Bug 1128381: Part3. Handle on the fly video format change. r=cpearce

Add monitoring of the current SPS NAL and destroy/recreate H264 decoder as
required.

--HG--
extra : rebase_source : fbab04b0ae3b4be42eea34a1c6f1b19bf39ad2f0

dom/media/fmp4/AVCCDecoderModule.cpp

@@ -44,6 +44,7 @@ private:
   // will set mError accordingly.
   nsresult CreateDecoder();
   nsresult CreateDecoderAndInit(mp4_demuxer::MP4Sample* aSample);
+  nsresult CheckForSPSChange(mp4_demuxer::MP4Sample* aSample);
 
   nsRefPtr<PlatformDecoderModule> mPDM;
   mp4_demuxer::VideoDecoderConfig mCurrentConfig;
@@ -92,18 +93,21 @@ AVCCMediaDataDecoder::Input(mp4_demuxer::MP4Sample* aSample)
   if (!mp4_demuxer::AnnexB::ConvertSampleToAVCC(aSample)) {
     return NS_ERROR_FAILURE;
   }
+  nsresult rv;
   if (!mDecoder) {
     // It is not possible to create an AVCC H264 decoder without SPS.
     // As such, creation will fail if the extra_data just extracted doesn't
     // contain a SPS.
-    nsresult rv = CreateDecoderAndInit(aSample);
+    rv = CreateDecoderAndInit(aSample);
     if (rv == NS_ERROR_NOT_INITIALIZED) {
       // We are missing the required SPS to create the decoder.
       // Ignore for the time being, the MP4Sample will be dropped.
       return NS_OK;
     }
-    NS_ENSURE_SUCCESS(rv, rv);
+  } else {
+    rv = CheckForSPSChange(aSample);
   }
+  NS_ENSURE_SUCCESS(rv, rv);
 
   aSample->extra_data = mCurrentConfig.extra_data;
 
@@ -230,6 +234,23 @@ AVCCMediaDataDecoder::IsHardwareAccelerated() const
   return MediaDataDecoder::IsHardwareAccelerated();
 }
 
+nsresult
+AVCCMediaDataDecoder::CheckForSPSChange(mp4_demuxer::MP4Sample* aSample)
+{
+  nsRefPtr<mp4_demuxer::ByteBuffer> extra_data =
+    mp4_demuxer::AnnexB::ExtractExtraData(aSample);
+  if (!mp4_demuxer::AnnexB::HasSPS(extra_data) ||
+      mp4_demuxer::AnnexB::CompareExtraData(extra_data,
+                                            mCurrentConfig.extra_data)) {
+    return NS_OK;
+  }
+  // The SPS has changed, signal to flush the current decoder and create a
+  // new one.
+  mDecoder->Flush();
+  mDecoder->Shutdown();
+  return CreateDecoderAndInit(aSample);
+}
+
 // AVCCDecoderModule
 
 AVCCDecoderModule::AVCCDecoderModule(PlatformDecoderModule* aPDM)

media/libstagefright/binding/AnnexB.cpp

@@ -378,4 +378,12 @@ AnnexB::IsAnnexB(const MP4Sample* aSample)
   return header == 0x00000001 || (header >> 8) == 0x000001;
 }
 
+bool
+AnnexB::CompareExtraData(const ByteBuffer* aExtraData1,
+                         const ByteBuffer* aExtraData2)
+{
+  // Very crude comparison.
+  return aExtraData1 == aExtraData2 || *aExtraData1 == *aExtraData2;
+}
+
 } // namespace mp4_demuxer

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

@@ -39,6 +39,9 @@ public:
   static bool IsAVCC(const MP4Sample* aSample);
   // Returns true if format is AnnexB.
   static bool IsAnnexB(const MP4Sample* aSample);
+  // Return true if both extradata are equal.
+  static bool CompareExtraData(const ByteBuffer* aExtraData1,
+                               const ByteBuffer* aExtraData2);
 
 private:
   // AVCC box parser helper.