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/ IRIX Base Documentation 2002 November / SGI IRIX Base Documentation 2002 November.iso / usr / share / catman / p_man / cat3dm / audiofile / afGetPCMMapping.z / afGetPCMMapping
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Text File  |  2002-10-03  |  6.9 KB  |  133 lines
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  4. aaaaffffGGGGeeeettttPPPPCCCCMMMMMMMMaaaappppppppiiiinnnngggg((((3333ddddmmmm))))                                      aaaaffffGGGGeeeettttPPPPCCCCMMMMMMMMaaaappppppppiiiinnnngggg((((3333ddddmmmm))))
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  8. NNNNAAAAMMMMEEEE
  9.      afGetPCMMapping, afGetVirtualPCMMapping - get the track / virtual PCM
  10.      mapping values for a specified audio track from an AAAAFFFFffffiiiilllleeeehhhhaaaannnnddddlllleeee structure
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  12. SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS
  13.      ####iiiinnnncccclllluuuuddddeeee <<<<ddddmmmmeeeeddddiiiiaaaa////aaaauuuuddddiiiiooooffffiiiilllleeee....hhhh>>>>
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  15.      vvvvooooiiiidddd aaaaffffGGGGeeeettttPPPPCCCCMMMMMMMMaaaappppppppiiiinnnngggg((((AAAAFFFFffffiiiilllleeeehhhhaaaannnnddddlllleeee ffffiiiilllleeee,,,, iiiinnnntttt ttttrrrraaaacccckkkk,,,,
  16.                                  ddddoooouuuubbbblllleeee ****ssssllllooooppppeeee,,,, ddddoooouuuubbbblllleeee ****iiiinnnntttteeeerrrrcccceeeepppptttt,,,,
  17.                                  ddddoooouuuubbbblllleeee ****mmmmiiiinnnncccclllliiiipppp,,,, ddddoooouuuubbbblllleeee ****mmmmaaaaxxxxcccclllliiiipppp))))
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  19.      vvvvooooiiiidddd aaaaffffGGGGeeeettttVVVViiiirrrrttttuuuuaaaallllPPPPCCCCMMMMMMMMaaaappppppppiiiinnnngggg((((AAAAFFFFffffiiiilllleeeehhhhaaaannnnddddlllleeee ffffiiiilllleeee,,,, iiiinnnntttt ttttrrrraaaacccckkkk,,,,
  20.                                  ddddoooouuuubbbblllleeee ****ssssllllooooppppeeee,,,, ddddoooouuuubbbblllleeee ****iiiinnnntttteeeerrrrcccceeeepppptttt,,,,
  21.                                  ddddoooouuuubbbblllleeee ****mmmmiiiinnnncccclllliiiipppp,,,, ddddoooouuuubbbblllleeee ****mmmmaaaaxxxxcccclllliiiipppp))))
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  23. PPPPAAAARRRRAAAAMMMMEEEETTTTEEEERRRR
  24.      _f_i_l_e    is an AAAAFFFFffffiiiilllleeeehhhhaaaannnnddddlllleeee structure, previously created by a call to
  25.              aaaaffffOOOOppppeeeennnnFFFFiiiilllleeee(3dm).
  26.  
  27.      _t_r_a_c_k   is an integer which identifies an audio track in _f_i_l_e.
  28.  
  29.              Since all currently supported file formats contain exactly one
  30.              audio track per file, the constant AAAAFFFF____DDDDEEEEFFFFAAAAUUUULLLLTTTT____TTTTRRRRAAAACCCCKKKK should always
  31.              be used here for now.
  32.  
  33.      _s_l_o_p_e   is a pointer to a double precision floating point value which
  34.              specifies the amplitude scaling factor for the audio waveform
  35.              associated with _t_r_a_c_k
  36.  
  37.      _i_n_t_e_r_c_e_p_t
  38.              is a pointer to a double precision floating point value which
  39.              specifies the audio waveform vertical midpoint (zero-crossing)
  40.              value associated with _t_r_a_c_k
  41.  
  42.      _m_i_n_c_l_i_p is a pointer to a double precision floating point value
  43.              indicating the minimum or most negative audio data sample value
  44.              that will be returned.  Any value less than this is set to
  45.              _m_i_n_c_l_i_p
  46.  
  47.      _m_a_x_c_l_i_p is a pointer to a double precision floating point value
  48.              indicating the maximum or most positive audio data sample value
  49.              to be returned.  Any value greater than this is set to _m_a_x_c_l_i_p
  50.  
  51. DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
  52.      aaaaffffGGGGeeeettttPPPPCCCCMMMMMMMMaaaappppppppiiiinnnngggg(((()))) returns the four values associated with the PCM (Pulse
  53.      Code Modulation) mapping in an audio track in the file represented by the
  54.      AAAAFFFFffffiiiilllleeeehhhhaaaannnnddddlllleeee argument, using the double pointer arguments.
  55.  
  56.      aaaaffffGGGGeeeettttVVVViiiirrrrttttuuuuaaaallllPPPPCCCCMMMMMMMMaaaappppppppiiiinnnngggg(((()))) does the same for the virtual format for the
  57.      given _t_r_a_c_k, as set by any combination of calls to
  58.      aaaaffffSSSSeeeettttVVVViiiirrrrttttuuuuaaaallllPPPPCCCCMMMMMMMMaaaappppppppiiiinnnngggg(3dm) and aaaaffffSSSSeeeettttTTTTrrrraaaacccckkkkPPPPCCCCMMMMMMMMaaaappppppppiiiinnnngggg(3dm).
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  63.                                                                         PPPPaaaaggggeeee 1111
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  70. aaaaffffGGGGeeeettttPPPPCCCCMMMMMMMMaaaappppppppiiiinnnngggg((((3333ddddmmmm))))                                      aaaaffffGGGGeeeettttPPPPCCCCMMMMMMMMaaaappppppppiiiinnnngggg((((3333ddddmmmm))))
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  73.  
  74.      See _a_f_I_n_t_r_o(3dm) for a detailed description of the PCM mapping technique.
  75.  
  76. CCCCAAAAVVVVEEEEAAAATTTTSSSS
  77.      PCM mapping is only useful for modifying frames as they are read into or
  78.      written out from a buffer via aaaaffffRRRReeeeaaaaddddFFFFrrrraaaammmmeeeessss(3dm) or aaaaffffWWWWrrrriiiitttteeeeFFFFrrrraaaammmmeeeessss(3dm).
  79.      None of the currently supported file formats have the capability to store
  80.      this information, even though the actual mapping can and will be applied
  81.      to the frames stored in those files.  Therefor, it is important to be
  82.      careful what values you specify.  In general, all two's complement and
  83.      floating point sample formats are expected to be symmetrical about zero,
  84.      i.e., the iiiinnnntttteeeerrrrcccceeeepppptttt will be 0.0 and _m_i_n_c_l_i_p and _m_a_x_c_l_i_p will be negative
  85.      and positive N, where N is some non-zero positive value.
  86.  
  87. SSSSEEEEEEEE AAAALLLLSSSSOOOO
  88.      afWriteFrames(3dm), afReadFrames(3dm), afInitPCMMapping(3dm),
  89.      afSetVirtualPCMMapping(3dm)
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  129.                                                                         PPPPaaaaggggeeee 2222
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