generic/framerate.hpp

   1 #ifndef _framerate__hpp__included__
   2 #define _framerate__hpp__included__
   3
   4 #include <cstdint>
   5
   6 /**
   7  * Number clocks per field/frame on NTSC/PAL
   8  */
   9 #define DURATION_NTSC_FRAME 357366
  10 #define DURATION_NTSC_FIELD 357368
  11 #define DURATION_PAL_FRAME 425568
  12 #define DURATION_PAL_FIELD 425568
  13
  14 /**
  15  * Sets the nominal frame rate. Framerate limiting tries to maintain the nominal framerate when there is no other
  16  * explict framerate to maintain.
  17  */
  18 void set_nominal_framerate(double fps) throw();
  19
  20 /**
  21  * Returns the current realized framerate.
  22  *
  23  * returns: The framerate the system is currently archiving.
  24  */
  25 double get_framerate() throw();
  26
  27 /**
  28  * Acknowledge frame start for timing purposes.
  29  *
  30  * parameter usec: Current time (relative to some unknown epoch) in microseconds.
  31  */
  32 void ack_frame_tick(uint64_t usec) throw();
  33
  34 /**
  35  * Computes the number of microseconds to wait for next frame.
  36  *
  37  * parameter usec: Current time (relative to some unknown epoch) in microseconds.
  38  * returns: Number of more microseconds to wait.
  39  */
  40 uint64_t to_wait_frame(uint64_t usec) throw();
  41
  42 /**
  43  * Return microsecond-resolution time since unix epoch.
  44  */
  45 uint64_t get_utime();
  46
  47 /**
  48  * Wait specified number of microseconds.
  49  */
  50 void wait_usec(uint64_t usec);
  51
  52 #endif