麻黄附子细辛汤。:stagefright框架(二)- 和OpenMAX的运作

来源:百度文库 编辑:九乡新闻网 时间:2024/04/24 14:58:01
Stagefright的编解码功能是利用OpenMAX框架,而且用的还是OpenCORE之OMX的实作,我們来看一下Stagefright和OMX是如何运作的。
(1) OMX_Init
OMXClient mClient;
AwesomePlayer::AwesomePlayer()
{
mClient.connect();
}
status_t OMXClient::connect()
{
mOMX = service->getOMX();
}
sp MediaPlayerService::getOMX()
{
mOMX = new OMX;
}
OMX::OMX() : mMaster(new OMXMaster)
OMXMaster::OMXMaster()
{
addPlugin(new OMXPVCodecsPlugin);
}
OMXPVCodecsPlugin::OMXPVCodecsPlugin()
{
OMX_MasterInit();
}
OMX_ERRORTYPE OMX_MasterInit() <-- under OpenCORE
{
return OMX_Init();
}
(2) OMX_SendCommand
OMXCodec::function_name()
{
mOMX->sendCommand(mNode, OMX_CommandStateSet, OMX_StateIdle);
}
status_t OMX::sendCommand(node, cmd, param)
{
return findInstance(node)->sendCommand(cmd, param);
}
status_t OMXNodeInstance::sendCommand(cmd, param)
{
OMX_SendCommand(mHandle, cmd, param, NULL);
}
(3) 其他作用在 OMX 元件的指令
其他作用在OMX元件的指令也和OMX_SendCommand的call path一样,请见下表:
OMXCodec
OMX
OMXNodeInstance
useBuffer
useBuffer (OMX_UseBuffer)
getParameter
getParameter (OMX_GetParameter)
fillBuffer
fillBuffer (OMX_FillThisBuffer)
emptyBuffer
emptyBuffer (OMX_EmptyThisBuffer)

(4) Callback Functions
OMX_CALLBACKTYPE OMXNodeInstance::kCallbacks =
{
&OnEvent, <--------------- omx_message::EVENT
&OnEmptyBufferDone, <----- omx_message::EMPTY_BUFFER_DONE
&OnFillBufferDone <------- omx_message::FILL_BUFFER_DONE
}