An Experiment in Csound Blogging

download: thumbuki20061222.csd

Welcome to my first blog entry that is simulcast both at and within a Csound file. This is a personal blogging experiment. Often times, I’ll finish a Csound file that isn’t a composition, nor a bank of instruments, but more like a personal exercise or proof-of-concept. I never distribute these files because, as is, they aren’t really helpful to anybody. Perhaps by embedding a blog entry, these files will be placed into proper context, and allow them to be useful for others in the community.

I took an extensive break from Csound. By extensive, I mean years. I have recently returned to my computer music roots, with a fresh mind and new-found enthusiasm. I wouldn’t say I’ve forgotten much while on hiatus. In fact, I’m finding it’s much like riding a bike. However, I’m still without practice, and am in need of some serious honing.

Despite being something I’ve always wanted to do, I’ve never gotten around to synthesizing drums. I figured this was as good a time as any to tackle this subject. I found two places on the net that were uber-helpful. The first being Hans Mikelson’s Csound magazine articles (article 2). The second being Sound on Sound: Synth Secrets. Between these two sources, I ended up with the four electronic percussive instruments.

The other thing I wanted to do was to take a new approach to tackling Csound instruments. Traditionally, I’ve had my individual instruments write directly to the audio stream. However, I’ve been aware of the advantages of using the zak opcodes for mixing for years now.

In this file, I use two mixers. The first is a drum mixer. The four drums instruments produce mono-streams. These streams are sent to the drum mixer, via zak, where their relative amplitudes are set, placed into a stereo field, and sent to two zak audio busses. The second mixer reads the corresponding left and right zak channels, amplifies them, and sends the audio to the dac or file.

I experimented with two more zak-related techniques. The first is using a dedicated lfo instrument that writes to a zak k-rate channel. In this example, I implemented four synced LFOs, each featuring a different waveform. Including a sine, triangle, saw-down and square wave. Each waveform is assigned a unique k-rate zak bus. I’m using only one of the LFO channels, to modulate the frequency of a highpass filter in the reverb instrument 110. Note to self: learn to design better spatial processors.

The second zak technique I explored was implementing a gate. Every time an “Electro Bell” event occurs, the schedule opcode is used to instantiate an instr 90 event. instr 90 is basically an attack-sustain-decay envelope with razor thin sides. The gated delay processor, instr 120, responds to the gate by briefly capturing a segment of the drums, processing this audio chunk with filters and delay lines, and mixing the resulting effects back into the stereo zak channels.

The one last thing I played with was the macro system. Macros are a great thing. They dramatically reduced the difficulty of managing and adding zak channels. The one thing I’m disappointed about them is that macros defined in the orchestra aren’t recognized in the score and vice-versa. Perhaps there is a Csound way that I’m just not aware of. If not, no big deal, as I still have Perl to fall back onto.

I guess that’s it for now.

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