torchaudio top-level module provides the following functions that make
it easy to handle audio data.
Get signal information of an audio file.
Load audio data from source.
Save audio data to file.
List available backends
Backend and Dispatcher¶
Decoding and encoding media is highly elaborated process. Therefore, TorchAudio
relies on third party libraries to perform these operations. These third party
libraries are called
backend, and currently TorchAudio integrates the
Please refer to Installation for how to enable backends.
Conventionally, TorchAudio has had its I/O backend set globally at runtime based on availability. However, this approach does not allow applications to use different backends, and it is not well-suited for large codebases.
For these reasons, in v2.0, we introduced a dispatcher, a new mechanism to allow users to choose a backend for each function call.
When dispatcher mode is enabled, all the I/O functions accept extra keyward argument
backend, which specifies the desired backend. If the specified
backend is not available, the function call will fail.
If a backend is not explicitly chosen, the functions will select a backend to use given order of precedence and library availability.
The following table summarizes the backends.
Linux, macOS, Windows
This backend Supports various protocols, such as HTTPS and MP4, and file-like objects.
This backend does not support file-like objects.
Linux, macOS, Windows
Please refer to the official document for the supported codecs.
This backend supports file-like objects.
We are migrating the I/O functions to use the dispatcher mechanism, and this incurs multiple changes, some of which involve backward-compatibility-breaking changes, and require users to change their function call.
The (planned) changes are as follows. For up-to-date information, please refer to https://github.com/pytorch/audio/issues/2950
In 2.0, audio I/O backend dispatcher was introduced. Users can opt-in to using dispatcher by setting the environment variable
In 2.1, the disptcher became the default mechanism for I/O.
In 2.2, the legacy global backend mechanism is removed. Utility functions
Furthermore, we removed file-like object support from libsox backend, as this is better supported by FFmpeg backend and makes the build process simpler. Therefore, beginning with 2.1, FFmpeg and Soundfile are the sole backends that support file-like objects.