downloads from ITUNES -- and on my third point that MacBooks can pass PCM 24/96 information through a Toslink cable to our receivers.

I apologize for any confusion, but we all should be concerned that ITUNES clearly states, This file is "Lossless 16/44" when it clearly is not. Why not develop an industry-standard disclaimer that says, "This is compressed MP3 information stored in a 16/44 file".

Dave

__________________________________________________________

JA's explanation -- You are right about iTunes converting the 128kbps AAC to Apple Lossless. But remember that the lossless file format doesn't define the audio quality of the data it contains. That still depends on the original file format.

If you convert a 128 kbps AAC file to lossless, it will still preserve the original quality of the file. But that original quality has already been damaged by a lossy codec, which threw away most of the audio quality to get the data rate down from 1.1M bps to 128 kpbs. Converting the compressed file to lossless will not get you back the quality of the original recording. JA