Consolidate MPEG*_AAC_* MimeUtil::Codec enum values

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 11 matching lines @@
 
 enum MediaFormatType { COMMON, PROPRIETARY };
 
 struct MediaFormat {
   const char* const mime_type;
   MediaFormatType format_type;
   const char* const codecs_list;
 };
 
 #if defined(USE_PROPRIETARY_CODECS)
-// Following is the list of RFC 6381 compliant codecs:
-//   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
-//   mp4a.6B     - MPEG-1 audio
-//   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)
-//   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";
+    "mp4a.66,mp4a.69,mp4a.40.2";  // MPEG-2 AAC, MP3, and MPEG-4 AAC.

[chcunningham, 2016/03/08 02:36:58]

For posterity: It took me a while to follow why you're able to do this
particular reduction. The comment above for ac-3 explained it (they all reduce
to just AAC).

[ddorwin, 2016/03/08 18:40:03]

That comment applies to all these strings. I moved it up.

 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,"
+    "avc1.42E00A,"
 #if BUILDFLAG(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";
+    "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,vp8.0,vp9,vp9.0"},
+    {"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"},
@@ skipping 27 matching lines @@
 
 // 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},
-    {"mp4a.66", MimeUtil::MPEG2_AAC_MAIN},
-    {"mp4a.67", MimeUtil::MPEG2_AAC_LC},
-    {"mp4a.68", MimeUtil::MPEG2_AAC_SSR},
+    // Following is the list of RFC 6381 compliant audio codecs:
+    //   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)
+    //   mp4a.40.29  - MPEG-4 HE-AAC v2 (AAC LC + SBR + PS)
+    {"mp4a.66", MimeUtil::MPEG2_AAC},
+    {"mp4a.67", MimeUtil::MPEG2_AAC},
+    {"mp4a.68", MimeUtil::MPEG2_AAC},
     {"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},
+    {"mp4a.40.2", MimeUtil::MPEG4_AAC},
+    {"mp4a.40.02", MimeUtil::MPEG4_AAC},
+    {"mp4a.40.5", MimeUtil::MPEG4_AAC},
+    {"mp4a.40.05", MimeUtil::MPEG4_AAC},
+    {"mp4a.40.29", MimeUtil::MPEG4_AAC},
 #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.
 // The codec in these entries indicate the codec and profile
 // we assume the user is trying to indicate.
 static const CodecIDMappings kAmbiguousCodecStringMap[] = {
-    {"mp4a.40", MimeUtil::MPEG4_AAC_LC},
+    {"mp4a.40", MimeUtil::MPEG4_AAC},
     {"avc1", MimeUtil::H264},
     {"avc3", MimeUtil::H264},
     // avc1/avc3.XXXXXX may be ambiguous; handled by ParseAVCCodecId().
 };
 
 #if BUILDFLAG(ENABLE_MSE_MPEG2TS_STREAM_PARSER)
 static const char kHexString[] = "0123456789ABCDEF";
 static char IntToHex(int i) {
   DCHECK_GE(i, 0) << i << " not a hex value";
   DCHECK_LE(i, 15) << i << " not a hex value";
@@ skipping 276 matching lines @@
     case EAC3:
     case THEORA:
       return false;
 
     // ----------------------------------------------------------------------
     // The remaining codecs may be supported depending on platform abilities.
     // ----------------------------------------------------------------------
 
     case PCM:
     case MP3:
-    case MPEG4_AAC_LC:
-    case MPEG4_AAC_SBR_v1:
-    case MPEG4_AAC_SBR_PS_v2:
+    case MPEG4_AAC:
     case VORBIS:
       // These codecs are always supported; via a platform decoder (when used
       // with MSE/EME), a software decoder (the unified pipeline), or with
       // MediaPlayer.
       DCHECK(!is_encrypted || platform_info.has_platform_decoders);
       return true;
 
-    case MPEG2_AAC_LC:
-    case MPEG2_AAC_MAIN:
-    case MPEG2_AAC_SSR:
+    case MPEG2_AAC:
       // MPEG-2 variants of AAC are not supported on Android unless the unified
       // media pipeline can be used. These codecs will be decoded in software.
+      // See https:crbug.com/544268 for details.
       return !is_encrypted && platform_info.is_unified_media_pipeline_enabled;
 
     case OPUS:
       // If clear, the unified pipeline can always decode Opus in software.
       if (!is_encrypted && platform_info.is_unified_media_pipeline_enabled)
         return true;
 
       // Otherwise, platform support is required.
       if (!platform_info.supports_opus)
         return false;
@@ skipping 109 matching lines @@
 
   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 MPEG2_AAC:
+    case MPEG4_AAC:
     case H264:
     case HEVC_MAIN:
       return true;
 
     case PCM:
     case VORBIS:
     case OPUS:
     case VP8:
     case VP9:
     case THEORA:
       return false;
   }
 
   return true;
 }
 
 bool MimeUtil::GetDefaultCodecLowerCase(const std::string& mime_type_lower_case,
                                         Codec* default_codec) const {
   if (mime_type_lower_case == "audio/mpeg" ||
       mime_type_lower_case == "audio/mp3" ||
       mime_type_lower_case == "audio/x-mp3") {
     *default_codec = MimeUtil::MP3;
     return true;
   }
 
   if (mime_type_lower_case == "audio/aac") {
-    *default_codec = MimeUtil::MPEG4_AAC_LC;
+    *default_codec = MimeUtil::MPEG4_AAC;
     return true;
   }
 
   return false;
 }
 
 bool MimeUtil::IsDefaultCodecSupportedLowerCase(
     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