A Funky Space Reincarnation

High resolution digital audio is big data. For any sizeable collection, we aren't talking gigabytes of data, more like terabytes (1 TB = 1,000 GB = 1,000,000 MB). Where do you store it all, and is your solution reliable?

I'll admit to hard drive paranoia — too many moving parts, too many failure modes Flash drives are my preferred storage solution.

But the 1TB flash drive housing my WAV library of nearly 1,000 full-length titles is nearly full, and my other drives are also maxing out. What's next?

Enter the LaCie Blade Runner, a 4TB USB 3.0 hard drive in a physical package by designer Phillipe Starck that is both beautiful and practical. (See photo, above.) The series of ribs will be immediately recognizable to anyone in the automotive audio business. They serve as a heat sink, dissipating the heat generated by the internal mechanism over a large surface area, eliminating the need for a cooling fan. The sealed enclosure also dampens vibration, and the raised rubber feet prevent vibration from being transferred to the desktop. The result is cool and quiet operation at state-of-the art transfer speed.

 

Where does all the space go? CD-quality WAV audio (16-bit/44.1 KHz) consumes 1GB for every 95 minutes of material. High-resolution lossless (24-bit/96 KHz) will cost you 1GB for every 29 minutes of audio. (Lossless compression — e.g. FLAC — will cut down the storage requirement, but not all media players support it as a native format and decompression is an additional step in the playback pipeline for those that do.) I prefer keeping material uncompressed.

 

In my weightless digital library I have 677 titles (600 hours) of 16/44.1 audio, and 300 titles (212 hours) in 24/96. The former is, not surpisingly, source from CD. The latter is almost entirely mastered from vinyl. Together they occupy more than 800 GB of disc space. Factor in album art and miscellaneous other audio and you can see that a 1TB drive will run out of space before I can add ten new 24/96 titles. The 2 TB drive holding the backup copies of mastering projects and FLAC downloads (compression is good for transport) is nearly full as well.

 

I see a Blade Runner in my future.  

 

            Vinyl-to-Digital Restoration #51            

Artist: Marvin Gaye

Title: Here, My Dear
Genre: Soul and R&B
Year: 1978





Ordered by a judge to turn over the profits from two albums to the first wife he'd left, Marvin Gaye produced this bitter, sad, bewildered masterwork. [N.B. The album includes the track used as the title of this piece.] Over sprawling funk tracks, he questions her, himself, love, family, and, of course,  asks, "Why do I have to pay attorney fees?" Both incomparably smooth and incontrovertibly twisted, Here, My Dear is Gaye with the mask off: even the multiple vocal overdubs can't hide his pain and his weariness. — Rickey Wright

© 2013 Thomas G. Dennehy. All rights reserved.

'Mastered for iTunes is BS?' Bad Science Meets Rampant Retweeting

Mastering engineer and writer Ian Shepherd took exception to Apple's new Mastered for iTunes process being characterized in an interview as 'sounding closer to the CD.' So he took to YouTube and his website to prove that it does not. "Not true. Testably not true."

His result was re-blogged and re-tweeted without comment (2000+ times) until it not only became news, it threatens to become fact.

Unfortunately, his test design and logic are flawed, and the false conclusion he draws is the only conclusion possible under the test conditions. Let's take a look. [Disclaimer: I have no connection to Apple or its products.]

Basically, Mr. Sheppard used a well-known test that identifies differences between sound waves to compare a 16-44 WAV file ripped from a CD against two files.

1. File A: Mastered for iTunes AAC of the same track professionally created from a 24-96 master, downloaded from iTunes store.
2. File B: AAC created on his computer from the 16-44 WAV using iTunes with default program settings.

He then listenened to the files and concluded that File B sounded subjectively closer to the CD than File A. So it was "testably not true" (extrapolated from a sample set of 1) that Mastered for iTunes files sound closer to the CD than regular iTunes files. (Viewers of the YouTube video proof have to take his word for it; they can't hear exactly what he is hearing.) Test set size and possible equipment bias aside, I have two hypotheses as to why his conclusion isn't significant or surprising.

• Hypothesis #1. Files A & B were produced from different sources. The basic iTunes WAV-to-AAC converter will create a unique result from any particular master recording of a song (varied by sampling rate, bit depth, equalization, etc.).
• Hypothesis #2. An AAC file will have a stronger statistical correlation to its specific master file than to any other version.

If both hypotheses can be proven objectively, File B sounded closer to the CD because there was no other result possible. Mr. Shepherd's pronouncement is a tautology, a logical statement in which the conclusion is equivalent to the premise. And, as confirmed by the blogosphere and twittershpere,  another definition for tautology is "needless repetition of an idea, without imparting additional force or clearness."

My full test methodology can be found here. Using results from a sample set of three songs, we find the following:

Hypothesis #1. In all cases, the iTunes encoder produced a different AAC file from the 24-96 version of a song than from the 16-44 version, verified with the same null test used by Mr. Shepherd. The titles were chosen essentially at random from my 24-96 WAV collection and cross genres, so there is no reason to believe the result won't be repeated for any 24-96/16-44 file pair that does not have special characteristics.

Hypothesis #2. To get an objective measure of correlation, I mixed aligned versions of all WAV/AAC pairs (one in-phase, the other phase-inverted) and calculated the RMS volume of the resulting difference wave. That is, on average, how measurable the difference is between the WAV file and AAC file tested. Results below.

(Lower values indicate closer correlation between AAC and WAV files.)

In all cases, the closest correlation was between the 16-44 WAV and its corresponding AAC. This makes sense, as there is less information lost from compressing a 16-44 master to AAC than a 24-96. And in all cases, the off-diagonal files (an AAC mixed with a file other than its master) showed no closer correlation than the main-diagonal files (AAC mixed with its master), to the precision of the measuring tools.

Therefore, we can conclude that Mr. Shepherd's test was unwittingly biased toward hearing a closer match between the CD master and File B (created directly from the CD by standard iTunes) than File A (ceated by Mastered for iTunes from a different master). It is not surprising or significant that he did, in fact, prefer File B.

Nowhere in Apple's technical literature or advertising do they actually say the goal of Mastered for iTunes is to create audio files that sound 'closer to the CD.' Apple does say they set out to create a process and tools that produce audio files that are closer to the source. So we repeated our test method to compare Mastered for iTunes v. standard iTunes to see which produces files closer to a 24-96 master. Come back to see results.


            Vinyl-to-Digital Restoration #25            

Title: Ella Fitzgerald Sings the Cole Porter Songbook

Artist: Ella Fitzgerald

Genre: Jazz

Year: 1956

I didn't become aware of Ella Fitzgerald until the 70s, when her TV commercials. ("Is it live, or is it Memorex?") made her almost seem a caricature of herself. I'm very glad to have restored an original-edition copy of this LP from my father-in-law's collection to get insight into her earlier career. It reveals Ms. Fitzgerald delivering interpretations of Cole Porter songs that the composer himself must have thought true to his intent.

© 2012 Thomas G. Dennehy. All rights reserved.