Re-add AC3/EAC3 audio demuxing support

media/base/mime_util.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <map>
 
 #include "base/containers/hash_tables.h"
@@ skipping 12 matching lines @@
 
 namespace media {
 
 // Singleton utility class for mime types.
 class MimeUtil {
  public:
   enum Codec {
     INVALID_CODEC,
     PCM,
     MP3,
+    AC3,
+    EAC3,
     MPEG2_AAC_LC,
     MPEG2_AAC_MAIN,
     MPEG2_AAC_SSR,
     MPEG4_AAC_LC,
     MPEG4_AAC_SBR_v1,
     MPEG4_AAC_SBR_PS_v2,
     VORBIS,
     OPUS,
     H264_BASELINE,
     H264_MAIN,
@@ skipping 102 matching lines @@
     case MimeUtil::MPEG4_AAC_LC:
     case MimeUtil::MPEG4_AAC_SBR_v1:
     case MimeUtil::MPEG4_AAC_SBR_PS_v2:
     case MimeUtil::VORBIS:
     case MimeUtil::H264_BASELINE:
     case MimeUtil::H264_MAIN:
     case MimeUtil::H264_HIGH:
     case MimeUtil::VP8:
       return true;
 
+    case MimeUtil::AC3:
+    case MimeUtil::EAC3:
+      // TODO(servolk): Revisit this for AC3/EAC3 support on AndroidTV
+      return false;
+
     case MimeUtil::MPEG2_AAC_LC:
     case MimeUtil::MPEG2_AAC_MAIN:
     case MimeUtil::MPEG2_AAC_SSR:
       // MPEG-2 variants of AAC are not supported on Android.
       return false;
 
     case MimeUtil::OPUS:
       // Opus is supported only in Lollipop+ (API Level 21).
       return base::android::BuildInfo::GetInstance()->sdk_int() >= 21;
 
@@ skipping 38 matching lines @@
 //   mp4a.40.5   - MPEG-4 HE-AAC v1 (AAC LC + SBR)
 //   mp4a.40.05  - MPEG-4 HE-AAC v1 (AAC LC + SBR) (leading 0 in aud-oti for
 //                 compatibility)
 //   mp4a.40.29  - MPEG-4 HE-AAC v2 (AAC LC + SBR + PS)
 //
 //   avc1.42E0xx - H.264 Baseline
 //   avc1.4D40xx - H.264 Main
 //   avc1.6400xx - H.264 High
 static const char kMP4AudioCodecsExpression[] =
     "mp4a.66,mp4a.67,mp4a.68,mp4a.69,mp4a.6B,mp4a.40.2,mp4a.40.02,mp4a.40.5,"
+#if BUILDFLAG(ENABLE_AC3_EAC3_AUDIO_DEMUXING)
+    // Only one variant each of ac3 and eac3 codec string is sufficient here,
+    // since these strings are parsed and mapped to MimeUtil::Codec enum values.
+    "ac-3,ec-3,"
+#endif
     "mp4a.40.05,mp4a.40.29";
 static const char kMP4VideoCodecsExpression[] =
     // This is not a complete list of supported avc1 codecs. It is simply used
     // to register support for the corresponding Codec enum. Instead of using
     // strings in these three arrays, we should use the Codec enum values.
     // This will avoid confusion and unnecessary parsing at runtime.
     // kUnambiguousCodecStringMap/kAmbiguousCodecStringMap should be the only
     // mapping from strings to codecs. See crbug.com/461009.
     "avc1.42E00A,avc1.4D400A,avc1.64000A,"
 #if defined(ENABLE_HEVC_DEMUXING)
     // Any valid unambiguous HEVC codec id will work here, since these strings
     // are parsed and mapped to MimeUtil::Codec enum values.
     "hev1.1.6.L93.B0,"
 #endif
     "mp4a.66,mp4a.67,mp4a.68,mp4a.69,mp4a.6B,mp4a.40.2,mp4a.40.02,mp4a.40.5,"
+#if BUILDFLAG(ENABLE_AC3_EAC3_AUDIO_DEMUXING)
+    // Only one variant each of ac3 and eac3 codec string is sufficient here,
+    // since these strings are parsed and mapped to MimeUtil::Codec enum values.
+    "ac-3,ec-3,"
+#endif
     "mp4a.40.05,mp4a.40.29";
 #endif  // USE_PROPRIETARY_CODECS
 
 // A list of media types (https://en.wikipedia.org/wiki/Media_type) and
 // corresponding media codecs supported by these types/containers.
 // Media formats marked as PROPRIETARY are not supported by Chromium, only
 // Google Chrome browser supports them.
 static const MediaFormat kFormatCodecMappings[] = {
     {"video/webm", COMMON, "opus,vorbis,vp8,vp8.0,vp9,vp9.0"},
     {"audio/webm", COMMON, "opus,vorbis"},
@@ skipping 46 matching lines @@
     {"mp4a.66", MimeUtil::MPEG2_AAC_MAIN},
     {"mp4a.67", MimeUtil::MPEG2_AAC_LC},
     {"mp4a.68", MimeUtil::MPEG2_AAC_SSR},
     {"mp4a.69", MimeUtil::MP3},
     {"mp4a.6B", MimeUtil::MP3},
     {"mp4a.40.2", MimeUtil::MPEG4_AAC_LC},
     {"mp4a.40.02", MimeUtil::MPEG4_AAC_LC},
     {"mp4a.40.5", MimeUtil::MPEG4_AAC_SBR_v1},
     {"mp4a.40.05", MimeUtil::MPEG4_AAC_SBR_v1},
     {"mp4a.40.29", MimeUtil::MPEG4_AAC_SBR_PS_v2},
+#if BUILDFLAG(ENABLE_AC3_EAC3_AUDIO_DEMUXING)
+    // TODO(servolk): Strictly speaking only mp4a.A5 and mp4a.A6 codec ids are
+    // valid according to RFC 6381 section 3.3, 3.4. Lower-case oti (mp4a.a5 and
+    // mp4a.a6) should be rejected. But we used to allow those in older versions
+    // of Chromecast firmware and some apps (notably MPL) depend on those codec
+    // types being supported, so they should be allowed for now
+    // (crbug.com/564960).
+    {"ac-3", MimeUtil::AC3},
+    {"mp4a.a5", MimeUtil::AC3},
+    {"mp4a.A5", MimeUtil::AC3},
+    {"ec-3", MimeUtil::EAC3},
+    {"mp4a.a6", MimeUtil::EAC3},
+    {"mp4a.A6", MimeUtil::EAC3},
+#endif
     {"vorbis", MimeUtil::VORBIS},
     {"opus", MimeUtil::OPUS},
     {"vp8", MimeUtil::VP8},
     {"vp8.0", MimeUtil::VP8},
     {"vp9", MimeUtil::VP9},
     {"vp9.0", MimeUtil::VP9},
     {"theora", MimeUtil::THEORA}};
 
 // List of codec IDs that are ambiguous and don't provide
 // enough information to determine the codec and profile.
@@ skipping 327 matching lines @@
   if (!IsCodecSupportedOnAndroid(codec))
     return false;
 #endif
 
   return allow_proprietary_codecs_ || !IsCodecProprietary(codec);
 }
 
 bool MimeUtil::IsCodecProprietary(Codec codec) const {
   switch (codec) {
     case INVALID_CODEC:
+    case AC3:
+    case EAC3:
     case MP3:
     case MPEG2_AAC_LC:
     case MPEG2_AAC_MAIN:
     case MPEG2_AAC_SSR:
     case MPEG4_AAC_LC:
     case MPEG4_AAC_SBR_v1:
     case MPEG4_AAC_SBR_PS_v2:
     case H264_BASELINE:
     case H264_MAIN:
     case H264_HIGH:
@@ skipping 50 matching lines @@
                       std::vector<std::string>* codecs_out,
                       const bool strip) {
   g_media_mime_util.Get().ParseCodecString(codecs, codecs_out, strip);
 }
 
 void RemoveProprietaryMediaTypesAndCodecsForTests() {
   g_media_mime_util.Get().RemoveProprietaryMediaTypesAndCodecsForTests();
 }
 
 }  // namespace media