Compatibility Definition

Device implementations MAY omit a microphone. However, if a device implementation omits a
microphone, it MUST NOT report the android.hardware.microphone feature constant, and MUST
implement the audio recording API at least as no-ops, per section 7. Conversely, device
implementations that do possess a microphone:
MUST report the android.hardware.microphone feature constant
MUST meet the audio recording requirements in section 5.4
MUST meet the audio latency requirements in section 5.6
STRONGLY RECOMMENDED to support near-ultrasound recording as described in
section 7.8.3
7.8.2. Audio Output
Android Watch devices MAY include an audio output.
Device implementations including a speaker or with an audio/multimedia output port for an audio
output peripheral as a headset or an external speaker:
MUST report the android.hardware.audio.output feature constant.
MUST meet the audio playback requirements in section 5.5.
MUST meet the audio latency requirements in section 5.6.
STRONGLY RECOMMENDED to support near-ultrasound playback as described in
section 7.8.3
Conversely, if a device implementation does not include a speaker or audio output port, it MUST NOT
report the android.hardware.audio output feature, and MUST implement the Audio Output related APIs
as no-ops at least.
Android Watch device implementation MAY but SHOULD NOT have audio output, but other types of
Android device implementations MUST have an audio output and declare
android.hardware.audio.output.
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 [Resources, 122], if a device implementation includes one or more
analog audio ports, at least one of the audio port(s) SHOULD be a 4 conductor 3.5mm audio jack. If a
device implementation has a 4 conductor 3.5mm audio jack, it:
MUST support audio playback to stereo headphones and stereo headsets with a
microphone, and SHOULD support audio recording from stereo headsets with a
microphone.
MUST support TRRS audio plugs with the CTIA pin-out order, and SHOULD support audio
plugs with the OMTP pin-out order.
MUST support the detection of microphone on the plugged in audio accessory, if the
device implementation supports a microphone, and broadcast the
android.intent.action.HEADSET_PLUG with the extra value microphone set as 1.
SHOULD 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
SHOULD support the detection and mapping to the keycode for the following range of
equivalent impedance between the microphone and ground conductors on the audio plug:
Page 59 of 74