feat(rife): add support for frame interpolation and RIFE (#1244)

* feat: add RIFE files and processor/interpolator abstractions
* feat: add `rife` as processor option
* feat: add frame interpolation math except first frame
* feat: complete motion interpolation and add scene detection
* feat: improve Vulkan device validation
* fix: fix casting issues and variable names
* refactor: improve error-checking; add abstractions and factories
* refactor: improve readability of the frames processor
* docs: update changelog

Signed-off-by: k4yt3x <i@k4yt3x.com>

include/libvideo2x/interpolator_rife.h

@@ -0,0 +1,64 @@
+#ifndef INTERPOLATOR_RIFE_H
+#define INTERPOLATOR_RIFE_H
+
+extern "C" {
+#include <libavcodec/avcodec.h>
+}
+
+#include "char_defs.h"
+#include "processor.h"
+#include "rife.h"
+
+// InterpolatorRIFE class definition
+class InterpolatorRIFE : public Interpolator {
+   private:
+    RIFE *rife_;
+    int gpuid_;
+    bool tta_mode_;
+    bool tta_temporal_mode_;
+    bool uhd_mode_;
+    int num_threads_;
+    bool rife_v2_;
+    bool rife_v4_;
+    const StringType model_name_;
+    AVRational in_time_base_;
+    AVRational out_time_base_;
+    AVPixelFormat out_pix_fmt_;
+
+   public:
+    // Constructor
+    InterpolatorRIFE(
+        int gpuid = 0,
+        bool tta_mode = false,
+        bool tta_temporal_mode = false,
+        bool uhd_mode = false,
+        int num_threads = 1,
+        bool rife_v2 = false,
+        bool rife_v4 = true,
+        const StringType model_name = STR("rife-v4.6")
+    );
+
+    // Destructor
+    virtual ~InterpolatorRIFE() override;
+
+    // Initializes the interpolator with decoder and encoder contexts
+    int init(AVCodecContext *dec_ctx, AVCodecContext *enc_ctx, AVBufferRef *hw_ctx) override;
+
+    // Processes an input frame and returns the processed frame
+    int interpolate(AVFrame *prev_frame, AVFrame *in_frame, AVFrame **out_frame, float time_step)
+        override;
+
+    // Returns the interpolator's type
+    ProcessorType get_processor_type() const override { return PROCESSOR_RIFE; }
+
+    // Returns the interpolator's output dimensions
+    void get_output_dimensions(
+        const ProcessorConfig *processor_config,
+        int in_width,
+        int in_height,
+        int &out_width,
+        int &out_height
+    ) const override;
+};
+
+#endif  // INTERPOLATOR_RIFE_H