## 5.5\. Audio Playback

Android includes the support to allow apps to playback audio through the audio
output peripheral as defined in section 7.8.2.

### 5.5.1\. Raw Audio Playback

If device implementations declare `android.hardware.audio.output`, they:

*   [C-1-1] MUST allow playback of raw audio content with the following
characteristics:

   *   **Format**: Linear PCM, 16-bit
   *   **Sampling rates**: 8000, 11025, 16000, 22050, 32000, 44100
   *   **Channels**: Mono, Stereo

*   SHOULD allow playback of raw audio content with the following
characteristics:

   *   **Sampling rates**: 24000, 48000

### 5.5.2\. Audio Effects

Android provides an [API for audio effects](
http://developer.android.com/reference/android/media/audiofx/AudioEffect.html)
for device implementations.

If device implementations declare the feature `android.hardware.audio.output`,
they:

*   [C-1-1] MUST support the `EFFECT_TYPE_EQUALIZER` and
`EFFECT_TYPE_LOUDNESS_ENHANCER` implementations controllable through the
AudioEffect subclasses `Equalizer`, `LoudnessEnhancer`.
*   [C-1-2] 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

Television device implementations:

*   [T-0-1] 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).

Automotive device implementations:

*   SHOULD allow adjusting audio volume
separately per each audio stream using the content type or usage as defined
by [AudioAttributes]("http://developer.android.com/reference/android/media/AudioAttributes.html")
and car audio usage as publicly defined in `android.car.CarAudioManager`.