Android Audio 数据流详解

Android Audio Architecture 图如下所示


详细调用路径如下

1.       音频播放

示例代码

MediaPlayer mp = new MediaPlayer();

mp.setDataSource(PATH_TO_FILE);

mp.prepare();

mp.start();

 

1.1 MediaPlayer mp = new MediaPlayer()

函数调用	文件
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)

函数调用	文件
MediaPlayer:: setDataSource	MediaPlayer.Java
MediaPlayer::setDataSource	MediaPlayer.Java
android_media_MediaPlayer_setDataSource	android_media_MediaPlayer.cpp
MediaPlayer:: setDataSource	MediaPlayer.cpp
MediaPlayer::getMediaPlayerService	MediaPlayer.cpp
IMediaPlayerService	IMediaPlayerService.h
MediaPlayerService:: [f1]	MediaPlayerService.cpp
MediaPlayerService::create	MediaPlayerService.cpp
MediaPlayerService::Client::Client	MediaPlayerService.cpp
MediaPlayerService::Client::setDataSource	MediaPlayerService.cpp
[f2]	MediaPlayerService.cpp
MediaPlayerService::Client::createPlayer	MediaPlayerService.cpp
createPlayer	MediaPlayerService.cpp
PVPlayer	PVPlayer.h
MidiFile	MidiFile.cpp
VorbisPlayer	VorbisPlayer.cpp
AudioOutput::AudioOutput	MediaPlayerService.cpp

 

1.3 mp.prepare()

函数调用	文件
MediaPlayer:: prepare	MediaPlayer.Java
MediaPlayer:: prepare	MediaPlayer.Java
android_media_MediaPlayer_ prepare	android_media_MediaPlayer.cpp
MediaPlayer:: prepare	MediaPlayer.cpp
PVPlayer:: prepare	PVPlayer.h
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()

函数调用	文件
MediaPlayer:: start	MediaPlayer.Java
MediaPlayer:: start	MediaPlayer.Java
android_media_MediaPlayer_ start	android_media_MediaPlayer.cpp
MediaPlayer:: start	MediaPlayer.cpp
PVPlayer:: start	PVPlayer.h
MidiFile:: p start	MidiFile.cpp
VorbisPlayer:: start	VorbisPlayer.cpp
AudioTrack::start	AudioTrack.cpp

---

 [f1]由systemserver进程创建，在文件system_init.cpp里的函数system_init()调用MediaPlayerService::instantiate创建

 [f2]返回3种player

PV_PLAYER:播放mp3

SONIVOX_PLAYER:播放midi

VORBIS_PLAYER:播放ogg,

简单说来，轨迹如下：

Java端发起调用，MediaPlayer会转至MediaPlayerService, 然后会调用相应的解码工具解码后创建AudioTrack，所有待输出的AudioTrack在AudioFlinger::AudioMixer里合 成，然后通过AudioHAL(AudioHardwareInterface的实际实现者)传至实际的硬件来实现播放