Media: Do not support new codecs with legacy MIME type names.

media/base/mime_util_internal.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 "media/base/mime_util_internal.h"
 
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
 #include "build/build_config.h"
@@ skipping 13 matching lines @@
 
 struct MediaFormat {
   const char* const mime_type;
   MediaFormatType format_type;
   const char* const codecs_list;
 };
 
 // Strings used as the |codecs_list| only need one valid unambiguous variant for
 // each supported MimeUtil::Codec enum value. Each codec string is parsed and
 // mapped to corresponding MimeUtil::Codec value. See https://crbug.com/461009.
-#if defined(USE_PROPRIETARY_CODECS)
-static const char kMP4AudioCodecsExpression[] =
-#if BUILDFLAG(ENABLE_AC3_EAC3_AUDIO_DEMUXING)
-    "ac-3,ec-3,"  // AC-3 and E-AC-3.
-#endif
-    "mp4a.66,mp4a.69,mp4a.40.2";  // MPEG-2 AAC, MP3, and MPEG-4 AAC.
-static const char kMP4VideoCodecsExpression[] =
-    "avc1.42E00A,"
-#if BUILDFLAG(ENABLE_HEVC_DEMUXING)
-    "hev1.1.6.L93.B0,"
-#endif
-#if BUILDFLAG(ENABLE_AC3_EAC3_AUDIO_DEMUXING)
-    "ac-3,ec-3,"  // AC-3 and E-AC-3.
-#endif
-    "mp4a.66,mp4a.69,mp4a.40.2";  // MPEG-2 AAC, MP3, and MPEG-4 AAC.
-#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,vp9"},
     {"audio/webm", COMMON, "opus,vorbis"},
     {"audio/wav", COMMON, "1"},
     {"audio/x-wav", COMMON, "1"},
 #if defined(OS_ANDROID)
     // Android does not support Opus in Ogg container.
     // Android does not support Theora and thus video/ogg.
     {"audio/ogg", COMMON, "vorbis"},
     {"application/ogg", COMMON, "vorbis"},
 #else
     {"video/ogg", COMMON, "opus,theora,vorbis"},
     {"audio/ogg", COMMON, "opus,vorbis"},
     {"application/ogg", COMMON, "opus,theora,vorbis"},
 #endif
 #if defined(USE_PROPRIETARY_CODECS)
     {"audio/mpeg", PROPRIETARY, "mp3"},
     {"audio/mp3", PROPRIETARY, ""},
     {"audio/x-mp3", PROPRIETARY, ""},
     {"audio/aac", PROPRIETARY, ""},  // AAC / ADTS
-    {"audio/mp4", PROPRIETARY, kMP4AudioCodecsExpression},
-    {"audio/x-m4a", PROPRIETARY, kMP4AudioCodecsExpression},
-    {"video/mp4", PROPRIETARY, kMP4VideoCodecsExpression},
-    {"video/x-m4v", PROPRIETARY, kMP4VideoCodecsExpression},
-#if BUILDFLAG(ENABLE_MSE_MPEG2TS_STREAM_PARSER)
-    {"video/mp2t", PROPRIETARY, kMP4VideoCodecsExpression},
-#endif
-#if defined(OS_ANDROID)
-    // HTTP Live Streaming (HLS)
-    {"application/x-mpegurl", PROPRIETARY, kMP4VideoCodecsExpression},
-    {"application/vnd.apple.mpegurl", PROPRIETARY, kMP4VideoCodecsExpression}
-#endif
+// Most MPEG MIME types are added in InitializeMimeTypeMaps().

[ddorwin, 2016/03/17 20:52:54]

We now have this information scattered. Should we move this entire table to
InitializeMimeTypeMaps? it seems better to have them together. Also, this would
allow us to clean up the OS_ANDROID code above in a similar way.

 #endif  // USE_PROPRIETARY_CODECS
 };
 
 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 ParseAVCCodecId().
     // hev1/hvc1.XXXXXX may be unambiguous; handled by ParseHEVCCodecID().
     {"mp3", MimeUtil::MP3},
-    // Following is the list of RFC 6381 compliant audio codecs:
+    // Following is the list of RFC 6381 compliant audio codec strings:
     //   mp4a.66     - MPEG-2 AAC MAIN
     //   mp4a.67     - MPEG-2 AAC LC
     //   mp4a.68     - MPEG-2 AAC SSR
     //   mp4a.69     - MPEG-2 extension to MPEG-1 (MP3)
     //   mp4a.6B     - MPEG-1 audio (MP3)
     //   mp4a.40.2   - MPEG-4 AAC LC
     //   mp4a.40.02  - MPEG-4 AAC LC (leading 0 in aud-oti for compatibility)
     //   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)
@@ skipping 177 matching lines @@
     }
 
     if (is_ambiguous)
       result = MayBeSupported;
   }
 
   return result;
 }
 
 void MimeUtil::InitializeMimeTypeMaps() {
-// Initialize the supported media types.
 #if defined(USE_PROPRIETARY_CODECS)
   allow_proprietary_codecs_ = true;
 #endif
 
   for (size_t i = 0; i < arraysize(kUnambiguousCodecStringMap); ++i) {
     string_to_codec_map_[kUnambiguousCodecStringMap[i].codec_id] =
         CodecEntry(kUnambiguousCodecStringMap[i].codec, false);
   }
 
   for (size_t i = 0; i < arraysize(kAmbiguousCodecStringMap); ++i) {
     string_to_codec_map_[kAmbiguousCodecStringMap[i].codec_id] =
         CodecEntry(kAmbiguousCodecStringMap[i].codec, true);
   }
 
   // Initialize the supported media formats.
   for (size_t i = 0; i < arraysize(kFormatCodecMappings); ++i) {
-    std::vector<std::string> mime_type_codecs;
-    ParseCodecString(kFormatCodecMappings[i].codecs_list, &mime_type_codecs,
-                     false);
+    AddContainerWithCodecs(kFormatCodecMappings[i].mime_type,
+                           kFormatCodecMappings[i].codecs_list);
+  }
 
-    CodecSet codecs;
-    for (size_t j = 0; j < mime_type_codecs.size(); ++j) {
-      Codec codec = INVALID_CODEC;
-      bool is_ambiguous = true;
-      CHECK(StringToCodec(mime_type_codecs[j], &codec, &is_ambiguous));
-      DCHECK(!is_ambiguous);
-      codecs.insert(codec);
-    }
+#if defined(USE_PROPRIETARY_CODECS)

[DaleCurtis, 2016/03/17 21:00:21]

Could have an InitializeProprietaryCodecMimeTypeMaps() here.

[ddorwin, 2016/03/17 21:44:25]

Yes, though that would separate the lists of types even further, and it may not
always be appropriate (i.e. https://crbug.com/327115).

+  // Initialize the supported media formats not in kFormatCodecMappings.
+  // TODO: Should we move all mappings to this style?
+  const std::string aac = "mp4a.66,mp4a.40.2";  // MPEG-2 AAC and MPEG-4 AAC.

[DaleCurtis, 2016/03/17 21:00:21]

You can keep these as const char* up above and just initialize the std::string
versions for globing here; that might make the readability better.

[ddorwin, 2016/03/17 21:44:25]

I've uploaded this change, but I plan to revert - I think this is worse because
it further separates those literals from others and I have to add std::string()
in places.

This is really a minor issue, though, because https://crbug.com/461009 should
eliminate the need for theses.

+  const std::string avc = "avc1.42E00A";
+  const std::string avc_and_aac = avc + "," + aac;
+  const std::string mp4_audio_codecs =
+#if BUILDFLAG(ENABLE_AC3_EAC3_AUDIO_DEMUXING)
+      "ac-3,ec-3,"  // AC-3 and E-AC-3.
+#endif
+      "mp4a.69," +  // MP3
+      aac;
+  const std::string mp4_video_codecs =
+#if BUILDFLAG(ENABLE_HEVC_DEMUXING)
+      "hev1.1.6.L93.B0," +
+#endif
+      avc;
+  const std::string mp4_codecs = mp4_video_codecs + "," + mp4_audio_codecs;
 
-    media_format_map_[kFormatCodecMappings[i].mime_type] = codecs;
+  // TODO: Fix before committing. This breaks
+  // RemoveProprietaryMediaTypesAndCodecs() because the containers are not in
+  // kFormatCodecMappings with PROPRIETARY.

[ddorwin, 2016/03/17 20:52:54]

I will add this parameter to AddContainerWithCodecs() and use it to build a
vector of proprietary MIME types to be removed (rather than iterating through
kFormatCodecMappings to identify them).

+  AddContainerWithCodecs("audio/mp4", mp4_audio_codecs);

[ddorwin, 2016/03/17 20:52:55]

Each entry remaining in kFormatCodecMappings would look something like this, but
with a literal. Those should be a lot cleaner than this.

Still, the strings above will be in the middle of such entries unless we want
multiple #ifdef's.

+  AddContainerWithCodecs("video/mp4", mp4_codecs);
+  // These strings are supported for backwards compatibility only and thus only
+  // support the codecs needed for compatibility.
+  AddContainerWithCodecs("audio/x-m4a", aac);
+  AddContainerWithCodecs("video/x-m4v", avc_and_aac);
+
+#if BUILDFLAG(ENABLE_MSE_MPEG2TS_STREAM_PARSER)
+  // TODO(ddorwin): Exactly which codecs should be supported?
+  AddContainerWithCodecs("video/mp2t", mp4_codecs);
+#endif
+#if defined(OS_ANDROID)
+  // HTTP Live Streaming (HLS)
+  AddContainerWithCodecs("application/x-mpegurl", avc_and_aac);
+  AddContainerWithCodecs("application/vnd.apple.mpegurl", avc_and_aac);
+#endif
+#endif  // USE_PROPRIETARY_CODECS
+}
+
+// TODO(ddorwin): Replace |codecs_list| with a vector of MimeUtil::Codec values.
+// See https://crbug.com/461009
+void MimeUtil::AddContainerWithCodecs(const std::string& mime_type,
+                                      const std::string& codecs_list) {
+  std::vector<std::string> mime_type_codecs;
+  ParseCodecString(codecs_list, &mime_type_codecs, false);
+
+  CodecSet codecs;
+  for (size_t j = 0; j < mime_type_codecs.size(); ++j) {
+    Codec codec = INVALID_CODEC;
+    bool is_ambiguous = true;
+    CHECK(StringToCodec(mime_type_codecs[j], &codec, &is_ambiguous));
+    DCHECK(!is_ambiguous);
+    codecs.insert(codec);
   }
+
+  media_format_map_[mime_type] = codecs;
 }
 
 bool MimeUtil::IsSupportedMediaMimeType(const std::string& mime_type) const {
   return media_format_map_.find(base::ToLowerASCII(mime_type)) !=
          media_format_map_.end();
 }
 
 void MimeUtil::ParseCodecString(const std::string& codecs,
                                 std::vector<std::string>* codecs_out,
                                 bool strip) {
@@ skipping 57 matching lines @@
     }
     return AreSupportedCodecs(it_media_format_map->second, codecs_to_check,
                               mime_type_lower_case, is_encrypted);
   }
 #endif
 
   return AreSupportedCodecs(it_media_format_map->second, codecs,
                             mime_type_lower_case, is_encrypted);
 }
 
+// TODO: Stop using kFormatCodecMappings since it no longer contains all types.
 void MimeUtil::RemoveProprietaryMediaTypesAndCodecs() {
   for (size_t i = 0; i < arraysize(kFormatCodecMappings); ++i)
     if (kFormatCodecMappings[i].format_type == PROPRIETARY)
       media_format_map_.erase(kFormatCodecMappings[i].mime_type);
   allow_proprietary_codecs_ = false;
 }
 
 // static
 bool MimeUtil::IsCodecSupportedOnPlatform(
     Codec codec,
@@ skipping 206 matching lines @@
     const std::string& mime_type_lower_case,
     bool is_encrypted) const {
   Codec default_codec = Codec::INVALID_CODEC;
   if (!GetDefaultCodecLowerCase(mime_type_lower_case, &default_codec))
     return false;
   return IsCodecSupported(default_codec, mime_type_lower_case, is_encrypted);
 }
 
 }  // namespace internal
 }  // namespace media