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/ IRIX Base Documentation 2001 May / SGI IRIX Base Documentation 2001 May.iso / usr / share / catman / p_man / cat3dm / dmedia / dmAudioRateConverterGetParams.z / dmAudioRateConverterGetParams
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Text File  |  1998-10-20  |  6.6 KB  |  133 lines
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  4. ddddmmmmAAAAuuuuddddiiiiooooRRRRaaaatttteeeeCCCCoooonnnnvvvveeeerrrrtttteeeerrrrGGGGeeeettttPPPPaaaarrrraaaammmmssss((((3333ddddmmmm))))          ddddmmmmAAAAuuuuddddiiiiooooRRRRaaaatttteeeeCCCCoooonnnnvvvveeeerrrrtttteeeerrrrGGGGeeeettttPPPPaaaarrrraaaammmmssss((((3333ddddmmmm))))
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  8. NNNNAAAAMMMMEEEE
  9.      dmAudioRateConverterGetParams - get rate converter parameter values
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  12. SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS
  13.      ####iiiinnnncccclllluuuuddddeeee <<<<ddddmmmmeeeeddddiiiiaaaa////ddddmmmm____aaaauuuuddddiiiioooouuuuttttiiiillll....hhhh>>>>
  14.      ####iiiinnnncccclllluuuuddddeeee <<<<ddddmmmmeeeeddddiiiiaaaa////ddddmmmm____aaaauuuuddddiiiioooo....hhhh>>>>
  15.      ####iiiinnnncccclllluuuuddddeeee <<<<ddddmmmmeeeeddddiiiiaaaa////ddddmmmm____ppppaaaarrrraaaammmmssss....hhhh>>>>
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  17.      DDDDMMMMssssttttaaaattttuuuussss ddddmmmmAAAAuuuuddddiiiiooooRRRRaaaatttteeeeCCCCoooonnnnvvvveeeerrrrtttteeeerrrrGGGGeeeettttPPPPaaaarrrraaaammmmssss((((DDDDMMMMaaaauuuuddddiiiioooorrrraaaatttteeeeccccoooonnnnvvvveeeerrrrtttteeeerrrr hhhhaaaannnnddddlllleeee,,,,
  18.                                    DDDDMMMMppppaaaarrrraaaammmmssss ****ppppaaaarrrraaaammmmssss))))
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  21. PPPPAAAARRRRAAAAMMMMEEEETTTTEEEERRRR
  22.      _h_a_n_d_l_e   DDDDMMMMaaaauuuuddddiiiioooorrrraaaatttteeeeccccoooonnnnvvvveeeerrrrtttteeeerrrr structure, created by
  23.               ddddmmmmAAAAuuuuddddiiiiooooRRRRaaaatttteeeeCCCCoooonnnnvvvveeeerrrrtttteeeerrrrCCCCrrrreeeeaaaatttteeee((((3333ddddmmmm)))).
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  26.      _p_a_r_a_m_s   List of parameters for query.
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  29. RRRREEEETTTTUUUURRRRNNNNEEEEDDDD VVVVAAAALLLLUUUUEEEE
  30.      Returns DDDDMMMM____SSSSUUUUCCCCCCCCEEEESSSSSSSS or DDDDMMMM____FFFFAAAAIIIILLLLUUUURRRREEEE.
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  33. DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
  34.      ddddmmmmAAAAuuuuddddiiiiooooRRRRaaaatttteeeeCCCCoooonnnnvvvveeeerrrrtttteeeerrrrGGGGeeeettttPPPPaaaarrrraaaammmmssss((((3333ddddmmmm)))) gets state of converter with _p_a_r_a_m_s.
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  36.  
  37.      The set of parameters of _p_a_r_a_m_s for query are, defined in
  38.      _d_m_e_d_i_a/_d_m__a_u_d_i_o_u_t_i_l._h:
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  40.      DDDDMMMM____AAAAUUUUDDDDIIIIOOOO____RRRRCCCC____AAAATTTTOOOOMMMMIIIICCCC____IIIINNNN____LLLLEEEENNNNGGGGTTTTHHHH
  41.      DDDDMMMM____AAAAUUUUDDDDIIIIOOOO____RRRRCCCC____AAAATTTTOOOOMMMMIIIICCCC____OOOOUUUUTTTT____LLLLEEEENNNNGGGGTTTTHHHH
  42.      DDDDMMMM____AAAAUUUUDDDDIIIIOOOO____RRRRCCCC____GGGGRRRROOOOUUUUPPPP____DDDDEEEELLLLAAAAYYYY
  43.  
  44.      The rate convert algorithm processes blocks of a fixed length determined
  45.      by the conversion process parameters.  The input and output lengths must
  46.      be a multiple of DDDDMMMM____AAAAUUUUDDDDIIIIOOOO____RRRRCCCC____AAAATTTTOOOOMMMMIIIICCCC____IIIINNNN____LLLLEEEENNNNGGGGTTTTHHHH and
  47.      DDDDMMMM____AAAAUUUUDDDDIIIIOOOO____RRRRCCCC____AAAATTTTOOOOMMMMIIIICCCC____OOOOUUUUTTTT____LLLLEEEENNNNGGGGTTTTHHHH, respectively.  See further description in
  48.      ddddmmmmAAAAuuuuddddiiiiooooRRRRaaaatttteeeeCCCCoooonnnnvvvveeeerrrrtttt((((3333ddddmmmm)))).
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  50.      DDDDMMMM____AAAAUUUUDDDDIIIIOOOO____RRRRCCCC____GGGGRRRROOOOUUUUPPPP____DDDDEEEELLLLAAAAYYYY measured in output samples.  These sampling rate
  51.      conversion algorithms use filter operations that convolve a N past input
  52.      samples with a filter M-coefficient array to create N+M-1 output samples.
  53.      Note that the filtered signal contains more samples than the unfiltered
  54.      signal.
  55.  
  56.      We use linear phase filters with a constant group delay G = (M-1)/2
  57.      samples.  In real time operation, convolution simply delays the output by
  58.      G samples.  In file conversion expecting N samples in and out, the output
  59.      signal is offset by G samples from the first sample thus omits the last G
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  63.                                                                         PPPPaaaaggggeeee 1111
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  70. ddddmmmmAAAAuuuuddddiiiiooooRRRRaaaatttteeeeCCCCoooonnnnvvvveeeerrrrtttteeeerrrrGGGGeeeettttPPPPaaaarrrraaaammmmssss((((3333ddddmmmm))))          ddddmmmmAAAAuuuuddddiiiiooooRRRRaaaatttteeeeCCCCoooonnnnvvvveeeerrrrtttteeeerrrrGGGGeeeettttPPPPaaaarrrraaaammmmssss((((3333ddddmmmm))))
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  74.      samples from the output file.  Multiple conversions compound the delays
  75.      and data loss.
  76.  
  77.      SGI audio applications manage the above problems by omitting the first G
  78.      samples while computing more than N+G samples.  In practice, G is rounded
  79.      to the nearest sample and thus sample time alignment is occasionally
  80.      ahead or behind one sample.  G specifies the number of output samples to
  81.      omit.
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  84. NNNNOOOOTTTTEEEE
  85. SSSSEEEEEEEE AAAALLLLSSSSOOOO
  86.      dmAudioRateConverterCreate(3dm), dmAudioRateConverterSetParams(3dm),
  87.      dmAudioRateConvert(3dm).
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  129.                                                                         PPPPaaaaggggeeee 2222
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