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 <map>
 
 #include "base/containers/hash_tables.h"
 #include "base/lazy_instance.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_split.h"
@@ skipping 22 matching lines @@
     MPEG4_AAC_SBR_PS_v2,
     VORBIS,
     OPUS,
     H264_BASELINE,
     H264_MAIN,
     H264_HIGH,
     HEVC_MAIN,
     VP8,
     VP9,
     THEORA
+#if defined(ENABLE_AC3_EAC3_AUDIO_DEMUXING)

[ddorwin, 2015/11/25 22:24:08]

Do we need to ifdef this? There are other proprietary codecs, including HEVC,
that are not and the previous files did not.

Yes, it is dead code on most platforms, but this also hurts readability.

[servolk, 2015/12/03 00:56:14]

Done.

+    ,
+    AC3,

[ddorwin, 2015/11/25 22:24:08]

Regardless, keep similar types (at least audio) together. There is no indication
that this list cannot be modified.

[servolk, 2015/12/03 00:56:15]

Done.

+    EAC3
+#endif
   };
 
   bool IsSupportedMediaMimeType(const std::string& mime_type) const;
 
   bool AreSupportedMediaCodecs(const std::vector<std::string>& codecs) const;
 
   void ParseCodecString(const std::string& codecs,
                         std::vector<std::string>* codecs_out,
                         bool strip);
 
@@ skipping 157 matching lines @@
 #else
       return false;
 #endif
 
     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;
 
+#if defined(ENABLE_AC3_EAC3_AUDIO_DEMUXING)
+    case MimeUtil::AC3:
+    case MimeUtil::EAC3:
+      // TODO(servolk): Revisit this for AC3/EAC3 support on AndroidTV
+      return false;
+#endif
+
     case MimeUtil::VP9:
       // VP9 is supported only in KitKat+ (API Level 19).
       return base::android::BuildInfo::GetInstance()->sdk_int() >= 19;
 
     case MimeUtil::OPUS:
       // Opus is supported only in Lollipop+ (API Level 21).
       return base::android::BuildInfo::GetInstance()->sdk_int() >= 21;
 
     case MimeUtil::THEORA:
       return false;
@@ skipping 19 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 defined(ENABLE_AC3_EAC3_AUDIO_DEMUXING)
+    "ac-3,ec-3,"  // Note: only one variant of eac codec string is sufficient

[ddorwin, 2015/11/25 22:24:08]

Same as the next comment.

[servolk, 2015/12/03 00:56:15]

Done.

+                  // here since these are converted into enums in
+                  // InitializeMimeTypeMaps
+#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 defined(ENABLE_AC3_EAC3_AUDIO_DEMUXING)
+    "ac-3,ec-3,"  // Note: only one variant of eac codec string is sufficient

[ddorwin, 2015/11/25 22:24:08]

Here and above, be consistent with existing text and start the comment above the
string. Also, perhaps use text more similar to the others?

[servolk, 2015/12/03 00:56:15]

Done.

+                  // here since these are converted into enums in
+                  // InitializeMimeTypeMaps
+#endif
     "mp4a.40.05,mp4a.40.29";
 
 // These containers are also included in
 // common_media_types/proprietary_media_types. See crbug.com/461012.
 static const MediaFormatStrict format_codec_mappings[] = {
     {"video/webm", "opus,vorbis,vp8,vp8.0,vp9,vp9.0"},
     {"audio/webm", "opus,vorbis"},
     {"audio/wav", "1"},
     {"audio/x-wav", "1"},
 // Android does not support Opus in Ogg container.
@@ skipping 10 matching lines @@
     {"audio/mp3", ""},
     {"audio/x-mp3", ""},
     {"audio/aac", ""},
     {"audio/mp4", kMP4AudioCodecsExpression},
     {"audio/x-m4a", kMP4AudioCodecsExpression},
     {"video/mp4", kMP4VideoCodecsExpression},
     {"video/x-m4v", kMP4VideoCodecsExpression},
 #if defined(ENABLE_MPEG2TS_STREAM_PARSER)
     {"video/mp2t", kMP4VideoCodecsExpression},
 #endif
     {"application/x-mpegurl", kMP4VideoCodecsExpression},

[ddorwin, 2015/11/25 22:24:08]

Do you want to support this in HLS? The current code does.

[servolk, 2015/12/03 00:56:14]

HLS is only enabled on Clank/Android, where AC3/EAC3 is not currently supported,
AFAIK. But once AC3_EAC3_DEMUXING is enabled on Android, I don't see any reasons
to block AC3/EAC3 in HLS.

     {"application/vnd.apple.mpegurl", kMP4VideoCodecsExpression}};
 
 struct CodecIDMappings {
   const char* const codec_id;
   MimeUtil::Codec codec;
 };
 
 // List of codec IDs that provide enough information to determine the
 // codec and profile being requested.
 //
 // The "mp4a" strings come from RFC 6381.
 static const CodecIDMappings kUnambiguousCodecStringMap[] = {
     {"1", MimeUtil::PCM},  // We only allow this for WAV so it isn't ambiguous.
     // avc1/avc3.XXXXXX may be unambiguous; handled by ParseH264CodecID().

[ddorwin, 2015/11/25 22:24:08]

Please add a similar comment for HEVC.

     {"mp3", MimeUtil::MP3},
     {"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 defined(ENABLE_AC3_EAC3_AUDIO_DEMUXING)
+    {"ac-3", MimeUtil::AC3},
+    {"ec-3", MimeUtil::EAC3},

[ddorwin, 2015/11/25 22:24:07]

group the codecs together

[servolk, 2015/12/03 00:56:15]

Done.

+    {"mp4a.a5", MimeUtil::AC3},
+    {"mp4a.A5", MimeUtil::AC3},

[ddorwin, 2015/11/25 22:24:08]

Why both cases? Is one not "correct?" With everything else case sensitive, this
seems odd.

[servolk, 2015/12/03 00:56:15]

I've copied the comment from the unit test that references crbug.com/564960 to
explain why we need both.

+    {"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 349 matching lines @@
 #if defined(OS_ANDROID)
   if (!IsCodecSupportedOnAndroid(codec))
     return false;
 #endif
 
   return allow_proprietary_codecs_ || !IsCodecProprietary(codec);
 }
 
 bool MimeUtil::IsCodecProprietary(Codec codec) const {
   switch (codec) {
+#if defined(ENABLE_AC3_EAC3_AUDIO_DEMUXING)

[ddorwin, 2015/11/25 22:24:08]

ditto and match order of enum.

[servolk, 2015/12/03 00:56:15]

Done.

+    case AC3:
+    case EAC3:
+#endif
     case INVALID_CODEC:
     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:
@@ skipping 61 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