Various improvements to nuplayer playback

- Drastically cut down the number of times we supply the AudioSink with data
by estimating the time until the sink would run out of data and then scheduling
a refill in advance of that.

- Use a dedicated looper for video decoders since they are currently taking
too long to return from OMX_FillThisBuffer (bug 5325201)

- Revise thread priorities for the OMX dispatcher and software codecs, instead
of running them at ANDROID_PRIORITY_AUDIO, they now only run at
ANDROID_PRIORITY_FOREGROUND

- Since threads created by pthread_create inherit all of the parent threads
attributes including thread priority, briefly reset thread priority to
ANDROID_PRIORITY_FOREGROUND before instantiating OMX components and then
restore it.

Change-Id: If9332a3a20dad5485333d68c11de0d2d5d3fffc3
diff --git a/media/libmediaplayerservice/nuplayer/NuPlayerDecoder.cpp b/media/libmediaplayerservice/nuplayer/NuPlayerDecoder.cpp
index 81b41ef..56c2773 100644
--- a/media/libmediaplayerservice/nuplayer/NuPlayerDecoder.cpp
+++ b/media/libmediaplayerservice/nuplayer/NuPlayerDecoder.cpp
@@ -59,8 +59,21 @@
         format->setObject("native-window", mNativeWindow);
     }
 
+    // Current video decoders do not return from OMX_FillThisBuffer
+    // quickly, violating the OpenMAX specs, until that is remedied
+    // we need to invest in an extra looper to free the main event
+    // queue.
+    bool needDedicatedLooper = !strncasecmp(mime, "video/", 6);
+
     mCodec = new ACodec;
-    looper()->registerHandler(mCodec);
+
+    if (needDedicatedLooper && mCodecLooper == NULL) {
+        mCodecLooper = new ALooper;
+        mCodecLooper->setName("NuPlayerDecoder");
+        mCodecLooper->start(false, false, ANDROID_PRIORITY_AUDIO);
+    }
+
+    (needDedicatedLooper ? mCodecLooper : looper())->registerHandler(mCodec);
 
     mCodec->setNotificationMessage(notifyMsg);
     mCodec->initiateSetup(format);