Bug 1035059 - Add input padding for libav; r=edwin

content/media/fmp4/ffmpeg/FFmpegAACDecoder.cpp

@@ -71,6 +71,7 @@ FFmpegAACDecoder<LIBAV_VER>::DecodePacket(MP4Sample* aSample)
   AVPacket packet;
   av_init_packet(&packet);
 
+  aSample->Pad(FF_INPUT_BUFFER_PADDING_SIZE);
   packet.data = aSample->data;
   packet.size = aSample->size;
   packet.pos = aSample->byte_offset;

content/media/fmp4/ffmpeg/FFmpegDataDecoder.cpp

@@ -88,8 +88,11 @@ FFmpegDataDecoder<LIBAV_VER>::Init()
   mCodecContext.thread_type = FF_THREAD_SLICE | FF_THREAD_FRAME;
   mCodecContext.thread_safe_callbacks = false;
 
-  mCodecContext.extradata = mExtraData.begin();
   mCodecContext.extradata_size = mExtraData.length();
+  for (int i = 0; i < FF_INPUT_BUFFER_PADDING_SIZE; i++) {
+    mExtraData.append(0);
+  }
+  mCodecContext.extradata = mExtraData.begin();
 
   AVDictionary* opts = nullptr;
   if (avcodec_open2(&mCodecContext, codec, &opts) < 0) {

content/media/fmp4/ffmpeg/FFmpegH264Decoder.cpp

@@ -53,6 +53,7 @@ FFmpegH264Decoder<LIBAV_VER>::DecodeFrame(mp4_demuxer::MP4Sample* aSample)
   AVPacket packet;
   av_init_packet(&packet);
 
+  aSample->Pad(FF_INPUT_BUFFER_PADDING_SIZE);
   packet.data = aSample->data;
   packet.size = aSample->size;
   packet.pts = aSample->composition_timestamp;

media/libstagefright/binding/DecoderData.cpp

@@ -128,6 +128,31 @@ MP4Sample::Update()
   size = mMediaBuffer->range_length();
 }
 
+void
+MP4Sample::Pad(size_t aPaddingBytes)
+{
+  MOZ_ASSERT(data == mMediaBuffer->data());
+
+  size_t newSize = size + aPaddingBytes;
+
+  // If the existing MediaBuffer has enough space then we just recycle it. If
+  // not then we copy to a new buffer.
+  uint8_t* newData = mMediaBuffer && newSize <= mMediaBuffer->size()
+                       ? data
+                       : new uint8_t[newSize];
+
+  memset(newData + size, 0, aPaddingBytes);
+
+  if (newData != data) {
+    memcpy(newData, data, size);
+    extra_buffer = data = newData;
+    if (mMediaBuffer) {
+      mMediaBuffer->release();
+      mMediaBuffer = nullptr;
+    }
+  }
+}
+
 void
 MP4Sample::Prepend(const uint8_t* aData, size_t aSize)
 {

media/libstagefright/binding/include/mp4_demuxer/DecoderData.h

@@ -80,6 +80,7 @@ public:
   MP4Sample();
   ~MP4Sample();
   void Update();
+  void Pad(size_t aPaddingBytes);
 
   stagefright::MediaBuffer* mMediaBuffer;