diff --git a/trunk/src/app/srs_app_rtc_source.cpp b/trunk/src/app/srs_app_rtc_source.cpp
index 9fe42f62d7..c74b59e9e4 100644
--- a/trunk/src/app/srs_app_rtc_source.cpp
+++ b/trunk/src/app/srs_app_rtc_source.cpp
@@ -1513,22 +1513,22 @@ srs_error_t SrsRtcFrameBuilder::packet_video_key_frame(SrsRtpPacket* pkt)
 {
     srs_error_t err = srs_success;
 
-    bool raw_is_sps_pps = false;
-
-    // For OBS WHIP, it uses RTP Raw packet with SPS/PPS/IDR frame.
+    // For OBS WHIP, it uses RTP Raw packet with SPS/PPS/IDR frame. Note that not all
+    // raw payload is SPS/PPS.
+    bool has_sps_pps_in_raw_payload = false;
     SrsRtpRawPayload* raw_payload = dynamic_cast<SrsRtpRawPayload*>(pkt->payload());
     if (raw_payload) {
         if (pkt->nalu_type == SrsAvcNaluTypeSPS) {
-            raw_is_sps_pps = true;
+            has_sps_pps_in_raw_payload = true;
             srs_freep(obs_whip_sps_);
             obs_whip_sps_ = pkt->copy();
         } else if (pkt->nalu_type == SrsAvcNaluTypePPS) {
-            raw_is_sps_pps = true;
+            has_sps_pps_in_raw_payload = true;
             srs_freep(obs_whip_pps_);
             obs_whip_pps_ = pkt->copy();
         }
         // Ignore if one of OBS WHIP SPS/PPS is not ready.
-        if (raw_is_sps_pps && (!obs_whip_sps_ || !obs_whip_pps_)) {
+        if (has_sps_pps_in_raw_payload && (!obs_whip_sps_ || !obs_whip_pps_)) {
             return err;
         }
     }
@@ -1537,7 +1537,7 @@ srs_error_t SrsRtcFrameBuilder::packet_video_key_frame(SrsRtpPacket* pkt)
     SrsRtpSTAPPayload* stap_payload = dynamic_cast<SrsRtpSTAPPayload*>(pkt->payload());
 
     // Handle SPS/PPS in cache or STAP-A packet.
-    if (stap_payload || (raw_payload && raw_is_sps_pps)) {
+    if (stap_payload || has_sps_pps_in_raw_payload) {
         // Get the SPS/PPS from cache or STAP-A packet.
         SrsSample* sps = stap_payload ? stap_payload->get_sps() : NULL;
         if (!sps && obs_whip_sps_) sps = dynamic_cast<SrsRtpRawPayload*>(obs_whip_sps_->payload())->sample_;