Re-add AC3/EAC3 audio demuxing support

Chrome used to have EAC3/DD+ support (crbug.com/215773),
but it was removed last year (crbug.com/334126). This CL
partially restores the old code and adds AC3 support.
This will allow AC3/EAC3 audio demuxing and can be used
for AC3/EAC3 pass-through support.

BUG=448878

Review URL: https://codereview.chromium.org/812643005

Cr-Commit-Position: refs/heads/master@{#368476}

4 files changed, 69 insertions, 10 deletions

diff --git a/media/formats/mp4/es_descriptor.h b/media/formats/mp4/es_descriptor.h
index 26ca86d..9066291 100644
--- a/media/formats/mp4/es_descriptor.h
+++ b/media/formats/mp4/es_descriptor.h
@@ -21,8 +21,10 @@ namespace mp4 {
 // objectTypeIndication Values. Only values currently in use are included.
 enum ObjectType {
   kForbidden = 0,
-  kISO_14496_3 = 0x40,  // MPEG4 AAC
-  kISO_13818_7_AAC_LC = 0x67  // MPEG2 AAC-LC
+  kISO_14496_3 = 0x40,         // MPEG4 AAC
+  kISO_13818_7_AAC_LC = 0x67,  // MPEG2 AAC-LC
+  kAC3 = 0xa5,                 // AC3
+  kEAC3 = 0xa6                 // EAC3 / Dolby Digital Plus
 };
 
 // This class parse object type and decoder specific information from an
diff --git a/media/formats/mp4/fourccs.h b/media/formats/mp4/fourccs.h
index fd97797..38834fb 100644
--- a/media/formats/mp4/fourccs.h
+++ b/media/formats/mp4/fourccs.h
@@ -7,11 +7,17 @@
 
 #include <string>
 
+#include "media/media_features.h"
+
 namespace media {
 namespace mp4 {
 
 enum FourCC {
   FOURCC_NULL = 0,
+#if BUILDFLAG(ENABLE_AC3_EAC3_AUDIO_DEMUXING)
+  FOURCC_AC3 = 0x61632d33,   // "ac-3"
+  FOURCC_EAC3 = 0x65632d33,  // "ec-3"
+#endif
   FOURCC_AVC1 = 0x61766331,
   FOURCC_AVC3 = 0x61766333,
   FOURCC_AVCC = 0x61766343,
diff --git a/media/formats/mp4/mp4_stream_parser.cc b/media/formats/mp4/mp4_stream_parser.cc
index ee88ea1..966d250 100644
--- a/media/formats/mp4/mp4_stream_parser.cc
+++ b/media/formats/mp4/mp4_stream_parser.cc
@@ -220,9 +220,18 @@ bool MP4StreamParser::ParseMoov(BoxReader* reader) {
       const AudioSampleEntry& entry = samp_descr.audio_entries[desc_idx];
       const AAC& aac = entry.esds.aac;
 
-      if (!(entry.format == FOURCC_MP4A ||
-            (entry.format == FOURCC_ENCA &&
-             entry.sinf.format.format == FOURCC_MP4A))) {
+      // For encrypted audio streams entry.format is FOURCC_ENCA and actual
+      // format is in entry.sinf.format.format.
+      FourCC audio_format = (entry.format == FOURCC_ENCA)
+                                ? entry.sinf.format.format
+                                : entry.format;
+
+#if BUILDFLAG(ENABLE_AC3_EAC3_AUDIO_DEMUXING)
+      if (audio_format != FOURCC_MP4A && audio_format != FOURCC_AC3 &&
+          audio_format != FOURCC_EAC3) {
+#else
+      if (audio_format != FOURCC_MP4A) {
+#endif
         MEDIA_LOG(ERROR, media_log_) << "Unsupported audio format 0x"
                                      << std::hex << entry.format
                                      << " in stsd box.";
@@ -230,12 +239,20 @@ bool MP4StreamParser::ParseMoov(BoxReader* reader) {
       }
 
       uint8_t audio_type = entry.esds.object_type;
-      DVLOG(1) << "audio_type " << std::hex << static_cast<int>(audio_type);
+#if BUILDFLAG(ENABLE_AC3_EAC3_AUDIO_DEMUXING)
+      if (audio_type == kForbidden) {
+        if (audio_format == FOURCC_AC3)
+          audio_type = kAC3;
+        if (audio_format == FOURCC_EAC3)
+          audio_type = kEAC3;
+      }
+#endif
+      DVLOG(1) << "audio_type 0x" << std::hex << static_cast<int>(audio_type);
       if (audio_object_types_.find(audio_type) == audio_object_types_.end()) {
         MEDIA_LOG(ERROR, media_log_)
-            << "audio object type 0x" << std::hex << audio_type
-            << " does not match what is specified in the"
-            << " mimetype.";
+            << "audio object type 0x" << std::hex
+            << static_cast<int>(audio_type)
+            << " does not match what is specified in the mimetype.";
         return false;
       }
 
@@ -252,9 +269,20 @@ bool MP4StreamParser::ParseMoov(BoxReader* reader) {
 #if defined(OS_ANDROID)
         extra_data = aac.codec_specific_data();
 #endif
+#if BUILDFLAG(ENABLE_AC3_EAC3_AUDIO_DEMUXING)
+      } else if (audio_type == kAC3) {
+        codec = kCodecAC3;
+        channel_layout = GuessChannelLayout(entry.channelcount);
+        sample_per_second = entry.samplerate;
+      } else if (audio_type == kEAC3) {
+        codec = kCodecEAC3;
+        channel_layout = GuessChannelLayout(entry.channelcount);
+        sample_per_second = entry.samplerate;
+#endif
       } else {
         MEDIA_LOG(ERROR, media_log_) << "Unsupported audio object type 0x"
-                                     << std::hex << audio_type << " in esds.";
+                                     << std::hex << static_cast<int>(audio_type)
+                                     << " in esds.";
         return false;
       }
 
diff --git a/media/formats/mp4/mp4_stream_parser_unittest.cc b/media/formats/mp4/mp4_stream_parser_unittest.cc
index 79f68c1..eec9824 100644
--- a/media/formats/mp4/mp4_stream_parser_unittest.cc
+++ b/media/formats/mp4/mp4_stream_parser_unittest.cc
@@ -22,6 +22,7 @@
 #include "media/base/video_decoder_config.h"
 #include "media/formats/mp4/es_descriptor.h"
 #include "media/formats/mp4/mp4_stream_parser.h"
+#include "media/media_features.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -341,5 +342,27 @@ TEST_F(MP4StreamParserTest, NaturalSizeWithPASP) {
   EXPECT_EQ(gfx::Size(639, 360), video_decoder_config_.natural_size());
 }
 
+#if BUILDFLAG(ENABLE_AC3_EAC3_AUDIO_DEMUXING)
+TEST_F(MP4StreamParserTest, DemuxingAC3) {
+  std::set<int> audio_object_types;
+  audio_object_types.insert(kAC3);
+  parser_.reset(new MP4StreamParser(audio_object_types, false));
+  InitializeParserAndExpectLiveness(DemuxerStream::LIVENESS_RECORDED);
+  scoped_refptr<DecoderBuffer> buffer =
+      ReadTestDataFile("bear-ac3-only-frag.mp4");
+  EXPECT_TRUE(AppendDataInPieces(buffer->data(), buffer->data_size(), 512));
+}
+
+TEST_F(MP4StreamParserTest, DemuxingEAC3) {
+  std::set<int> audio_object_types;
+  audio_object_types.insert(kEAC3);
+  parser_.reset(new MP4StreamParser(audio_object_types, false));
+  InitializeParserAndExpectLiveness(DemuxerStream::LIVENESS_RECORDED);
+  scoped_refptr<DecoderBuffer> buffer =
+      ReadTestDataFile("bear-eac3-only-frag.mp4");
+  EXPECT_TRUE(AppendDataInPieces(buffer->data(), buffer->data_size(), 512));
+}
+#endif
+
 }  // namespace mp4
 }  // namespace media