rtp send rtp g711 audio can config duration (#3325)

optimization for this
[issue](https://github.com/ZLMediaKit/ZLMediaKit/issues/3316)

src/Common/config.cpp

@@ -338,6 +338,7 @@ const string kH265PT = RTP_PROXY_FIELD "h265_pt";
 const string kPSPT = RTP_PROXY_FIELD "ps_pt";
 const string kOpusPT = RTP_PROXY_FIELD "opus_pt";
 const string kGopCache = RTP_PROXY_FIELD "gop_cache";
+const string kRtpG711DurMs = RTP_PROXY_FIELD "rtp_g711_dur_ms";
 
 static onceToken token([]() {
     mINI::Instance()[kDumpDir] = "";
@@ -348,6 +349,7 @@ static onceToken token([]() {
     mINI::Instance()[kPSPT] = 96;
     mINI::Instance()[kOpusPT] = 100;
     mINI::Instance()[kGopCache] = 1;
+    mINI::Instance()[kRtpG711DurMs] = 100;
 });
 } // namespace RtpProxy
 

src/Common/config.h

@@ -382,6 +382,9 @@ extern const std::string kPSPT;
 extern const std::string kOpusPT;
 // RtpSender相关功能是否提前开启gop缓存优化级联秒开体验，默认开启
 extern const std::string kGopCache;
+//国标发送g711 rtp 打包时，每个包的语音时长是多少，默认是100 ms，范围为20~180ms (gb28181-2016，c.2.4规定)，
+//最好为20 的倍数，程序自动向20的倍数取整
+extern const std::string kRtpG711DurMs;
 } // namespace RtpProxy
 
 /**

src/Rtp/RawEncoder.cpp

@@ -34,6 +34,12 @@ bool RawEncoderImp::addTrack(const Track::Ptr &track) {
         auto ring = std::make_shared<RtpRing::RingType>();
         ring->setDelegate(std::make_shared<RingDelegateHelper>([this](RtpPacket::Ptr rtp, bool is_key) { onRTP(std::move(rtp), true); }));
         _rtp_encoder->setRtpRing(std::move(ring));
+        if (track->getCodecId() == CodecG711A || track->getCodecId() == CodecG711U) {
+            GET_CONFIG(uint32_t, dur_ms, RtpProxy::kRtpG711DurMs);
+            Any param;
+            param.set<uint32_t>(dur_ms);
+            _rtp_encoder->setOpt(RtpCodec::RTP_ENCODER_PKT_DUR_MS, param);
+        }
         return true;
     }
 

src/Rtsp/RtpCodec.h

@@ -93,6 +93,17 @@ public:
 
     RtpInfo &getRtpInfo() { return *_rtp_info; }
 
+    enum {
+        RTP_ENCODER_PKT_DUR_MS = 1 // 主要应用于g711 rtp 打包器每个包的时间长度，option_value 为int*, option_len 为4
+    };
+    /**
+     * @brief 设置rtp打包器与解包器的相关参数，主要应用与g711 rtp 打包器，使用方法类似setsockopt
+     *
+     * @param opt 设置的选项
+     * @param param 设置的参数
+     */
+    virtual void setOpt(int opt, const toolkit::Any &param) {};
+
 private:
     std::unique_ptr<RtpInfo> _rtp_info;
 };