sndpipe/examples/synth.py

#Copyright 2017 Yann Weber
#
#This file is part of SndPipe.
#
#SndPipe is free software: you can redistribute it and/or modify
#it under the terms of the GNU General Public License as published by
#the Free Software Foundation, either version 3 of the License, or
#any later version.
#
#SndPipe is distributed in the hope that it will be useful,
#but WITHOUT ANY WARRANTY; without even the implied warranty of
#MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#GNU General Public License for more details.
#
#You should have received a copy of the GNU General Public License
#along with SndPipe.  If not, see <http://www.gnu.org/licenses/>.


import math
import sys
import struct

BITMAX = lambda bsz: (1<<bsz)-1

def sinwave_float32(step=0.01, endianess='little'):
    i = 0.0
    if endianess is None:
        e = ''
    elif endianess == 'little':
        e = '<'
    else:
        e = '>'
    while True:
        i += step
        i %= (math.pi*2)
        yield struct.pack('%cf'%e, math.sin(i))

def sinwave(step=0.01, bitsz=8, signed=False):
    i = 0.0
    while True:
        i += step
        i %= (math.pi*2)
        if signed:
            yield int(math.sin(i) * (BITMAX(bitsz)/2))
        else:
            yield int((math.sin(i)+1)/2 * BITMAX(bitsz))

def mixer(*waves):
    channels = []
    for wave in waves:
        if isinstance(wave, tuple):
            wave, vol = wave
        else:
            wave, vol = wave, 1.0
        channels.append((wave, vol/len(waves)))
    while True:
        yield int(sum([next(wave)*vol for wave, vol in channels]))

def filter(wave, freq=10, high=True, glitch=False, bitsz=8):
    hist = [next(wave)]

    while True:
        c = next(wave)
        r = int(sum(hist)/len(hist))
        if high:
            if glitch:
                r = (c - r) % BITMAX(bitsz)
            elif c < r:
                r = 0
            else:
                r = c - r
        hist = [c] + (hist if len(hist) < freq else hist[:-1])
        yield r

def lowpass(wave, freq=500):
    return filter(wave, freq, False)

def highpass(wave, freq=500):
    return filter(wave, freq, True)


def vol_lfo(wave, wave_arg, bitsz=8):
    while True:
        yield int(next(wave) * next(wave_arg) / BITMAX(bitsz))


def output_sampler(*args, channels=2, samples=4096, freq=48000, bitsz=8,
        endianess='little', signed=False):
    if channels < 1:
        raise ValueError("channels must be > 1 but %d given" % channels)
    if len(args) == 0:
        raise ValueError("You must give at least one generator")
    if len(args) > 1 and channels != len(args):
        msg = "If more than one generator given, the count must match the \
channel argument. But %d generator given and channels is %d"
        raise ValueError(msg % (len(args), channels))

    if len(args) == 1:
        if channels == 1:
            nxt_sample = lambda waves: [next(waves[0])]
        else:
            nxt_sample = lambda waves: [next(waves[0])]*2
    else:
        nxt_sample = lambda waves: map(next, waves)

    if bitsz != 8 or signed:
        nxt_arg = lambda: nxt_sample(args)
        gen = _output_sampler_multibits(nxt_arg, channels, samples, freq, bitsz,
                                        endianess, signed)
        while True:
            yield next(gen)
        raise StopIteration()
        return

    buff = bytearray([0 for _ in range(samples*channels)])
    while True:
        for i in range(0,samples*channels, channels):
            buff[i:i+channels] = nxt_sample(args)
        yield buff

def _output_sampler_multibits(nxt_sample, channels, samples, freq, bitsz,
        endianess, signed):
    if bitsz not in (8,16,32):
        raise ValueError("Bitsize must be in (8,16,32) but %d given" % bitsz)
    Bsz = bitsz//8
    buff = bytearray([0 for _ in range(samples * channels * Bsz)])
    while True:
        for i in range(0, samples*channels*Bsz, channels*Bsz):
            nxt = nxt_sample()
            for j in range(channels):
                st = i + (j*Bsz)
                buff[st:st+Bsz] = nxt[j].to_bytes(Bsz, endianess,
                                                    signed=signed)
        yield buff