rtsp/rtp 新增支持mjpeg编码 (#2166)

* Trying to send mjpeg via MultiMediaSourceMuxer

* Improved JPEGRtpEncoder::inputFrame code but still not working

* 优化代码

* 完善jpeg相关逻辑

* Micro fix

* FrameJPEG renamed to JPEGFrame according to ZLM style

* Modified  JPEGRtpEncoder::inputFrame and JPEGRtpEncoder::rtp_send_jpeg

* getVideoHeight(), getVideoWidth() and getVideoFps() in JPEGTrack

* mjpeg rtp打包避免内存拷贝/修复mjpeg rtp解包huffman_table size字段错误的bug

* 支持mjpeg pix type

* 优化性能

* add bom header

src/Extension/JPEGRtp.h

@@ -0,0 +1,59 @@
+#ifndef ZLMEDIAKIT_JPEGRTP_H
+#define ZLMEDIAKIT_JPEGRTP_H
+
+#include "Frame.h"
+#include "Rtsp/RtpCodec.h"
+
+namespace mediakit{
+
+/**
+ * RTP/JPEG specific private data.
+ */
+struct PayloadContext {
+    std::string frame;         ///< current frame buffer
+    uint32_t timestamp;      ///< current frame timestamp
+    int hdr_size;       ///< size of the current frame header
+    uint8_t qtables[128][128];
+    uint8_t qtables_len[128];
+};
+
+/**
+ * 通用 rtp解码类
+ */
+class JPEGRtpDecoder : public RtpCodec {
+public:
+    typedef std::shared_ptr <JPEGRtpDecoder> Ptr;
+
+    JPEGRtpDecoder();
+    ~JPEGRtpDecoder() override = default;
+
+    /**
+     * 返回编码类型ID
+     */
+    CodecId getCodecId() const override;
+
+    /**
+     * 输入rtp并解码
+     * @param rtp rtp数据包
+     * @param key_pos 此参数内部强制转换为false,请忽略之
+     */
+    bool inputRtp(const RtpPacket::Ptr &rtp, bool key_pos = false) override;
+
+private:
+    struct PayloadContext _ctx;
+};
+
+class JPEGRtpEncoder : public JPEGRtpDecoder, public RtpInfo {
+public:
+    using Ptr = std::shared_ptr<JPEGRtpEncoder>;
+
+    JPEGRtpEncoder(uint32_t ssrc, uint32_t mtu = 1400, uint32_t sample_rate = 90000, uint8_t payload_type = 96, uint8_t interleaved = TrackVideo * 2);
+    ~JPEGRtpEncoder() = default;
+
+    bool inputFrame(const Frame::Ptr &frame) override;
+
+private:
+    void rtpSendJpeg(const uint8_t *buf, int size, uint64_t pts, uint8_t type);
+};
+}//namespace mediakit
+#endif //ZLMEDIAKIT_JPEGRTP_H