docs: Update the recording default rate from 11k to 7812.

docs/audio.rst

@@ -12,7 +12,7 @@ a speaker to pin 0 and GND on the edge connector to hear the sounds.
 The ``audio`` module can be imported as ``import audio`` or accessed via
 the ``microbit`` module as ``microbit.audio``.
 
-There are three different kinds of audio sources that can be played using the
+There are five different kinds of audio sources that can be played using the
 :py:meth:`audio.play` function:
 
 1. `Built in sounds <#built-in-sounds-v2>`_ (**V2**),
@@ -268,7 +268,7 @@ AudioRecording
 --------------
 
 .. py:class::
-    AudioRecording(duration, rate=11_000)
+    AudioRecording(duration, rate=7812)
 
     The ``AudioRecording`` object contains audio data and the sampling rate
     associated to it.
@@ -305,6 +305,10 @@ AudioRecording
         Create an `AudioTrack <#audio.AudioTrack>`_ instance from a portion of
         the data in this ``AudioRecording`` instance.
 
+        Out-of-range values will be truncated to the recording limits.
+        If ``end_ms`` is lower than ``start_ms``, an empty track will be
+        created.
+
         :param start_ms: Where to start of the track in milliseconds.
         :param end_ms: The end of the track in milliseconds.
             If the default value of ``-1`` is provided it will end the track
@@ -335,7 +339,7 @@ AudioTrack
 
     When the input buffer has an associated rate (e.g. an ``AudioRecording``
     or ``AudioTrack``), the rate is copied. If the buffer object does not have
-    a rate, the default value of 11_000 is used.
+    a rate, the default value of 7812 is used.
 
     Changes to an ``AudioTrack`` rate won't affect the original source rate,
     so multiple instances pointing to the same buffer can have different

docs/microbit_micropython_api.rst

@@ -109,7 +109,7 @@ The Microphone is accessed via the `microphone` object::
     # Returns a representation of the sound pressure level in the range 0 to 255.
     sound_level()
     # Record audio into a new `AudioRecording`
-    recording = record(duration, rate=11_000)
+    recording = record(duration, rate=7812)
     # Record audio into an existing `AudioRecording`
     record_into(recording, wait=True)
     # Returns `True` if the microphone is currently recording audio

docs/microphone.rst

@@ -141,7 +141,7 @@ Functions
 
     :return: A representation of the sound pressure level in the range 0 to 255.
 
-.. py:function:: record(duration, rate=11000)
+.. py:function:: record(duration, rate=7812)
 
     Record sound into an ``AudioRecording`` for the amount of time indicated by
     ``duration`` at the sampling rate indicated by ``rate``.
@@ -267,10 +267,8 @@ An example of recording and playback with a display animation::
         "00000"
     )
 
-    RECORDING_RATE = 3906
-    RECORDING_MS = 5000
-
-    my_recording = audio.AudioRecording(duration=RECORDING_MS, rate=RECORDING_RATE)
+    RECORDING_RATE = 7812   # The default sample rate
+    my_recording = audio.AudioRecording(duration=5000, rate=RECORDING_RATE)
 
     while True:
         if button_a.is_pressed():
@@ -283,7 +281,10 @@ An example of recording and playback with a display animation::
         if button_b.is_pressed():
             audio.play(clipped_recording, wait=False)
             while audio.is_playing():
-                x = accelerometer.get_x()
-                audio.set_rate(scale(x, (-1000, 1000), (2250, 11000)))
+                clipped_recording.set_rate(scale(
+                    accelerometer.get_x(),
+                    (-1000, 1000),
+                    (RECORDING_RATE // 2, RECORDING_RATE * 2)
+                ))
                 sleep(50)
         sleep(100)