b-tracker

new graphics/music demos - bitshifters, 0xc0de, The Master + others
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hjalfi
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b-tracker

Post by hjalfi »

I think this better belongs here than anywhere else?

I wrote a chiptune tracker for the BBC Micro. It'll run on a B or Master (haven't tried a Compact); Second Processors need not apply.

http://cowlark.com/btracker/

(Yes, this is the thing I was asking about on the programming forums. On a B there's enough space for 70 patterns, each of which occupying 256 bytes. It'd be trivial to do a Master rebuild with more space if anyone's interested. The sample track uses 54.)
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dominicbeesley
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Re: b-tracker

Post by dominicbeesley »

That is absolutely brilliant! I've been toying with that idea for months but not got round to it - you've done a better job that I would have managed.

And you've covered SpaceDebris my favourite protracker too - it sounds pretty good!

D
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kieranhj
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Re: b-tracker

Post by kieranhj »

This is great! =D> It's also been on my very long backlog, for a very long time, to write a Tracker on the Beeb - shame there wasn't one available BITD.
Bitshifters Collective | Retro Code & Demos for BBC Micro & Acorn computers | https://bitshifters.github.io/
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hjalfi
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Re: b-tracker

Post by hjalfi »

Thanks!

I have actually been wondering whether it's worth restricting the range a bit --- right now it goes from midi notes 48 to 115, or C3 to G8. Except, the sound chip can't really reproduce the top octave very well and it's pretty screechy at the best of times. By reducing it to midi notes 48 to 108, or C3 to C8, then I get increase the pitch resolution to a quarter of a semitone. Currently trying to do vibrato using the pitch graph sounds pretty bad because the minimum deflection is a third of a semitone, which I think is too great.

The downside is that the high octaves are useful for controlling the noise channel...
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tricky
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Re: b-tracker

Post by tricky »

Is it a storage issue?
It is a bit annoying that it is 33 bits for frequency and 16 for volumes for full range on everything.
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hjalfi
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Re: b-tracker

Post by hjalfi »

Yeah, pretty much. Each note is stored as two bytes --- one for the note or command itself, and one for the envelope number and volume (both nibbles). That makes a single pattern 256 bytes. There are 26 possible commands, each of which is a letter, which leaves a note range of 229.

Re volume: the BBC sound chip is actually heavily weighted at the top end. Anything below 8 might as well be silent. Switching between 15 and 14 is quite noticeable.

Not sure what you mean by 33-bit frequency; the sound chip uses 10-bit pitch IDs internally, which are looked up from the b-tracker note number by a table.
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cmorley
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Re: b-tracker

Post by cmorley »

hjalfi wrote:
Sun Dec 20, 2020 12:19 am
Not sure what you mean by 33-bit frequency; the sound chip uses 10-bit pitch IDs internally, which are looked up from the b-tracker note number by a table.
I assumed Richard was talking about the total bits to program the sound chip VGM style...
3x10bit (tones freq) + 2bit (prng freq) + 1bit (periodic/white noise) = 33
4x4bit (attenuation) = 16

I am very impressed by the tracker. I tried it on jsbeeb with your link first then within 10s grabbed the SSD and moved to a real model B :)
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hjalfi
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Re: b-tracker

Post by hjalfi »

Ah, right! Yes, that makes sense.

How well does this work on real hardware? I don't have one, and had to work with an emulator. b-em has an option to enable an audio filter that's supposed to the tinny speaker but I don't know what it's like in practice.
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pixelblip
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Re: b-tracker

Post by pixelblip »

That is great. Good on ya! The Beeb needs a tracker :) =D>
Love it mode 7! Very creative. Listening to Debris it's amazing what you can do with the limitations.
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Re: b-tracker

Post by thoughstar »

hjalfi wrote:
Sat Dec 19, 2020 12:13 pm

I wrote a chiptune tracker for the BBC Micro. It'll run on a B or Master (haven't tried a Compact); Second Processors need not apply.
ok, that was pretty amazing. where were you in the 80's? we needed this then! :D
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Re: b-tracker

Post by Arcadian »

Woah, finally a tracker on the Beeb. I'm not musical myself, but I might ask some of my Gameboy chiptune friends whether they're up for composing on a new platform... :)

Btw, if anybody fancies having a bash at using it to try and create a version of the New Rally-X theme music, Tricky is struggling to find a version of theme he can use to port to the Beebto complement his conversion: viewtopic.php?f=53&t=21371#p302213

I think it could sound great with some extra drum beats thrown in there that have been generated by the Beeb's white noise channel ... !
For a "Complete BBC Games Archive" visit www.bbcmicro.co.uk
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pixelblip
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Re: b-tracker

Post by pixelblip »

Where have I heard that music before. It is another game! It's not Frak is it......of course it's Rally X but I am sure I've heard it on another game....maybe it is just Rally X from years ago at the arcade and it's still in my head. I really enjoyed playing Rally X back in the day!
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Re: b-tracker

Post by Pernod »

pixelblip wrote:
Wed Jan 06, 2021 7:46 pm
Where have I heard that music before. It is another game! It's not Frak is it......of course it's Rally X but I am sure I've heard it on another game....maybe it is just Rally X from years ago at the arcade and it's still in my head. I really enjoyed playing Rally X back in the day!
It's also in Caveman Capers, I always thought it was an original tune and only now know it's from Rally X.
- Nigel

BBC Model B: ATPL Sidewise, Acorn Speech, 2xWatford Floppy Drives, AMX Mouse, Viglen case, BeebZIF, etc.
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pixelblip
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Re: b-tracker

Post by pixelblip »

Well done Pernod. Caveman Capers. Oh joy that brings back memories! :D
Just watching it now. Gosh I'd forgotten about that game. The amount of times I heard that tune!

https://www.youtube.com/watch?v=elDf7meYyjE
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Arcadian
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Re: b-tracker

Post by Arcadian »

Yep, I originally only knew it from Caveman Capers too, however Capers only features the first half of the track - whilst Rally-X uses a longer version.
For a "Complete BBC Games Archive" visit www.bbcmicro.co.uk
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