{"id":17213,"date":"2023-05-30T22:29:15","date_gmt":"2023-05-31T02:29:15","guid":{"rendered":"https:\/\/scruss.com\/blog\/?p=17213"},"modified":"2023-12-02T09:00:34","modified_gmt":"2023-12-02T14:00:34","slug":"a-terrible-guide-to-singing-with-dectalk","status":"publish","type":"post","link":"https:\/\/scruss.com\/blog\/2023\/05\/30\/a-terrible-guide-to-singing-with-dectalk\/","title":{"rendered":"A terrible guide to singing with DECtalk"},"content":{"rendered":"\n

It’s now possible to build and run the DECtalk<\/a> text to speech system on Linux. It even builds under emscripten, enabling DECtalk for Web<\/a> in your browser. You too can annoy everyone within earshot making it prattle on about John Madden.<\/p>\n\n\n\n

But DECTalk can sing! Because it’s been around so long, there are huge archives of songs in DECtalk format out there. The largest archive is at THE FLAME OF HOPE<\/a> website, under the Dectalk<\/a> section.<\/p>\n\n\n\n

Building DECtalk songs isn’t easy, especially for a musical numpty like me. You need a decent grasp of music notation, phonemic\/phonetic markup and patience with DECtalk’s weird and ancient text formats.<\/p>\n\n\n\n

DECtalk phonemes<\/h2>\n\n\n\n

While DECtalk can accept text and turn it into a fair approximation of spoken English, for singing you have to use phonemes. Let’s say we have a solf\u00e8ge<\/em><\/a>-ish major scale:<\/p>\n\n\n\n

do re mi fa sol la ti do<\/pre>\n\n\n\n
If we’re all fancy-like and know our International Phonetic Alphabet (IPA)<\/a>, that would translate to:<\/p>\n\n\n\n
\/do\u028a \u0279e\u026a mi\u02d0 fa\u02d0 so\u028a la\u02d0 ti\u02d0 do\u028a\/<\/pre>\n\n\n\n
or if your fonts aren’t up to IPA:<\/p>\n\n\n\n
\"\/do\u028a<\/figure>\n\n\n\n
DECtalk uses a variant on the ARPABET<\/a> convention to represent IPA symbols as ASCII text. The initial consonant sounds remain as you might expect: D<\/strong>, R<\/strong>, M<\/strong>, F<\/strong>, S<\/strong>, L<\/strong> and T<\/strong>. The vowel sounds, however, are much more complex. This will give us a DECtalk-speakable phrase:<\/p>\n\n\n\n
[dow rey miy faa sow laa tiy dow].<\/pre>\n\n\n\n
Note the opening and closing brackets and the full stop at the end. The brackets introduce phonemes, and the full stop tells DECtalk that the text is at an end. Play it in the DECtalk for Web<\/a> window and be unimpressed: while the pitch changes are non-existent, the sounds are about right.<\/p>\n\n\n\n
For more information about DECtalk phonemes, please see Phonemic Symbols Listed By Language<\/a> and chapter 7 of DECtalk DTC03 Text-to-Speech System Owner’s Manual<\/a>.<\/p>\n\n\n\n
If you want to have a rough idea of what the phonemes in a phrase might be, you can use DECtalk’s :log phonemes<\/em> option. You might still have to massage the input and output a bit, like using sed to remove language codes:<\/p>\n\n\n\n
say -l us -pre '[:log phonemes on]' -post '[:log phonemes off]' -a \"doe ray me fah so lah tea doe\" | sed 's\/us_\/\/g;'\nd ' ow  r ' ey  m iy  f ' aa) s ow  ll' aa  t ' iy  d ' ow.<\/pre>\n\n\n\n
Music notation<\/h2>\n\n\n\n
To me \u2014 a not very musical person \u2014 staff notation looks like it was designed by a maniac. A more impractical system to indicate arrangement of notes and their durations I don’t think I could come up with: and yet we’re stuck with it.<\/p>\n\n\n\n
DECtalk uses a series of numbered pitches plus durations in milliseconds for its singing mode. The notes (1\u201337) correspond to C2 to C5. If you’re familiar with MIDI note numbers<\/a>, DECtalk’s 1\u201337 correspond to MIDI note numbers 36\u201372. This is how DECtalk’s pitch numbers would look as major scales on the treble clef:<\/p>\n\n\n\n
\"a
The entire singing range of DECtalk as a C Major scale, from note 1 (C2, 65.4 Hz) to note 37 (C5, 523.4 Hz)<\/figcaption><\/figure>\n\n\n\n
I’m not sure browsers can play MIDI any more, but here you go (doremi-abc.mid<\/a>):<\/p>\n\n\n\n
and since I had to learn abc notation<\/a> to make these noises, here is the source:<\/p>\n\n\n\n
%abc-2.1\nX:1\nT:Do Re Mi\nC:Trad.\nM:4\/4\nL:1\/4\nQ:1\/4=120\nK:C\n%1\nC,, D,, E,, F,,| G,, A,, B,, C,| D, E, F, G,| A, B, C D| E F G A| B c z2 |]\nw:do re mi fa sol la ti do re mi fa sol la ti do re mi fa sol la ti do<\/pre>\n\n\n\n
Each element of a DECtalk song takes the following form:<\/p>\n\n\n\n
phoneme <duration, pitch number><\/pre>\n\n\n\n
The older DTC-03 manual hints that it takes around 100 ms for DECtalk to hit pitch, so for each \u00bd second utterance (or quarter note at 120 bpm, ish), I split it up as:<\/p>\n\n\n\n