rename roDecMapVideoFrame to rocDecoGetVideoFrame and some other minor code cleanups (#222)

src/rocdecode/roc_decoder.h

@@ -60,11 +60,11 @@ public:
     rocDecStatus DecodeFrame(RocdecPicParams *pic_params);
     rocDecStatus GetDecodeStatus(int pic_idx, RocdecDecodeStatus* decode_status);
     rocDecStatus ReconfigureDecoder(RocdecReconfigureDecoderInfo *reconfig_params);
-    rocDecStatus MapVideoFrame(int pic_idx, void *dev_mem_ptr[3], uint32_t horizontal_pitch[3], RocdecProcParams *vid_postproc_params);
-    rocDecStatus UnMapVideoFrame(int pic_idx);
+    rocDecStatus GetVideoFrame(int pic_idx, void *dev_mem_ptr[3], uint32_t horizontal_pitch[3], RocdecProcParams *vid_postproc_params);
 
 private:
     rocDecStatus InitHIP(int device_id);
+    rocDecStatus ReleaseVideoFrame(int pic_idx);
     int num_devices_;
     RocDecoderCreateInfo decoder_create_info_;
     VaapiVideoDecoder va_video_decoder_;