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/ IRIX Base Documentation 2001 May / SGI IRIX Base Documentation 2001 May.iso / usr / share / catman / p_man / cat3dm / dmedia / dmAudioRateConverterSetParams.z / dmAudioRateConverterSetParams
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Text File  |  1998-10-20  |  12.0 KB  |  199 lines
  1.  
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  4. ddddmmmmAAAAuuuuddddiiiiooooRRRRaaaatttteeeeCCCCoooonnnnvvvveeeerrrrtttteeeerrrrSSSSeeeettttPPPPaaaarrrraaaammmmssss((((3333ddddmmmm))))          ddddmmmmAAAAuuuuddddiiiiooooRRRRaaaatttteeeeCCCCoooonnnnvvvveeeerrrrtttteeeerrrrSSSSeeeettttPPPPaaaarrrraaaammmmssss((((3333ddddmmmm))))
  5.  
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  7.  
  8. NNNNAAAAMMMMEEEE
  9.      dmAudioRateConverterSetParams - set rate converter parameter values
  10.  
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  12. SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS
  13.      ####iiiinnnncccclllluuuuddddeeee <<<<ddddmmmmeeeeddddiiiiaaaa////ddddmmmm____aaaauuuuddddiiiioooouuuuttttiiiillll....hhhh>>>>
  14.      ####iiiinnnncccclllluuuuddddeeee <<<<ddddmmmmeeeeddddiiiiaaaa////ddddmmmm____aaaauuuuddddiiiioooo....hhhh>>>>
  15.      ####iiiinnnncccclllluuuuddddeeee <<<<ddddmmmmeeeeddddiiiiaaaa////ddddmmmm____ppppaaaarrrraaaammmmssss....hhhh>>>>
  16.  
  17.      DDDDMMMMssssttttaaaattttuuuussss ddddmmmmAAAAuuuuddddiiiiooooRRRRaaaatttteeeeCCCCoooonnnnvvvveeeerrrrtttteeeerrrrSSSSeeeettttPPPPaaaarrrraaaammmmssss((((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)))).
  24.  
  25.  
  26.      _p_a_r_a_m_s   List of parameters for specification/query. Null (0) value ok.
  27.  
  28.  
  29. RRRREEEETTTTUUUURRRRNNNNEEEEDDDD VVVVAAAALLLLUUUUEEEE
  30.      Returns DDDDMMMM____SSSSUUUUCCCCCCCCEEEESSSSSSSS or DDDDMMMM____FFFFAAAAIIIILLLLUUUURRRREEEE.
  31.  
  32.  
  33. DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
  34.      ddddmmmmAAAAuuuuddddiiiiooooRRRRaaaatttteeeeCCCCoooonnnnvvvveeeerrrrtttteeeerrrrSSSSeeeettttPPPPaaaarrrraaaammmmssss((((3333ddddmmmm)))) sets state of converter with _p_a_r_a_m_s.
  35.      Unrecognized parameters are ignored.
  36.  
  37.  
  38.      The set of parameters for _p_a_r_a_m_s are, defined in _d_m_e_d_i_a/_d_m__a_u_d_i_o_u_t_i_l._h:
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  41.      DDDDMMMM____AAAAUUUUDDDDIIIIOOOO____RRRRCCCC____IIIINNNNPPPPUUUUTTTT____RRRRAAAATTTTEEEE
  42.      DDDDMMMM____AAAAUUUUDDDDIIIIOOOO____RRRRCCCC____OOOOUUUUTTTTPPPPUUUUTTTT____RRRRAAAATTTTEEEE
  43.  
  44.      Audio Util rate conversion input, output rate parameters (rate given in
  45.      Hz).  The corresponding values for the rates are doubles.  The jitter-
  46.      free algorithm supports sampling rate conversion between any two of the
  47.      following rates in the set {8000, 11025, 16000, 22050, 32000, 44100,
  48.      48000} (sample frames/second or Hertz).  Polynomial_order_{1,3}
  49.      algorithms support arbitrary input and output rate.
  50.  
  51.  
  52.  
  53.      DDDDMMMM____AAAAUUUUDDDDIIIIOOOO____RRRRCCCC____AAAALLLLGGGGOOOORRRRIIIITTTTHHHHMMMM
  54.           DM_AUDIO_RC_JITTER_FREE      DM_AUDIO_RC_POLYNOMIAL_ORDER_1
  55.           DM_AUDIO_RC_POLYNOMIAL_ORDER_3
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  63.                                                                         PPPPaaaaggggeeee 1111
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  70. ddddmmmmAAAAuuuuddddiiiiooooRRRRaaaatttteeeeCCCCoooonnnnvvvveeeerrrrtttteeeerrrrSSSSeeeettttPPPPaaaarrrraaaammmmssss((((3333ddddmmmm))))          ddddmmmmAAAAuuuuddddiiiiooooRRRRaaaatttteeeeCCCCoooonnnnvvvveeeerrrrtttteeeerrrrSSSSeeeettttPPPPaaaarrrraaaammmmssss((((3333ddddmmmm))))
  71.  
  72.  
  73.  
  74.      Currently, the algorithms supported are jitter-free, which is at least
  75.      one integer interpolator / integer decimator stage, polynomial-order-1,
  76.      which is linear interpolation between 2 proximal samples, and
  77.      polynomial-order-3, which is rate convert block by 3rd order polynomial
  78.      interpolation between four proximal samples.
  79.  
  80.  
  81.      DDDDMMMM____AAAAUUUUDDDDIIIIOOOO____RRRRCCCC____JJJJIIIITTTTTTTTEEEERRRR____FFFFRRRREEEEEEEE____SSSSTTTTOOOOPPPPBBBBAAAANNNNDDDD____AAAATTTTTTTTEEEENNNNUUUUAAAATTTTIIIIOOOONNNN
  82.           DM_AUDIO_RC_JITTER_FREE_STOPBAND_ATTENUATION_78_DB
  83.           DM_AUDIO_RC_JITTER_FREE_STOPBAND_ATTENUATION_96_DB
  84.           DM_AUDIO_RC_JITTER_FREE_STOPBAND_ATTENUATION_120_DB
  85.  
  86.      The parameter is specific to the jitter free rate converter filter
  87.      stopband attenuation.  The values are limited to set {78, 96, 120}. The
  88.      values correspond to the minimum attenuation level of the out-of-band
  89.      frequencies, those frequencies which do not fit in the smaller of the
  90.      output or input bandwidths.  Higher values correspond to better noise
  91.      suppression.
  92.  
  93.  
  94.      DDDDMMMM____AAAAUUUUDDDDIIIIOOOO____RRRRCCCC____JJJJIIIITTTTTTTTEEEERRRR____FFFFRRRREEEEEEEE____TTTTRRRRAAAANNNNSSSSIIIITTTTIIIIOOOONNNN____BBBBAAAANNNNDDDDWWWWIIIIDDDDTTTTHHHH
  95.           DM_AUDIO_RC_JITTER_FREE_TRANSITION_BANDWIDTH_1_PERCENT
  96.           DM_AUDIO_RC_JITTER_FREE_TRANSITION_BANDWIDTH_10_PERCENT
  97.           DM_AUDIO_RC_JITTER_FREE_TRANSITION_BANDWIDTH_20_PERCENT
  98.  
  99.      The parameter is specific to the jitter free rate converter filter
  100.      transition bandwidth.  The values are limited to set {1, 10, 20}. The
  101.      values correspond to the % of the high frequency response of the output
  102.      signal lost in the conversion process.  Lower percentages correspond to
  103.      better high frequency response.
  104.  
  105.  
  106.      _P_a_r_a_m_e_t_e_r_s _f_o_r _q_u_e_r_y _o_n_l_y:
  107.  
  108.      DDDDMMMM____AAAAUUUUDDDDIIIIOOOO____RRRRCCCC____AAAATTTTOOOOMMMMIIIICCCC____IIIINNNN____LLLLEEEENNNNGGGGTTTTHHHH
  109.      DDDDMMMM____AAAAUUUUDDDDIIIIOOOO____RRRRCCCC____AAAATTTTOOOOMMMMIIIICCCC____OOOOUUUUTTTT____LLLLEEEENNNNGGGGTTTTHHHH
  110.  
  111.      The rate convert algorithm processes blocks of a fixed length determined
  112.      by the conversion process parameters.  The input and output lengths must
  113.      be a multiple of DDDDMMMM____AAAAUUUUDDDDIIIIOOOO____RRRRCCCC____AAAATTTTOOOOMMMMIIIICCCC____IIIINNNN____LLLLEEEENNNNGGGGTTTTHHHH and
  114.      DDDDMMMM____AAAAUUUUDDDDIIIIOOOO____RRRRCCCC____AAAATTTTOOOOMMMMIIIICCCC____OOOOUUUUTTTT____LLLLEEEENNNNGGGGTTTTHHHH, respectively.  Query these parameters on a
  115.      configured converter can also be done by using
  116.      ddddmmmmAAAAuuuuddddiiiiooooRRRRaaaatttteeeeCCCCoooonnnnvvvveeeerrrrtttteeeerrrrGGGGeeeettttPPPPaaaarrrraaaammmmssss((((3333ddddmmmm)))).
  117.  
  118.  
  119.      DDDDMMMM____AAAAUUUUDDDDIIIIOOOO____RRRRCCCC____GGGGRRRROOOOUUUUPPPP____DDDDEEEELLLLAAAAYYYY Type DM_TYPE_FLOAT
  120.  
  121.      The group delay measured in output samples.
  122.  
  123.      These sampling rate conversion algorithms use filter operations that
  124.      convolve a N past input samples with a filter M-coefficient array to
  125.      create N+M-1 output samples.  Note that he filtered signal contains more
  126.  
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  129.                                                                         PPPPaaaaggggeeee 2222
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  136. ddddmmmmAAAAuuuuddddiiiiooooRRRRaaaatttteeeeCCCCoooonnnnvvvveeeerrrrtttteeeerrrrSSSSeeeettttPPPPaaaarrrraaaammmmssss((((3333ddddmmmm))))          ddddmmmmAAAAuuuuddddiiiiooooRRRRaaaatttteeeeCCCCoooonnnnvvvveeeerrrrtttteeeerrrrSSSSeeeettttPPPPaaaarrrraaaammmmssss((((3333ddddmmmm))))
  137.  
  138.  
  139.  
  140.      samples than the unfiltered signal.
  141.  
  142.      We use linear phase filters with a constant group delay G = (M-1)/2
  143.      samples.  In real time operation, convolution simply delays the output by
  144.      G samples.  In file conversion expecting N samples in and out, the output
  145.      signal is offset by G samples from the first sample thus omits the last G
  146.      samples from the output file.  Multiple conversions compound the delays
  147.      and data loss.
  148.  
  149.      SGI audio applications manage the above problems by omitting the first G
  150.      samples while computing more than N+G samples.  In practice, G is rounded
  151.      to the nearest sample and thus sample time alignment is occasionally
  152.      ahead or behind one sample.  G specifies the number of output samples to
  153.      omit.
  154.  
  155.      Query DDDDMMMM____AAAAUUUUDDDDIIIIOOOO____RRRRCCCC____GGGGRRRROOOOUUUUPPPP____DDDDEEEELLLLAAAAYYYY on a configured converter can also be done
  156.      by using ddddmmmmAAAAuuuuddddiiiiooooRRRRaaaatttteeeeCCCCoooonnnnvvvveeeerrrrtttteeeerrrrGGGGeeeettttPPPPaaaarrrraaaammmmssss((((3333ddddmmmm)))).
  157.  
  158.  
  159. NNNNOOOOTTTTEEEE
  160.      ddddmmmmAAAAuuuuddddiiiiooooRRRRaaaatttteeeeCCCCoooonnnnvvvveeeerrrrtttteeeerrrrSSSSeeeettttPPPPaaaarrrraaaammmmssss((((3333ddddmmmm)))) calls ddddmmmmAAAAuuuuddddiiiiooooRRRRaaaatttteeeeCCCCoooonnnnvvvveeeerrrrtttteeeerrrrRRRReeeesssseeeetttt((((3333ddddmmmm))))
  161.      internally.
  162.  
  163.      Files converted using jitter-free algorithm with decibels set to 96 and
  164.      bandwidth set to 10 will sound most excellent.  For the highest quality
  165.      conversion algorithm, however, you can set decibels to 120 and bandwidth
  166.      to 1.  By decreasing decibels and increasing bandwidth, you increase the
  167.      speed of the rate conversion at a loss of high frequency response.
  168.  
  169.      The following table shows the relationships between the bandwidth
  170.      parameter, and the pass band ripple:
  171.  
  172.      bandwidth    % final     passband
  173.      parameter    bandwidth   ripple
  174.                   tapered
  175.  
  176.      20           20%         +/- 0.05   dB
  177.      10           10%         +/- 0.05   dB
  178.       1           1%          +/- 0.0005 dB
  179.  
  180.  
  181. SSSSEEEEEEEE AAAALLLLSSSSOOOO
  182.      dmAudioRateConverterCreate(3dm), dmAudioRateConvert(3dm),
  183.      dmAudioRateConverterGetParams(3dm).
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  195.                                                                         PPPPaaaaggggeeee 3333
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  199.