From 032a2ac91d1b04fdfa8c7033c320fedeb7c6a3f0 Mon Sep 17 00:00:00 2001
From: dengjfzh <76604422+dengjfzh@users.noreply.github.com>
Date: Fri, 26 May 2023 17:34:47 +0800
Subject: [PATCH] =?UTF-8?q?=E4=BF=AE=E5=A4=8DTCP=20RTP=202=E5=AD=97?=
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当RFC4571封装的RTP包大小在0x2400到0x24ff之间时，会被误认为是RTSP Interleaved
封装的数据。因为0x24正好是'$'的ASCII码，而RtpSplitter::onSearchPacketTail通过'$'来识别RTSP
Interleaved数据。暂时没有想到什么好的办法能够百分之百的正确区分RFC4571数据和RTSP
Interleaved数据。增加一个状态变量记录之前的状态，一旦检测到数据不是RTSP
Interleaved格式，则后续不再进行尝试，以减小误判的可能性。
---
 src/Rtp/RtpSplitter.cpp | 12 ++++++++----
 src/Rtp/RtpSplitter.h   |  1 +
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/src/Rtp/RtpSplitter.cpp b/src/Rtp/RtpSplitter.cpp
index f7175b30..78c5223c 100644
--- a/src/Rtp/RtpSplitter.cpp
+++ b/src/Rtp/RtpSplitter.cpp
@@ -59,11 +59,15 @@ const char *RtpSplitter::onSearchPacketTail(const char *data, size_t len) {
         return onSearchPacketTail_l(data + kEHOME_OFFSET + 2, len - kEHOME_OFFSET - 2);
     }
 
-    if (data[0] == '$') {
-        //可能是4个字节的rtp头
-        _offset = 4;
-        return onSearchPacketTail_l(data + 2, len - 2);
+    if ( _is_rtsp_interleaved ) {
+        if (data[0] == '$') {
+            //可能是4个字节的rtp头
+            _offset = 4;
+            return onSearchPacketTail_l(data + 2, len - 2);
+        }
+        _is_rtsp_interleaved = false;
     }
+    
     //两个字节的rtp头
     _offset = 2;
     return onSearchPacketTail_l(data, len);
diff --git a/src/Rtp/RtpSplitter.h b/src/Rtp/RtpSplitter.h
index 9401691e..50e3af43 100644
--- a/src/Rtp/RtpSplitter.h
+++ b/src/Rtp/RtpSplitter.h
@@ -36,6 +36,7 @@ protected:
 
 private:
     bool _is_ehome = false;
+    bool _is_rtsp_interleaved = true;
     size_t _offset = 0;
 };