[C-1-3] MUST meet the audio latency requirements in
section 5.6
.
[SR] STRONGLY RECOMMENDED to support near-ultrasound playback as described in
section 7.8.3
.
If device implementations do not include a speaker or audio output port, they:
[C-2-1] MUST NOT report the
android.hardware.audio.output
feature.
[C-2-2] MUST implement the Audio Output related APIs as no-ops at least.
For the purposes of this section, an "output port" is a
physical interface
such as a 3.5mm audio jack,
HDMI, or USB host mode port with USB audio class. Support for audio output over radio-based
protocols such as Bluetooth, WiFi, or cellular network does not qualify as including an "output port".
7.8.2.1. Analog Audio Ports
In order to be compatible with the
headsets and other audio accessories
using the 3.5mm audio plug
across the Android ecosystem, if device implementations include one or more analog audio ports,
they:
[C-SR] Are STRONGLY RECOMMENDED to include at least one of the audio port(s) to be a
4 conductor 3.5mm audio jack.
If device implementations have a 4 conductor 3.5mm audio jack, they:
[C-1-1] MUST support audio playback to stereo headphones and stereo headsets with a
microphone.
[C-1-2] MUST support TRRS audio plugs with the CTIA pin-out order.
[C-1-3] MUST support the detection and mapping to the keycodes for the following 3
ranges of equivalent impedance between the microphone and ground conductors on the
audio plug:
70 ohm or less
:
KEYCODE_HEADSETHOOK
210-290 ohm
:
KEYCODE_VOLUME_UP
360-680 ohm
:
KEYCODE_VOLUME_DOWN
[C-1-4] MUST trigger
ACTION_HEADSET_PLUG
upon a plug insert, but only after all
contacts on plug are touching their relevant segments on the jack.
[C-1-5] MUST be capable of driving at least 150mV ± 10% of output voltage on a 32 ohm
speaker impedance.
[C-1-6] MUST have a microphone bias voltage between 1.8V ~ 2.9V.
[C-1-7] MUST detect and map to the keycode for the following range of equivalent
impedance between the microphone and ground conductors on the audio plug:
110-180 ohm:
KEYCODE_VOICE_ASSIST
[C-SR] Are STRONGLY RECOMMENDED to support audio plugs with the OMTP pin-out
order.
[C-SR] Are STRONGLY RECOMMEND to support audio recording from stereo headsets
with a microphone.
If device implementations have a 4 conductor 3.5mm audio jack and support a microphone, and
broadcast the
android.intent.action.HEADSET_PLUG
with the extra value microphone set as 1, they:
[C-2-1] MUST support the detection of microphone on the plugged in audio accessory.
7.8.3. Near-Ultrasound
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