From 06ae6e08e7a20a44c8c7c1f5c0547a9a61cb5c73 Mon Sep 17 00:00:00 2001
From: Jean-Yves Avenard <jyavenard@mozilla.com>
Date: Thu, 12 Mar 2015 11:07:19 +1100
Subject: [PATCH] Bug 1128381: Part2. Properly extract extradata from AVC1
 sample. r=rillian

--HG--
extra : rebase_source : a67173bfcc4184211ab0b90e3b7634b1730288d5
---
 media/libstagefright/binding/AnnexB.cpp       | 32 +++++++++++++++----
 .../binding/include/mp4_demuxer/AnnexB.h      |  6 ++++
 2 files changed, 32 insertions(+), 6 deletions(-)

diff --git a/media/libstagefright/binding/AnnexB.cpp b/media/libstagefright/binding/AnnexB.cpp
index c5f65e4e2c06..0a88e5092aa6 100644
--- a/media/libstagefright/binding/AnnexB.cpp
+++ b/media/libstagefright/binding/AnnexB.cpp
@@ -217,11 +217,9 @@ AnnexB::ConvertSampleToAVCC(MP4Sample* aSample)
   if (IsAVCC(aSample)) {
     return ConvertSampleTo4BytesAVCC(aSample);
   }
-
-  uint32_t header = mozilla::BigEndian::readUint32(aSample->data);
-  if (header != 0x00000001 && (header >> 8) != 0x000001) {
+  if (!IsAnnexB(aSample)) {
     // Not AnnexB, can't convert.
-    return true;
+    return false;
   }
 
   mozilla::Vector<uint8_t> nalu;
@@ -236,7 +234,13 @@ already_AddRefed<ByteBuffer>
 AnnexB::ExtractExtraData(const MP4Sample* aSample)
 {
   nsRefPtr<ByteBuffer> extradata = new ByteBuffer;
-  if (!IsAVCC(aSample)) {
+  if (IsAVCC(aSample) && HasSPS(aSample->extra_data)) {
+    // We already have an explicit extradata, re-use it.
+    extradata = aSample->extra_data;
+    return extradata.forget();
+  }
+
+  if (IsAnnexB(aSample)) {
     return extradata.forget();
   }
   // SPS content
@@ -248,7 +252,14 @@ AnnexB::ExtractExtraData(const MP4Sample* aSample)
   ByteWriter ppsw(pps);
   int numPps = 0;
 
-  int nalLenSize = ((*aSample->extra_data)[4] & 3) + 1;
+  int nalLenSize;
+  if (IsAVCC(aSample)) {
+    nalLenSize = ((*aSample->extra_data)[4] & 3) + 1;
+  } else {
+    // We do not have an extradata, assume it's AnnexB converted to AVCC via
+    // ConvertSampleToAVCC.
+    nalLenSize = 4;
+  }
   ByteReader reader(aSample->data, aSample->size);
 
   // Find SPS and PPS NALUs in AVCC data
@@ -357,5 +368,14 @@ AnnexB::IsAVCC(const MP4Sample* aSample)
     aSample->extra_data->Length() >= 7 && (*aSample->extra_data)[0] == 1;
 }
 
+bool
+AnnexB::IsAnnexB(const MP4Sample* aSample)
+{
+  if (aSample->size < 4) {
+    return false;
+  }
+  uint32_t header = mozilla::BigEndian::readUint32(aSample->data);
+  return header == 0x00000001 || (header >> 8) == 0x000001;
+}
 
 } // namespace mp4_demuxer
diff --git a/media/libstagefright/binding/include/mp4_demuxer/AnnexB.h b/media/libstagefright/binding/include/mp4_demuxer/AnnexB.h
index 76f09ee559aa..5a4968ddd57c 100644
--- a/media/libstagefright/binding/include/mp4_demuxer/AnnexB.h
+++ b/media/libstagefright/binding/include/mp4_demuxer/AnnexB.h
@@ -28,11 +28,17 @@ public:
   // Parse an AVCC extradata and construct the Annex B sample header.
   static already_AddRefed<ByteBuffer> ConvertExtraDataToAnnexB(
     const ByteBuffer* aExtraData);
+  // Extract SPS and PPS NALs from aSample, aSample must be in AVCC format.
+  // If aSample already contains an extradata with an SPS, it will be returned
+  // otherwise the SPS/PPS NALs are searched in-band.
   static already_AddRefed<ByteBuffer> ExtractExtraData(
     const MP4Sample* aSample);
   static bool HasSPS(const MP4Sample* aSample);
   static bool HasSPS(const ByteBuffer* aExtraData);
+  // Returns true if format is AVCC and sample has valid extradata.
   static bool IsAVCC(const MP4Sample* aSample);
+  // Returns true if format is AnnexB.
+  static bool IsAnnexB(const MP4Sample* aSample);
 
 private:
   // AVCC box parser helper.