Add codec comparison function to SdpVideoFormat

SdpVideoFormat is used to configure video encoder and decoders.
This CL adds support for comparing two SdpVideoFormat objects
to determine if they specify the same video codec.

This functionality previously only existed in media/base/codec.h
which made the code sensitive to circular dependencies. Once
downstream projects stop using cricket::IsSameCodec, this code
can be removed.

Bug: chromium:1187565
Change-Id: I242069aa6af07917637384c80ee4820887defc7d
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/213427
Commit-Queue: Johannes Kron <kron@webrtc.org>
Reviewed-by: Niels Moller <nisse@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#33794}

api/video_codecs/BUILD.gn

@@ -44,6 +44,7 @@ rtc_library("video_codecs_api") {
   deps = [
     "..:fec_controller_api",
     "..:scoped_refptr",
+    "../../api:array_view",
     "../../modules/video_coding:codec_globals_headers",
     "../../rtc_base:checks",
     "../../rtc_base:rtc_base_approved",

api/video_codecs/builtin_video_encoder_factory.cc

@@ -26,18 +26,6 @@ namespace webrtc {
 
 namespace {
 
-bool IsFormatSupported(const std::vector<SdpVideoFormat>& supported_formats,
-                       const SdpVideoFormat& format) {
-  for (const SdpVideoFormat& supported_format : supported_formats) {
-    if (cricket::IsSameCodec(format.name, format.parameters,
-                             supported_format.name,
-                             supported_format.parameters)) {
-      return true;
-    }
-  }
-  return false;
-}
-
 // This class wraps the internal factory and adds simulcast.
 class BuiltinVideoEncoderFactory : public VideoEncoderFactory {
  public:
@@ -47,8 +35,8 @@ class BuiltinVideoEncoderFactory : public VideoEncoderFactory {
   VideoEncoderFactory::CodecInfo QueryVideoEncoder(
       const SdpVideoFormat& format) const override {
     // Format must be one of the internal formats.
-    RTC_DCHECK(IsFormatSupported(
-        internal_encoder_factory_->GetSupportedFormats(), format));
+    RTC_DCHECK(
+        format.IsCodecInList(internal_encoder_factory_->GetSupportedFormats()));
     VideoEncoderFactory::CodecInfo info;
     return info;
   }
@@ -57,8 +45,8 @@ class BuiltinVideoEncoderFactory : public VideoEncoderFactory {
       const SdpVideoFormat& format) override {
     // Try creating internal encoder.
     std::unique_ptr<VideoEncoder> internal_encoder;
-    if (IsFormatSupported(internal_encoder_factory_->GetSupportedFormats(),
-                          format)) {
+    if (format.IsCodecInList(
+            internal_encoder_factory_->GetSupportedFormats())) {
       internal_encoder = std::make_unique<EncoderSimulcastProxy>(
           internal_encoder_factory_.get(), format);
     }

api/video_codecs/sdp_video_format.cc

@@ -10,10 +10,57 @@
 
 #include "api/video_codecs/sdp_video_format.h"
 
+#include "absl/strings/match.h"
+#include "api/video_codecs/h264_profile_level_id.h"
+#include "api/video_codecs/video_codec.h"
+#include "api/video_codecs/vp9_profile.h"
+#include "rtc_base/checks.h"
 #include "rtc_base/strings/string_builder.h"
 
 namespace webrtc {
 
+namespace {
+
+std::string H264GetPacketizationModeOrDefault(
+    const SdpVideoFormat::Parameters& params) {
+  constexpr char kH264FmtpPacketizationMode[] = "packetization-mode";
+  const auto it = params.find(kH264FmtpPacketizationMode);
+  if (it != params.end()) {
+    return it->second;
+  }
+  // If packetization-mode is not present, default to "0".
+  // https://tools.ietf.org/html/rfc6184#section-6.2
+  return "0";
+}
+
+bool H264IsSamePacketizationMode(const SdpVideoFormat::Parameters& left,
+                                 const SdpVideoFormat::Parameters& right) {
+  return H264GetPacketizationModeOrDefault(left) ==
+         H264GetPacketizationModeOrDefault(right);
+}
+
+// Some (video) codecs are actually families of codecs and rely on parameters
+// to distinguish different incompatible family members.
+bool IsSameCodecSpecific(const SdpVideoFormat& format1,
+                         const SdpVideoFormat& format2) {
+  // The assumption when calling this function is that the two formats have the
+  // same name.
+  RTC_DCHECK(absl::EqualsIgnoreCase(format1.name, format2.name));
+
+  VideoCodecType codec_type = PayloadStringToCodecType(format1.name);
+  switch (codec_type) {
+    case kVideoCodecH264:
+      return H264IsSameProfile(format1.parameters, format2.parameters) &&
+             H264IsSamePacketizationMode(format1.parameters,
+                                         format2.parameters);
+    case kVideoCodecVP9:
+      return VP9IsSameProfile(format1.parameters, format2.parameters);
+    default:
+      return true;
+  }
+}
+}  // namespace
+
 SdpVideoFormat::SdpVideoFormat(const std::string& name) : name(name) {}
 
 SdpVideoFormat::SdpVideoFormat(const std::string& name,
@@ -37,6 +84,23 @@ std::string SdpVideoFormat::ToString() const {
   return builder.str();
 }
 
+bool SdpVideoFormat::IsSameCodec(const SdpVideoFormat& other) const {
+  // Two codecs are considered the same if the name matches (case insensitive)
+  // and certain codec-specific parameters match.
+  return absl::EqualsIgnoreCase(name, other.name) &&
+         IsSameCodecSpecific(*this, other);
+}
+
+bool SdpVideoFormat::IsCodecInList(
+    rtc::ArrayView<const webrtc::SdpVideoFormat> formats) const {
+  for (const auto& format : formats) {
+    if (IsSameCodec(format)) {
+      return true;
+    }
+  }
+  return false;
+}
+
 bool operator==(const SdpVideoFormat& a, const SdpVideoFormat& b) {
   return a.name == b.name && a.parameters == b.parameters;
 }

api/video_codecs/sdp_video_format.h

@@ -14,6 +14,7 @@
 #include <map>
 #include <string>
 
+#include "api/array_view.h"
 #include "rtc_base/system/rtc_export.h"
 
 namespace webrtc {
@@ -32,6 +33,13 @@ struct RTC_EXPORT SdpVideoFormat {
 
   ~SdpVideoFormat();
 
+  // Returns true if the SdpVideoFormats have the same names as well as codec
+  // specific parameters. Please note that two SdpVideoFormats can represent the
+  // same codec even though not all parameters are the same.
+  bool IsSameCodec(const SdpVideoFormat& other) const;
+  bool IsCodecInList(
+      rtc::ArrayView<const webrtc::SdpVideoFormat> formats) const;
+
   std::string ToString() const;
 
   friend RTC_EXPORT bool operator==(const SdpVideoFormat& a,

api/video_codecs/test/BUILD.gn

@@ -14,6 +14,7 @@ if (rtc_include_tests) {
     sources = [
       "builtin_video_encoder_factory_unittest.cc",
       "h264_profile_level_id_unittest.cc",
+      "sdp_video_format_unittest.cc",
       "video_decoder_software_fallback_wrapper_unittest.cc",
       "video_encoder_software_fallback_wrapper_unittest.cc",
     ]

api/video_codecs/test/sdp_video_format_unittest.cc

@@ -0,0 +1,74 @@
+/*
+ *  Copyright (c) 2021 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "api/video_codecs/sdp_video_format.h"
+
+#include <stdint.h>
+
+#include "test/gtest.h"
+
+namespace webrtc {
+
+typedef SdpVideoFormat Sdp;
+typedef SdpVideoFormat::Parameters Params;
+
+TEST(SdpVideoFormatTest, SameCodecNameNoParameters) {
+  EXPECT_TRUE(Sdp("H264").IsSameCodec(Sdp("h264")));
+  EXPECT_TRUE(Sdp("VP8").IsSameCodec(Sdp("vp8")));
+  EXPECT_TRUE(Sdp("Vp9").IsSameCodec(Sdp("vp9")));
+  EXPECT_TRUE(Sdp("AV1").IsSameCodec(Sdp("Av1")));
+}
+TEST(SdpVideoFormatTest, DifferentCodecNameNoParameters) {
+  EXPECT_FALSE(Sdp("H264").IsSameCodec(Sdp("VP8")));
+  EXPECT_FALSE(Sdp("VP8").IsSameCodec(Sdp("VP9")));
+  EXPECT_FALSE(Sdp("AV1").IsSameCodec(Sdp("")));
+}
+TEST(SdpVideoFormatTest, SameCodecNameSameParameters) {
+  EXPECT_TRUE(Sdp("VP9").IsSameCodec(Sdp("VP9", Params{{"profile-id", "0"}})));
+  EXPECT_TRUE(Sdp("VP9", Params{{"profile-id", "0"}})
+                  .IsSameCodec(Sdp("VP9", Params{{"profile-id", "0"}})));
+  EXPECT_TRUE(Sdp("VP9", Params{{"profile-id", "2"}})
+                  .IsSameCodec(Sdp("VP9", Params{{"profile-id", "2"}})));
+  EXPECT_TRUE(
+      Sdp("H264", Params{{"profile-level-id", "42e01f"}})
+          .IsSameCodec(Sdp("H264", Params{{"profile-level-id", "42e01f"}})));
+  EXPECT_TRUE(
+      Sdp("H264", Params{{"profile-level-id", "640c34"}})
+          .IsSameCodec(Sdp("H264", Params{{"profile-level-id", "640c34"}})));
+}
+
+TEST(SdpVideoFormatTest, SameCodecNameDifferentParameters) {
+  EXPECT_FALSE(Sdp("VP9").IsSameCodec(Sdp("VP9", Params{{"profile-id", "2"}})));
+  EXPECT_FALSE(Sdp("VP9", Params{{"profile-id", "0"}})
+                   .IsSameCodec(Sdp("VP9", Params{{"profile-id", "1"}})));
+  EXPECT_FALSE(Sdp("VP9", Params{{"profile-id", "2"}})
+                   .IsSameCodec(Sdp("VP9", Params{{"profile-id", "0"}})));
+  EXPECT_FALSE(
+      Sdp("H264", Params{{"profile-level-id", "42e01f"}})
+          .IsSameCodec(Sdp("H264", Params{{"profile-level-id", "640c34"}})));
+  EXPECT_FALSE(
+      Sdp("H264", Params{{"profile-level-id", "640c34"}})
+          .IsSameCodec(Sdp("H264", Params{{"profile-level-id", "42f00b"}})));
+}
+
+TEST(SdpVideoFormatTest, DifferentCodecNameSameParameters) {
+  EXPECT_FALSE(Sdp("VP9", Params{{"profile-id", "0"}})
+                   .IsSameCodec(Sdp("H264", Params{{"profile-id", "0"}})));
+  EXPECT_FALSE(Sdp("VP9", Params{{"profile-id", "2"}})
+                   .IsSameCodec(Sdp("VP8", Params{{"profile-id", "2"}})));
+  EXPECT_FALSE(
+      Sdp("H264", Params{{"profile-level-id", "42e01f"}})
+          .IsSameCodec(Sdp("VP9", Params{{"profile-level-id", "42e01f"}})));
+  EXPECT_FALSE(
+      Sdp("H264", Params{{"profile-level-id", "640c34"}})
+          .IsSameCodec(Sdp("VP8", Params{{"profile-level-id", "640c34"}})));
+}
+
+}  // namespace webrtc

media/base/codec.cc

@@ -58,18 +58,6 @@ bool IsSameCodecSpecific(const std::string& name1,
   return true;
 }
 
-bool IsCodecInList(
-    const webrtc::SdpVideoFormat& format,
-    const std::vector<webrtc::SdpVideoFormat>& existing_formats) {
-  for (auto existing_format : existing_formats) {
-    if (IsSameCodec(format.name, format.parameters, existing_format.name,
-                    existing_format.parameters)) {
-      return true;
-    }
-  }
-  return false;
-}
-
 }  // namespace
 
 FeedbackParams::FeedbackParams() = default;
@@ -452,6 +440,8 @@ const VideoCodec* FindMatchingCodec(
   return nullptr;
 }
 
+// TODO(crbug.com/1187565): Remove once downstream projects stopped using this
+// method in favor of SdpVideoFormat::IsSameCodec().
 bool IsSameCodec(const std::string& name1,
                  const CodecParameterMap& params1,
                  const std::string& name2,
@@ -493,7 +483,7 @@ void AddH264ConstrainedBaselineProfileToSupportedFormats(
   std::copy_if(cbr_supported_formats.begin(), cbr_supported_formats.end(),
                std::back_inserter(*supported_formats),
                [supported_formats](const webrtc::SdpVideoFormat& format) {
-                 return !IsCodecInList(format, *supported_formats);
+                 return !format.IsCodecInList(*supported_formats);
                });
 
   if (supported_formats->size() > original_size) {

media/engine/internal_decoder_factory.cc

@@ -23,23 +23,6 @@
 
 namespace webrtc {
 
-namespace {
-
-bool IsFormatSupported(
-    const std::vector<webrtc::SdpVideoFormat>& supported_formats,
-    const webrtc::SdpVideoFormat& format) {
-  for (const webrtc::SdpVideoFormat& supported_format : supported_formats) {
-    if (cricket::IsSameCodec(format.name, format.parameters,
-                             supported_format.name,
-                             supported_format.parameters)) {
-      return true;
-    }
-  }
-  return false;
-}
-
-}  // namespace
-
 std::vector<SdpVideoFormat> InternalDecoderFactory::GetSupportedFormats()
     const {
   std::vector<SdpVideoFormat> formats;
@@ -55,7 +38,7 @@ std::vector<SdpVideoFormat> InternalDecoderFactory::GetSupportedFormats()
 
 std::unique_ptr<VideoDecoder> InternalDecoderFactory::CreateVideoDecoder(
     const SdpVideoFormat& format) {
-  if (!IsFormatSupported(GetSupportedFormats(), format)) {
+  if (!format.IsCodecInList(GetSupportedFormats())) {
     RTC_LOG(LS_WARNING) << "Trying to create decoder for unsupported format. "
                         << format.ToString();
     return nullptr;

media/engine/webrtc_video_engine.cc

@@ -759,8 +759,8 @@ WebRtcVideoChannel::SelectSendVideoCodecs(
       // following the spec in https://tools.ietf.org/html/rfc6184#section-8.2.2
       // since we should limit the encode level to the lower of local and remote
       // level when level asymmetry is not allowed.
-      if (IsSameCodec(format_it->name, format_it->parameters,
-                      remote_codec.codec.name, remote_codec.codec.params)) {
+      if (format_it->IsSameCodec(
+              {remote_codec.codec.name, remote_codec.codec.params})) {
         encoders.push_back(remote_codec);
 
         // To allow the VideoEncoderFactory to keep information about which
@@ -954,8 +954,8 @@ void WebRtcVideoChannel::RequestEncoderSwitch(
   RTC_DCHECK_RUN_ON(&thread_checker_);
 
   for (const VideoCodecSettings& codec_setting : negotiated_codecs_) {
-    if (IsSameCodec(format.name, format.parameters, codec_setting.codec.name,
-                    codec_setting.codec.params)) {
+    if (format.IsSameCodec(
+            {codec_setting.codec.name, codec_setting.codec.params})) {
       VideoCodecSettings new_codec_setting = codec_setting;
       for (const auto& kv : format.parameters) {
         new_codec_setting.codec.params[kv.first] = kv.second;