pc: make codec comparison for static codecs case-insensitive

BUG=webrtc:14211,webrtc:14140

Change-Id: Ib51de4c8961a4cf7c71aea27a55c115613296aae
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/266371
Commit-Queue: Philipp Hancke <philipp.hancke@googlemail.com>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#37295}

pc/webrtc_sdp.cc

@@ -26,6 +26,7 @@
 
 #include "absl/algorithm/container.h"
 #include "absl/strings/ascii.h"
+#include "absl/strings/match.h"
 #include "api/candidate.h"
 #include "api/crypto_params.h"
 #include "api/jsep_ice_candidate.h"
@@ -3601,7 +3602,7 @@ bool ParseRtpmapAttribute(absl::string_view line,
     VideoContentDescription* video_desc = media_desc->as_video();
     for (const cricket::VideoCodec& existing_codec : video_desc->codecs()) {
       if (!existing_codec.name.empty() && payload_type == existing_codec.id &&
-          (encoding_name != existing_codec.name ||
+          (!absl::EqualsIgnoreCase(encoding_name, existing_codec.name) ||
            clock_rate != existing_codec.clockrate)) {
         rtc::StringBuilder description;
         description
@@ -3633,7 +3634,7 @@ bool ParseRtpmapAttribute(absl::string_view line,
     AudioContentDescription* audio_desc = media_desc->as_audio();
     for (const cricket::AudioCodec& existing_codec : audio_desc->codecs()) {
       if (!existing_codec.name.empty() && payload_type == existing_codec.id &&
-          (encoding_name != existing_codec.name ||
+          (!absl::EqualsIgnoreCase(encoding_name, existing_codec.name) ||
            clock_rate != existing_codec.clockrate ||
            channels != existing_codec.channels)) {
         rtc::StringBuilder description;

pc/webrtc_sdp_unittest.cc

@@ -4699,6 +4699,21 @@ TEST_F(WebRtcSdpTest, FmtpBeforeRtpMap) {
   EXPECT_TRUE(SdpDeserialize(sdp, &jdesc_output));
 }
 
+TEST_F(WebRtcSdpTest, StaticallyAssignedPayloadTypeWithDifferentCasing) {
+  std::string sdp =
+      "v=0\r\n"
+      "o=- 11 22 IN IP4 127.0.0.1\r\n"
+      "s=-\r\n"
+      "t=0 0\r\n"
+      "m=audio 49232 RTP/AVP 18\r\n"
+      // Casing differs from statically assigned type, this should
+      // still be accepted.
+      "a=rtpmap:18 g729/8000\r\n";
+
+  JsepSessionDescription jdesc_output(kDummyType);
+  EXPECT_TRUE(SdpDeserialize(sdp, &jdesc_output));
+}
+
 // This tests parsing of SDP with unknown ssrc-specific attributes.
 TEST_F(WebRtcSdpTest, ParseIgnoreUnknownSsrcSpecificAttribute) {
   std::string sdp = kSdpString;