Re-add AC3/EAC3 audio demuxing support

net/base/mime_util.cc

 // Copyright (c) 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 <algorithm>
 #include <iterator>
 #include <map>
 #include <string>
 
 #include "base/containers/hash_tables.h"
@@ skipping 51 matching lines @@
     MPEG4_AAC_SBR_v1,
     MPEG4_AAC_SBR_PS_v2,
     VORBIS,
     OPUS,
     H264_BASELINE,
     H264_MAIN,
     H264_HIGH,
     VP8,
     VP9,
     THEORA
+#if defined(ENABLE_AC3_EAC3_AUDIO_DEMUXING)
+    ,
+    AC3,
+    EAC3
+#endif
   };
 
   bool GetMimeTypeFromExtension(const base::FilePath::StringType& ext,
                                 std::string* mime_type) const;
 
   bool GetMimeTypeFromFile(const base::FilePath& file_path,
                            std::string* mime_type) const;
 
   bool GetWellKnownMimeTypeFromExtension(const base::FilePath::StringType& ext,
                                          std::string* mime_type) const;
@@ skipping 402 matching lines @@
     case MimeUtil::VP8:
     case MimeUtil::VORBIS:
       return true;
 
     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:
+      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:
       // TODO(vigneshv): Change this similar to the VP9 check once Opus is
       // supported on Android (http://crbug.com/318436).
       return false;
 
     case MimeUtil::THEORA:
@@ skipping 30 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,mp4a.a5,mp4a.a6,"

[ddorwin, 2015/02/26 20:49:32]

You only need one each for AC3 and EAC3.

[servolk, 2015/02/26 22:00:59]

Why? I believe these are just two different ways to indicate the same codec. For
example for EAC3, the ec-3 corresponds to the standard ETSI TS 102 366 v1.2.1,
while mp4a.a6 corresponds to the preferred way to specify codec according to RFC
6381. I think we should support both. I know for sure that, for example, Netflix
is using mp4a.a6, whereas I've seen other content providers using ec-3.

[ddorwin, 2015/02/26 22:06:18]

Because this doesn't do what you think it does. (That code is at line 606.) See
the comment in this area in tip of tree.

[servolk, 2015/02/26 22:29:20]

Could you elaborate? As far as I can see this adds those codecs to
format_codec_mappings for audio/mp4 and audio/x-m4a types, which leads to those
codecs being added to strict_format_map_ and consequently properly recognized in
IsSupportedStrictMediaMimeType, which is probably something that we want to do
in order to fully support those codecs on all code paths. Am I missing something
here?

[ddorwin, 2015/02/26 22:34:15]

Yes, but format_codec_mappings is converted to enums during initialization. See
https://codereview.chromium.org/952673002/diff/1/net/base/mime_util.cc#newcod...

[servolk, 2015/02/26 22:43:54]

Ah, ok, you are right, I missed the fact that they are converted into enums
instead of being registered as strings. So we should be good with adding just
one of the variants here, as long as we have all the variations in
format_codec_mappings. Working on it.

+#endif
     "mp4a.40.05,mp4a.40.29";
 static const char kMP4VideoCodecsExpression[] =
     "avc1.42E00A,avc1.4D400A,avc1.64000A,"
     "mp4a.66,mp4a.67,mp4a.68,mp4a.69,mp4a.6B,mp4a.40.2,mp4a.40.02,mp4a.40.5,"

[ddorwin, 2015/02/26 22:06:18]

You probably need to add those strings here too if you want "video/mp4" to
support them.

[servolk, 2015/02/26 22:29:20]

Yes, that's probably a good idea, I'll do this. But it's still not completely
clear to me - should we add all 5 strings here (i.e. including ec-3/mp4a.a6
variants) or just some subset of that (e.g. only aac51,ec-3,ac-3)?

[ddorwin, 2015/02/26 22:34:15]

Same as above: 2,
BTW, aac51 is not part of this CL (nor standardized I believe).

     "mp4a.40.05,mp4a.40.29";
 
 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" },
   { "video/ogg", "opus,theora,vorbis" },
   { "audio/ogg", "opus,vorbis" },
   { "application/ogg", "opus,theora,vorbis" },
@@ skipping 23 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 defined(ENABLE_AC3_EAC3_AUDIO_DEMUXING)
+    {"ac-3", MimeUtil::AC3},

[ddorwin, 2015/02/26 20:49:32]

Please add browser tests.

[servolk, 2015/02/27 01:21:14]

Done.

+    {"ec-3", MimeUtil::EAC3},
+    {"mp4a.a5", MimeUtil::AC3},
+    {"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 279 matching lines @@
   base::TrimString(codecs, "\"", &no_quote_codecs);
   base::SplitString(no_quote_codecs, ',', codecs_out);
 
   if (!strip)
     return;
 
   // Strip everything past the first '.'
   for (std::vector<std::string>::iterator it = codecs_out->begin();
        it != codecs_out->end();
        ++it) {
+#if defined(ENABLE_AC3_EAC3_AUDIO_DEMUXING)
+    // We need to know the codec subtype to properly support AC3/EAC3.

[ddorwin, 2015/02/26 20:49:32]

Why is stripping okay? I don't think that is the intent of strip. Instead, you
should check whether the entire string is valid as we do for AVC levels.

[servolk, 2015/02/26 22:00:59]

Actually I'm not sure about that myself, that just a piece of code that we had
in downstream (Chromecast) code, that was added by somebody else, so I assumed
it was needed. I'll look into this some more.
Btw, note that this actually prevents the stripping.

+    // Do not strip the first '.' for mp4a.a5 and mp4a.a6.
+    if (it->compare("mp4a.a5") == 0 || it->compare("mp4a.a6") == 0) {
+      continue;
+    }
+#endif
     size_t found = it->find_first_of('.');
     if (found != std::string::npos)
       it->resize(found);
   }
 }
 
 bool MimeUtil::IsStrictMediaMimeType(const std::string& mime_type) const {
   return strict_format_map_.find(mime_type) != strict_format_map_.end();
 }
 
@@ skipping 152 matching lines @@
     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:
+#if defined(ENABLE_AC3_EAC3_AUDIO_DEMUXING)
+    case AC3:
+    case EAC3:
+#endif
       return true;
 
     case PCM:
     case VORBIS:
     case OPUS:
     case VP8:
     case VP9:
     case THEORA:
       return false;
   }
@@ skipping 337 matching lines @@
   post_data->append("\r\n" + value + "\r\n");
 }
 
 void AddMultipartFinalDelimiterForUpload(const std::string& mime_boundary,
                                          std::string* post_data) {
   DCHECK(post_data);
   post_data->append("--" + mime_boundary + "--\r\n");
 }
 
 }  // namespace net