Mainly fix two mistakes that I made:

1. When the ERROR_END_OF_STREAM is returned from read, the input buffer is not initialized
   release it would lead to crash

2. The mPrevTimestampUs is not initialized and thus fail in the CHECK(mPrevTimestampUs, timeUs)

Change-Id: Id1e51575fb8b3ca48e80547efd3a3a82dfac773b
diff --git a/media/libstagefright/codecs/avc/enc/AVCEncoder.cpp b/media/libstagefright/codecs/avc/enc/AVCEncoder.cpp
index a99186b..389180c 100644
--- a/media/libstagefright/codecs/avc/enc/AVCEncoder.cpp
+++ b/media/libstagefright/codecs/avc/enc/AVCEncoder.cpp
@@ -98,6 +98,7 @@
     : mSource(source),
       mMeta(meta),
       mNumInputFrames(-1),
+      mPrevTimestampUs(-1),
       mStarted(false),
       mInputBuffer(NULL),
       mInputFrameData(NULL),
diff --git a/media/libstagefright/codecs/m4v_h263/enc/M4vH263Encoder.cpp b/media/libstagefright/codecs/m4v_h263/enc/M4vH263Encoder.cpp
index 5ea5859..a011137 100644
--- a/media/libstagefright/codecs/m4v_h263/enc/M4vH263Encoder.cpp
+++ b/media/libstagefright/codecs/m4v_h263/enc/M4vH263Encoder.cpp
@@ -69,6 +69,7 @@
       mMeta(meta),
       mNumInputFrames(-1),
       mNextModTimeUs(0),
+      mPrevTimestampUs(-1),
       mStarted(false),
       mInputBuffer(NULL),
       mInputFrameData(NULL),
@@ -292,8 +293,6 @@
     if (OK != mSource->read(&mInputBuffer, options)) {
         LOGE("Failed to read from data source");
         outputBuffer->release();
-        mInputBuffer->release();
-        mInputBuffer = NULL;
         return UNKNOWN_ERROR;
     }