Stagefright: NuPlayer implementations

Question

I am going through the NuPlayer implementations in Android Stagefright. As per my understanding NuPlayerFactory is creating NuPlayerDriver in turn it creates ALooper and NuPlayer. I Couldn't understand ALooper and what does it do. I can see all the implementations in NuPlayer are invoking AMessage calls e.g as below:

NuPlyercpp: new AMessage(kWhatSourceNotify, id());

I am not sure how does it trigger NuPlayer::onMessageReceived(). Could readers please explain?

The ALooper / AMessage stuff is used to pass messages between threads. — fadden, May 18 '14 at 17:03

score 2 · Accepted Answer · edited May 19 '14 at 05:12

2

In NuPlayerDriver constructor, you see

mPlayer = new NuPlayer;
mLooper->registerHandler(mPlayer);

This ALooper::registerHandler() uses a global ALooperRoster to remember the relation between a handler (mPlayer) and a looper (mLooper).

In NuPlyer.cpp, the general pattern is:

sp<AMessage> msg = new AMessage(..., id());
....
msg->post();

AMessage::post() calls the global ALooperRoster to post the message with 0 delay, using the relation that was established in NuPlayerDriver constructor.

edited May 19 '14 at 05:12

Ganesh

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answered May 18 '14 at 21:01

Alex Cohn

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@Ganesh: thanks for the enhancements, but I am not sure it was worth the effort. – Alex Cohn May 19 '14 at 09:43

Stagefright: NuPlayer implementations

1 Answers1