Source code for cutcutcodec.core.generation.audio.empty

"""Dedicated to tests, it is an empty audio stream containing no samples."""

import typing
from fractions import Fraction

from cutcutcodec.core.classes.container import ContainerInput
from cutcutcodec.core.classes.frame_audio import FrameAudio
from cutcutcodec.core.classes.layout import Layout
from cutcutcodec.core.classes.stream import Stream
from cutcutcodec.core.classes.stream_audio import StreamAudio
from cutcutcodec.core.exceptions import OutOfTimeRange




class GeneratorAudioEmpty(ContainerInput):
    """Contains an empty audio stream.

    Examples
    --------
    >>> from cutcutcodec.core.exceptions import OutOfTimeRange
    >>> from cutcutcodec.core.generation.audio.empty import GeneratorAudioEmpty
    >>> (stream,) = GeneratorAudioEmpty().out_streams
    >>> try:
    ...     stream.snapshot(0)
    ... except OutOfTimeRange as err:
    ...     print(err)
    ...
    this stream does not contain any samples
    >>>

    """

    def __init__(self):
        out_streams = [_StreamAudioEmpty(self)]
        super().__init__(out_streams)

    def _getstate(self) -> dict:
        return {}

    def _setstate(self, in_streams: typing.Iterable[Stream], state: dict) -> None:
        assert state == {}, state
        GeneratorAudioEmpty.__init__(self)



class _StreamAudioEmpty(StreamAudio):
    """An audio stream containing no sample."""

    def __init__(self, node: GeneratorAudioEmpty):
        assert isinstance(node, GeneratorAudioEmpty), node.__class__.__name__
        super().__init__(node)

    def _snapshot(self, timestamp: Fraction, rate: int, samples: int) -> FrameAudio:
        raise OutOfTimeRange("this stream does not contain any samples")

    @property
    def beginning(self) -> Fraction:
        return Fraction(0)

    @property
    def duration(self) -> Fraction | float:
        return Fraction(0)

    @property
    def layout(self) -> Layout:
        """Return the signification of each channels."""
        raise KeyError("it makes no sense to give an audio layout to an absence of sample")