refactor ffmpeg super class into more maintainable package, cmake is catigorized now ; removed old engine, replaced with new one

src/engine/ffmpeg/CodecContext.h

@@ -0,0 +1,38 @@
+#pragma once
+#include <memory>
+
+struct AVCodecContext;
+struct AVCodecParameters;
+struct AVPacket;
+struct AVFrame;
+
+namespace engine {
+
+class CodecContext {
+public:
+    CodecContext()  = default;
+    ~CodecContext() = default;
+    CodecContext(const CodecContext &) = delete;
+    CodecContext &operator=(const CodecContext &) = delete;
+
+    bool open(const AVCodecParameters *par);
+    void close();
+
+    bool sendPacket(const AVPacket *pkt) const;
+
+    bool receiveFrame(AVFrame *frame) const;
+
+    void flush();
+
+    bool isOpen()    const { return m_ctx != nullptr; }
+    int  sampleRate()const;
+    int  channels()  const;
+
+    const AVCodecContext *get() const { return m_ctx.get(); }
+
+private:
+    struct Deleter { void operator()(AVCodecContext *p) const; };
+    std::unique_ptr<AVCodecContext, Deleter> m_ctx;
+};
+
+} // namespace engine