修复rtp ext解析相关bug

webrtc/RtpExt.cpp

@@ -162,9 +162,9 @@ size_t RtpExt::size() const {
     return _size;
 }
 
-const char& RtpExt::operator[](size_t pos) const{
+const uint8_t& RtpExt::operator[](size_t pos) const{
     CHECK(pos < _size);
-    return _data[pos];
+    return ((uint8_t*)_data)[pos];
 }
 
 RtpExt::operator std::string() const{

webrtc/RtpExt.h

@@ -99,7 +99,7 @@ private:
     RtpExt(void *ptr, bool one_byte_ext, const char *str, size_t size);
     const char *data() const;
     size_t size() const;
-    const char& operator[](size_t pos) const;
+    const uint8_t& operator[](size_t pos) const;
     operator std::string() const;
 
 private: