stagefright: detect output format changes without event

Bug: 27688967
Change-Id: I538560e61928903160333866886dbc763503546f
diff --git a/include/media/stagefright/ACodec.h b/include/media/stagefright/ACodec.h
index bc11da2..fab92bd 100644
--- a/include/media/stagefright/ACodec.h
+++ b/include/media/stagefright/ACodec.h
@@ -506,7 +506,10 @@
     void notifyOfRenderedFrames(
             bool dropIncomplete = false, FrameRenderTracker::Info *until = NULL);
 
-    void onOutputFormatChanged();
+    // Pass |expectedFormat| to print a warning if the format differs from it.
+    // Using sp<> instead of const sp<>& because expectedFormat is likely the current mOutputFormat
+    // which will get updated inside.
+    void onOutputFormatChanged(sp<const AMessage> expectedFormat = NULL);
     void addKeyFormatChangesToRenderBufferNotification(sp<AMessage> &notify);
     void sendFormatChange();
 
diff --git a/include/media/stagefright/foundation/AMessage.h b/include/media/stagefright/foundation/AMessage.h
index 83b9444..09d2ad8 100644
--- a/include/media/stagefright/foundation/AMessage.h
+++ b/include/media/stagefright/foundation/AMessage.h
@@ -127,6 +127,15 @@
     // their refcount incremented.
     sp<AMessage> dup() const;
 
+    // Performs a shallow or deep comparison of |this| and |other| and returns
+    // an AMessage with the differences.
+    // Warning: RefBase items, i.e. "objects" are _not_ copied but only have
+    // their refcount incremented.
+    // This is true for AMessages that have no corresponding AMessage equivalent in |other|.
+    // (E.g. there is no such key or the type is different.) On the other hand, changes in
+    // the AMessage (or AMessages if deep is |false|) are returned in new objects.
+    sp<AMessage> changesFrom(const sp<const AMessage> &other, bool deep = false) const;
+
     AString debugString(int32_t indent = 0) const;
 
     enum Type {
diff --git a/media/libstagefright/ACodec.cpp b/media/libstagefright/ACodec.cpp
index 87625d5..d6a9f53 100644
--- a/media/libstagefright/ACodec.cpp
+++ b/media/libstagefright/ACodec.cpp
@@ -5019,7 +5019,7 @@
             transfer, asString((ColorTransfer)transfer));
 }
 
-void ACodec::onOutputFormatChanged() {
+void ACodec::onOutputFormatChanged(sp<const AMessage> expectedFormat) {
     // store new output format, at the same time mark that this is no longer the first frame
     mOutputFormat = mBaseOutputFormat->dup();
 
@@ -5028,6 +5028,16 @@
         return;
     }
 
+    if (expectedFormat != NULL) {
+        sp<const AMessage> changes = expectedFormat->changesFrom(mOutputFormat);
+        sp<const AMessage> to = mOutputFormat->changesFrom(expectedFormat);
+        if (changes->countEntries() != 0 || to->countEntries() != 0) {
+            ALOGW("[%s] BAD CODEC: Output format changed unexpectedly from (diff) %s to (diff) %s",
+                    mComponentName.c_str(),
+                    changes->debugString(4).c_str(), to->debugString(4).c_str());
+        }
+    }
+
     if (!mIsVideo && !mIsEncoder) {
         AudioEncoding pcmEncoding = kAudioEncodingPcm16bit;
         (void)mConfigFormat->findInt32("pcm-encoding", (int32_t*)&pcmEncoding);
@@ -5805,7 +5815,7 @@
             if (mCodec->mOutputFormat != mCodec->mLastOutputFormat && rangeLength > 0) {
                 // pretend that output format has changed on the first frame (we used to do this)
                 if (mCodec->mBaseOutputFormat == mCodec->mOutputFormat) {
-                    mCodec->onOutputFormatChanged();
+                    mCodec->onOutputFormatChanged(mCodec->mOutputFormat);
                 }
                 mCodec->addKeyFormatChangesToRenderBufferNotification(reply);
                 mCodec->sendFormatChange();
diff --git a/media/libstagefright/foundation/AMessage.cpp b/media/libstagefright/foundation/AMessage.cpp
index 725a574..855ac95 100644
--- a/media/libstagefright/foundation/AMessage.cpp
+++ b/media/libstagefright/foundation/AMessage.cpp
@@ -749,6 +749,126 @@
     }
 }
 
+sp<AMessage> AMessage::changesFrom(const sp<const AMessage> &other, bool deep) const {
+    if (other == NULL) {
+        return const_cast<AMessage*>(this);
+    }
+
+    sp<AMessage> diff = new AMessage;
+    if (mWhat != other->mWhat) {
+        diff->setWhat(mWhat);
+    }
+    if (mHandler != other->mHandler) {
+        diff->setTarget(mHandler.promote());
+    }
+
+    for (size_t i = 0; i < mNumItems; ++i) {
+        const Item &item = mItems[i];
+        const Item *oitem = other->findItem(item.mName, item.mType);
+        switch (item.mType) {
+            case kTypeInt32:
+                if (oitem == NULL || item.u.int32Value != oitem->u.int32Value) {
+                    diff->setInt32(item.mName, item.u.int32Value);
+                }
+                break;
+
+            case kTypeInt64:
+                if (oitem == NULL || item.u.int64Value != oitem->u.int64Value) {
+                    diff->setInt64(item.mName, item.u.int64Value);
+                }
+                break;
+
+            case kTypeSize:
+                if (oitem == NULL || item.u.sizeValue != oitem->u.sizeValue) {
+                    diff->setSize(item.mName, item.u.sizeValue);
+                }
+                break;
+
+            case kTypeFloat:
+                if (oitem == NULL || item.u.floatValue != oitem->u.floatValue) {
+                    diff->setFloat(item.mName, item.u.sizeValue);
+                }
+                break;
+
+            case kTypeDouble:
+                if (oitem == NULL || item.u.doubleValue != oitem->u.doubleValue) {
+                    diff->setDouble(item.mName, item.u.sizeValue);
+                }
+                break;
+
+            case kTypeString:
+                if (oitem == NULL || *item.u.stringValue != *oitem->u.stringValue) {
+                    diff->setString(item.mName, *item.u.stringValue);
+                }
+                break;
+
+            case kTypeRect:
+                if (oitem == NULL || memcmp(&item.u.rectValue, &oitem->u.rectValue, sizeof(Rect))) {
+                    diff->setRect(
+                            item.mName, item.u.rectValue.mLeft, item.u.rectValue.mTop,
+                            item.u.rectValue.mRight, item.u.rectValue.mBottom);
+                }
+                break;
+
+            case kTypePointer:
+                if (oitem == NULL || item.u.ptrValue != oitem->u.ptrValue) {
+                    diff->setPointer(item.mName, item.u.ptrValue);
+                }
+                break;
+
+            case kTypeBuffer:
+            {
+                sp<ABuffer> myBuf = static_cast<ABuffer *>(item.u.refValue);
+                if (myBuf == NULL) {
+                    if (oitem == NULL || oitem->u.refValue != NULL) {
+                        diff->setBuffer(item.mName, NULL);
+                    }
+                    break;
+                }
+                sp<ABuffer> oBuf = oitem == NULL ? NULL : static_cast<ABuffer *>(oitem->u.refValue);
+                if (oBuf == NULL
+                        || myBuf->size() != oBuf->size()
+                        || (!myBuf->data() ^ !oBuf->data()) // data nullness differs
+                        || (myBuf->data() && memcmp(myBuf->data(), oBuf->data(), myBuf->size()))) {
+                    diff->setBuffer(item.mName, myBuf);
+                }
+                break;
+            }
+
+            case kTypeMessage:
+            {
+                sp<AMessage> myMsg = static_cast<AMessage *>(item.u.refValue);
+                if (myMsg == NULL) {
+                    if (oitem == NULL || oitem->u.refValue != NULL) {
+                        diff->setMessage(item.mName, NULL);
+                    }
+                    break;
+                }
+                sp<AMessage> oMsg =
+                    oitem == NULL ? NULL : static_cast<AMessage *>(oitem->u.refValue);
+                sp<AMessage> changes = myMsg->changesFrom(oMsg, deep);
+                if (changes->countEntries()) {
+                    diff->setMessage(item.mName, deep ? changes : myMsg);
+                }
+                break;
+            }
+
+            case kTypeObject:
+                if (oitem == NULL || item.u.refValue != oitem->u.refValue) {
+                    diff->setObject(item.mName, item.u.refValue);
+                }
+                break;
+
+            default:
+            {
+                ALOGE("Unknown type %d", item.mType);
+                TRESPASS();
+            }
+        }
+    }
+    return diff;
+}
+
 size_t AMessage::countEntries() const {
     return mNumItems;
 }