Bug 1150853: Part3. Do not modify provided extradata array. r=edwin

The extradata provided may be modified elsewhere, prevent potential conflict.

dom/media/fmp4/ffmpeg/FFmpegAudioDecoder.cpp

@@ -22,7 +22,9 @@ FFmpegAudioDecoder<LIBAV_VER>::FFmpegAudioDecoder(
   , mCallback(aCallback)
 {
   MOZ_COUNT_CTOR(FFmpegAudioDecoder);
-  mExtraData = aConfig.audio_specific_config;
+  // Use a new DataBuffer as the object will be modified during initialization.
+  mExtraData = new DataBuffer;
+  mExtraData->AppendElements(*aConfig.audio_specific_config);
 }
 
 nsresult

dom/media/fmp4/ffmpeg/FFmpegDataDecoder.cpp

@@ -96,9 +96,9 @@ FFmpegDataDecoder<LIBAV_VER>::Init()
 
   if (mExtraData) {
     mCodecContext->extradata_size = mExtraData->Length();
-    for (int i = 0; i < FF_INPUT_BUFFER_PADDING_SIZE; i++) {
-      mExtraData->AppendElement(0);
-    }
+    // FFmpeg may use SIMD instructions to access the data which reads the
+    // data in 32 bytes block. Must ensure we have enough data to read.
+    mExtraData->AppendElements(FF_INPUT_BUFFER_PADDING_SIZE);
     mCodecContext->extradata = mExtraData->Elements();
   } else {
     mCodecContext->extradata_size = 0;

dom/media/fmp4/ffmpeg/FFmpegH264Decoder.cpp

@@ -32,7 +32,9 @@ FFmpegH264Decoder<LIBAV_VER>::FFmpegH264Decoder(
   , mDisplayHeight(aConfig.display_height)
 {
   MOZ_COUNT_CTOR(FFmpegH264Decoder);
-  mExtraData = aConfig.extra_data;
+  // Use a new DataBuffer as the object will be modified during initialization.
+  mExtraData = new DataBuffer;
+  mExtraData->AppendElements(*aConfig.extra_data);
 }
 
 nsresult