1 Player的组成
OpenCore的Player的编译文件是pvplayer/Android.mk,将生成动态库文件
libopencoreplayer.so。这个库包含了两方面的内容:一方是Player的engine(引擎),一方面是为
Android构件的Player,这实际上是一个适配器(adapter)。engine的路径是engine/player;adapter的路径是
android。
2 Player Engine部分
OpenCore
的
Player Engine
具有清晰明确的接口。在这个接口之上,不同的系统可以根据自己的情况实现不同
Player
。目录
engines
中的文件结构如下所示:
engines/player/
|-- Android.mk
|-- build
| |-- linux_nj
| |-- make
| `-- makefile.conf
|-- config
| `-- linux_nj
|-- include
| |-- pv_player_datasink.h
| |-- pv_player_datasinkfilename.h
| |-- pv_player_datasinkpvmfnode.h
| |-- pv_player_datasource.h
| |-- pv_player_datasourcepvmfnode.h
| |-- pv_player_datasourceurl.h
| |-- pv_player_events.h
| |-- pv_player_factory.h
| |-- pv_player_interface.h
| |-- pv_player_license_acquisition_interface.h
| |-- pv_player_registry_interface.h
| |-- pv_player_track_selection_interface.h
| `-- pv_player_types.h
|-- sample_app
| |-- Android.mk
| |-- build
| |-- sample_player_app_release.txt
| `-- src
|-- src
| |-- pv_player_datapath.cpp
| |-- pv_player_datapath.h
| |-- pv_player_engine.cpp
| |-- pv_player_engine.h
| |-- pv_player_factory.cpp
| |-- pv_player_node_registry.h
| `-- pv_player_sdkinfo.h
`-- test
|-- Android.mk
|-- build
|-- config
`-- src
其中,engines/player/include目录中是接口头文件,engines/player/src目录源文件和私有头文件,主要头文件的功能如下所示:
pv_player_types.h
:定义一些数据结构和枚举值
pv_player_events.h
:定义UUID和一些错误值。
pv_player_datasink.h
:datasink
是媒体数据的输出
,
定义类
PVPlayerDataSink
,
这是媒体数据输出的基类
,
作为接口使用
pv_player_datasinkfilename.h
:
定义类
PVPlayerDataSinkFilename
继承
PVPlayerDataSink
。
pv_player_datasinkpvmfnode.h
:
定义类
PVPlayerDataSinkPVMFNode
继承
PVPlayerDataSink
。
pv_player_datasource.h
:datasource
是媒体数据的输入
,
定义类
PVPlayerDataSource
,这是媒体数据输入的基类,作为接口使用。
pv_player_datasourcepvmfnode.h
:定义类PVPlayerDataSourcePVMFNode继承PVPlayerDataSource。
pv_player_datasourceurl.h
:定义类PVPlayerDataSourceURL继承PVPlayerDataSource。
pv_player_interface.h
:
定义
Player
的接口
PVPlayerInterface
,
这是一个接口类。
pv_player_factory.h
:
主要定义工厂类
PVPlayerFactory
,用于创建和销毁PVPlayerInterface。
事实上,在engines/player/src
目录中
,
主要实现类为
pv_player_engine.cpp
,
其中定义了类
PVPlayerEngine
,PVPlayerEngine继承了PVPlayerInterface,这是一个实现类,在PVPlayerFactory创建PVPlayerInterface接口的时候,实际创建的是PVPlayerEngine。
在
Player Engine
的实现中,包含了编解码和流控制等功能,而输出的介质需要从外部设置进来。
PVPlayerInterface
定义的接口基本是按照操作顺序的,主要的接口如下所示:
在Player Engine的实现中,包含了编解码和流控制等功能,而输出的介质需要从外部设置进来。PVPlayerInterface定义的接口基本是按照操作顺序的,主要的接口如下所示:
PVCommandId AddDataSource(PVPlayerDataSource& aDataSource, const OsclAny* aContextData = NULL);
PVCommandId Init(const OsclAny* aContextData = NULL);
PVCommandId AddDataSink(PVPlayerDataSink& aDataSink, const OsclAny* aContextData = NULL);
PVCommandId Prepare(const OsclAny* aContextData = NULL);
PVCommandId Start(const OsclAny* aContextData = NULL);
PVCommandId Pause(const OsclAny* aContextData = NULL);
PVCommandId Resume(const OsclAny* aContextData = NULL);
PVCommandId Stop(const OsclAny* aContextData = NULL);
PVCommandId RemoveDataSink(PVPlayerDataSink& aDataSink, const OsclAny* aContextData = NULL);
PVCommandId Reset(const OsclAny* aContextData = NULL);
PVCommandId RemoveDataSource(PVPlayerDataSource& aDataSource, const OsclAny* aContextData = NULL);
这里面的DataSink可能包含Video的输出和Audio的输出两者部分。在pv_player_types.h文件中,定义了Player的状态机,以PVP_STATE_为开头,如下所示:
typedef enum
{
PVP_STATE_IDLE = 1,
PVP_STATE_INITIALIZED = 2,
PVP_STATE_PREPARED = 3,
PVP_STATE_STARTED = 4,
PVP_STATE_PAUSED = 5,
PVP_STATE_ERROR = 6
} PVPlayerState;
PVPlayerInterface
中的各个操作如果成功,可以更改Player的状态机:初始化的时候Player是PVP_STATE_IDLE状态,调用Init后,进入
PVP_STATE_INITIALIZED状态;调用AddDataSink,进入PVP_STATE_PREPARED状态;调用Prepare后,
进入PVP_STATE_PREPARED状态;调用start后进入PVP_STATE_STARTED状态,之后可以调用
pause进入PVP_STATE_PAUSED状态。
PVP_STATE_STARTED和PVP_STATE_PAUSED状态是播放情况下的状态,可以使用start和pause函数在这两个状态中切换。
在播放过程中,调用stop可以返回PVP_STATE_INITIALIZED状态,在调用RemoveDataSource返回PVP_STATE_IDLE状态。
3 Android Player Adapter
在android目录中定义为Player的适配器,这个目录主要包含的文件如下所示:
android
|-- Android.mk
|-- android_audio_mio.cpp
|-- android_audio_mio.h
|-- android_audio_output.cpp
|-- android_audio_output.h
|-- android_audio_output_threadsafe_callbacks.cpp
|-- android_audio_output_threadsafe_callbacks.h
|-- android_audio_stream.cpp
|-- android_audio_stream.h
|-- android_log_appender.h
|-- android_surface_output.cpp
|-- android_surface_output.h
|-- mediascanner.cpp
|-- metadatadriver.cpp
|-- metadatadriver.h
|-- playerdriver.cpp
|-- playerdriver.h
`-- thread_init.cpp
这个Android的Player的“适配器”需要调用OpenCore的Player
Engine的接口,实现Android的媒体播放器的服务所需要接口,即最终实现一个PVPlayer,而PVPlayer实际上是继承了
MediaPlayerInterface。
在实现过程中,首先实现了一个PlayerDriver,然后再使用PVPlayer,PVPlayer通过调用PlayerDriver来完成具体的功能。整个实现的结构图如图所示:
对PVPlayerDriver的各种操作使用各种命令来完成,这些命令在playerdriver.h中进行的定义。
enum player_command_type {
PLAYER_QUIT = 1,
PLAYER_SETUP = 2,
PLAYER_SET_DATA_SOURCE = 3,
PLAYER_SET_VIDEO_SURFACE = 4,
PLAYER_SET_AUDIO_SINK = 5,
PLAYER_INIT = 6,
PLAYER_PREPARE = 7,
PLAYER_START = 8,
PLAYER_STOP = 9,
PLAYER_PAUSE = 10,
PLAYER_RESET = 11,
PLAYER_SET_LOOP = 12,
PLAYER_SEEK = 13,
PLAYER_GET_POSITION = 14,
PLAYER_GET_DURATION = 15,
PLAYER_GET_STATUS = 16,
PLAYER_REMOVE_DATA_SOURCE = 17,
PLAYER_CANCEL_ALL_COMMANDS = 18,
};
这些命令一般实现的是PVPlayerInterface各个接口的简单封装,例如对于较为简单的暂停播放这个操作,整个系统执行的过程如下所示:
1.在PVPlayer中的pause函数(在playerdriver.cpp文件中)
status_t PVPlayer::pause()
{
LOGV("pause");
return mPlayerDriver->enqueueCommand(new PlayerPause(0,0));
}
这时调用其成员mPlayerDriver(PlayerDriver类型)的函数,将一个PlayerPause命令加入了命令序列,具体的各种命令功能在playerdriver.h文件中。
2.PlayerDriver类的enqueueCommand将间接调用各个以handle为开头的函数,对于PlayerPause命令,调用的函数是handlePause
void PlayerDriver::handlePause(PlayerPause* ec)
{
LOGV("call pause");
mPlayer->Pause(0);
FinishSyncCommand(ec);
}
这里的mPlayer是一个PVPlayerInterface类型的指针,使用这个指针调用到了OpenCore的 Player Engine中的PVPlayerEngine类。
在这个播放器适配器的实现中,一个主要工作是
将Android框架中定义的媒体的输出(包括Audio的输出和Video的输出)转换成,OpenCore的 Player
Engine需要的形式。在这里两个重要的类是android_surface_output.cpp实现的
AndroidSurfaceOutput,android_audio_output.cpp实现的AndroidAudioOutput。
对于Video输出的设置过程,在类PlayerDriver中定义了3个成员:
PVPlayerDataSink *mVideoSink;
PVMFNodeInterface *mVideoNode;
PvmiMIOControl *mVideoOutputMIO;
这里的mVideoSink 的类型为PVPlayerDataSink,这是Player
Engine中定义的类接口,mVideoNode的类型为VMFNodeInterface,在pvmi/pvmf/include的
pvmf_node_interface.h中定义,这是所有的PVMF的NODE都需要继承的统一接口,mVideoOutputMIO的类型为
PvmiMIOControl也在pvmi/pvmf/include中定义,这是媒体图形输出控制的接口类。
1.在PVPlayer的setVideoSurface用以设置一个Video输出的界面,这里使用的参数的类型是ISurface指针:
status_t PVPlayer::setVideoSurface(const sp& surface)
{
LOGV("setVideoSurface(%p)", surface.get());
mSurface = surface;
return OK;
}
setVideoSurface函数设置的是PVPlayer中的一个成员mSurface,真正设置Video输出的界面的功能在run_set_video_surface()函数中实现:
void PVPlayer::run_set_video_surface(status_t s, void *cookie)
{
LOGV("run_set_video_surface s=%d", s);
if (s == NO_ERROR) {
PVPlayer *p = (PVPlayer*)cookie;
if (p->mSurface == NULL) {
run_set_audio_output(s, cookie);
} else {
p->mPlayerDriver->enqueueCommand(new PlayerSetVideoSurface(p->mSurface, run_set_audio_output, cookie));
}
}
}
这时使用的命令是PlayerSetVideoSurface,最终将调用到PlayerDriver中的handleSetVideoSurface函数。
2.handleSetVideoSurface函数的实现如下所示:
void PlayerDriver::handleSetVideoSurface(PlayerSetVideoSurface* ec)
{
int error = 0;
mVideoOutputMIO = new AndroidSurfaceOutput(ec->surface());
mVideoNode = PVMediaOutputNodeFactory::CreateMediaOutputNode(mVideoOutputMIO);
mVideoSink = new PVPlayerDataSinkPVMFNode;
((PVPlayerDataSinkPVMFNode *)mVideoSink)->SetDataSinkNode(mVideoNode);
((PVPlayerDataSinkPVMFNode *)mVideoSink)->SetDataSinkFormatType(PVMF_YUV420);
OSCL_TRY(error, mPlayer->AddDataSink(*mVideoSink, ec));
OSCL_FIRST_CATCH_ANY(error, commandFailed(ec));
}
在这里首先建立的创建成员mVideoOutputMIO(类型为PvmiMIOControl),这时建立的类是类
AndroidSurfaceOutput,这个类继承了PvmiMIOControl,所以可以作为PvmiMIOControl使用。然后调用
PVMediaOutputNodeFactory::CreateMediaOutputNode建立了PVMFNodeInterface
类型的mVideoNode。随后创建PVPlayerDataSinkPVMFNode类型的
mVideoSink,PVPlayerDataSinkPVMFNode本身继承了PVPlayerDataSink,因此可以作为
PVPlayerDataSink使用。调用SetDataSinkNode函数将mVideoNode设置为mVideoSink的数据输出节点。
事实上,对于Video的输出,基本的功能都是在类AndroidSurfaceOutput中完成的,在这个类当中,主要的工作是将Android的
ISurface输出作为Player
Engine的输出。最后调用了AddDataSink将mVideoSink增加为了PVPlayerInterface的输出。
在android_surface_output.cpp文件中实现了类AndroidSurfaceOutput,这个类相当于一个OpenCore
Player Engine的Video输出和Android输出的“适配器”。AndroidSurfaceOutput类本身继承了类
PvmiMIOControl,而其构造函数又以ISurface类型为参数。这个类的实现是使用ISurface实现PvmiMIOControl的各
个接口。
--------------------------------华丽的分割线-----------------------------------------
我们知道,MediaPlayerInterface接口是Android框架中承上启下的关键接口,Android下面几个播放器都是冲这个接口派生过
来的,前面在写flac的时候已经基本看了一些关于OGG
player的相关东西,但是那个只是音频,还没有涉及到视频,下面简单的介绍一下其中最复杂的PVPlayer
class PVPlayer : public MediaPlayerInterface
{
public:
PVPlayer();
virtual ~PVPlayer();
virtual status_t initCheck(); //1
virtual status_t setDataSource(const char *url);//2
virtual status_t setDataSource(int fd, int64_t offset, int64_t length);//2
virtual status_t setVideoSurface(const sp<ISurface>& surface);//3
virtual status_t prepare();//4
virtual status_t prepareAsync();//5
virtual status_t start();//5
virtual status_t stop();//6
virtual status_t pause();//6
virtual bool isPlaying();
virtual status_t seekTo(int msec);
virtual status_t getCurrentPosition(int *msec);
virtual status_t getDuration(int *msec);
virtual status_t reset();
virtual status_t setLooping(int loop);
virtual player_type playerType() { return PV_PLAYER; }
// make available to PlayerDriver
void sendEvent(int msg, int ext1=0, int ext2=0) { MediaPlayerBase::sendEvent(msg, ext1, ext2); }
private:
static void do_nothing(status_t s, void *cookie, bool cancelled) { }
static void run_init(status_t s, void *cookie, bool cancelled);
static void run_set_video_surface(status_t s, void *cookie, bool cancelled);
static void run_set_audio_output(status_t s, void *cookie, bool cancelled);
static void run_prepare(status_t s, void *cookie, bool cancelled);
PlayerDriver* mPlayerDriver;
char * mDataSourcePath;
bool mIsDataSourceSet;
sp<ISurface> mSurface;
int mSharedFd;
status_t mInit;
int mDuration;
#ifdef MAX_OPENCORE_INSTANCES
static volatile int32_t sNumInstances;
#endif
};
|
1、 virtual status_t initCheck(); //这个函数会在我们创建播放器的时候调用,可以做一些基本的初始化工作,如下所示:
sp<MediaPlayerBase> createPlayer(player_type playerType, void* cookie,
notify_callback_f notifyFunc)
{
sp<MediaPlayerBase> p;
switch (playerType) {
case PV_PLAYER:
LOGV(" create PVPlayer");
p = new PVPlayer();
break;
case SONIVOX_PLAYER:
LOGV(" create MidiFile");
p = new MidiFile();
break;
case VORBIS_PLAYER:
LOGV(" create VorbisPlayer");
p = new VorbisPlayer();
break;
}
if (p != NULL) {
if (p->initCheck() == NO_ERROR) {
p->setNotifyCallback(cookie, notifyFunc);
} else {
p.clear();
}
}
if (p == NULL) {
LOGE("Failed to create player object");
}
return p;
}
|
发现还有setNotifyCallback函数也会一起调用。
2、 两种设置源的方式 setDataSource,一个是打开一个文件重头开始,一个事从文件的中间开始。
status_t MediaPlayerService::Client::setDataSource(const char *url)
{
LOGV("setDataSource(%s)", url);
if (url == NULL)
return UNKNOWN_ERROR;
if (strncmp(url, "content://", 10) == 0) {
// get a filedescriptor for the content Uri and
// pass it to the setDataSource(fd) method
String16 url16(url);
int fd = android::openContentProviderFile(url16);//.content.......
if (fd < 0)
{
LOGE("Couldn't open fd for %s", url);
return UNKNOWN_ERROR;
}
setDataSource(fd, 0, 0x7fffffffffLL); // this sets mStatus
close(fd);
return mStatus;
} else {
player_type playerType = getPlayerType(url);
LOGV("player type = %d", playerType);
// create the right type of player
sp<MediaPlayerBase> p = createPlayer(playerType);
if (p == NULL) return NO_INIT;
if (!p->hardwareOutput()) {
mAudioOutput = new AudioOutput();
static_cast<MediaPlayerInterface*>(p.get())->setAudioSink(mAudioOutput);
}
// now set data source
LOGV(" setDataSource");
mStatus = p->setDataSource(url);
if (mStatus == NO_ERROR) mPlayer = p;
return mStatus;
}
}
status_t MediaPlayerService::Client::setDataSource(int fd, int64_t offset, int64_t length)
{
LOGV("setDataSource fd=%d, offset=%lld, length=%lld", fd, offset, length);
struct stat sb;
int ret = fstat(fd, &sb);
if (ret != 0) {
LOGE("fstat(%d) failed: %d, %s", fd, ret, strerror(errno));
return UNKNOWN_ERROR;
}
LOGV("st_dev = %llu", sb.st_dev);
LOGV("st_mode = %u", sb.st_mode);
LOGV("st_uid = %lu", sb.st_uid);
LOGV("st_gid = %lu", sb.st_gid);
LOGV("st_size = %llu", sb.st_size);
if (offset >= sb.st_size) {
LOGE("offset error");
::close(fd);
return UNKNOWN_ERROR;
}
if (offset + length > sb.st_size) {
length = sb.st_size - offset;
LOGV("calculated length = %lld", length);
}
player_type playerType = getPlayerType(fd, offset, length);
LOGV("player type = %d", playerType);
// create the right type of player
sp<MediaPlayerBase> p = createPlayer(playerType);
if (p == NULL) return NO_INIT;
if (!p->hardwareOutput()) {
mAudioOutput = new AudioOutput();
static_cast<MediaPlayerInterface*>(p.get())->setAudioSink(mAudioOutput);
}
// now set data source
mStatus = p->setDataSource(fd, offset, length);
if (mStatus == NO_ERROR) mPlayer = p;
return mStatus;
}
|
3 、
status_t MediaPlayerService::Client::setVideoSurface(const sp<ISurface>& surface)
{
LOGV("[%d] setVideoSurface(%p)", mConnId, surface.get());
sp<MediaPlayerBase> p = getPlayer();
if (p == 0) return UNKNOWN_ERROR;
return p->setVideoSurface(surface);
}
|
//
由此可见,其实框架把显示的功能并没有替你做下来,因为这个地方很多p->setVideoSurface(surface);返回值都是空的,这
个函数只是给你一个接口,把上层的一个
sp
给你,至于你在他上面画什么东西,是你的事情,如果你调用这个函数就有,不调用就没有,很明白简单。所以说,显示的
工作还得自己来做。
4、5、 都是设置了源,但是在播放前的一些准备工作,一个是同步,一个是异步。
sp<IMemory> MediaPlayerService::decode(const char* url, uint32_t *pSampleRate, int* pNumChannels, int* pFormat)
{
LOGV("decode(%s)", url);
sp<MemoryBase> mem;
sp<MediaPlayerBase> player;
// Protect our precious, precious DRMd ringtones by only allowing
// decoding of http, but not filesystem paths or content Uris.
// If the application wants to decode those, it should open a
// filedescriptor for them and use that.
if (url != NULL && strncmp(url, "http:// ", 7) != 0) {
LOGD("Can't decode %s by path, use filedescriptor instead", url);
return mem;
}
player_type playerType = getPlayerType(url);
LOGV("player type = %d", playerType);
// create the right type of player
sp<AudioCache> cache = new AudioCache(url);
player = android::createPlayer(playerType, cache.get(), cache->notify);
if (player == NULL) goto Exit;
if (player->hardwareOutput()) goto Exit;
static_cast<MediaPlayerInterface*>(player.get())->setAudioSink(cache);
// set data source
if (player->setDataSource(url) != NO_ERROR) goto Exit;
LOGV("prepare");
player->prepareAsync();
LOGV("wait for prepare");
if (cache->wait() != NO_ERROR) goto Exit;
LOGV("start");
player->start();
LOGV("wait for playback complete");
if (cache->wait() != NO_ERROR) goto Exit;
mem = new MemoryBase(cache->getHeap(), 0, cache->size());
*pSampleRate = cache->sampleRate();
*pNumChannels = cache->channelCount();
*pFormat = cache->format();
LOGV("return memory @ %p, sampleRate=%u, channelCount = %d, format = %d", mem->pointer(), *pSampleRate, *pNumChannels, *pFormat);
Exit:
if (player != 0) player->reset();
return mem;
}
|
这个工程有这样几步,准备,然后等待准备完成,然后开始,然后等待start完成,完成之后就可以得到解码后的数据。上面的几个接口函数基本上是没有什么东西的,下面我们具体来看这个PVPlayer怎么实现的。主要看他的几个私有函数:
static void do_nothing(status_t s, void *cookie, bool cancelled) { }
static void run_init(status_t s, void *cookie, bool cancelled);
static void run_set_video_surface(status_t s, void *cookie, bool cancelled);
static void run_set_audio_output(status_t s, void *cookie, bool cancelled);
static void run_prepare(status_t s, void *cookie, bool cancelled);
和几个私有成员;
PlayerDriver* mPlayerDriver; //整个pv的播放引擎
char * mDataSourcePath;//数据源
bool mIsDataSourceSet;//一个数据源的标识符
sp mSurface;//显示面
int mSharedFd; //这个估计是文件句柄
status_t mInit; //一个状态标志
int mDuration; //文件播放长度
我们来看实现:
// ----------------------------------------------------------------------------
// implement the Packet Video player
// ----------------------------------------------------------------------------
PVPlayer::PVPlayer()
{
LOGV("PVPlayer constructor");
mDataSourcePath = NULL;
mSharedFd = -1;
mIsDataSourceSet = false;
mDuration = -1;
mPlayerDriver = NULL;
LOGV("construct PlayerDriver");
mPlayerDriver = new PlayerDriver(this);
LOGV("send PLAYER_SETUP");
mInit = mPlayerDriver->enqueueCommand(new PlayerSetup(0,0));//................
}
status_t PVPlayer::initCheck()
{
return mInit;
}.......................
PVPlayer::~PVPlayer()
{
LOGV("PVPlayer destructor");
if (mPlayerDriver != NULL) {
PlayerQuit quit = PlayerQuit(0,0);//.........
mPlayerDriver->enqueueCommand(&quit); // will wait on mSyncSem, signaled by player thread
}
free(mDataSourcePath); //..............
if (mSharedFd >= 0) {
close(mSharedFd);
}
}
status_t PVPlayer::setDataSource(const char *url)
{
LOGV("setDataSource(%s)", url);
if (mSharedFd >= 0) {
close(mSharedFd);
mSharedFd = -1;
}
free(mDataSourcePath);
mDataSourcePath = NULL;
// Don't let somebody trick us in to reading some random block of memory
if (strncmp("sharedfd://", url, 11) == 0)
return android::UNKNOWN_ERROR;
mDataSourcePath = strdup(url);
return OK;
} //...........mDataSourcePath..........opencore.........
status_t PVPlayer::setDataSource(int fd, int64_t offset, int64_t length) {
// This is all a big hack to allow PV to play from a file descriptor.
// Eventually we'll fix PV to use a file descriptor directly instead
// of using mmap().
LOGV("setDataSource(%d, %lld, %lld)", fd, offset, length);
if (mSharedFd >= 0) {
close(mSharedFd);
mSharedFd = -1;
}
free(mDataSourcePath);
mDataSourcePath = NULL;
char buf[80];
mSharedFd = dup(fd);
sprintf(buf, "sharedfd://%d:%lld:%lld", mSharedFd, offset, length);
mDataSourcePath = strdup(buf);
return OK;
}
|
然后是:
status_t PVPlayer::setVideoSurface(const sp& surface)
{
LOGV("setVideoSurface(%p)", surface.get());
mSurface = surface;
return OK;
}
然后是prepare,这个函数如果你在setsource里面没有做什么事情的话,这个里面就开始忙了
status_t PVPlayer::prepare()
{
status_t ret;
// We need to differentiate the two valid use cases for prepare():
// 1. new PVPlayer/reset()->setDataSource()->prepare()
// 2. new PVPlayer/reset()->setDataSource()->prepare()/prepareAsync()
// ->start()->...->stop()->prepare()
// If data source has already been set previously, no need to run
// a sequence of commands and only the PLAYER_PREPARE command needs
// to be run.
if (!mIsDataSourceSet) {//首先看我们的源设置了没有,需不需要重新设置
// set data source
LOGV("prepare");
LOGV(" data source = %s", mDataSourcePath);
ret = mPlayerDriver->enqueueCommand(new PlayerSetDataSource(mDataSourcePath,0,0));//如果需要,首先发送设置源的命令
if (ret != OK)
return ret;
// init然后是初始化的命令
LOGV(" init");
ret = mPlayerDriver->enqueueCommand(new PlayerInit(0,0));
if (ret != OK)
return ret;
// set video surface, if there is one然后设置显示面
if (mSurface != NULL) {
LOGV(" set video surface");
ret = mPlayerDriver->enqueueCommand(new PlayerSetVideoSurface(mSurface,0,0));
if (ret != OK)
return ret;
}
// set audio output然后设置音频
// If we ever need to expose selectable audio output setup, this can be broken
// out. In the meantime, however, system audio routing APIs should suffice.
LOGV(" set audio sink");
ret = mPlayerDriver->enqueueCommand(new PlayerSetAudioSink(mAudioSink,0,0));
if (ret != OK)
return ret;
// New data source has been set successfully.
mIsDataSourceSet = true;
}
// prepare 一些列的搞好了之后,才发送准备命令
LOGV(" prepare");
return mPlayerDriver->enqueueCommand(new PlayerPrepare(0,0));
}
如果是异步的话 就涉及到回调
status_t PVPlayer::prepareAsync()
{
LOGV("prepareAsync");
status_t ret = OK;
if (!mIsDataSourceSet) { // If data source has NOT been set.
// Set our data source as cached in setDataSource() above.
LOGV(" data source = %s", mDataSourcePath);
ret = mPlayerDriver->enqueueCommand(new PlayerSetDataSource(mDataSourcePath,run_init,this));
//这里设置了一个回调函数run_init,表明我们的setdatasource完成后会干哈,
mIsDataSourceSet = true;
} else { // If data source has been already set.
// No need to run a sequence of commands.
// The only command needed to run is PLAYER_PREPARE.
ret = mPlayerDriver->enqueueCommand(new PlayerPrepare(do_nothing, NULL));
}
return ret;
}
初始化的函数
void PVPlayer::run_init(status_t s, void *cookie, bool cancelled)
{
LOGV("run_init s=%d, cancelled=%d", s, cancelled);
if (s == NO_ERROR && !cancelled) {
PVPlayer *p = (PVPlayer*)cookie;
p->mPlayerDriver->enqueueCommand(new PlayerInit(run_set_video_surface, cookie));
}//这里发现初始化完成之后还有下步run_set_video_surface
}
void PVPlayer::run_set_video_surface(status_t s, void *cookie, bool cancelled)
{
LOGV("run_set_video_surface s=%d, cancelled=%d", s, cancelled);
if (s == NO_ERROR && !cancelled) {
// If we don't have a video surface, just skip to the next step.
PVPlayer *p = (PVPlayer*)cookie;
if (p->mSurface == NULL) {
run_set_audio_output(s, cookie, false);
} else {
p->mPlayerDriver->enqueueCommand(new PlayerSetVideoSurface(p->mSurface, run_set_audio_output, cookie));
//设置视频之后还要run_set_audio_output
}
}
}
void PVPlayer::run_set_audio_output(status_t s, void *cookie, bool cancelled)
{
LOGV("run_set_audio_output s=%d, cancelled=%d", s, cancelled);
if (s == NO_ERROR && !cancelled) {
PVPlayer *p = (PVPlayer*)cookie;
p->mPlayerDriver->enqueueCommand(new PlayerSetAudioSink(p->mAudioSink, run_prepare, cookie));
}
}
void PVPlayer::run_prepare(status_t s, void *cookie, bool cancelled)
{
LOGV("run_prepare s=%d, cancelled=%d", s, cancelled);
if (s == NO_ERROR && !cancelled) {
PVPlayer *p = (PVPlayer*)cookie;
p->mPlayerDriver->enqueueCommand(new PlayerPrepare(do_nothing,0));
}
}
最后才是do_nothing,把同步做的事情分成几步来做了。
剩下的基本都是很简单的,就是发送一条又一条的命令即可,其实主要的操作,都在PlayerDriver中。
下
面我们来简单的看看这个PlayerDriver,这个事实现播放的主要成员,首先他是一个管理器,他管理者OpenCore的整个框架,最后的输出的
MIO,其次,他是一个异步的东东,存在着一个命令的队列。这个里面虽然代码很多,但是思路很清晰,我们就不一一的列出来,这个里面主要的播放功能被封装
到一个叫PVPlayerInterface的接口中了。
这里我们首先分析它的视频显示,在接收到设置显示面的时候,有这样的一个处理:
// if no device-specific MIO was created, use the generic one
if (mio == NULL) {
LOGW("Using generic video MIO");
mio = new AndroidSurfaceOutput();
}
// initialize the MIO parameters
status_t ret = mio->set(mPvPlayer, command->surface(), mEmulation);
if (ret != NO_ERROR) {
LOGE("Video MIO set failed");
commandFailed(command);
delete mio;
return;
}
mVideoOutputMIO = mio;
mVideoNode = PVMediaOutputNodeFactory::CreateMediaOutputNode(mVideoOutputMIO);
mVideoSink = new PVPlayerDataSinkPVMFNode;
((PVPlayerDataSinkPVMFNode *)mVideoSink)->SetDataSinkNode(mVideoNode);
((PVPlayerDataSinkPVMFNode *)mVideoSink)->SetDataSinkFormatType(PVMF_YUV420);
OSCL_TRY(error, mPlayer->AddDataSink(*mVideoSink, command));
这
个mPlayer就是一个PVPlayerInterface的成员。在opencore中我们的最终都是要封装成NODE的,MIO可以属于
NODE,MIO主要负责和硬件打交道的一部分,这几行代码首先创建一个AndroidSurfaceOutput的MIO,创建了之后设置一些基本的属
性set函数,然后,由MIO创建OutPutNode,这就是一个NOde了,这个东东创建了之后,就要把这个Node添加到整个数据链路中,并且设置
一下基本的属性。这样我们的输出Node就添加到了数据链路中了,那么我们的MIO是如何工作的呢?
创建MIO之后有这样的一个函数
status_t AndroidSurfaceOutput::set(PVPlayer* pvPlayer, const sp& surface, bool emulation)
{
mPvPlayer = pvPlayer;
mSurface = surface;
mEmulation = emulation;
return NO_ERROR;
}
这个函数就设置了我们Vedio out MIO最主要的几个属性,一个是pvPlayer,一个是surface,最后的一个参数应该是表明是不是模拟器。
我们来看看这个MIO。关于MIO前面我们基本已经讲过,可能没有放在blog上。一般由这几个接口派生:
public OsclTimerObject, public PvmiMIOControl,
public PvmiMediaTransfer, public PvmiCapabilityAndConfig
但是作为一个视频输出的MIO,这里有几个自己特色的函数:
// For frame buffer
virtual bool initCheck();
virtual PVMFStatus writeFrameBuf(uint8* aData, uint32 aDataLen, const PvmiMediaXferHeader& data_header_info);
virtual void postLastFrame();
virtual void closeFrameBuf();
bool GetVideoSize(int *w, int *h);
我们一跳一条的分析:
首先是initCheck,这个函数什么时候开始调用?
// create a frame buffer for software codecs
OSCL_EXPORT_REF bool AndroidSurfaceOutput::initCheck()
{
// initialize only when we have all the required parameters
//首先看看是不是视频相关的属性发生改变了,如果不是视频就不用管他,直接返回
if (!checkVideoParameterFlags())
return mInitialized;
// release resources if previously initialized 删除以前分配的缓存
closeFrameBuf();
// reset flags in case display format changes in the middle of a stream
resetVideoParameterFlags(); //视频改变的标志位还原
// copy parameters in case we need to adjust them
//得到新的宽和高,(包括视频和显示器,我们在横屏的时候就可以这样搞)
int displayWidth = iVideoDisplayWidth;
int displayHeight = iVideoDisplayHeight;
int frameWidth = iVideoWidth;
int frameHeight = iVideoHeight;
int frameSize;
// RGB-565 frames are 2 bytes/pixel //因为我们的数据都是565的16位的像素点
//&-2 表明取偶数
displayWidth = (displayWidth + 1) & -2;
displayHeight = (displayHeight + 1) & -2;
frameWidth = (frameWidth + 1) & -2;
frameHeight = (frameHeight + 1) & -2;
frameSize = frameWidth * frameHeight * 2;
// create frame buffer heap and register with surfaceflinger //然后分配两帧的数据
mFrameHeap = new MemoryHeapBase(frameSize * kBufferCount);
if (mFrameHeap->heapID() < 0) {
LOGE("Error creating frame buffer heap");
return false;
}
//分配之后把数据指明给buffer,这样我们的buffer是到是一个什么样的格式,长和宽分别是多少
ISurface::BufferHeap buffers(displayWidth, displayHeight,
frameWidth, frameHeight, PIXEL_FORMAT_RGB_565, mFrameHeap);
//然后注册这个buffer
mSurface->registerBuffers(buffers);
// create frame buffers
//mFrameBuffers[i]保存的是第I帧的起始位置
for (int i = 0; i < kBufferCount; i++) {
mFrameBuffers[i] = i * frameSize;
}
//然后初始化视频数据转换器
// initialize software color converter
iColorConverter = ColorConvert16::NewL();
iColorConverter->Init(displayWidth, displayHeight, frameWidth, displayWidth, displayHeight, displayWidth, CCROTATE_NONE);
iColorConverter->SetMemHeight(frameHeight);
iColorConverter->SetMode(1);
LOGV("video = %d x %d", displayWidth, displayHeight);
LOGV("frame = %d x %d", frameWidth, frameHeight);
LOGV("frame #bytes = %d", frameSize);
// register frame buffers with SurfaceFlinger
mFrameBufferIndex = 0;
mInitialized = true;
mPvPlayer->sendEvent(MEDIA_SET_VIDEO_SIZE, iVideoDisplayWidth, iVideoDisplayHeight);
return mInitialized;
}
然后我们的东东就搞定了。
第二个函数:writeFrameBuf这个函数是什么时候用的呢?我们前面看MIO的时候就已经知道MIO的数据传递是通过队列的方式,消息和数据可以再一个队列里传输。在MIO的writeAsync函数中有这样的一个case:
case PVMI_MEDIAXFER_FMT_TYPE_DATA :
switch(aFormatIndex)
{
case PVMI_MEDIAXFER_FMT_INDEX_FMT_SPECIFIC_INFO:
……………………
case PVMI_MEDIAXFER_FMT_INDEX_DATA:
//data contains the media bitstream.
//Verify the state
if (iState!=STATE_STARTED)
{
PVLOGGER_LOGMSG(PVLOGMSG_INST_REL, iLogger, PVLOGMSG_ERR,
(0,"AndroidSurfaceOutput::writeAsync: Error - Invalid state"));
status=PVMFErrInvalidState;
}
else
{
//printf("V WriteAsync { seq=%d, ts=%d }\n", data_header_info.seq_num, data_header_info.timestamp);
// Call playback to send data to IVA for Color Convert
status = writeFrameBuf(aData, aDataLen, data_header_info);
PVLOGGER_LOGMSG(PVLOGMSG_INST_REL, iLogger, PVLOGMSG_ERR,
(0,"AndroidSurfaceOutput::writeAsync: Playback Progress - frame %d",iFrameNumber++));
}
break;
这个地方就开始调用我们的画屏幕的函数。这个时候就是我们接受到一帧数据的时候,注意我们这里基本上音频和视频的同步在NODE框架中已经做了,这里能够收到数据,叫表明一定是要显示的数据,不用考虑什么音视频同步了。
OSCL_EXPORT_REF
PVMFStatus AndroidSurfaceOutput::writeFrameBuf(uint8* aData, uint32
aDataLen, const PvmiMediaXferHeader& data_header_info)
{
if (mSurface == 0) return PVMFFailure;
if (++mFrameBufferIndex == kBufferCount) mFrameBufferIndex = 0;
iColorConverter->Convert(aData, static_cast(mFrameHeap->base()) + mFrameBuffers[mFrameBufferIndex]);
// post to SurfaceFlinger
mSurface->postBuffer(mFrameBuffers[mFrameBufferIndex]);
return PVMFSuccess;
}
这个函数其实很简单,直接把对应的数据转换到我们显示屏支持的,然后直接postBuffer即可显示。
看下面的一个函数:
// post the last video frame to refresh screen after pause
void AndroidSurfaceOutput::postLastFrame()
{
mSurface->postBuffer(mFrameBuffers[mFrameBufferIndex]);
}
把数据显示在屏幕上。在暂停的时候,这个函数就可以调用,我们的视频会不变。
OSCL_EXPORT_REF void AndroidSurfaceOutput::closeFrameBuf()
{
LOGV("closeFrameBuf");
if (!mInitialized) return;
mInitialized = false;
if (mSurface.get()) {
LOGV("unregisterBuffers");
mSurface->unregisterBuffers();
mSurface.clear();
}
// free frame buffers
LOGV("free frame buffers");
for (int i = 0; i < kBufferCount; i++) {
mFrameBuffers[i] = 0;
}
// free heaps
LOGV("free mFrameHeap");
mFrameHeap.clear();
// free color converter
if (iColorConverter != 0)
{
LOGV("free color converter");
delete iColorConverter;
iColorConverter = 0;
}
}
这个函数前面已经说过,是一个简单的清空操作。
OSCL_EXPORT_REF bool AndroidSurfaceOutput::GetVideoSize(int *w, int *h) {
*w = iVideoDisplayWidth;
*h = iVideoDisplayHeight;
return iVideoDisplayWidth != 0 && iVideoDisplayHeight != 0;
}
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