From 8437370c1e71debe6c3b54913a6caa80711a17a2 Mon Sep 17 00:00:00 2001
From: winlin <winlin@vip.126.com>
Date: Wed, 8 Jun 2022 20:38:07 +0800
Subject: [PATCH] SRT: Refine packet error handler.

---
 trunk/src/app/srs_app_srt_conn.cpp   | 19 ++++++++++++++-----
 trunk/src/app/srs_app_srt_source.cpp |  3 ++-
 2 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/trunk/src/app/srs_app_srt_conn.cpp b/trunk/src/app/srs_app_srt_conn.cpp
index 8c024978f..144410ad9 100644
--- a/trunk/src/app/srs_app_srt_conn.cpp
+++ b/trunk/src/app/srs_app_srt_conn.cpp
@@ -312,6 +312,7 @@ srs_error_t SrsMpegtsSrtConn::playing()
     return err;
 }
 
+// TODO: FIXME: It's not atomic and has risk between multiple source checking.
 srs_error_t SrsMpegtsSrtConn::acquire_publish()
 {
     srs_error_t err = srs_success;
@@ -370,8 +371,6 @@ srs_error_t SrsMpegtsSrtConn::do_publishing()
         }
 
         pprint->elapse();
-
-        // reportable
         if (pprint->can_print()) {
             SrsSrtStat s;
             if ((err = s.fetch(srt_fd_, true)) != srs_success) {
@@ -485,9 +484,19 @@ srs_error_t SrsMpegtsSrtConn::on_srt_packet(char* buf, int nb_buf)
 {
     srs_error_t err = srs_success;
 
-    // Check srt payload, mpegts must be N times of SRS_TS_PACKET_SIZE, and the first byte must be 0x47
-    if ((nb_buf <= 0) || (nb_buf % SRS_TS_PACKET_SIZE != 0) || (buf[0] != 0x47)) {
-        return srs_error_new(ERROR_SRT_CONN, "invalid ts packet");
+    // Ignore if invalid length.
+    if (nb_buf <= 0) {
+        return err;
+    }
+
+    // Check srt payload, mpegts must be N times of SRS_TS_PACKET_SIZE
+    if ((nb_buf % SRS_TS_PACKET_SIZE) != 0) {
+        return srs_error_new(ERROR_SRT_CONN, "invalid ts packet len=%d", nb_buf);
+    }
+
+    // Check srt payload, the first byte must be 0x47
+    if (buf[0] != 0x47) {
+        return srs_error_new(ERROR_SRT_CONN, "invalid ts packet first=%#x", (uint8_t)buf[0]);
     }
 
     SrsSrtPacket* packet = new SrsSrtPacket();
diff --git a/trunk/src/app/srs_app_srt_source.cpp b/trunk/src/app/srs_app_srt_source.cpp
index 78b1d7054..4d4f68a31 100644
--- a/trunk/src/app/srs_app_srt_source.cpp
+++ b/trunk/src/app/srs_app_srt_source.cpp
@@ -287,7 +287,8 @@ srs_error_t SrsRtmpFromSrtBridge::on_packet(SrsSrtPacket *pkt)
         SrsBuffer* stream = new SrsBuffer(p, SRS_TS_PACKET_SIZE);
         SrsAutoFree(SrsBuffer, stream);
         
-        // process each ts packet
+        // Process each ts packet. Note that the jitter of UDP may cause video glitch when packet loss or wrong seq. We
+        // don't handle it because SRT will, see tlpkdrop at https://github.com/ossrs/srs/wiki/v5_EN_SRTParams
         if ((err = ts_ctx_->decode(stream, this)) != srs_success) {
             srs_warn("parse ts packet err=%s", srs_error_desc(err).c_str());
             srs_error_reset(err);