AMP: Are we there yet?

I am aware that as new AMP feature follows new AMP feature, it can feel like a never-ending ride to who-knows-where, prompting the ‘Oh God, not another one!’ reaction, as well as the ‘Will it never end?’ one -as well as the one alluded to in the thumbnail at the right!

For the record, I think we are closing in on a feature-complete AMP that needs no major bug-fixes nor has use for substantial new pieces of functionality. [...] 

Continue Reading

Another round of AMP enhancements…

Let’s start with a warning: this is quite a long post and covers quite a lot of ground! I don’t normally ‘section up’ my posts, but I will on this occasion, to try to make things clearer. So, this time we have:

  • Two new override switches for AMP
  • The removal of a switch
  • The fixing of quite a nasty bug
  • The introduction of a new composition-specific selection switch
  • An increase to the number of play ‘selections’ you’re allowed

Taking each of those in turn, therefore… [...] 

Continue Reading

Hi-Res Audio – Part 56

I hate to keep banging on about hi-res audio formats (especially when I am not keen on them myself), but now that AUAC can do DSF as well as ISO conversions (see my last post), some interesting things have come out of the woodwork that needed tackling. It’s also the case that as lockdown finally eases, this will likely draw to a close a period of time in which I obsess about software and not a lot else… so, it’s probably best to get these things out of the way whilst there’s not a lot else to be doing!

First off is the question of why AUAC treats SACD ISOs differently from SACD DSFs. In other words, when you say auac -i=iso, you have to specify -o=hires if you want high resolution FLAC files extracted from the source SACD ISO (otherwise you get standard resolution ones)… but, if you say auac -i=dsf, you don’t (you’ll get hi-res ones by default). [...] 

Continue Reading

Hi-Res Audio

Let’s begin by defining what ‘hi-res audio’ is, and then I’ll explain why it’s marketing baloney and no-one should touch it with a barge-pole… and why I’ve just enhanced my various software offerings to work with it anyway!

So, to begin at the beginning: there’s a thing called the Nyquist-Shannon Sampling Theorem. It says that a continuous wave-form can be perfectly reproduced as a set of fixed, discrete samples if the waveform being sampled has a finite bandwidth, and your sampling rate is twice the maximum signal frequency. That is, so long as you can say ‘this audio signal has a fixed upper-limit of (say) 20KHz’, then it is mathematically provable that a sampling rate of 40KHz can capture that wave form perfectly. When the Sony and Philps engineers were developing the Compact Disc audio format in the 1970s, they relied on this theory to determine the characteristics of CD audio. Since the best human ear can really only hear up to 20KHz (and even then, you’ve got to be young and genetically-blessed to hear that high), we can record an orchestra and chop off any part of the audio signal above 20KHz and no-one will be any the wiser: we’re disposing of frequencies no-one of mortal woman born can hear anyway. Then, once we have a continuous audio signal with a firm upper cut-off of 20KHz, we can digitise that by sampling the signal at 40KHz and be mathematically sure of being able to perfectly re-create the original analogue audio signal. Being clever people of the 1970s, however, the Philps and Sony engineers also realised that cut-off filters aren’t linearly perfect. Tell them to cut off at 20KHz, and they’ll maybe kick in a bit early and chop some sub-20KHz signal off, too; they’ll alternatively knock-off a bit early and leave some 20KHz+ signal behind that ought to have been removed. Frequency filters being imperfect, therefore, the CD developers decided to cut a little slack for the filtering process and thus decided to cut off the audio signal at 22.05KHz, rather than at precisely 20KHz. The extra 2005Hz were there to deal with the electronic filtering imperfections of the time. The consequence of that is that for Nyquist-Shannon to remain applicable, the sampling rate had to be twice this higher ‘highest frequency’ – and that’s why CDs have a sampling rate of 44,100 Hertz. [...] 

Continue Reading

A Locking Problem

I have been aware for quite some time that, occasionally, plays of music made by AMP would not get recorded in the PLAYS table as they should. It’s difficult to know precisely why: when you’re developing the code and saving changes to the script as it’s playing something, it could well be that your editing has caused the ‘record in PLAYS’ bit of code to get skipped.

Or it could be a locking issue. Putting it at its simplest, databases cannot have one person modifying data whilst simultaneously allowing a second person to read that data. If I am in the process of withdrawing £5000 from my bank account just as a credit check is being performed, do we let the credit agency see the £5000 in the account? Or do we see it missing the £5000, even though I might be about to type ‘Cancel’ at the ATM? To resolve these data concurrency issues, all databases implement a form of ‘locking’: if I am going to withdraw money from my account, we lock the data until my withdrawal is complete, so that no-one can see it, either with or without the £5000, then when I’m finished at the ATM, we unlock and people can read the definite results. [...] 

Continue Reading

Scarlatti In Bulk

Thanks to another recent video by David Hurwitz, I was finally persuaded to bite the bullet and splash out on the complete Domenico Scarlatti keyboard sonatas as performed by Scott Ross (the album artwork of which appears off to the left). It’s a 34-CD collection, available for purchase from Presto Classical at only around £2.50 a box, which seems reasonable value to me.

Curiously, this collection of works has previously been discussed by me in comments on this blog piece, where I was asked by ‘DACO’ how I would go about tagging the multiple Chopin Nocturnes or the even more multitudinous Scarlatti keyboard sonatas. I had to answer DACO in that exchange in the abstract, since I didn’t at that point actually own the Scarlatti. The general principle I advanced, however, was: group lots of little pieces together in whatever way makes them accessible and attractive to play. Thus, I could speak from experience: a CD of Britten arrangements of folksongs would be ripped and catalogued as a single collection of folksongs, rather than 21 short pieces of (usually) less than 3 minutes’ duration. Similarly, I had only just completed a re-rip of the complete works of Percy Grainger, where because of the quantity of music involved, and its overall great similarity, I found it more expedient to essentially rip entire CDs as ‘Grainger Compilations’ than try to separate out each individual composition as its own ‘album’. [...] 

Continue Reading

AMP Doing Its Job

It’s been a little over a fortnight since I modified my AMP player to work with a database -and, when it does so, to record every ‘play’ it decides on in a database table of its own.

So now, 15 days later, I can analyze that ‘plays’ table to determine if AMP has been doing the job I designed it for: picking a wide variety of composers and music genres, at random, and thus not creating any ‘favourites’! [...] 

Continue Reading

Let’s not get physical!

I had a slight mishap with my main PC on New Years’ Eve: Manjaro released a new kernel and I installed it without thinking -and, though I believe the PC rebooted fine, I couldn’t actually see anything on my monitor, so whether it had or not was really kind of moot!

So, a swift rebuild later, and we’re back in business -though it’s not quite how I imagined I would spend my New Years’ Eve! [...] 

Continue Reading