diff --git a/webrtc/RtpExt.cpp b/webrtc/RtpExt.cpp
index d1ade57011..a6ccf6eced 100644
--- a/webrtc/RtpExt.cpp
+++ b/webrtc/RtpExt.cpp
@@ -204,7 +204,7 @@ static unordered_map<string/*ext*/, RtpExtType/*id*/> s_url_to_type = {RTP_EXT_M
 RtpExtType RtpExt::getExtType(const string &url) {
     auto it = s_url_to_type.find(url);
     if (it == s_url_to_type.end()) {
-        throw std::invalid_argument(string("未识别的rtp ext url类型:") + url);
+        throw std::invalid_argument(string("unknown rtp ext url type: ") + url);
     }
     return it->second;
 }
diff --git a/webrtc/RtpExt.h b/webrtc/RtpExt.h
index a7aea2811b..8eb8c4f2f1 100644
--- a/webrtc/RtpExt.h
+++ b/webrtc/RtpExt.h
@@ -35,14 +35,15 @@ namespace mediakit {
     XX(video_orientation,           "urn:3gpp:video-orientation") \
     XX(toffset,                     "urn:ietf:params:rtp-hdrext:toffset") \
     XX(av1,                         "https://aomediacodec.github.io/av1-rtp-spec/#dependency-descriptor-rtp-header-extension") \
-    XX(encrypt,                     "urn:ietf:params:rtp-hdrext:encrypt")
+    XX(encrypt,                     "urn:ietf:params:rtp-hdrext:encrypt")   \
+    XX(video_layers_allocation00,   "http://www.webrtc.org/experiments/rtp-hdrext/video-layers-allocation00")   \
 
 enum class RtpExtType : uint8_t {
     padding = 0,
 #define XX(type, uri) type,
     RTP_EXT_MAP(XX)
 #undef XX
-    reserved = 15,
+    reserved,
 };
 
 class RtcMedia;