Fix: Changing canPlayType behaviour for MP4 containers

net/base/mime_util.cc

Index: net/base/mime_util.cc
diff --git a/net/base/mime_util.cc b/net/base/mime_util.cc
index 9d15256172ff9fc99f2a5c9e27021cfd785a6263..ae0df51c7ed6ca1541b17b3e0cb63979161283d2 100644
--- a/net/base/mime_util.cc
+++ b/net/base/mime_util.cc
@@ -93,7 +93,6 @@ class MimeUtil : public PlatformMimeUtil {
   friend struct base::DefaultLazyInstanceTraits<MimeUtil>;
 
   typedef base::hash_set<std::string> MimeMappings;
-  typedef std::map<std::string, MimeMappings> StrictMappings;
 
   typedef std::vector<std::string> MimeExpressionMappings;
   typedef std::map<std::string, MimeExpressionMappings>
@@ -103,13 +102,8 @@ class MimeUtil : public PlatformMimeUtil {
 
   // Returns true if |codecs| is nonempty and all the items in it are present in
   // |supported_codecs|.
-  static bool AreSupportedCodecs(const MimeMappings& supported_codecs,
+  static bool AreSupportedCodecs(const MimeExpressionMappings& supported_codecs,
                                  const std::vector<std::string>& codecs);
-  // Returns true is |codecs| is nonempty and all the items in it match with the
-  // codecs expression in |supported_codecs|.
-  static bool AreSupportedCodecsWithProfile(
-      const MimeExpressionMappings& supported_codecs,
-      const std::vector<std::string>& codecs);
 
   // For faster lookup, keep hash sets.
   void InitializeMimeTypeMaps();
@@ -123,13 +117,14 @@ class MimeUtil : public PlatformMimeUtil {
   MimeMappings non_image_map_;
   MimeMappings unsupported_text_map_;
   MimeMappings javascript_map_;
-  MimeMappings codecs_map_;
+  MimeExpressionMappings codecs_map_;
 
   // A map of mime_types and hash map of the supported codecs for the mime_type.
-  StrictMappings strict_format_map_;
-  // A map of MP4 mime_types which expect codecs with profile parameter and
-  // vector of supported codecs expressions for the mime_type.
-  StrictExpressionMappings strict_mp4_format_map_;
+  StrictExpressionMappings strict_format_map_;
+  // A map of mime_types, which expect codecs which are RFC compliant but do not
+  // have sufficient informatation whether they are supported or not, and vector
+  // of supported codecs expressions for the mime_type.
+  StrictExpressionMappings inconclusive_format_map_;
 };  // class MimeUtil
 
 // This variable is Leaky because we need to access it from WorkerPool threads.
@@ -290,9 +285,7 @@ static const char* const common_media_types[] = {
   // Ogg.
   "audio/ogg",
   "application/ogg",
-#if !defined(OS_ANDROID)  // Android doesn't support Ogg Theora.
   "video/ogg",

[Ryan Sleevi, 2014/07/09 23:56:13]

This is no longer consistent with the comment on line 283, as evidenced by line
455.

-#endif
 
   // WebM.
   "video/webm",
@@ -332,9 +325,7 @@ static const char* const proprietary_media_types[] = {
 // The codecs for WAV are integers as defined in Appendix A of RFC2361:
 // http://tools.ietf.org/html/rfc2361
 static const char* const common_media_codecs[] = {
-#if !defined(OS_ANDROID)  // Android doesn't support Ogg Theora.
   "theora",
-#endif
   "opus",
   "vorbis",
   "vp8",
@@ -443,19 +434,35 @@ static bool IsCodecSupportedOnAndroid(const std::string& codec) {
 
   // TODO(vigneshv): Change this similar to the VP9 check once Opus is
   // supported on Android (http://crbug.com/318436).
-  if (!codec.compare("opus")) {
+  if (!codec.compare("opus"))
+    return false;
+
+  // MPEG-2 AAC is not supported on Android
+  if (!codec.compare("mp4a.67"))
+    return false;
+
+  // H.264 Main and High profiles are not supported on Android
+  if (!codec.compare("avc1.4d40??") || !codec.compare("avc3.4d40??") ||
+      !codec.compare("avc1.4D40??") || !codec.compare("avc3.4D40??") ||
+      !codec.compare("avc1.6400??") || !codec.compare("avc3.6400??")) {
     return false;
   }
+
   return true;
 }
 
 static bool IsMimeTypeSupportedOnAndroid(const std::string& mimeType) {
+  // Ogg Theora is not supported on Android
+  if (!mimeType.compare("video/ogg"))
+    return false;
+
   // HLS codecs are supported in ICS and above (API level 14)
   if ((!mimeType.compare("application/vnd.apple.mpegurl") ||
       !mimeType.compare("application/x-mpegurl")) &&
       base::android::BuildInfo::GetInstance()->sdk_int() < 14) {
     return false;
   }
+
   return true;
 }
 #endif
@@ -465,48 +472,64 @@ struct MediaFormatStrict {
   const char* codecs_list;
 };
 
-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" },
-  { "audio/mpeg", "" },
-  { "audio/mp3", "" },
-  { "audio/x-mp3", "" }
-};
-
 // Following is the list of RFC 6381 compliant codecs:
 //   mp4a.6B     - MPEG-1 audio
 //   mp4a.69     - MPEG-2 extension to MPEG-1
 //   mp4a.67     - MPEG-2 AAC
 //   mp4a.40.2   - MPEG-4 AAC
-//   mp4a.40.5   - MPEG-4 HE-AAC
+//   mp4a.40.5   - MPEG-4 HE-AACv1
 //
 //   avc1.42E0xx - H.264 Baseline
 //   avc1.4D40xx - H.264 Main
 //   avc1.6400xx - H.264 High
+static const char kProprietaryAudioCodecsExpression[] =
+    "mp4a.6B,mp4a.69,mp4a.67,mp4a.40.2,mp4a.40.5";
+static const char kProprietaryCodecsExpression[] =
+    "avc1.42E0??,avc1.42e0??,avc1.4D40??,avc1.4d40??,avc1.6400??,"
+    "avc3.42E0??,avc3.42e0??,avc3.4D40??,avc3.4d40??,avc3.6400??,"
+    "mp4a.6B,mp4a.69,mp4a.67,mp4a.40.2,mp4a.40.5";
+
+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"},
+    {"audio/mpeg", ""},
+    {"audio/mp3", ""},
+    {"audio/x-mp3", ""},
+    {"audio/mp4", kProprietaryAudioCodecsExpression},
+    {"audio/x-m4a", kProprietaryAudioCodecsExpression},
+    {"video/mp4", kProprietaryCodecsExpression},
+    {"video/x-m4v", kProprietaryCodecsExpression},
+    {"application/x-mpegurl", kProprietaryCodecsExpression},
+    {"application/vnd.apple.mpegurl", kProprietaryCodecsExpression}
+};
+
+// Following is the list of codecs that are RFC 6381 compliant but browser
+// cannot be sure whether the platform supports them or not

[Ryan Sleevi, 2014/07/09 23:56:13]

grammar rewrite:

// The following is the list of codecs that are RFC 6381 compliant, but
// which support for varies by platform and cannot be determined
// beforehand.

(Context: "browser" concepts should not exist in //net)

+//   mp4a.40
+//   avc1
+//   avc3
 //
 // Additionally, several non-RFC compliant codecs are allowed, due to their
 // existing use on web.
-//   mp4a.40
 //   avc1.xxxxxx
 //   avc3.xxxxxx
-//   mp4a.6x
-static const char kProprietaryAudioCodecsExpression[] =
-    "mp4a.6?,mp4a.40,mp4a.40.?";
-static const char kProprietaryCodecsExpression[] =
-    "avc1,avc3,avc1.??????,avc3.??????,mp4a.6?,mp4a.40,mp4a.40.?";
-
-static const MediaFormatStrict format_mp4_codec_mappings[] = {
-  { "audio/mp4", kProprietaryAudioCodecsExpression },
-  { "audio/x-m4a", kProprietaryAudioCodecsExpression },
-  { "video/mp4", kProprietaryCodecsExpression },
-  { "video/x-m4v", kProprietaryCodecsExpression },
-  { "application/x-mpegurl", kProprietaryCodecsExpression },
-  { "application/vnd.apple.mpegurl", kProprietaryCodecsExpression }
+static const char kInconclusiveProprietaryAudioCodecsExpression[] =
+    "mp4a.40,mp4a.66,mp4a.68";
+static const char kInconclusiveProprietaryCodecsExpression[] =
+    "avc1,avc1.??????,avc3,avc3.??????,mp4a.40,mp4a.66,mp4a.68";
+
+static const MediaFormatStrict format_inconclusive_codec_mappings[] = {
+    {"audio/mp4", kInconclusiveProprietaryAudioCodecsExpression},
+    {"audio/x-m4a", kInconclusiveProprietaryAudioCodecsExpression},
+    {"video/mp4", kInconclusiveProprietaryCodecsExpression},
+    {"video/x-m4v", kInconclusiveProprietaryCodecsExpression},
+    {"application/x-mpegurl", kInconclusiveProprietaryCodecsExpression},
+    {"application/vnd.apple.mpegurl", kInconclusiveProprietaryCodecsExpression}
 };
 
 MimeUtil::MimeUtil() {
@@ -514,25 +537,15 @@ MimeUtil::MimeUtil() {
 }
 
 // static
-bool MimeUtil::AreSupportedCodecs(const MimeMappings& supported_codecs,
-                                  const std::vector<std::string>& codecs) {
-  if (supported_codecs.empty())
-    return codecs.empty();
-
-  for (size_t i = 0; i < codecs.size(); ++i) {
-    if (supported_codecs.find(codecs[i]) == supported_codecs.end())
-      return false;
-  }
-  return !codecs.empty();
-}
-
 // Checks all the codecs present in the |codecs| against the entries in
 // |supported_codecs|. Returns true only if |codecs| is non-empty and all the
 // codecs match |supported_codecs| expressions.
-bool MimeUtil::AreSupportedCodecsWithProfile(
+bool MimeUtil::AreSupportedCodecs(
     const MimeExpressionMappings& supported_codecs,
     const std::vector<std::string>& codecs) {
-  DCHECK(!supported_codecs.empty());
+  if (supported_codecs.empty())
+    return codecs.empty();
+
   for (size_t i = 0; i < codecs.size(); ++i) {
     bool codec_matched = false;
     for (size_t j = 0; j < supported_codecs.size(); ++j) {
@@ -558,6 +571,7 @@ bool MimeUtil::AreSupportedCodecsWithProfile(
     if (!codec_matched)
       return false;
   }
+
   return !codecs.empty();
 }
 
@@ -607,11 +621,11 @@ void MimeUtil::InitializeMimeTypeMaps() {
     if (!IsCodecSupportedOnAndroid(common_media_codecs[i]))
       continue;
 #endif
-    codecs_map_.insert(common_media_codecs[i]);
+    codecs_map_.push_back(common_media_codecs[i]);
   }
 #if defined(USE_PROPRIETARY_CODECS)
   for (size_t i = 0; i < arraysize(proprietary_media_codecs); ++i)
-    codecs_map_.insert(proprietary_media_codecs[i]);
+    codecs_map_.push_back(proprietary_media_codecs[i]);
 #endif
 
   // Initialize the strict supported media types.
@@ -621,25 +635,39 @@ void MimeUtil::InitializeMimeTypeMaps() {
                      &mime_type_codecs,
                      false);
 
-    MimeMappings codecs;
+    MimeExpressionMappings codecs;
     for (size_t j = 0; j < mime_type_codecs.size(); ++j) {
 #if defined(OS_ANDROID)
       if (!IsCodecSupportedOnAndroid(mime_type_codecs[j]))
         continue;
 #endif
-      codecs.insert(mime_type_codecs[j]);
+      codecs.push_back(mime_type_codecs[j]);
     }
     strict_format_map_[format_codec_mappings[i].mime_type] = codecs;
   }
-  for (size_t i = 0; i < arraysize(format_mp4_codec_mappings); ++i) {
+  for (size_t i = 0; i < arraysize(format_inconclusive_codec_mappings); ++i) {
     std::vector<std::string> mime_type_codecs;
     ParseCodecString(
-        format_mp4_codec_mappings[i].codecs_list, &mime_type_codecs, false);
+        format_inconclusive_codec_mappings[i].codecs_list, &mime_type_codecs,
+        false);
 
     MimeExpressionMappings codecs;
-    for (size_t j = 0; j < mime_type_codecs.size(); ++j)
+    for (size_t j = 0; j < mime_type_codecs.size(); ++j) {
+#if defined(OS_ANDROID)
+      if (!IsCodecSupportedOnAndroid(mime_type_codecs[j]))
+        continue;
+#endif
       codecs.push_back(mime_type_codecs[j]);
-    strict_mp4_format_map_[format_mp4_codec_mappings[i].mime_type] = codecs;
+    }
+    // Merge codecs from conclusive list into inconclusive list so that querries
+    // with one conclusive and one inconclusive codec do not get an empty
+    // string in reply.

[Ryan Sleevi, 2014/07/09 23:56:13]

This comment needs rewording, but unfortunately, it's confusing enough that I'm
not sure what to suggest here, as I'm not clear why you merge the two.

[amogh.bihani, 2014/07/10 04:02:49]

Here is the scenario... "type=video/mp4; codecs= avc1.64001F, mp4a.40"
in this case, avc1.64001F is in the conclusive list but mp4a.40 is in
inconclusive list, so if we do not merge the two list, we will give "" in reply
instead of "maybe".

Another aproach could have been that I rewrite all the entries of conclusive
list in inconclusive list... but then to make it robust we need to have a check
that - if in the future any new entry is added in conclusive list, then it has
to be added in both.

[Ryan Sleevi, 2014/07/10 20:58:44]

Both of the solutions you've describe involve significant copying.

What's not clear is why you can't break apart the codecs parameter, and test if
it's in either list, and make an appropriate decision from that?

This accomplishes the same thing (AFAICT), but without having to copy these
strings around and reparse them. Have I missed something?

+    StrictExpressionMappings::const_iterator it = strict_format_map_.find(
+        format_inconclusive_codec_mappings[i].mime_type);
+    if (it != strict_format_map_.end())
+      codecs.insert(codecs.end(), it->second.begin(), it->second.end());
+    inconclusive_format_map_[format_inconclusive_codec_mappings[i].mime_type] =
+        codecs;
   }
 }
 
@@ -821,8 +849,7 @@ void MimeUtil::ParseCodecString(const std::string& codecs,
 }
 
 bool MimeUtil::IsStrictMediaMimeType(const std::string& mime_type) const {
-  if (strict_format_map_.find(mime_type) == strict_format_map_.end() &&
-      strict_mp4_format_map_.find(mime_type) == strict_mp4_format_map_.end())
+  if (strict_format_map_.find(mime_type) == strict_format_map_.end())
     return false;
   return true;
 }
@@ -830,7 +857,7 @@ bool MimeUtil::IsStrictMediaMimeType(const std::string& mime_type) const {
 SupportsType MimeUtil::IsSupportedStrictMediaMimeType(
     const std::string& mime_type,
     const std::vector<std::string>& codecs) const {
-  StrictMappings::const_iterator it_strict_map =
+  StrictExpressionMappings::const_iterator it_strict_map =
       strict_format_map_.find(mime_type);
   if ((it_strict_map != strict_format_map_.end()) &&
       AreSupportedCodecs(it_strict_map->second, codecs)) {
@@ -838,9 +865,9 @@ SupportsType MimeUtil::IsSupportedStrictMediaMimeType(
   }
 
   StrictExpressionMappings::const_iterator it_expression_map =
-      strict_mp4_format_map_.find(mime_type);
-  if ((it_expression_map != strict_mp4_format_map_.end()) &&
-      AreSupportedCodecsWithProfile(it_expression_map->second, codecs)) {
+      inconclusive_format_map_.find(mime_type);
+  if ((it_expression_map != inconclusive_format_map_.end()) &&
+      AreSupportedCodecs(it_expression_map->second, codecs)) {
     return MayBeSupported;
   }
 
@@ -855,8 +882,12 @@ void MimeUtil::RemoveProprietaryMediaTypesAndCodecsForTests() {
     non_image_map_.erase(proprietary_media_types[i]);
     media_map_.erase(proprietary_media_types[i]);
   }
-  for (size_t i = 0; i < arraysize(proprietary_media_codecs); ++i)
-    codecs_map_.erase(proprietary_media_codecs[i]);
+  for (size_t i = 0; i < arraysize(proprietary_media_codecs); ++i) {
+    codecs_map_.erase(std::remove(codecs_map_.begin(),
+                                  codecs_map_.end(),
+                                  proprietary_media_codecs[i]),
+                      codecs_map_.end());
+  }
 }
 
 //----------------------------------------------------------------------------