Follow-up on audio playback function (#3051)

Summary:
- Add documentation
- Tweak docsrting
- Fix import

Pull Request resolved: https://github.com/pytorch/audio/pull/3051

Reviewed By: weiwangmeta, atalman, nateanl

Differential Revision: D43166081

Pulled By: mthrok

fbshipit-source-id: 7d77aa34a6318a64824626cff8372f8b9aebf6f9

docs/source/_templates/autosummary/io_class.rst

@@ -32,6 +32,8 @@ Properties
 {%- endfor %}
 {%- endif %}
 
+{%- if members %}
+
 Methods
 -------
 
@@ -46,6 +48,7 @@ Methods
 
 {%- endif %}
 {%- endfor %}
+{%- endif %}
 
 {%- if name == "StreamReader" %}
 

docs/source/io.rst

@@ -12,6 +12,7 @@ torchaudio.io
 
    StreamReader
    StreamWriter
+   play_audio
 
 .. rubric:: Tutorials using ``torchaudio.io``
 

torchaudio/io/__init__.py

+from ._playback import play_audio
 from ._stream_reader import StreamReader
 from ._stream_writer import StreamWriter
 

torchaudio/io/_playback.py

@@ -4,7 +4,6 @@ from typing import Optional
 
 import torch
 import torchaudio
-from torchaudio.io import StreamWriter
 
 dict_format = {
     torch.uint8: "u8",
@@ -23,8 +22,13 @@ def play_audio(
     device: Optional[str] = None,
 ) -> None:
     """Plays audio through specified or available output device.
-    This function is currently only supported on MacOS, which has access
-    to "audiotoolbox" output device that can play up to two audio channels.
+
+    .. warning::
+       This function is currently only supported on MacOS, and requires
+       libavdevice (FFmpeg) with ``audiotoolbox`` output device.
+
+    .. note::
+       This function can play up to two audio channels.
 
     Args:
         waveform: Tensor containing the audio to play.
@@ -57,7 +61,7 @@ def play_audio(
         )
 
     # Write to speaker device
-    s = StreamWriter(dst=path, format=device)
+    s = torchaudio.io.StreamWriter(dst=path, format=device)
     s.add_audio_stream(sample_rate, num_channels, format=format)
 
     # write audio to the device