DVI audio can play 44.1 kHz and 32 kHz sound too

docs/environment.rst

@@ -241,6 +241,22 @@ Example: Configure the display to 640x480 black and white (1 bit per pixel):
 `Adafruit Feather RP2350 <https://circuitpython.org/board/adafruit_feather_rp2350/>`_
 `Adafruit Metro RP2350 <https://circuitpython.org/board/adafruit_metro_rp2350/>`_
 
+CIRCUITPY_PICODVI_AUDIO (boolean)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Whether the display configured at board initialization also sends sound through
+the DVI cable, as ``supervisor.runtime.audio``. Defaults to true. It needs a 640-wide
+output: 640x480, 320x240 or 160x120. Audio uses about 37 KB of internal RAM
+next to a 640x480 display. Set this to false to keep that RAM free, for
+example on a monitor without speakers.
+
+``supervisor.runtime.audio`` is a :py:class:`picodvi.AudioOut`. It becomes ``None`` when
+the display is released by ``displayio.release_displays()`` or when it is
+deinitialized, and stays ``None`` until the next reset.
+
+`Adafruit Feather RP2350 <https://circuitpython.org/board/adafruit_feather_rp2350/>`_
+`Adafruit Fruit Jam <https://circuitpython.org/board/adafruit_fruit_jam/>`_
+`Adafruit Metro RP2350 <https://circuitpython.org/board/adafruit_metro_rp2350/>`_
+
 CIRCUITPY_SAFEMODE_DELAY (float)
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 Wait for the specified amount of time, in seconds, for the user to press the reset button

ports/raspberrypi/bindings/picodvi/AudioOut.c

@@ -16,17 +16,24 @@
 //| class AudioOut:
 //|     """Plays audio through the DVI cable of a `Framebuffer`, on displays
 //|     that have speakers or an audio output. RP2350 only: elsewhere the
-//|     constructor raises `NotImplementedError`."""
+//|     constructor raises `NotImplementedError`.
+//|
+//|     On boards with a default DVI display, `supervisor.runtime.audio` is an AudioOut
+//|     for the display configured at startup. It is ``None`` if that display
+//|     was not configured, its mode has no room for audio, or it was released.
+//|     Set ``CIRCUITPY_PICODVI_AUDIO = false`` in ``settings.toml`` to turn it
+//|     off."""
 //|
 //|     def __init__(self, framebuffer: Framebuffer) -> None:
 //|         """Create an AudioOut that sends audio with ``framebuffer``'s video.
 //|
 //|         The framebuffer must use a 640-pixel-wide output mode, such as
-//|         640x480 or 320x240. This reserves about 120 KB (640 wide) or
-//|         150 KB (320 or 160 wide) of internal RAM until `deinit`, so create
-//|         the AudioOut soon after the Framebuffer. A 640x480 framebuffer with
-//|         8-bit color leaves too little RAM. The display receives silence
-//|         whenever nothing is playing.
+//|         640x480 or 320x240. This reserves about 37 KB (640 wide) or
+//|         50 KB (320 or 160 wide) of internal RAM until `deinit`, so create
+//|         the AudioOut soon after the Framebuffer. With 640x480 and 8-bit
+//|         color, usually only the display configured at startup has room
+//|         for audio. The display receives silence whenever nothing is
+//|         playing.
 //|
 //|         :param Framebuffer framebuffer: The display output to add audio to
 //|
@@ -109,7 +116,9 @@ static void check_for_deinit(picodvi_audioout_obj_t *self) {
 //|         Does not block. Use `playing` to block.
 //|
 //|         Sample must be an `audiocore.WaveFile`, `audiocore.RawSample`, `audiomixer.Mixer`,
-//|         `synthio.Synthesizer` or `audiomp3.MP3Decoder` with a sample rate of 48000 Hz.
+//|         `synthio.Synthesizer` or `audiomp3.MP3Decoder` with a sample rate of 32000, 44100
+//|         or 48000 Hz. Other rates raise `ValueError`; use `audiospeed.Resampler` to convert
+//|         them. Changing rate between samples can make the display mute briefly.
 //|
 //|         Mono samples will be converted to stereo by copying value to both the left channel and the right channel.
 //|