Module livekit.rtc.audio_frame

Classes

class AudioFrame (data: Union[bytes, bytearray, memoryview], sample_rate: int, num_channels: int, samples_per_channel: int)

A class that represents a frame of audio data with specific properties such as sample rate, number of channels, and samples per channel.

The format of the audio data is 16-bit signed integers (int16) interleaved by channel.

Initialize an AudioFrame instance.

Args

data : Union[bytes, bytearray, memoryview]

The raw audio data, which must be at least num_channels * samples_per_channel * sizeof(int16) bytes long.

sample_rate : int

The sample rate of the audio in Hz.

num_channels : int

The number of audio channels (e.g., 1 for mono, 2 for stereo).

samples_per_channel : int

The number of samples per channel.

Raises

ValueError

If the length of data is smaller than the required size.

Expand source code

class AudioFrame:
    """
    A class that represents a frame of audio data with specific properties such as sample rate,
    number of channels, and samples per channel.

    The format of the audio data is 16-bit signed integers (int16) interleaved by channel.
    """

    def __init__(
        self,
        data: Union[bytes, bytearray, memoryview],
        sample_rate: int,
        num_channels: int,
        samples_per_channel: int,
    ) -> None:
        """
        Initialize an AudioFrame instance.

        Args:
            data (Union[bytes, bytearray, memoryview]): The raw audio data, which must be at least
                `num_channels * samples_per_channel * sizeof(int16)` bytes long.
            sample_rate (int): The sample rate of the audio in Hz.
            num_channels (int): The number of audio channels (e.g., 1 for mono, 2 for stereo).
            samples_per_channel (int): The number of samples per channel.

        Raises:
            ValueError: If the length of `data` is smaller than the required size.
        """
        if len(data) < num_channels * samples_per_channel * ctypes.sizeof(
            ctypes.c_int16
        ):
            raise ValueError(
                "data length must be >= num_channels * samples_per_channel * sizeof(int16)"
            )

        self._data = bytearray(data)
        self._sample_rate = sample_rate
        self._num_channels = num_channels
        self._samples_per_channel = samples_per_channel

    @staticmethod
    def create(
        sample_rate: int, num_channels: int, samples_per_channel: int
    ) -> "AudioFrame":
        """
        Create a new empty AudioFrame instance with specified sample rate, number of channels,
        and samples per channel.

        Args:
            sample_rate (int): The sample rate of the audio in Hz.
            num_channels (int): The number of audio channels (e.g., 1 for mono, 2 for stereo).
            samples_per_channel (int): The number of samples per channel.

        Returns:
            AudioFrame: A new AudioFrame instance with uninitialized (zeroed) data.
        """
        size = num_channels * samples_per_channel * ctypes.sizeof(ctypes.c_int16)
        data = bytearray(size)
        return AudioFrame(data, sample_rate, num_channels, samples_per_channel)

    @staticmethod
    def _from_owned_info(owned_info: proto_audio.OwnedAudioFrameBuffer) -> "AudioFrame":
        info = owned_info.info
        size = info.num_channels * info.samples_per_channel
        cdata = (ctypes.c_int16 * size).from_address(info.data_ptr)
        data = bytearray(cdata)
        FfiHandle(owned_info.handle.id)
        return AudioFrame(
            data, info.sample_rate, info.num_channels, info.samples_per_channel
        )

    def remix_and_resample(self, sample_rate: int, num_channels: int) -> "AudioFrame":
        """Resample the audio frame to the given sample rate and number of channels.

        .. warning::
            This method is deprecated and will be removed in a future release.
            Please use the `rtc.AudioResampler` class instead.
        """
        req = proto_ffi.FfiRequest()
        req.new_audio_resampler.CopyFrom(proto_audio.NewAudioResamplerRequest())

        resp = FfiClient.instance.request(req)
        resampler_handle = FfiHandle(resp.new_audio_resampler.resampler.handle.id)

        resample_req = proto_ffi.FfiRequest()
        resample_req.remix_and_resample.resampler_handle = resampler_handle.handle
        resample_req.remix_and_resample.buffer.CopyFrom(self._proto_info())
        resample_req.remix_and_resample.sample_rate = sample_rate
        resample_req.remix_and_resample.num_channels = num_channels

        resp = FfiClient.instance.request(resample_req)
        return AudioFrame._from_owned_info(resp.remix_and_resample.buffer)

    def _proto_info(self) -> proto_audio.AudioFrameBufferInfo:
        audio_info = proto_audio.AudioFrameBufferInfo()
        audio_info.data_ptr = get_address(memoryview(self._data))
        audio_info.sample_rate = self.sample_rate
        audio_info.num_channels = self.num_channels
        audio_info.samples_per_channel = self.samples_per_channel
        return audio_info

    @property
    def data(self) -> memoryview:
        """
        Returns a memory view of the audio data as 16-bit signed integers.

        Returns:
            memoryview: A memory view of the audio data.
        """
        return memoryview(self._data).cast("h")

    @property
    def sample_rate(self) -> int:
        """
        Returns the sample rate of the audio frame.

        Returns:
            int: The sample rate in Hz.
        """
        return self._sample_rate

    @property
    def num_channels(self) -> int:
        """
        Returns the number of channels in the audio frame.

        Returns:
            int: The number of audio channels (e.g., 1 for mono, 2 for stereo).
        """
        return self._num_channels

    @property
    def samples_per_channel(self) -> int:
        """
        Returns the number of samples per channel.

        Returns:
            int: The number of samples per channel.
        """
        return self._samples_per_channel

    @property
    def duration(self) -> float:
        """
        Returns the duration of the audio frame in seconds.

        Returns:
            float: The duration in seconds.
        """
        return self.samples_per_channel / self.sample_rate

    def to_wav_bytes(self) -> bytes:
        """
        Convert the audio frame data to a WAV-formatted byte stream.

        Returns:
            bytes: The audio data encoded in WAV format.
        """
        import wave
        import io

        with io.BytesIO() as wav_file:
            with wave.open(wav_file, "wb") as wav:
                wav.setnchannels(self.num_channels)
                wav.setsampwidth(2)
                wav.setframerate(self.sample_rate)
                wav.writeframes(self._data)

            return wav_file.getvalue()

    def __repr__(self) -> str:
        return (
            f"rtc.AudioFrame(sample_rate={self.sample_rate}, "
            f"num_channels={self.num_channels}, "
            f"samples_per_channel={self.samples_per_channel}, "
            f"duration={self.duration:.3f})"
        )

Static methods

def create(sample_rate: int, num_channels: int, samples_per_channel: int) ‑> AudioFrame

Create a new empty AudioFrame instance with specified sample rate, number of channels, and samples per channel.

Args

sample_rate : int

The sample rate of the audio in Hz.

num_channels : int

The number of audio channels (e.g., 1 for mono, 2 for stereo).

samples_per_channel : int

The number of samples per channel.

Returns

AudioFrame

A new AudioFrame instance with uninitialized (zeroed) data.

Instance variables

prop data : memoryview

Returns a memory view of the audio data as 16-bit signed integers.

Returns

memoryview

A memory view of the audio data.

Expand source code

@property
def data(self) -> memoryview:
    """
    Returns a memory view of the audio data as 16-bit signed integers.

    Returns:
        memoryview: A memory view of the audio data.
    """
    return memoryview(self._data).cast("h")

prop duration : float

Returns the duration of the audio frame in seconds.

Returns

float

The duration in seconds.

Expand source code

@property
def duration(self) -> float:
    """
    Returns the duration of the audio frame in seconds.

    Returns:
        float: The duration in seconds.
    """
    return self.samples_per_channel / self.sample_rate

prop num_channels : int

Returns the number of channels in the audio frame.

Returns

int

The number of audio channels (e.g., 1 for mono, 2 for stereo).

Expand source code

@property
def num_channels(self) -> int:
    """
    Returns the number of channels in the audio frame.

    Returns:
        int: The number of audio channels (e.g., 1 for mono, 2 for stereo).
    """
    return self._num_channels

prop sample_rate : int

Returns the sample rate of the audio frame.

Returns

int

The sample rate in Hz.

Expand source code

@property
def sample_rate(self) -> int:
    """
    Returns the sample rate of the audio frame.

    Returns:
        int: The sample rate in Hz.
    """
    return self._sample_rate

prop samples_per_channel : int

Returns the number of samples per channel.

Returns

int

The number of samples per channel.

Expand source code

@property
def samples_per_channel(self) -> int:
    """
    Returns the number of samples per channel.

    Returns:
        int: The number of samples per channel.
    """
    return self._samples_per_channel

Methods

def remix_and_resample(self, sample_rate: int, num_channels: int) ‑> AudioFrame

Resample the audio frame to the given sample rate and number of channels.

Warning

This method is deprecated and will be removed in a future release. Please use the rtc.AudioResampler class instead.

def to_wav_bytes(self) ‑> bytes

Convert the audio frame data to a WAV-formatted byte stream.

Returns

bytes

The audio data encoded in WAV format.