Short introduction about the audio playback in Firefox OS.

1. Text
FxOS Audio Playback 101
Alastor Wu
2015/06/12

2. OUTLINE
2
Data flow
!
Outputs selection

3. GECKO
3
mVideoQueue
MDSM
mAudioQueue
AudioSink AudioStream
AudioLoop()
mAudioSink mAudioStream
Write()
mBuffer
AUDIO PLAYBACK OVERVIEW

4. GONK
4
AudioTrack
Audio
Buffer
MediaServer
AudioFlinger
AudioPolicy
Service
HAL
Audio
Module
AudioPolicy
Module
Linux
Kernel
ALSA/OSS
Custom Driver
AUDIO PLAYBACK OVERVIEW

5. FXOS
5
AUDIO PLAYBACK OVERVIEW
Gecko
Gonk
MDSM AudioSink AudioStream Lib Cubeb
AudioTrack AudioSystemNative Framework
AudioFlinger
AudioPolicy
Service
Media Server
AudioHardware AudioPolicyManagerHAL
Linux Kernel
OpenSL NDK

6. ANDROID
6
AUDIO OUTPUT DEVICES
StreamTypes Strategies Devices
Audio
Channel
Types
Output
device
Earpiece
Speaker
Wired headset/phone
Bluetooth SCO headset/carkit
Bluetooth A2DP headphone/speaker
…
Media
Phone
Sonification
Sonification respectful
DTMF
Enforce audible
Voice call
System
Ring
Music
Alarm
Notification
BT SCO
Enforce audible
DTMF
TTS
FM

7. ANDROID
7
AUDIO OUTPUT PROFILES
Inputs
Outputs
IOProfiles
IOProfiles
Sample rates
Channel masks
Formats
Devices
Modules
primary/a2dp/usb
khz
mono/stereo
mp3/aac/…
speaker/headset…

8. ANDROID
8
AUDIO PLAYBACK FLOW
AudioTrack
AudioSystem
AudioPolicy
Service
GetOutput() OpenOutput()
Data flow
AudioFlinger
PlaybackThread
mTracks
Audio
Mixer
AudioHardware

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