feat: add support of codec plugin

ext-codec/JPEG.h

@@ -0,0 +1,64 @@
+#ifndef ZLMEDIAKIT_JPEG_H
+#define ZLMEDIAKIT_JPEG_H
+
+#include "Extension/Frame.h"
+#include "Extension/Track.h"
+
+namespace mediakit {
+
+class JPEGTrack : public VideoTrack {
+public:
+    using Ptr = std::shared_ptr<JPEGTrack>;
+
+    CodecId getCodecId() const override { return CodecJPEG; }
+    int getVideoHeight() const override { return _height; }
+    int getVideoWidth() const override { return _width; }
+    float getVideoFps() const override { return _fps; }
+    bool ready() const override { return _fps > 0; }
+    bool inputFrame(const Frame::Ptr &frame) override;
+
+private:
+    Sdp::Ptr getSdp(uint8_t payload_type) const override;
+    Track::Ptr clone() const override { return std::make_shared<JPEGTrack>(*this); }
+    void getVideoResolution(const uint8_t *buf, int len);
+
+private:
+    int _width = 0;
+    int _height = 0;
+    float _fps = 0;
+    uint64_t _tmp = 0;
+};
+
+class JPEGFrameType {
+public:
+    virtual ~JPEGFrameType() = default;
+    virtual uint8_t pixType() const = 0;
+};
+
+template <typename Parent>
+class JPEGFrame : public Parent, public JPEGFrameType {
+public:
+    static constexpr auto kJFIFSize = 20u;
+    /**
+     *  JPEG/MJPEG帧
+     * @param pix_type pixel format type; AV_PIX_FMT_YUVJ422P || (AVCOL_RANGE_JPEG && AV_PIX_FMT_YUV422P) : 1; AV_PIX_FMT_YUVJ420P || (AVCOL_RANGE_JPEG && AV_PIX_FMT_YUV420P) : 0
+     */
+    template <typename... ARGS>
+    JPEGFrame(uint8_t pix_type, ARGS &&...args) : Parent(std::forward<ARGS>(args)...) {
+        _pix_type = pix_type;
+        // JFIF头固定20个字节长度
+        CHECK(this->size() > kJFIFSize);
+    }
+    size_t prefixSize() const override { return 0; }
+    bool keyFrame() const override { return true; }
+    bool configFrame() const override { return false; }
+    CodecId getCodecId() const override { return CodecJPEG; }
+    uint8_t pixType() const override { return _pix_type; }
+
+private:
+    uint8_t _pix_type;
+};
+
+}//namespace mediakit
+
+#endif //ZLMEDIAKIT_JPEG_H