Audio – Literature Analogy

An audio recording is a bit like a book: created through artistic or intellectual endeavour, then ‘fixed’ as a collection of pure information and distributed to customers for them to ‘consume’ in their own environments. In the case of digital audio, a recording is literally the same as a book, being stored as numbers in a file; you could store a book as a WAV, or an audio recording as a MSWORD file if you wanted.

In rendering the content to be read, there are things you could do to detract from the content of a book:

  • printed too big/too small
  • lighting too dim/too bright
  • inappropriate use of colour
  • blotchy printout
  • typeface varies with content, or randomly
  • corrupted: missing/duplicated/erroneous characters
  • peculiar paper
  • non-neutral typeface – difficult to read or inappropriate e.g. science fiction font for a Jane Austen novel
  • in the case of some ‘boutique’ printing, an appropriate analogy might be a book that spontaneously becomes too hot to touch, or occasionally ruins valuable furniture.

The emotional or intellectual force of the book would actually be reduced because of these problems. In other words, it is not true to say that the quality of reproduction doesn’t matter.

However, there is a finite envelope of neutral, even ‘mundane’, reproduction which achieves an optimal result for the reader – after reading the book they can’t tell you anything about the quality of the printing; all they remember is the content, and the content was thrilling.

Maybe the author specifies the typeface. Some books may include fine illustrations or intricate frontispieces which are intrinsic to the book. In these cases, the reproduction needs to be particularly accurate in order to do justice to what the author has created.

Beyond this, is there anything that the printer can do to enhance the appeal of the book? Well, they can create a fancy binding that the reader notices before they start reading; they can use particularly high quality paper; they can print the characters with micron precision. But only a book collector or printing technology enthusiast would care about these refinements – they have no effect on the actual experience of reading the content, and could easily detract from it.

The manufacturers of the ink and the mains cable that powers the printing press could read lots of books in their spare time, attend evening classes in English Literature, study the physiology of the eye, get diplomas in grammar, and tell us in interviews with speciality magazines about how it all informs their craft. But clearly the results would do nothing whatsoever to change the reading experience.

The printer might decide to dabble in science for the first time since they left printing college. They could do scientific trials in aspects of book reproduction where lucky participants get to read snippets of text or passages from ‘typical’ books, responding with their perceptions of differences, preferences, or even ‘emotional stimulation level’ in aspects such as:

  • typeface
  • ink
  • reading light
  • paper texture and weight
  • reading room shape/dimensions/finishes

But the results would be rather obvious and predictable, with anything slightly interesting being clearly the result of fashion, novelty and human fickleness rather than being a universal law.

The only way to actually enhance the book would be to change its content. An algorithm that replaces certain words? Re-writes sections to make them longer or shorter? Clearly in the case of literature, such a thing would be meaningless and idiotic. It is not so different in the case of audio. There is nothing but the recording: there is no technology, effect or algorithm that can meaningfully enhance it.

Conclusion

Domestic hi-fi is no more than the equivalent of rendering the printed content of a book: it can be done adequately or badly, and beyond that there is no meaningful way of improving on it. People become deluded by the idea that the rendering technology can enhance the content – which is obviously ridiculous in the case of books, but less obvious with audio.

But this is not to say that hi-fi is, in itself, boring: achieving ‘adequate’ is not trivial.

Many people are simply not used to hearing adequate reproduction regardless of how much money they spend, so they are not aware that the experience vs. quality graph has a horizontal flat top. And needless to say, the audiophile quality vs. cost graph is more-or-less random, which makes it even more confusing.

The audio enthusiast would be much happier and richer if they got a sense of proportion of what matters, then put all their creativity (and money if they’ve got nothing else to spend it on) into building the equivalent of a pleasant reading room, comfy chair and attractive bookcases rather than a solid gold and diamond reading light.

[Last edited  30/05/17]

Data Over Sound

Just saw this mentioned. It’s interesting how an idea that, years ago, was just a method of harnessing existing technology, can re-appear as something funky and brand new. It joins those other technologies that aim to get data into our devices via cost-free, non-contact interfaces, such as QR Codes.

What is Chirp?

A Chirp™ is a sonic barcode. With Chirp technology, data and content can be encoded into a unique audio stream. Any device with a speaker can transmit a chirp and most devices with a microphone can decode them.

People of a certain age will be familiar with the use of audio cassettes as storage for their microcomputer programs back in the 1980s – I think I used reel-to-reel for a time.

I also remember, round about 1980, sending a computer program over the phone to a friend’s house by holding the phone close to the speaker and picking the sound up at the other end with a microphone. As I recall, our version wasn’t really very reliable or practical, but I think we did succeed in sending a short program. Obviously we were inspired by the audio coupler modems that we might have seen in films and documentaries.

full

SMPTE and MIDI timecodes can be recorded as audio signals on analogue tape and can survive multiple transfers and, I dare say, would be robust enough to work over a speaker-microphone link.

In the 1990s we were all familiar with ‘the sound of data’ when we used dial-up modems.

Over the years we have also had DTMF dialling, audio watermarking, Shazam, Siri, Alexa etc. and phone-based automated systems using speech recognition, all of which have to deal with extracting ‘data’ from noisy audio. You would think that the new audio barcodes should be pretty simple to make work reliably.

The Trouble with Hobbies

Have you ever suddenly been inspired to embark on a brand new hobby?

Maybe you’ve never owned a boat before, but having seen one chug by on the river you have thought “I’d love to do that!”. A quick browse in the classified ads shows lots of boats that look fine, and they don’t cost all that much. Basically any boat would be great, and you could gradually do it up, even if it is a bit shabby now. In your mind’s eye, your family will love you when you are able to take them on spur-of-the-moment, cheap weekends messing about on the water, starting in a few weeks’ time.

From this high point where the world is your oyster, you begin to take the advice of the magazines and other experienced hobbyists. Before you have even owned a boat, you become aware of the hierarchy of boat owners, and the boats that would render you a laughing stock if you owned them. You become aware of the general consensus on different types of bilge pump – not something you ever wanted to know. You begin to form an idea of the boat you should really go for – and it is not one of the bargain basement jobs you first saw. You might just about be able to stretch to a boat that would put you in the lower echelons of boat ownership but, importantly, not on the very lowest rung. You could always, perhaps, move up from there over time.

It now turns into an all-consuming hobby with the goal of having a boat on the river at the end of the year. In the end it costs thousands, and your children have grown up and left home before your boat finally takes to the water. You hit a bridge and rip the top off your boat the first time you take it out. You feel sick and abandon the whole hobby (a true story).

That’s the nature of male hobbies. They start out as wonderful, spontaneous ideas, but can turn into nightmares – mainly due to the existence of other hobbyists! Audio is one of those hobbies, I think. Ridiculously, the prices paid for bits of audio knickknackery rival the costs of boats.

A person could be seized one day by the idea of hi-fi as a way to improve their life, buy an amp and some secondhand speakers off Gumtree for £100, and plug their tablet or laptop headphone socket into the amp using a £2 cable. Hey presto, a hi-fi system that will sound much better than what they had before, and which has tinker-ability via the buying and selling of speakers and the audio streaming/library software options; there is no urgency in changing the amp and tablet hardware as they are pretty much perfect in what they do. The speakers are almost like pieces of furniture, so the person can indulge their tastes in how they look as well as how they sound, and they can be restored using standard DIY skills – a nice mini-hobby.

But what if the person does the natural male thing, and starts to read the magazines and forums? Immediately they will realise that their tablet’s headphone output is a joke in the audio world. They need to spend at least a few hundred pounds on a half-decent ‘DAC’, plus a couple of hundred on a budget cable. And of course, this is only for convenience: real audio quality can only be had if they own a decent turntable and a special vibration-free shelf to put it on. Where do they go from there? They need to make a decision on which turntable and which cartridge to go for. They need to take a view on cables, power conditioners, valve or solid state amps, accessories like cable lifters and record cleaning machines. Each decision, they are assured by their fellow hobbyists, will result in “night and day” differences in the sound.

After some months agonising over it, they assemble a beginner’s system for about £3,000 – they will upgrade as budget allows. It sounds OK, but they know that even though the brand is a highly recommended one, the particular model of valve amplifier they could afford has “hints of a slightly reticent mid range” – one of the magazines said so – and if they listen carefully, perhaps they can hear that… But the more powerful 18 Watt model cost £800 more and they decided against it. Perhaps they made the wrong decision. The nightmare unfolds…

Television’s first night

firstbroadcast

There was an interesting BBC programme last week which celebrated the 80th anniversary of the launch night of BBC television. It aimed to re-create the original event as closely as possible, even to the extent of building replicas of some of the technology in use at the time.

For those who don’t know the story, the BBC launched television in 1936 running two types of technology in parallel: the Logie Baird mechanical system and EMI’s vacuum tube-based electronic system. Baird’s system was used first, and then the whole thing was repeated using the electronic system. The original television receivers, of which only 300 had been sold by the launch, had a switch to allow the receiver to be put into Baird or EMI mode – I hadn’t realised that, even on launch day, some receivers were using electronic picture tubes even if the Baird camera system wasn’t.

The Baird mechanical system was incredible: for truly live images it had to use a “flying spot” camera where the scene (the face of a presenter sitting in a pitch black booth) was raster-scanned with a high intensity dot of light and the resulting reflected light level picked up by a photo-sensor. In order to achieve 240 lines of resolution, two rotating discs were used; one a metre in diameter and spinning so fast its edges were almost supersonic, and a synchronised slower disc with a spiral mask which selected one of several sets of dots on the main disc.

More general scenes of groups of performers and so on were recorded live to film which was developed in a portable ‘lab’ mounted beneath the camera, ready to be scanned by a flying spot scanner some 54 seconds later – this was effectively the first ever telecine machine. The transition from live to telecine sections required logistical coordination around the 54 second delay, meaning that the performers had to start 54 seconds before the live announcer stopped talking, and the announcer had to wait in silence after the performance ended before someone jabbed him in the ribs through a hole in the side of the booth and he could start talking again. (I found this whole thing baffling: why was it important that any of it was truly ‘live’? Why not just do it all delayed by 54 seconds? Perhaps, as was implied in the program, the telecine images were not quite as crisp as the live..?).

Anyway, the writing was on the wall for the mechanical system, and the six month competition was terminated after only three months. My question is: why did it take so long? Why did people go to such heroic lengths to pursue a solution that was so obviously doomed? Perhaps men’s fascination with spinning discs in preference to electronic solutions is universal. I have no doubt that there were some diehards who thought that the mechanical system somehow captured a better picture than a soulless glass tube.

The Engineering Department of Cambridge University had the fun of developing the replica flying spot camera (although with only 60 lines of resolution as opposed to the original 240). Things got a bit fraught in the build up to the ‘launch’ however: a persistent mechanical howl from the disc mechanism threatened to ruin everything. It seemed to take several hours of effort and anguish before someone had the bright idea of applying a drop of oil…

None of the original presenters, performers or staff present at the launch night are still with us, but the BBC did manage to track down a 104 year old engineer who worked for Baird. The launch of television seems like so long ago, and yet this man was already 24 when it happened. He is still sharp as a pin and when Hugh Hunt of Cambridge University told him he was building a replica flying spot machine using an aluminium disc instead of the original steel, his brow furrowed immediately and he asked “Are you sure aluminium will be strong enough to withstand the centrifugal force?”.

I enjoyed seeing the old abandoned studios in Alexandra Palace, and Paul Marshall‘s barn full of old TV equipment, including some of the earliest camera tubes in existence. He has built a working camera based on a genuine Iconoscope tube, using modern electronics to drive it, giving us a close re-creation of pre-war electronic TV pictures. I somehow find old TV equipment quite moving; TV was an important part of my childhood and I can’t help but think of the snippets of the golden past that might have been captured through those lenses.

The Machine Learning delusion

This morning my personal biological computer detected a correlation between these two articles:

Sony’s SenseMe™ – A Superior Smart Shuffle

Machine learning: why we mustn’t be slaves to the algorithm

In the first article, the author is praising a “smart shuffle” algorithm that sequences tracks in your music collection with various themes such as “energetic, relax, upbeat”. It does this by analysing the music’s mood and tempo. It sounds amazing:

“I would never think of playing Steve Earl’s “Loretta” right after listening to the Boulder Philharmonic’s performance of “Olvidala,” or Ry Cooder’s “Crazy About an Automobile” followed by Doc and Merle Watson playing “Take Me Out to the Ballgame,” but I enjoyed not only the selections themselves but the way SensMe™ juxtaposes one after another, like a DJ who knows your collection better than you do…what will “he” play next? Surprise! It’s all good.”

And the algorithm’s effects go beyond mere music:

“SenseMe™ has brought domestic harmony – interesting selections for me and music with a similar mood for her. That’s better than marriage counseling! “

The author of the second article takes a more sceptical view. He notes the dumbness of Machine LearningTM algorithms, but says that

“…because these outputs are computer-generated, they are currently regarded with awe and amazement by bemused citizens …”

He quotes someone who is aware of the limitations:

“Machine learning is like a deep-fat fryer. If you’ve never deep-fried something before, you think to yourself: ‘This is amazing! I bet this would work on anything!’ And it kind of does. In our case, the deep fryer is a toolbox of statistical techniques. The names keep changing – it used to be unsupervised learning, now it’s called big data or deep learning or AI. Next year it will be called something else. But the core ideas don’t change. You train a computer on lots of data, and it learns to recognise structure.”

“But,” continues Cegłowski, “the fact that the same generic approach works across a wide range of domains should make you suspicious about how much insight it’s adding.”

I have been there. Machine learning is one of the most seductive branches of computer science, and in my experience is a very “easy sell” to people – I use it in my job in actual engineering applications where it can be eerily effective.

But if algorithms are so clever and know us so well, why are we using them only to shuffle the order of music? Why not cut out the middleman and get the computer to compose the music for us directly? The answer is obvious: it doesn’t work because we don’t know how the human brain works, and it is not predictable. By extension, the algorithms that purport to help us in matters of taste don’t actually work either. As the Guardian article says, all we are responding to is the novelty of the idea.

Pop and click remover, old electronics magazines

Just saw a short article about a new product that aims to remove the pops and clicks from vinyl records. It…

…digitizes the signal at 192/24 bit resolution and then uses a “non-destructive” real time program that removes pops and clicks without, the company claims, damaging the music.

…In addition to real-time, non-destructive click & pop Removal the SC-1 features user controllable click & pop removal “strength”, a pushbutton audiophile-grade “bypass” that lets you hear non-digitized versus digitized signal (for when you don’t need pop and click removal), iOS and Android mobile app control and 192/24 bit hi-res digital processing.

Of course it is highly ironic that a vinyl enthusiast should need the services of the digital world to improve the sound of his recordings. And it is obvious (surely) that the digital stream could be stored for later replay without needing to further degrade the original vinyl or wear out the multi-thousand dollar stylus that is no doubt being used. (Omitting to mention the most obvious idea of just listening to a digital recording…)

The aim of the product reminded me of a certain project in an old electronics magazine, a huge number of which I still have in a set of bookshelves that I haven’t touched since 1990 – the date of the last magazine I seem to have bought. Sifting through them, it is amazing how familiar the front covers still are –  a measure of the intensity of youthful hobbies.

click-eliminator-2

From Electronics Today International in April 1979, the project I remembered was a ‘Click Eliminator’ for vinyl records based on an analogue CCD delay line. The idea was to insert a few milliseconds of silence in place of the offensive click. Here’s how it worked:

click-eliminator1

Electronics Today International was the magazine I would go to WH Smiths for on a Saturday, being terribly disappointed if the latest issue wasn’t in. I would say more than 50% of issues featured an audio or hi-fi project: from 1982 an active speaker project for example, or from 1986 “Can Valves make a comeback?” with an accompanying valve amp project. There were any number of MOSFET amps, phono pre-amps, tape noise reduction units. Electronic music featured prominently with projects for effects pedals and synthesisers galore. I devoured this stuff.

Other magazines included: Practical Electronics, Wireless World, Everyday Electronics, Elektor, Electronics and Music Maker, and one I didn’t recall Hobby Electronics. I also bought any number of computer magazines. I have never thrown any away, so I have hundreds of them gathering dust.

Hi-Fi Sci-Fi

stone tape

Last night I watched a BBC TV play from 1972 called The Stone Tape. An electronics company installs its R&D department in an old mansion, with the aim of developing “a new recording medium”. Tape is, apparently, “too delicate and it loses its memory”. They stumble upon a possible ready-made solution in a room in the oldest part of the house, which seems to have a ‘ghost’ – a Victorian maid frozen in time just before she fell to her death. What if it’s not a ghost, but a ‘recording’ of an event that has somehow become embedded in the stone itself? Maybe this could be “the big one” they have been looking for…

What I particularly liked about it, was the idea that – hard to believe – there once was a time before the world went digital, and when everything was still up for grabs. Digital computers do play a role in the story, but only as a way of “correlating” the experimental results in order to spot possible connections that a human might miss.

It’s also a well-observed portrayal of life in a certain kind of company – some of it seemed very familiar.

Vinyl in Space

jack white

Jack White aims to play the first vinyl record in space.

From The Guardian:

With the aid of a ‘space-proof’ turntable and high-altitude balloon, the singer’s Third Man Records will try to beam Carl Sagan’s A Glorious Dawn from orbit…

The Guardian link writers came up with

The Vinyl Frontier

Now that’s quite good…!

Digital Audio’s PR Problem

If you’d never heard of digital audio, but were told that it was now possible to store and play back audio signals on a computer, I don’t think you would raise an eyebrow. After all, how difficult can it be? An audio signal is no different from any other ‘wiggly line’ that computers seem to manipulate with ease: graphics, high quality fonts, CAD drawings, maps etc. for all intents and purposes at infinite resolution.

But somehow, digital audio is seen as a special case, where no one quite believes that it works. Looking at various forum discussions it is apparent that, in fact, it wouldn’t matter how many bits, how many MHz of sample rate, how few femtoseconds of jitter was specified, audiophiles would still be convinced they could hear the ‘1’s and ‘0’s, jitter, quantisation distortion and so on. The noise and distortion inherent in tape and vinyl that is many orders of magnitude greater gets a free pass; the noise in digital audio no matter how minuscule must always be portrayed as ear-bleedingly offensive. Why?

I think there are several reasons:

  1. Digital audio is mathematically-based. Long after real world signals have become buried in noise and distortion due to unavoidable physics, the theoretical numbers associated with the maths remain pristine and, quite unambiguously, show errors! Clearly we need better numbers. And so it goes on. In other words, no matter how high the resolution, you can always zoom in and see a theoretical error that looks just as big and clear on the screen or page.
  2. From the outset, the theory behind digital audio was discussed openly, but very few people actually understood it fully (including me). Thirty-odd years later, the misunderstandings persist. These vary from assuming that digital audio cannot know, or fill in, what is in “the gaps”, to failing to understand the significance of dither.
  3. Digital audio provided a complete mathematical solution, in many ways superior to other computer-based wiggly lines. The system is so elegant and simple that people just don’t believe it can work the way it does. [03.03.16 just saw an article that says exactly that“The intriguing aspect is that those who do understand refuse to believe”]
  4. Digital audio must always be chasing its tail, because as soon as a new performance level is achieved, it becomes possible for every Tom, Dick and Harry to buy the hardware for a small number of pounds, and even to start measuring signals at that level. Suddenly we’re all experts for whom -110dB is an average spec and must therefore be highly audible – although no one has ever heard a signal that quiet. No matter how good, digital audio will always seem mundane.
  5. Digital audio hardware is too complex to build using discrete circuitry. Integrated circuits are cheap. Audiophiles need to know they are buying better stuff than the hoi polloi, but digital audio doesn’t play the game. It remains persistently cheap enough for the masses to buy exactly the same measured performance as the most expensive fancily-boxed version of the same chip. (We are talking £30 versus £30,000, say). In the audiophile mind, this proves that measurements mean nothing and that “bits are not bits”, whereas in reality it shows the opposite.