Ozone in Luminescence

Lossy audio encoding and CD audio

2009-12-07T10:29:00.001-08:00

I return to this blog to provide some additional information to help fill in my father's onrunning A/V saga. This stuff comes more-or-less directly from one of my college courses.

MP3/AAC work by transforming the time-based audio signal to the frequency domain (which corresponds roughly to how our ears receive the incoming audio signal) and compressing the frequency-based signal, which we can envision as a sequence of frames, each of which contains a snapshot of the frequency spectrum for one short time period of the audio signal. Interestingly, to make sure that you don't lose anything going to the frequency domain and back, the time periods or "windows" that are converted actually overlap each other, so that one time period may be captured in three successive frequency frames. In other words, you're already saddled with a lot of redundancy by doing this! But lossy compression gets us back to way more than parity: to get compression, for each frequency frame they assign a limited pool of bits across the frequency spectrum, using psychoacoustic heuristics to figure out which parts of the spectrum need more fidelity than others, and by how much:

Equal loudness curves are used to calculate which frequencies are harder to hear and by how much, and fewer bits are given to the harder-to-hear frequencies. (One interesting thing about these is that our ears' ability to hear high/low frequencies naturally degrades with age. No compression algorithm I know takes into account the age/capabilities of the listener. OTOH, the older you get, the better your MP3s ought to sound. :-)
In addition, the masking phenomenon, where a strong pitch at a particular frequency will make it impossible to hear softer pitches at neighboring frequencies, can be employed to avoid throwing bits at inaudible parts of the recording.
Other dirty tricks can and will be pulled as well.

The psychoacoustic algorithms are the most jealously guarded part of these lossy formats, since they make a big difference on the kinds of artifacts that the lossy compression will produce. (Because of the patents and protection put around these algorithms, there has also been an attempt to create a format that is open-source from algorithms to the actual implementation, which is called Ogg Vorbis. This is getting quite far afield from the Home Theater realm though.)

Generally, the higher the bitrate, the bigger the pool is, and the better quality you get across the spectrum. As you dial down the bitrate, the format tries to keep the most important stuff--if you are listening in hostile environments like jogging and the car, low bitrates may be perfectly fine. VBR dials up/down the pool of bits as the audio track progresses depending on whether it's in a part of the audio track that needs particular attention (the calculation of that is an interesting problem in itself!), so that the overall bits per second is lowered.

As far as CD audio goes, the biggest problem with CD audio is that they picked a frequency that is just a little over twice the theoretical maximum frequency of 20KHz that a human ear can respond to. (Many audiophiles have claimed to be able to hear above this maximum frequency, thus defending their sticking to the analog domain, but I'm not aware of any claims that have passed scientific scrutiny.) A fact about digital sampling is that it reflects any freqency content over half the sampling rate back into the rest of the spectrum (this is called aliasing), which produces some really awful artifacts. To avoid this, folks had to come up with a filter so that audio up to 20 KHz could be heard just fine, but that audio above 22.05 KHz (half of 44.1KHz) was eliminated. This is actually a pretty difficult engineering problem, as that is a fairly narrow drop-off at that frequency, and the result was a number of "brickwall" filters early on which obtained that result, but seriously altered or "colored" the sound in the process. Complaints that early CDs sound overly bright or harsh probably have something to do with this process. Since the early days, though, oversampling and other technologies have been used to make sure that more gentle (and less audible) filters can be applied, and the result is the seemingly endless sequence of digital remasters of the same old analog recordings, as well as current recordings that can be amazingly precise and clear. And for those analog audiophiles, there are plenty of "analog fuzz/click/pop" filters that Pro Logic can add back onto the audio track for their enjoyment. :-)

Echolyn - Mei

2005-11-04T22:37:00.000-08:00

What is one to make of a song that fills an entire CD?

There are several ways in which "long" pieces can be constructed. First, and perhaps the earliest to develop historically, are the jams, extended solos and improvisation over and around a simple kernel. The music often noodles from one theme to another, sometimes planned, sometimes spontaneous. This music tends to not be goal-oriented at all; in fact, it invites you to get lost along with it.

Another sort of piece involves very slowly evolving themes. Immersion through repetition is key to this form of music. Two ways to respond to this music: trance (or other form of meditation), or placing this music in the background (i.e. as a soundscape). Though the meditation invites a goal of transcendence, the music itself is often not as explicit about goals, preferring to simply exist—this is, after all, what makes it great background music! Electronic music is well-suited to this kind of composition because it gives the composer various means of precise control over the sound, allowing the sound to move as quickly—or in this case, slowly—as the composer wishes.

Yet a third kind of piece manages to be long, yet ultimately goal oriented. It unfolds as a series of movements, or episodes, each generally having a definite structure, and often leading to a "grand finale" of sorts. These types of pieces tend to be carefully constructed—though, unsurprisingly, jams of the first variety often serve as the starting point for these compositions, and most of these compositions never completely lose their "jammy" flavor. To me, this use of structured, goal-oriented music, often extended to long periods of time, forms the principal characteristic of "symphonic rock," rather than the more common, flippant, and ultimately inaccurate definition as "music which resembles a symphony because it's bombastic." There is, however, a kernel of truth in the common definition: symphonic rock often employs longer song structures in an attempt to express more content than can be crammed into a radio-friendly format.

Which brings us to Mei. This is far from Echolyn's first experimentation with longer song structures. Their first album featured "Shades", a melodaramatic expression of lost love in a connected series of short episodes. The second half of their second album, Suffocating the Bloom, was "Suite for the Everyman," went for a different approach: a larger set of episodes were spun out into a collection of generally independent short pieces that were nevertheless closely related musically and lyrically, including pieces that served as reprisals and bridges between the rest of the music. The four-movement piece "Letters" in As the World kept the concept of a suite, but expanded the independence and scope of each of the four pieces in the suite. Mei represents yet another step in development. Here, each of the episodes is quite meaty, but fully integrated into a relatively loose, expansive structure.

What the pieces thereby lose in independence, they gain in gestalt. In Mei, the objective appears to be an attempt to musically recreate the style of a travelogue. Echolyn cites Kerouac as an influence on this piece, and one can only imagine that the image of a endless roll of paper, consumed by a typewriter at breakneck speed, had to be a major part of this influence. The extended form of Mei is the perfect representation of this image.

The images in the liner notes for Mei suggest a strong link between this album and the previous album Cowboy Poems Free, an album loosely themed around the Depression-era Midwest and its historical consequents. The tone is generally dark, touching here and there on melodrama. But the lyrics and melody represent in my opinion a great leap forward for Echolyn, consistently haunting and evocative, earning the more dramatic moments in the music with aplomb. The tempo is generally relaxed, though in pure Echolyn style, the music is often dense and punchy, sometimes almost overwhelmingly so. The addition of strings, far from invoking bombastic orchestral overtones, lends an chamber-like intimacy to the softer parts (as it has in Echolyn's earlier work); what seems new is the way the strings lend subtle support in the louder parts (with great results). But what stands out to me the most in this work is the same thing that has drawn me to Echolyn's songwriting again and again over the years: an idiosyncratic and imaginative approach to harmony—both instrumental and vocal—which is always fresh and fascinating.

Porcupine Tree—In Absentia—Trains

2005-10-24T21:52:00.000-07:00

This is an essay I've wanted to write for a long time now. I am absolutely convinced, ever since I first heard the song, that Porcupine Tree's "Trains" is one of the best pop songs ever written. Now I get to try to explain why.

Porcupine Tree has long been experimenting with incorporating softer sounds—Rhodes piano, acoustic guitar, atmospheric synth washes, gentle and frequently harmonized vocals—into a hard rock, sometimes even metal context. The first two tracks on In Absentia, "Blackest Eye" and "Trains," contain some of the most extreme examples of these contrasts. In "Trains," the contrast has everything to do with the song itself.

"Trains" opens with a childhood memory of the singer hearing his cousin play with a model train set on his bed. The words are sparse and telling. The scene is quiet enough for the singer to hear and focus on "the hiss of the train at the railway head." The music paints the scene with just an acoustic guitar, capo'd up to the fifth fret (Am) to get a delicate tone; this contributes to the sense of wonder that permeates the verse. It is interesting to note that, when played live, Steven Wilson only takes the capo up to the second fret (setting the piece in F#m); this allows him to hit the high note in the chorus in full voice, but robs the piece of much of its brightness. What a difference a simple transposition can make!

Now consider the main riff of the piece. The rhytmic figure is syncopated as it starts on an accented off-beat and also lands on an off-beat; this syncopation gives the feeling of a smooth yet slightly jarring motion—a rhythmic representation of the motion of a train. The harmony alternates between an ethereal F9 and the tonic full-bodied Am. The F9 gives me a sense of longing, the Am a sense of sorrow; both are key themes in the piece. This also sets up a framework for the dualisms that the rest of the piece centers around.

The first line of the chorus links the first two verses, and ties to the sense of nostalgia in the first verse by expressing regret for what has passed: "Always the summers are slipping away."

The second verse kicks in with the full band, and with full energy introduces a set of surprising and interesting dualisms:

F9	Am
Sixty-ton, falls to earth	Angel
Pile of old metal	Radiant blur
Scars in the country	Summer and Her

The train represents the sum of these conflicting elements, but the emphasis here is away from the physical presence of the train (here presented as heavy, massive, and unnatural) and towards the more intangible and positive aspects. Why? Both from the position of the second column in the musical phrasing, and the musical resolution of F9—Am. Note the curious inversion of order in the first line, which perhaps acts like a trochaic substitution in iambic verse: it helps keep the verse from reverting to singsong.

The chorus forms the emotional core of the piece. Again, the chorus expresses regret for time that has passed, now augmented with an impossible plea to freeze time. Since we now know that summer has to do with Her, we now know where the singer's heart is longing. The strong move to D, along with the jump to A in the voice, initiates a musical sigh; the harmony circles around F, ending the sigh in a harmonically suspended Fmaj7 and leading effortlessly back to the F9; the voice glides down gently to land an octave below. In the light of the chorus, trains are relics of a happy but distant past, just as the relationship between the singer and the woman in v. 2 is fated to become.

The guitar solo goes back to the chord structure of the verse (F9—Am). The solo on the album makes good use of B, using it to heighten the sense of longing against the Am. Then we are in the bridge, which has the same harmonic structure as the chorus. This time, however, the melody is more forceful, and the tone is darker, as the singer describes the thing that he wants to preserve. An impassioned kiss is exchanged on a train platform (note the interesting descriptive word "wide"); the hissing of the passing engine suggests a sharp intake of breath as the response, melting away into the kiss and the resulting euphoria as the sound of the engine subsides. This is contrasted by a sublimely masochistic expression: in the context of trains, the singer being tied up by the woman suggests a heroine being tied to train tracks by a villain. There is the threat of death in the act, but he is too wrapped up in love to care. The image is a slightly disturbing one, and is classic Porcupine Tree material; masochism, or the association of love with invited pain, forms a theme in many of their songs ("Waiting," "Sleep of No Dreaming," "Slave Called Shiver," perhaps even "Glass Arm Shattering").

From the short bridge, we are led to a beautifully harmonized vocal solo, again over the verse chord structure, and then to an instrumental interlude which paints a bucolic and thoroughly nostalgic picture of a train ride. Here, the feel shifts to a gentle 3/4, hand claps represent the clicking sound of train tracks under the wheel, a banjo represents the movement of the train, and a simple, reverberating guitar melody floats on top. Harmonically, we slide up from Am into an unfamiliar Bb6 which resolves to Fmaj7, forming a soft, inviting world which the melody drifts through.

From the interlude we kick back out to the bridge, which leads us finally to the end. The end features the F—Am chord structure of the verse, but now all trace of gentleness is gone; heavy guitar power chords drive home the despair and sorrow in the parting words, which echo the chorus: "always the summers are slipping away..."

"Trains" is a piece which is nuanced and complex, yet elegant and spare in its choice of materials. It is, quite simply, a beautifully structured and executed piece.

On the Curious Idiosyncracies of the Music Geek

2005-10-24T20:39:00.000-07:00

I identify myself, first and foremost, as a music geek. This invites a little explanation.

It should go without saying that I like music—a lot. But so do many if not most people on the net. I have a reasonably large music collection, but I know there are many people out there whose collections dwarf mine. I have a reasonably broad spectrum of musical interests, but there are people out there who know every major artist in all of the genres I express interest in—and many of the minor ones as well. I play several different instruments, but there are many people out there who can school me in each of the instruments I play—and a number of people, no doubt, who can best me in all of them.

The way, perhaps, in which I differ is this: when I hear a piece of music that I like, I am filled with a desire to take that piece of music apart, to find out what makes it tick. This has been the case ever since I started transcribing music I heard and liked when I was young. (I haven't done any transcription in a while, but my drive to understand music from the inside out remains the same.)

Of course, this kind of attitude is relatively commonplace among aficionados of classical music, even if practised almost exclusively by musicologists. On the other hand, it puts me directly at odds with most consumers of popular music nowadays—even the reviewers. Popular music, or rock, is supposed to make one feel something, or at least get up and dance, or so the conventional wisdom goes. At most, popular music can aspire to being part of a cultural zeitgeist. This goes especially for rock, whose highest aim is rebellion, revolution, and fun, if I have read Rolling Stone and the like correctly. So why bother attempting to understand it at an intellectual level? The attempt to do so can be seen as pretension, either on the part of the reviewer or on the part of the music for having such a level in it in the first place. I am reminded of Max Ernst here: Dada was a bomb... can you imagine anyone, around half a century after a bomb explodes, wanting to collect the pieces, sticking it together and displaying it?

My response is simply this: I'm a geek. To take things apart and look at them is second nature to me. And I disagree that the music I enjoy is pretentious, or that the exercise of taking it apart is fatuous. Pretentious music pretends to be something it's not. Yet the music I enjoy is, as far as I'm concerned, in its fullest sense, and holding it to scrutiny only increases my enjoyment of it. And I'm having too much fun with this music to take my own blatherings on it too seriously.

That I am a fan of progressive rock should therefore come as a surprise to noone. Anyone who has been to a progressive rock festival recently will notice, I hope, a distinct air of geekiness amongst the throng. These, to me, represent some of the best music fans a band could hope to have—generally open-minded, intelligent, opinionated, generous with their wallets, faithful beyond all reason to the music they love. Many reviewers of progressive music show these excellent qualities in the reviews they write.

Yet to me, there is a sense of disappointment that even these reviews don't go deep enough. Usually, the aim of reviews is simply to indicate whether an album is "worth picking up," or to place the album within a space defined by easily recognizable signposts (e.g. "This album is sort of like King Crimson meets Yes, with some zeuhl thrown in..."). My aim is to share what makes the music interesting to me, to attempt to get the reader (if reader indeed there is!) to see the music through my eyes, and therefore perhaps to love it better. My hope beyond hope is that others will be encouraged to do the same.

Capote

2005-10-21T01:49:00.000-07:00

Warning: spoilers follow.

This movie really hit uncomfortably close to home for me. I view the character of Capote in this movie and I as birds of a feather, to a large extent.

How many times have I, when faced with obligations to friends and family that I found onerous and difficult to deal with, usually through some fault of my own, simply cut and run? How many people have I allowed to be hurt while I sit quietly and miserably inside my turtle shell? How many times have I been dragged, often physically, back to reality to face the consequences of not dealing? How many times, on the other hand, have I managed to get away with it, returning home and assessing the damage long after the storm has passed?

The portrait of Capote, wallowing in self-pity at the end of the bar during Harper Lee's reception, stripts this fault to the core: an ostensibly protective measure that ultimately leads to addiction, arrogance, utter self-absorption, disconnection, falseness.

I have long believed that each of us has a great and terrible power of savagery and violence within us; that this power lies much closer to the surface than we care to admit; that the blanket statement "you would never do such a thing!" is so very rarely true; that we must be constantly on guard against this aspect of our nature, especially during times of crisis. Up until now, I've always thought of this as violence mediated through action: assault, physical and verbal abuse, etc. Capote raises a harrowing flip side to this evil: violence mediated through inaction, through neglect, slowly and inexorably developed to a horrifying extreme. It is the simple, even obvious statement that neglect can be violence that somehow I've managed to neglect—in spite of being well-aware of the consequences of neglect on a global scale—And the Band Played On is an unforgettable example of this.

You want to know my deepest, darkest secret? Could I see myself doing what Capote did? Yes, I can see myself all too clearly in his shoes. Clearly, I'm on guard against the wrong thing.

Doctor Atomic

2005-10-19T23:39:00.000-07:00

Doctor Atomic (link here) is John Adams's new opera. I got the chance to see it last night. Warning: spoilers follow.

The thing that struck me the most was the libretto—a wonderful, quixotic, and often challenging combination of contemporary, baroque, prosaic, and deeply spiritual texts. I was ready to lay all the credit for the words at the librettist's feet (i.e. those belonging to Adams's longtime collaborator, Peter Sellars). So absolutely mesmerized was I by the odd grace and intensity of the lyrics to the last aria of Act I ("Batter my heart, three-person'd God"), I went to intermission thinking Sellars an unmitigated poetic genius! Then I read the program in the intermission and found out those lyrics were penned by John Donne; moreover, Oppenheimer had discovered these words well before Sellars did. So much for crowning the 21st Century poet laureate! Nevertheless, it's been, oh, some fifteen years since I last encountered Donne, and I was most grateful to Sellars for the reacquaintance.

As far as music goes: there was no walking away from this one humming tunes or leitmotifs! Whatever musical organization underlay this production was more deeply buried. Primarily I focused on the gorgeous textures in the orchestra, both polytonal and atonal, coming and fading in endless, sometimes rapid succession, giving the music a brilliant, mercurial, but often shapeless quality. Yet what had the most effect on me were the arias, where the music had the most focus, and the melody was the most determined. My favorite musical piece was the in turns sly, brooding, and almost unbearably sensuous aria and duet between Kitty and Dr. Oppenheimer in I.ii ("Am I in your light?"). I was also strangely moved by the chorus's description of the nuclear core circumscribed by an icosahedron and dodecahedron early in I.i. Maybe it was some unrepetant mystical geometric fetish buried deep within my psyche—maybe it was the lush, possibly lydian choral harmony—more likely it was both.

In subject and treatment the opera slanted heavily towards the mythic and dramatic, not unlike Wagner. The main method of the opera was tension through juxtaposition. Some of these settings seemed heavy-handed to me—the lullaby and cradle underneath the hulking metal sphere comes to mind—but most of them worked to brilliant effect. Consider the all-too-natural phenomenon of a passing summer thunderstorm, set as unassuming backdrop to a myriad of elements in the second act—the terror of workers at the test tower working around The Bomb while the storm is blowing around them—a beleagured weatherman becoming an unwitting target of the general, furious about the delay—scientists and officers huddled anxiously around a bank of blinking lights and tape drives. Through the play of foreground and background, the storm quickly becomes a psychological one, capturing in a flash the maelstrom of torment, fear, and dreadful excitement surging through the characters below—with The Bomb hanging dispassionately at its center.

Ultimately, however, it is the spiritual texts that have the last word. John Donne's Holy Sonnet beautifully represents the apotheosis of Oppenheimer's spiritual and psychological turmoil. And the thunderstorm—when also set against the lullaby of an old Pueblo rain song, and a chorus singing a hymn of awe to Vishnu the destroyer—transcends the merely psychological, embodying a truly Romantic gesture of fury and ill omen. Here, Adams wisely chooses a certain amount of restraint for the music—however unassuming the music may seem in the second act, it gives ample breath to these loaded themes without spiralling into histrionics. Thus, the adjective "mythic," easily bandied about, is fully earned by this opera. For years artists have been exploring the birth of The Bomb as one of the defining myths of our age. In this tradition, Doctor Atomic is another compelling work of modern mythmaking.

John Adams appeared in person for the curtain call, to my great delight. I imagine it must have rankled the singers a bit that Adams pulled in the most enthusiastic applause (to my ear), with the conductor and orchestra a close second. Yet surely it's no coincidence that that's precisely in tune with how the opera was executed—with a heavy emphasis on orchestral texture and character? More than this, though, perhaps it shows that audiences these days are starved for, and deeply crave, some sort of deeper engagement with the creative forces that entertain them. Classical music, in particular, is ruled by composers who have long since passed away—how much more then must the audience pine for real living flesh to pin their accolades on! Hollywood writers, eat your hearts out.

First post

2005-10-19T22:50:00.000-07:00

You can blame Blind Jimmy for this. We were eating burritos at Mondo Burrito and were discussing my tendency at work to write not so much emails as Epistles—monumental edifices that, despite trailing the issue under discussion by several hours or sometimes even days, would stand the test of time, standing on their own right as works of Literature long after the rest of the discussion had faded away. With obsessive determination I would chisel away at the Epistle, sculpting a devastating series of bullet points here, delicately shaping poignant pointers to futher discussion there, while my Inbox and voicemail threatened to back up and overflow. Such a tendency, said Blind Jimmy, would form a perfect match for blogging. I don't know whether he's right, but I do know this: it just took me twenty minutes to write this paragraph.

Well, actually I had been considering writing a series of reviews of music, books, movies, and such that I liked for some time. So maybe I'll throw some of those up here too.

If you see a flurry of posts following this one, it will be the backlog of things I've been thinking about for some time but have committed to neither paper nor electron. Thereafter, we'll see where it goes.