Don't re-scan sources if no new ones will appear

The only scenario we might need to re-scan is when switching between
bitrate variants in HTTPLiveSources.

Bug: 23313819
Change-Id: I892033c8698f985de74801c39ac5b5417ed19e89
diff --git a/media/libmediaplayerservice/nuplayer/HTTPLiveSource.cpp b/media/libmediaplayerservice/nuplayer/HTTPLiveSource.cpp
index 126625a..3fffdc1a 100644
--- a/media/libmediaplayerservice/nuplayer/HTTPLiveSource.cpp
+++ b/media/libmediaplayerservice/nuplayer/HTTPLiveSource.cpp
@@ -101,15 +101,20 @@
 }
 
 sp<AMessage> NuPlayer::HTTPLiveSource::getFormat(bool audio) {
-    if (mLiveSession == NULL) {
-        return NULL;
+    sp<AMessage> format;
+    status_t err = -EWOULDBLOCK;
+    if (mLiveSession != NULL) {
+        err = mLiveSession->getStreamFormat(
+                audio ? LiveSession::STREAMTYPE_AUDIO
+                      : LiveSession::STREAMTYPE_VIDEO,
+                &format);
     }
 
-    sp<AMessage> format;
-    status_t err = mLiveSession->getStreamFormat(
-            audio ? LiveSession::STREAMTYPE_AUDIO
-                  : LiveSession::STREAMTYPE_VIDEO,
-            &format);
+    if (err == -EWOULDBLOCK) {
+        format = new AMessage();
+        format->setInt32("err", err);
+        return format;
+    }
 
     if (err != OK) {
         return NULL;
diff --git a/media/libmediaplayerservice/nuplayer/NuPlayer.cpp b/media/libmediaplayerservice/nuplayer/NuPlayer.cpp
index aabe989..3420cc9 100644
--- a/media/libmediaplayerservice/nuplayer/NuPlayer.cpp
+++ b/media/libmediaplayerservice/nuplayer/NuPlayer.cpp
@@ -845,16 +845,21 @@
 
             bool mHadAnySourcesBefore =
                 (mAudioDecoder != NULL) || (mVideoDecoder != NULL);
+            bool rescan = false;
 
             // initialize video before audio because successful initialization of
             // video may change deep buffer mode of audio.
             if (mSurface != NULL) {
-                instantiateDecoder(false, &mVideoDecoder);
+                if (instantiateDecoder(false, &mVideoDecoder) == -EWOULDBLOCK) {
+                    rescan = true;
+                }
             }
 
             // Don't try to re-open audio sink if there's an existing decoder.
             if (mAudioSink != NULL && mAudioDecoder == NULL) {
-                instantiateDecoder(true, &mAudioDecoder);
+                if (instantiateDecoder(true, &mAudioDecoder) == -EWOULDBLOCK) {
+                    rescan = true;
+                }
             }
 
             if (!mHadAnySourcesBefore
@@ -881,8 +886,7 @@
                 break;
             }
 
-            if ((mAudioDecoder == NULL && mAudioSink != NULL)
-                    || (mVideoDecoder == NULL && mSurface != NULL)) {
+            if (rescan) {
                 msg->post(100000ll);
                 mScanSourcesPending = true;
             }
@@ -1519,7 +1523,12 @@
     sp<AMessage> format = mSource->getFormat(audio);
 
     if (format == NULL) {
-        return -EWOULDBLOCK;
+        return UNKNOWN_ERROR;
+    } else {
+        status_t err;
+        if (format->findInt32("err", &err) && err) {
+            return err;
+        }
     }
 
     format->setInt32("priority", 0 /* realtime */);
diff --git a/media/libstagefright/httplive/LiveSession.cpp b/media/libstagefright/httplive/LiveSession.cpp
index 1557401..cebf95c 100644
--- a/media/libstagefright/httplive/LiveSession.cpp
+++ b/media/libstagefright/httplive/LiveSession.cpp
@@ -477,7 +477,7 @@
     sp<MetaData> meta = packetSource->getFormat();
 
     if (meta == NULL) {
-        return -EAGAIN;
+        return -EWOULDBLOCK;
     }
 
     if (stream == STREAMTYPE_AUDIO) {