Compatibility Definition

implementations that declare the feature android.hardware.audio.output:
MUST support the EFFECT_TYPE_EQUALIZER and
EFFECT_TYPE_LOUDNESS_ENHANCER implementations controllable through the
AudioEffect subclasses Equalizer, LoudnessEnhancer.
MUST support the visualizer API implementation, controllable through the Visualizer class.
SHOULD support the EFFECT_TYPE_BASS_BOOST, EFFECT_TYPE_ENV_REVERB,
EFFECT_TYPE_PRESET_REVERB, and EFFECT_TYPE_VIRTUALIZER
implementations controllable through the AudioEffect sub-classes BassBoost,
EnvironmentalReverb, PresetReverb, and Virtualizer.
5.5.3. Audio Output Volume
Android Television device implementations MUST include support for system Master Volume and
digital audio output volume attenuation on supported outputs, except for compressed audio
passthrough output (where no audio decoding is done on the device).
5.6. Audio Latency
Audio latency is the time delay as an audio signal passes through a system. Many classes of
applications rely on short latencies, to achieve real-time sound effects.
For the purposes of this section, use the following definitions:
output latency. The interval between when an application writes a frame of PCM-coded
data and when the corresponding sound can be heard by an external listener or observed
by a transducer.
cold output latency. The output latency for the first frame, when the audio output system
has been idle and powered down prior to the request.
continuous output latency. The output latency for subsequent frames, after the device is
playing audio.
input latency. The interval between when an external sound is presented to the device
and when an application reads the corresponding frame of PCM-coded data.
cold input latency. The sum of lost input time and the input latency for the first frame,
when the audio input system has been idle and powered down prior to the request.
continuous input latency. The input latency for subsequent frames, while the device is
capturing audio.
cold output jitter. The variance among separate measurements of cold output latency
values.
cold input jitter. The variance among separate measurements of cold input latency
values.
continuous round-trip latency. The sum of continuous input latency plus continuous
output latency plus one buffer period. The buffer period term allows processing time for the
app and for the app to mitigate phase difference between input and output streams.
OpenSL ES PCM buffer queue API. The set of PCM-related OpenSL ES APIs within
Android NDK; see NDK_root/docs/opensles/index.html.
Device implementations that declare android.hardware.audio.output are STRONGLY
RECOMMENDED to meet or exceed these audio output requirements:
cold output latency of 100 milliseconds or less
continuous output latency of 45 milliseconds or less
minimize the cold output jitter
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