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module  pixeltable.functions.audio

Pixeltable UDFs for AudioType.

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iterator  audio_splitter()

Signature
audio_splitter(
    audio: Any,
    chunk_duration_sec: float,
    *,
    overlap_sec: float = 0.0,
    min_chunk_duration_sec: float = 0.0
)
Iterator over chunks of an audio file. The audio file is split into smaller chunks, where the duration of each chunk is determined by chunk_duration_sec. The iterator yields audio chunks as pxt.Audio, along with the start and end time of each chunk. If the input contains no audio, no chunks are yielded. Parameters:
  • chunk_duration_sec (float): Audio chunk duration in seconds
  • overlap_sec (float, default: 0.0): Overlap between consecutive chunks in seconds
  • min_chunk_duration_sec (float, default: 0.0): Drop the last chunk if it is smaller than min_chunk_duration_sec
Examples: This example assumes an existing table tbl with a column audio of type pxt.Audio. Create a view that splits all audio files into chunks of 30 seconds with 5 seconds overlap: 
pxt.create_view(
    'audio_chunks',
    tbl,
    iterator=audio_splitter(
        tbl.audio, chunk_duration_sec=30.0, overlap_sec=5.0
    ),
)

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udf  encode_audio()

Signature
@pxt.udf
encode_audio(
    audio_data: pxt.Array[float32],
    *,
    input_sample_rate: pxt.Int,
    format: pxt.String,
    output_sample_rate: pxt.Int | None = None
) -> pxt.Audio
Encodes an audio clip represented as an array into a specified audio format. Parameters:
  • audio_data (pxt.Array[float32]): An array of sampled amplitudes. The accepted array shapes are (N,) or (1, N) for mono audio or (2, N) for stereo.
  • input_sample_rate (pxt.Int): The sample rate of the input audio data.
  • format (pxt.String): The desired output audio format. The supported formats are ‘wav’, ‘mp3’, ‘flac’, and ‘mp4’.
  • output_sample_rate (pxt.Int | None): The desired sample rate for the output audio. Defaults to the input sample rate if unspecified.
Examples: Add a computed column with encoded FLAC audio files to a table with audio data (as arrays of floats) and sample rates: 
t.add_computed_column(
    audio_file=encode_audio(
        t.audio_data, input_sample_rate=t.sample_rate, format='flac'
    )
)

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udf  get_metadata()

Signature
@pxt.udf
get_metadata(audio: pxt.Audio) -> pxt.Json
Gets various metadata associated with an audio file and returns it as a dictionary. Parameters:
  • audio (pxt.Audio): The audio to get metadata for.
Returns:
  • pxt.Json: A dict such as the following: 
    {
    'size': 2568827,
    'streams': [
        {
            'type': 'audio',
            'frames': 0,
            'duration': 2646000,
            'metadata': {},
            'time_base': 2.2675736961451248e-05,
            'codec_context': {
                'name': 'flac',
                'profile': None,
                'channels': 1,
                'codec_tag': '\x00\x00\x00\x00',
            },
            'duration_seconds': 60.0,
        }
    ],
    'bit_rate': 342510,
    'metadata': {'encoder': 'Lavf61.1.100'},
    'bit_exact': False,
}
Examples: Extract metadata for files in the audio_col column of the table tbl: 
tbl.select(tbl.audio_col.get_metadata()).collect()