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Text File  |  2002-10-03  |  7.5 KB  |  133 lines
  1.  
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  4. ddddmmmmTTTTCCCCTTTTooooSSSSeeeeccccoooonnnnddddssss((((3333ddddmmmm))))                                          ddddmmmmTTTTCCCCTTTTooooSSSSeeeeccccoooonnnnddddssss((((3333ddddmmmm))))
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  8. NNNNAAAAMMMMEEEE
  9.      dmTCToSeconds, dmTCFromSeconds - digital media timecode mathematics
  10.  
  11. SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS
  12.      ####iiiinnnncccclllluuuuddddeeee <<<<ddddmmmmeeeeddddiiiiaaaa////ddddmmmm____ttttiiiimmmmeeeeccccooooddddeeee....hhhh>>>>
  13.  
  14.      DDDDMMMMssssttttaaaattttuuuussss ddddmmmmTTTTCCCCTTTTooooSSSSeeeeccccoooonnnnddddssss
  15.          (((( ccccoooonnnnsssstttt DDDDMMMMttttiiiimmmmeeeeccccooooddddeeee ****ttttcccc,,,,
  16.            ddddoooouuuubbbblllleeee ****sssseeeeccccoooonnnnddddssss ))))
  17.  
  18.      DDDDMMMMssssttttaaaattttuuuussss ddddmmmmTTTTCCCCFFFFrrrroooommmmSSSSeeeeccccoooonnnnddddssss
  19.          (((( DDDDMMMMttttiiiimmmmeeeeccccooooddddeeee **** rrrreeeessssuuuulllltttt,,,,
  20.            ccccoooonnnnsssstttt iiiinnnntttt ttttcccc____ttttyyyyppppeeee,,,,
  21.            ccccoooonnnnsssstttt ddddoooouuuubbbblllleeee sssseeeeccccoooonnnnddddssss ))))
  22.  
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  25. TTTTYYYYPPPPEEEESSSS
  26.      _D_M_t_i_m_e_c_o_d_e   A structure containing a representation of SMPTE time code
  27.                   on which certain mathematical and utility functions can be
  28.                   performed.  Can be used with:  ddddmmmmTTTTCCCCAAAAddddddddTTTTCCCC((((3333ddddmmmm)))),
  29.                   ddddmmmmTTTTCCCCAAAAddddddddFFFFrrrraaaammmmeeeessss((((3333ddddmmmm)))), ddddmmmmTTTTCCCCTTTTooooSSSSttttrrrriiiinnnngggg((((3333ddddmmmm)))), ddddmmmmTTTTCCCCFFFFrrrroooommmmSSSSeeeeccccoooonnnnddddssss((((3333ddddmmmm)))),
  30.                   ddddmmmmTTTTCCCCTTTTooooSSSSeeeeccccoooonnnnddddssss((((3333ddddmmmm)))), ddddmmmmTTTTCCCCFFFFrrrroooommmmSSSSttttrrrriiiinnnngggg((((3333ddddmmmm)))),
  31.                   ddddmmmmTTTTCCCCFFFFrrrraaaammmmeeeessssPPPPeeeerrrrDDDDaaaayyyy((((3333ddddmmmm)))), and ddddmmmmTTTTCCCCFFFFrrrraaaammmmeeeessssBBBBeeeettttwwwweeeeeeeennnn((((3333ddddmmmm)))).  Can also
  32.                   be used with the ddddmmmmLLLLTTTTCCCC((((3333ddddmmmm)))) and ddddmmmmVVVVIIIITTTTCCCC((((3333ddddmmmm)))) routines.  See
  33.                   also DDDDMMMMttttiiiimmmmeeeeccccooooddddeeee((((3333ddddmmmm)))).
  34.  
  35.  
  36. AAAARRRRGGGGUUUUMMMMEEEENNNNTTTTSSSS
  37.      _r_e_s_u_l_t   The result of converting fractional seconds past midnight into a
  38.               timecode value.
  39.  
  40.  
  41.      _t_c       The timecode value to convert into seconds.
  42.  
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  44.      _s_e_c_o_n_d_s  The number of fractional seconds past midnight to convert, or
  45.               the result of converting a DDDDMMMMttttiiiimmmmeeeeccccooooddddeeee into fractional seconds
  46.               past midnight.
  47.  
  48.  
  49.      _t_c__t_y_p_e  When converting from fractional seconds to a DDDDMMMMttttiiiimmmmeeeeccccooooddddeeee, the
  50.               timecode format into which the seconds should be converted.  See
  51.               ttttcccc____ttttyyyyppppeeee((((3333ddddmmmm)))).
  52.  
  53.  
  54. DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
  55.      These functions provide a simple means of converting between fractional
  56.      seconds past midnight and DDDDMMMMttttiiiimmmmeeeeccccooooddddeeee timecodes.
  57.  
  58.      When converting from seconds to timecode, a valid _t_c__t_y_p_e must be
  59.      supplied (see ttttcccc____ttttyyyyppppeeee((((3333ddddmmmm))))). The _t_c__t_y_p_e of _r_e_s_u_l_t will be the same as
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  63.                                                                         PPPPaaaaggggeeee 1111
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  70. ddddmmmmTTTTCCCCTTTTooooSSSSeeeeccccoooonnnnddddssss((((3333ddddmmmm))))                                          ddddmmmmTTTTCCCCTTTTooooSSSSeeeeccccoooonnnnddddssss((((3333ddddmmmm))))
  71.  
  72.  
  73.  
  74.      the _t_c__t_y_p_e that is passed to ddddmmmmTTTTCCCCFFFFrrrroooommmmSSSSeeeeccccoooonnnnddddssss.
  75.  
  76.      For ddddmmmmTTTTCCCCFFFFrrrroooommmmSSSSeeeeccccoooonnnnddddssss, the _s_e_c_o_n_d_s value given will be rounded to the
  77.      nearest frame.
  78.  
  79.      In order to convert to and from seconds, these routines need to assume
  80.      some timecode rate in frames per second.  They will choose the rate given
  81.      in the DM_TC_RATE bits of the specified _t_c__t_y_p_e.  For drop-frame
  82.      timecode, this is nnnnooootttt the rate of the underlying video signal, and over
  83.      the long term there will be drift.  See ttttcccc____ttttyyyyppppeeee((((3333ddddmmmm)))) for more information
  84.      on this.
  85.  
  86.  
  87. RRRREEEETTTTUUUURRRRNNNN VVVVAAAALLLLUUUUEEEE
  88.      If a DDDDMMMMttttiiiimmmmeeeeccccooooddddeeee operand (_t_c) contains an illegal timecode value (e.g., a
  89.      negative entry, invalid frame number, etc.), ddddmmmmTTTTCCCCTTTTooooSSSSeeeeccccoooonnnnddddssss will return
  90.      DM_FAILURE, and the contents of _s_e_c_o_n_d_s will be undefined.
  91.  
  92.      If the number of seconds passed to ddddmmmmTTTTCCCCFFFFrrrroooommmmSSSSeeeeccccoooonnnnddddssss is negative, or
  93.      greater than the number of seconds in a 24-hour day, ddddmmmmTTTTCCCCFFFFrrrroooommmmSSSSeeeeccccoooonnnnddddssss will
  94.      return DM_FAILURE, and the contents of _r_e_s_u_l_t will be undefined.
  95.  
  96.      If an invalid _t_c__t_y_p_e value is passed in to ddddmmmmTTTTCCCCFFFFrrrroooommmmSSSSeeeeccccoooonnnnddddssss, DM_FAILURE
  97.      is returned.
  98.  
  99.      ddddmmmmTTTTCCCCTTTTooooSSSSeeeeccccoooonnnnddddssss and ddddmmmmTTTTCCCCFFFFrrrroooommmmSSSSeeeeccccoooonnnnddddssss return DM_SUCCESS upon successful
  100.      completion.
  101.  
  102.  
  103. SSSSEEEEEEEE AAAALLLLSSSSOOOO
  104.      dmTCFromSeconds(3dm), dmTCToSeconds(3dm), dmTCFromString(3dm),
  105.      dmTCFromString(3dm), dmTCFramesPerDay(3dm), dmTCFramesBetween(3dm),
  106.      dmLTC(3dm), dmVITC(3dm)
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  129.                                                                         PPPPaaaaggggeeee 2222
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