Note

Click here to download the full example code

AudioEffector Usages¶

This tutorial shows how to use torchaudio.io.AudioEffector to apply various effects and codecs to waveform tensor.

Note

This tutorial requires FFmpeg libraries. Please refer to FFmpeg dependency for the detail.

Overview¶

AudioEffector combines in-memory encoding, decoding and filtering that are provided by StreamWriter and StreamReader.

The following figure illustrates the process.

https://download.pytorch.org/torchaudio/tutorial-assets/AudioEffector.png

import torch
import torchaudio

print(torch.__version__)
print(torchaudio.__version__)

2.6.0.dev20241104
2.5.0.dev20241105

from torchaudio.io import AudioEffector, CodecConfig

import matplotlib.pyplot as plt
from IPython.display import Audio

for k, v in torchaudio.utils.ffmpeg_utils.get_versions().items():
    print(k, v)

libavcodec (60, 3, 100)
libavdevice (60, 1, 100)
libavfilter (9, 3, 100)
libavformat (60, 3, 100)
libavutil (58, 2, 100)

Usage¶

To use AudioEffector, instantiate it with effect and format, then either pass the waveform to apply() or stream() method.

effector = AudioEffector(effect=..., format=...,)

# Apply at once
applied = effector.apply(waveform, sample_rate)

apply method applies effect and codec to the entire waveform at once. So if the input waveform is long, and memory consumption is an issue, one can use stream method to process chunk by chunk.

# Apply chunk by chunk
for applied_chunk = effector.stream(waveform, sample_rate):
    ...

Example¶

src = torchaudio.utils.download_asset("tutorial-assets/Lab41-SRI-VOiCES-src-sp0307-ch127535-sg0042.wav")
waveform, sr = torchaudio.load(src, channels_first=False)

Gallery¶

def show(effect, *, stereo=False):
    wf = torch.cat([waveform] * 2, dim=1) if stereo else waveform
    figsize = (6.4, 2.1 if stereo else 1.2)

    effector = AudioEffector(effect=effect, pad_end=False)
    result = effector.apply(wf, int(sr))

    num_channels = result.size(1)
    f, ax = plt.subplots(num_channels, 1, squeeze=False, figsize=figsize, sharex=True)
    for i in range(num_channels):
        ax[i][0].specgram(result[:, i], Fs=sr)
    f.set_tight_layout(True)

    return Audio(result.numpy().T, rate=sr)

Original¶

show(effect=None)

Effects¶

tempo¶

https://ffmpeg.org/ffmpeg-filters.html#atempo

show("atempo=0.7")

show("atempo=1.8")

highpass¶

https://ffmpeg.org/ffmpeg-filters.html#highpass

show("highpass=frequency=1500")

lowpass¶

https://ffmpeg.org/ffmpeg-filters.html#lowpass

show("lowpass=frequency=1000")

allpass¶

https://ffmpeg.org/ffmpeg-filters.html#allpass

show("allpass")

bandpass¶

https://ffmpeg.org/ffmpeg-filters.html#bandpass

show("bandpass=frequency=3000")

bandreject¶

https://ffmpeg.org/ffmpeg-filters.html#bandreject

show("bandreject=frequency=3000")

echo¶

https://ffmpeg.org/ffmpeg-filters.html#aecho

show("aecho=in_gain=0.8:out_gain=0.88:delays=6:decays=0.4")

show("aecho=in_gain=0.8:out_gain=0.88:delays=60:decays=0.4")

show("aecho=in_gain=0.8:out_gain=0.9:delays=1000:decays=0.3")

chorus¶

https://ffmpeg.org/ffmpeg-filters.html#chorus

show("chorus=0.5:0.9:50|60|40:0.4|0.32|0.3:0.25|0.4|0.3:2|2.3|1.3")

fft filter¶

https://ffmpeg.org/ffmpeg-filters.html#afftfilt

# fmt: off
show(
    "afftfilt="
    "real='re * (1-clip(b * (b/nb), 0, 1))':"
    "imag='im * (1-clip(b * (b/nb), 0, 1))'"
)

show(
    "afftfilt="
    "real='hypot(re,im) * sin(0)':"
    "imag='hypot(re,im) * cos(0)':"
    "win_size=512:"
    "overlap=0.75"
)

show(
    "afftfilt="
    "real='hypot(re,im) * cos(2 * 3.14 * (random(0) * 2-1))':"
    "imag='hypot(re,im) * sin(2 * 3.14 * (random(1) * 2-1))':"
    "win_size=128:"
    "overlap=0.8"
)
# fmt: on

vibrato¶

https://ffmpeg.org/ffmpeg-filters.html#vibrato

show("vibrato=f=10:d=0.8")

/pytorch/audio/ci_env/lib/python3.10/site-packages/IPython/lib/display.py:188: RuntimeWarning: invalid value encountered in cast
  return scaled.astype("<h").tobytes(), nchan

tremolo¶

https://ffmpeg.org/ffmpeg-filters.html#tremolo

show("tremolo=f=8:d=0.8")

crystalizer¶

https://ffmpeg.org/ffmpeg-filters.html#crystalizer

show("crystalizer")

flanger¶

https://ffmpeg.org/ffmpeg-filters.html#flanger

show("flanger")

phaser¶

https://ffmpeg.org/ffmpeg-filters.html#aphaser

show("aphaser")

pulsator¶

https://ffmpeg.org/ffmpeg-filters.html#apulsator

show("apulsator", stereo=True)

haas¶

https://ffmpeg.org/ffmpeg-filters.html#haas

show("haas")

Codecs¶

def show_multi(configs):
    results = []
    for config in configs:
        effector = AudioEffector(**config)
        results.append(effector.apply(waveform, int(sr)))

    num_configs = len(configs)
    figsize = (6.4, 0.3 + num_configs * 0.9)
    f, axes = plt.subplots(num_configs, 1, figsize=figsize, sharex=True)
    for result, ax in zip(results, axes):
        ax.specgram(result[:, 0], Fs=sr)
    f.set_tight_layout(True)

    return [Audio(r.numpy().T, rate=sr) for r in results]

ogg¶

results = show_multi(
    [
        {"format": "ogg"},
        {"format": "ogg", "encoder": "vorbis"},
        {"format": "ogg", "encoder": "opus"},
    ]
)

ogg - default encoder (flac)¶

results[0]

ogg - vorbis¶

results[1]

ogg - opus¶

results[2]

mp3¶

https://trac.ffmpeg.org/wiki/Encode/MP3

results = show_multi(
    [
        {"format": "mp3"},
        {"format": "mp3", "codec_config": CodecConfig(compression_level=1)},
        {"format": "mp3", "codec_config": CodecConfig(compression_level=9)},
        {"format": "mp3", "codec_config": CodecConfig(bit_rate=192_000)},
        {"format": "mp3", "codec_config": CodecConfig(bit_rate=8_000)},
        {"format": "mp3", "codec_config": CodecConfig(qscale=9)},
        {"format": "mp3", "codec_config": CodecConfig(qscale=1)},
    ]
)

default¶

results[0]

compression_level=1¶

results[1]

compression_level=9¶

results[2]

bit_rate=192k¶

results[3]

bit_rate=8k¶

results[4]

qscale=9¶

results[5]

qscale=1¶

results[6]

Tag: torchaudio.io

Total running time of the script: ( 0 minutes 3.061 seconds)

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