Detailed description of Android audio data streams

The following figure shows the architecture of Android audio.

 

The detailed call path is as follows:

1. Audio Playback
Sample Code
Mediaplayer MP = new mediaplayer ();
MP. setdatasource (path_to_file );
MP. Prepare ();
MP. Start ();

 

1.1 mediaplayer MP = new mediaplayer ()

The implementation process is as follows:

Function Name	File Name
Mediaplayer: mediaplayer	Mediaplayer. Java
Mediaplayer: native_setup	Mediaplayer. Java
Android_media_mediaplayer_native_setup	Android_media_mediaplayer.cpp
Mediaplayer: mediaplayer	Mediaplayer. cpp

 

1.2 MP. setdatasource (path_to_file );

The implementation process is as follows:

Function Name	File Name
Mediaplayer: setdatasource	Mediaplayer. Java
Android_media_mediaplayer_setdatasource	Android_media_mediaplayer.cpp
Mediaplayer: setdatasource	Mediaplayer. cpp
-Mediaplayer: getmediaplayerservice	Mediaplayer. cpp
-Imediaplayerservice	Imediaplayerservice. h
-Imediaplayerservice: Create	Mediaplayer. cpp
-- Mediaplayerservice: Create	Mediaplayerservice. cpp
-Imediaplayer: setdatasource	Mediaplayer. cpp
-- Bpmediaplayer: setdatasource	Imediaplayer. cpp
-- Mediaplayerservice: Client: setdatasource (the actual operation is executed)	Mediaplayerservice. cpp
-- Android: createplayer	Mediaplayerservice. cpp
-- New stagefrightplayer	Mediaplayerservice. cpp
-- New audiooutput	Mediaplayerservice. cpp
-- Stagefrightplayer: setdatasource	Stagefrightplayer. cpp
-- Awesomeplayer: setdatasource	Awesomeplayer. cpp
-- Awesomeplayer: setperformance_l	Awesomeplayer. cpp

 

1.3 MP. Prepare ()

Function Name	File Name
Mediaplayer: Prepare	Mediaplayer. Java
Android_media_mediaplayer_prepare	Android_media_mediaplayer.cpp
Mediaplayer: Prepare	Mediaplayer. cpp
Midifile: Prepare	Midifile. cpp
Vorbisplayer: Prepare	Vorbisplayer. cpp
Vorbisplayer: createoutputtrack	Vorbisplayer. cpp
Audiooutput: Open	Mediaplayerservice. cpp
Audiotrack: audiotrack	Audiotrack. cpp
Audiosystem: get_audio_flinger	Audiosystem. cpp
Audioflinger: createtrack	Audioflinger. cpp

 

1.4 MP. Start ()

Function Name	File Name
Mediaplayer: Start	Mediaplayer. Java
Android_media_mediaplayer_start	Android_media_mediaplayer.cpp
Mediaplayer: Start	Mediaplayer. cpp
Pvplayer: Start	Pvplayer. h
Midifile: Start	Midifile. cpp
Vorbisplayer: Start	Vorbisplayer. cpp
Audiotrack: Start	Audiotrack. cpp

Mediaplayerservice: mediaplayerservice (mediaplayerservice. cpp) is created by the systemserver process. The system_init () function in the system_init.cpp file calls mediaplayerservice: instantiate to create

Getplayertype (mediaplayerservice. cpp) returns three types of player:
1) pv_player: play MP3
2) sonivox_player: play MIDI
3) vorbis_player: Play Ogg,

 

To put it simply, the playback process is as follows:
When the Java end initiates a call, mediaplayer will go to mediaplayerservice, and then call the corresponding decoding tool to decode and create audiotrack. All audiotracks to be output are merged in audioflinger: audiomixer, then, use audiohal (actual real-time player of audiohardwareinterface) to transmit it to the actual hardware for playing.