diff --git a/trunk/src/app/srs_app_rtc_conn.cpp b/trunk/src/app/srs_app_rtc_conn.cpp
index 8c448a4fa..347a34cf7 100644
--- a/trunk/src/app/srs_app_rtc_conn.cpp
+++ b/trunk/src/app/srs_app_rtc_conn.cpp
@@ -313,6 +313,8 @@ SrsRtcPlayStream::SrsRtcPlayStream(SrsRtcConnection* s, SrsContextId parent_cid)
 
     _srs_config->subscribe(this);
     timer_ = new SrsHourGlass(this, 1000 * SRS_UTIME_MILLISECONDS);
+
+    nack_epp = new SrsErrorPithyPrint();
 }
 
 SrsRtcPlayStream::~SrsRtcPlayStream()
@@ -336,6 +338,8 @@ SrsRtcPlayStream::~SrsRtcPlayStream()
             srs_freep(it->second);
         }
     }
+
+    srs_freep(nack_epp);
 }
 
 srs_error_t SrsRtcPlayStream::initialize(SrsRequest* req, std::map<uint32_t, SrsRtcTrackDescription*> sub_relations)
@@ -731,8 +735,12 @@ srs_error_t SrsRtcPlayStream::on_rtcp_nack(SrsRtcpNack* rtcp)
     for (int i = 0; i < (int)resend_pkts.size(); ++i) {
         SrsRtpPacket2* pkt = resend_pkts[i];
         info.nn_bytes += pkt->nb_bytes();
-        srs_trace("RTC NACK ARQ seq=%u, ssrc=%u, ts=%u, %d bytes", pkt->header.get_sequence(),
-            pkt->header.get_ssrc(), pkt->header.get_timestamp(), pkt->nb_bytes());
+
+        uint32_t nn = 0;
+        if (nack_epp->can_print(pkt->header.get_ssrc(), &nn)) {
+            srs_trace("RTC NACK ARQ seq=%u, ssrc=%u, ts=%u, count=%u/%u, %d bytes", pkt->header.get_sequence(),
+                pkt->header.get_ssrc(), pkt->header.get_timestamp(), nn, nack_epp->nn_count, pkt->nb_bytes());
+        }
     }
 
     // By default, we send packets by sendmmsg.
diff --git a/trunk/src/app/srs_app_rtc_conn.hpp b/trunk/src/app/srs_app_rtc_conn.hpp
index e366d37b9..fd17471cd 100644
--- a/trunk/src/app/srs_app_rtc_conn.hpp
+++ b/trunk/src/app/srs_app_rtc_conn.hpp
@@ -221,6 +221,8 @@ private:
     // key: publish_ssrc, value: send track to process rtp/rtcp
     std::map<uint32_t, SrsRtcAudioSendTrack*> audio_tracks_;
     std::map<uint32_t, SrsRtcVideoSendTrack*> video_tracks_;
+    // The pithy print for special stage.
+    SrsErrorPithyPrint* nack_epp;
 private:
     // For merged-write messages.
     int mw_msgs;
diff --git a/trunk/src/app/srs_app_rtc_source.cpp b/trunk/src/app/srs_app_rtc_source.cpp
index c88e09e32..9bbdbc2c7 100644
--- a/trunk/src/app/srs_app_rtc_source.cpp
+++ b/trunk/src/app/srs_app_rtc_source.cpp
@@ -41,6 +41,7 @@
 #include <srs_app_rtc_conn.hpp>
 #include <srs_protocol_utility.hpp>
 #include <srs_protocol_json.hpp>
+#include <srs_app_pithy_print.hpp>
 
 #ifdef SRS_FFMPEG_FIT
 #include <srs_app_rtc_codec.hpp>
@@ -1813,6 +1814,8 @@ SrsRtcSendTrack::SrsRtcSendTrack(SrsRtcConnection* session, SrsRtcTrackDescripti
     } else {
         rtp_queue_ = new SrsRtpRingBuffer(1000);
     }
+
+    nack_epp = new SrsErrorPithyPrint();
 }
 
 SrsRtcSendTrack::~SrsRtcSendTrack()
@@ -1820,6 +1823,7 @@ SrsRtcSendTrack::~SrsRtcSendTrack()
     srs_freep(rtp_queue_);
     srs_freep(track_desc_);
     srs_freep(statistic_);
+    srs_freep(nack_epp);
 }
 
 bool SrsRtcSendTrack::has_ssrc(uint32_t ssrc)
@@ -1836,12 +1840,18 @@ SrsRtpPacket2* SrsRtcSendTrack::fetch_rtp_packet(uint16_t seq)
     }
 
     // For NACK, it sequence must match exactly, or it cause SRTP fail.
-    if (pkt->header.get_sequence() != seq) {
-        srs_trace("miss match seq=%u, pkt seq=%u", seq, pkt->header.get_sequence());
-        return NULL;
+    // Return packet only when sequence is equal.
+    if (pkt->header.get_sequence() == seq) {
+        return pkt;
     }
 
-    return pkt;
+    // Ignore if sequence not match.
+    uint32_t nn = 0;
+    if (nack_epp->can_print(pkt->header.get_ssrc(), &nn)) {
+        srs_trace("RTC NACK miss seq=%u, require_seq=%u, ssrc=%u, ts=%u, count=%u/%u, %d bytes", seq, pkt->header.get_sequence(),
+            pkt->header.get_ssrc(), pkt->header.get_timestamp(), nn, nack_epp->nn_count, pkt->nb_bytes());
+    }
+    return NULL;
 }
 
 // TODO: FIXME: Should refine logs, set tracks in a time.
diff --git a/trunk/src/app/srs_app_rtc_source.hpp b/trunk/src/app/srs_app_rtc_source.hpp
index abd1d072d..cd292b767 100644
--- a/trunk/src/app/srs_app_rtc_source.hpp
+++ b/trunk/src/app/srs_app_rtc_source.hpp
@@ -55,6 +55,7 @@ class SrsRtpRingBuffer;
 class SrsRtpNackForReceiver;
 class SrsJsonObject;
 class SrsRtcPlayStreamStatistic;
+class SrsErrorPithyPrint;
 
 class SrsNtp
 {
@@ -530,11 +531,14 @@ protected:
     // send track description
     SrsRtcTrackDescription* track_desc_;
     SrsRtcTrackStatistic* statistic_;
-
+protected:
     // The owner connection for this track.
     SrsRtcConnection* session_;
     // NACK ARQ ring buffer.
     SrsRtpRingBuffer* rtp_queue_;
+private:
+    // The pithy print for special stage.
+    SrsErrorPithyPrint* nack_epp;
 public:
     SrsRtcSendTrack(SrsRtcConnection* session, SrsRtcTrackDescription* track_desc, bool is_audio);
     virtual ~SrsRtcSendTrack();