@@ -4196,7 +4221,7 @@ Methods
scheduled parameter changes with times greater than or equal to
{{AudioParam/cancelAndHoldAtTime()/cancelTime!!argument}}. However, in addition, the automation
value that would have happened at {{AudioParam/cancelAndHoldAtTime()/cancelTime!!argument}} is
- then proprogated for all future time until other automation
+ then propagated for all future time until other automation
events are introduced.
The behavior of the timeline in the face of
@@ -11662,7 +11687,7 @@ and a
rendering thread.
The
control thread is the thread from which the
{{AudioContext}} is instantiated, and from which authors
-manipulate the audio graph, that is, from where the operation on a
+manipulate the audio graph, that is, from where the operations on a
{{BaseAudioContext}} are invoked. The
rendering thread
is the thread on which the actual audio output is computed, in
reaction to the calls from the
control thread. It can be a
@@ -11769,7 +11794,7 @@ The algorithm for rendering a block of audio from a {{BaseAudioContext}}
in the algorithm of
rendering a graph.
The {{AudioContext}}
rendering thread is driven by a
-
system-level audio callback, that is periodically
+
system-level audio callback, that is periodically called
at regular intevals. Each call has a
system-level audio callback buffer
size, which is a varying number of sample-frames that needs to be
computed on time before the next
system-level audio callback arrives.
@@ -12089,6 +12114,102 @@ running the algorithm for an {{AudioNode}}, using an
input
buffer and the value(s) of the {{AudioParam}}(s) of this
{{AudioNode}} as the input for this algorithm.
+
Handling an interruption on the {{AudioContext}}
+
+An
interruption is an event generated by the user agent when it needs
+to halt audio playback for an {{AudioContext}}. For example, The user agent may
+create an interruption when another application requests exclusive access to the
+audio output hardware.
+
+When an [=interruption=] happens, the user agent must
queue a control message
+to interrupt the {{AudioContext}}.
+
+Running a
control message to
interrupt an {{AudioContext}} |context|
+means running these steps on the
rendering thread:
+
+1. If the |context|'s {{[[rendering thread state]]}} is
closed
+ or
interrupted:
+
+ 1. Abort these steps.
+
+1. If the |context|'s {{[[rendering thread state]]}} is
+
running:
+
+ 1. Attempt to
release system resources.
+
+ 1. [=Queue a media element task=] to execute the following steps:
+
+ 1. Set the |context|'s {{[[control thread state]]}} to
+
interrupted.
+
+ 1. [=Fire an event=] named {{BaseAudioContext/statechange}} at the
+ |context|.
+
+1. If the |context|'s {{[[rendering thread state]]}} is
+
suspended:
+
+ 1. [=Queue a media element task=] to execute the following steps:
+
+ 1. Set the |context|'s {{[[control thread state]]}} to
+
interrupted.
+
+1. Set the |context|'s {{[[rendering thread state]]}} to
+
interrupted.
+
+Note: If the {{AudioContext}} is
suspended a
+{{BaseAudioContext/statechange}} event is not fired for privacy reasons to avoid
+over-sharing user activity - e.g. when a phone call comes in or when the screen
+gets locked.
+
+When an [=interruption=] ends, the user agent must
queue a control message
+to
end the
+{{AudioContext}} interruption.
+
+
Linear pulse code modulation
+
+Running a
control message to end an {{AudioContext}} |context|
+[=interruption=] means running these steps on the
rendering thread:
+
+1. If the |context|'s {{[[rendering thread state]]}} is not
+
interrupted:
+
+ 1. Abort these steps.
+
+1. If the |context|'s {{[[rendering thread state]]}} was
+
running before the [=interruption=] or if the the
+ |context|'s {{[[rendering thread state]]}} was
suspended
+ and {{AudioContext/resume}} was called during the [=interruption=]:
+
+ 1. Attempt to
acquire system resources.
+
+ 1. Set the {{[[rendering thread state]]}} on the {{AudioContext}} to
+
running.
+
+ 1. Start
rendering the audio graph.
+
+ 1. [=Queue a media element task=] to execute the following steps:
+
+ 1. If the {{BaseAudioContext/state}} attribute of the {{AudioContext}}
+ is not already "{{AudioContextState/running}}":
+
+ 1. Set the |context|'s {{[[control thread state]]}} to
+
running.
+
+ 1. [=Fire an event=] named {{BaseAudioContext/statechange}} at the
+ |context|.
+
+1. If the |context|'s {{[[rendering thread state]]}} was
+
suspended before the [=interruption=]:
+
+ 1. Set the {{[[rendering thread state]]}} on the {{AudioContext}} to
+
suspended.
+
+ 1. [=Queue a media element task=] to execute the following steps:
+
+ 1. Set the |context|'s {{[[control thread state]]}} to
+
suspended.
+
Handling an error from System Audio Resources on the {{AudioContext}}