ysynth/ysynth.py

"""
    Python audio synthesis framework.
"""

from pymod import _ysynth_init, _ysynth_init, _ysynth_set_callback
from math import cos, sin, pi, modf
from itertools import izip
import numpy as np
from scipy.signal import lfilter

__all__ = ['YSynth', 'Sin', 'Cos', 'Saw', 'RevSaw', 'Square', 'Pulse']

class YSynth(object):
    """
    YSynth synthesis and audio context.
    """

    def __init__(self, samplerate=44100, channels=2):
        """
        Setup a simple synthesizer.

        samplerate: Samples/second
        channels: Number of output channels.
            e.g. 1 for mono, 2 for stereo
        """
        self.context = _ysynth_init(samplerate, channels)
        self.samples = 0
        self.volume = 0.75

        # XXX need to fetch 'acquired' values from ysynth context
        self.samplerate = samplerate
        self.channels = channels
        self.graph = None
        self.set_callback(self.default_callback)

    def deinit(self):
        """
        Shutdown synthesizer, afterwards this object becomes useless.
        """
        if self.context:
            _ysynth_shutdown(self.context)
            self.context = None

    def default_callback(self, *channels):
        """
        Default synthesis callback.
        """

        # Outputs silence if no graph available
        if not self.graph:
            return

        # Process audio graph
        buf_len = len(channels[0])
        self.chunk_size = buf_len

        next_chunk = next(self.graph)
        for j in xrange(len(channels)):
            for i in xrange(buf_len):
                channels[j][i] = next_chunk[i]

        # Advance sampleclock
        self.samples += buf_len

    def set_graph(self, graph):
        graph.set_synth(self)
        self.graph = iter(graph)

    def get_graph(self):
        return self.graph

    def __del__(self):
        """
        Deinitialise synth before being removed from mem
        """
        print "Deinitialising"
        self.deinit()

    def set_callback(self, func):
        """
        Set audio output function.

        Without any callback the synthesizer will simply output silence.

        The callback should adhere the following signature:
            def callback(channels):

        channels shall contain a list of lists and each list
        contains a large block of 0.0 floats describing the next set of samples.
        Those floats should be set to the chunk of audio.
        """

        _ysynth_set_callback(self.context, func)

    def get_callback(self):
        return _ysynth_get_callback(self.context)

class YConstant(object):
    """
    Unchanging signal output.
    """

    def __init__(self, const):
        self.const = float(const)

    def __iter__(self):
        return iter(self())

    def __call__(self):
        while True:
            yield self.const

    def set_synth(self, synth):
        pass

class YAudioGraphNode(object):
    """
    Base audio graph node

    This base class provides YSynth's DSL behaviours such as
    adding, substracting and the sample iteration protocol.
    """

    def __init__(self, *inputs):
        self.inputs = []
        lens = 0

        for stream in inputs:
            if not isinstance(stream, YAudioGraphNode):
                stream = YConstant(stream)
            self.inputs.append(stream)

        self.inputs = tuple(self.inputs)
        #for stream in inputs:
        #    if isinstance(stream, YAudioGraphNode):
        #        pass
        #    # Make sure all multi-channels share the same size
        #    if len(stream) != 1:
        #        if not lens:
        #            lens = len
        #        elif lens != len(stream):
        #            # TODO: Expand error info to contain sizes
        #            raise ValueError("Cannot combine different sized "
        #                "multi-channel streams")

        #self.channels = lens

    def __iter__(self):
        """
        Initialise graph for synthesis, link to sampleclock.
        """

        # XXX This function is not graph cycle safe

        # FIXME: I need to unpack the channels from the input streams
        # multiplex any mono-streams if there are multi-channel streams
        # available, and then initialise every set of streams' component
        # generator function by calling self with the correct arguments.

        # Setup input streams
        for stream in self.inputs:
            stream.set_synth(self.synth)

        # Setup self

        # The self.samples variable is used for protecting against
        # multiple next() calls, next will only evaluate the next
        # set of input samples if the synth's sampleclock has changed
        self.samples = self.synth.samples - 1

        # XXX self.last_sample is currently not initialised on purpose
        # maybe this must be changed at a later time.

        # Connect the actual generator components
        sample_iter = iter(self(izip(*self.inputs)))

        # Build the sample protection function
        def sample_func():
            """
            Make sure multiple next() calls during the same
            clock cycle yield the same sample value.
            """
            while True:
                if self.samples != self.synth.samples:
                    self.last_sample = next(sample_iter)
                    self.samples = self.synth.samples

                yield self.last_sample

        return sample_func()

    def set_synth(self, synth):
        """
        Set this component's synthesizer.

        This is mainly useful for reading the synth's sampleclock. However every
        active component requires a valid synthesizer.
        """
        self.synth = synth

    def get_synth(self, synth):
        """
        Return this component's synthesizer.
        """
        return self.synth

    def __add__(self, other):
        return Adder(self, other)

    def __radd__(self, other):
        return Adder(other, self)

    def __sub__(self, other):
        return Subtractor(self, other)

    def __rsub__(self, other):
        return Subtractor(other, self)

    def __mul__(self, other):
        return Multiplier(self, other)

    def __rmul__(self, other):
        return Multiplier(other, self)

    def __div__(self, other):
        return Divisor(self, other)

    def __rdiv__(self, other):
        return Divisor(other, self)

    def __getitem__(self, delay):
        """
        Return a delayed version of the output signal.
        """
        return Delay(self, delay)

    def __next__(self):
        """
        Process next sample.
        """

    def __call__(self):
        raise NotImplementedError("You need to inherit this class")

    def process(self, *streams):
        raise NotImplementedError("You need to inherit this class")

# Basic signal arithmetic
class Adder(YAudioGraphNode):
    def __call__(self, l):
        for a, b in l:
            yield a + b

class Subtractor(YAudioGraphNode):
    def __call__(self, l):
        for a, b in l:
            yield a - b

class Multiplier(YAudioGraphNode):
    def __call__(self, l):
        for a, b in l:
            yield a * b

class Divisor(YAudioGraphNode):
    def __call__(self, l):
        for a, b in l:
            yield a / b

# Sample delay
class Delay(YAudioGraphNode):
    def __call__(self, l):
        buf = [0.0] * 4096
        samples = 0
        for sig, delay in l:
            buf[samples] = sig
            yield buf[(samples - delay) % 4096]
            samples = (samples + 1) % 4096

# Base oscillator class
class YOscillator(YAudioGraphNode):
    def __call__(self, l):
        def cycle_gen():
            """
            This function generates the oscillation cycle
            upon which all basic decoupled oscillators base their output
            signal.
            A decoupled oscillator is an oscillator
            with its own cycle generator. These oscillators respond well to
            incoming frequency changes, but due to the limitations of floating
            point are at risk of drifting out of phase, coupled oscillators
            are always in phase with each other.
            The generated cycle ranges from 0.0 to 1.0 exclusive.
            """

            last_cycle = [0.0]

            for freq, in l:
                # The last_cycle will only be a list during the initial
                # iteration, perfect for a 'once' statement, we want
                # to force the first cycle value to 0.
                if isinstance(last_cycle, list):
                    if isinstance(freq, np.ndarray):
                        ifreq = freq[0]
                    else:
                        ifreq = freq
                    last_cycle = [-(ifreq / float(self.synth.samplerate))]

                # Compute cycle using IIR filter and np.fmod
                cycle, last_cycle = lfilter([1], [1, -1], freq /
                    float(self.synth.samplerate) *
                    np.ones(self.synth.chunk_size), zi=last_cycle)
                yield np.fmod(cycle, 1.0)
                last_cycle = np.fmod(last_cycle, 1.0)

        return self.oscillate(cycle_gen())

    def oscillate(self, l):
        raise NotImplementedError("Inherit this class")

# Basic oscillators
class Sin(YOscillator):
    """
    Sine wave oscillator
    """
    def oscillate(self, l):
        for pos in l:
            yield np.sin(2 * pi * pos)

class Cos(YOscillator):
    """
    Cosine wave oscillator
    """
    def oscillate(self, l):
        for pos in l:
            yield np.cos(2 * pi * pos)

class Saw(YOscillator):
    """
    Saw wave oscillator
    """
    def oscillate(self, l):
        for pos in l:
            yield pos * 2.0 - 1.0

class RevSaw(YOscillator):
    """
    Reverse Saw wave oscillator
    """
    def oscillate(self, l):
        for pos in l:
            yield -(pos * 2.0 - 1.0)

class Square(YOscillator):
    """
    Square wave oscillator
    """
    def oscillate(self, l):
        for pos in l:
            #yield 1.0 if pos < 0.5 else -1.0
            pos = pos - 0.5
            yield -(np.abs(pos) / pos)

class Pulse(YOscillator):
    """
    Pulse oscillator
    """
    def oscillate(self, l):
        zi = [1.0]
        for pos in l:
            pos, zi = lfilter([-1, 1], [1], pos, zi=zi)
            yield np.array(pos > 0, dtype=float)