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/ IRIX Base Documentation 2001 May / SGI IRIX Base Documentation 2001 May.iso / usr / share / catman / p_man / cat3dm / dmedia / dmG722Decode.z / dmG722Decode
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Text File  |  1998-10-20  |  4.4 KB  |  133 lines
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  4. ddddmmmmGGGG777722222222DDDDeeeeccccooooddddeeee((((3333ddddmmmm))))                                            ddddmmmmGGGG777722222222DDDDeeeeccccooooddddeeee((((3333ddddmmmm))))
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  8. NNNNAAAAMMMMEEEE
  9.      dmG722Decode - implements the ITU (International Telecommunication Union)
  10.      Recommendation G.722 decompression.
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  13. SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS
  14.      ####iiiinnnncccclllluuuuddddeeee <<<<ddddmmmmeeeeddddiiiiaaaa////ddddmmmm____aaaauuuuddddiiiioooouuuuttttiiiillll....hhhh>>>>
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  16.      DDDDMMMMssssttttaaaattttuuuussss ddddmmmmGGGG777722222222DDDDeeeeccccooooddddeeee((((DDDDMMMMGGGG777722222222ddddeeeeccccooooddddeeeerrrr hhhhaaaannnnddddlllleeee,,,,
  17.                           uuuunnnnssssiiiiggggnnnneeeedddd cccchhhhaaaarrrr ****iiiibbbbuuuuffff,,,, sssshhhhoooorrrrtttt ****oooobbbbuuuuffff,,,, iiiinnnntttt nnnnssssaaaammmmpppplllleeeessss))))
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  20. PPPPAAAARRRRAAAAMMMMEEEETTTTEEEERRRR
  21.      _h_a_n_d_l_e    DDDDMMMMGGGG777722222222ddddeeeeccccooooddddeeeerrrr structure, created by ddddmmmmGGGG777722222222DDDDeeeeccccooooddddeeeerrrrCCCCrrrreeeeaaaatttteeee((((3333ddddmmmm)))),
  22.                specifies the signal processing parameters.
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  25.      _i_b_u_f      pointer to input compressed data buffer. The data format is
  26.                unsigned char (8-bit).
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  29.      _o_b_u_f      pointer to output sample data buffer.  The data format is short
  30.                (16-bit).  The samples are assumed to be two's complement.
  31.                Sampling rate must be 16 kHz or less.
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  34.      _n_s_a_m_p_l_e_s  number of sample in the input buffer to be processed. the value
  35.                of nsamples passed to the G.722 decode/decode routines must
  36.                always be a multiple of 2.  It will fail if nsamples exceeds
  37.                the the maximum value specified when the DMG722decoder was
  38.                created.
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  41. RRRREEEETTTTUUUURRRRNNNNEEEEDDDD VVVVAAAALLLLUUUUEEEE
  42.      Returns DDDDMMMM____FFFFAAAAIIIILLLLUUUURRRREEEE or DDDDMMMM____SSSSUUUUCCCCCCCCEEEESSSSSSSS.
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  45. DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
  46.      ddddmmmmGGGG777722222222DDDDeeeeccccooooddddeeee((((3333ddddmmmm)))) implements the ITU Recommendation G.722 decompression.
  47.      The mode for decoding operation can be 1, 2, or 3, which correspond to
  48.      64, 56 or 48 kbit/sec for audio coding and 0, 8 or 16 kbit/sec. for data.
  49.      The mode is set by ddddmmmmGGGG777722222222DDDDeeeeccccooooddddeeeerrrrCCCCrrrreeeeaaaatttteeee((((3333ddddmmmm)))).
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  51.  
  52.      see DESCRIPTION in ddddmmmmGGGG777722222222EEEEnnnnccccooooddddeeee((((3333ddddmmmm)))) for the discussion of filter delay
  53.      and decompression of a part of compressed bit stream beginning in the
  54.      middle of a compressed data file.
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  63.                                                                         PPPPaaaaggggeeee 1111
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  70. ddddmmmmGGGG777722222222DDDDeeeeccccooooddddeeee((((3333ddddmmmm))))                                            ddddmmmmGGGG777722222222DDDDeeeeccccooooddddeeee((((3333ddddmmmm))))
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  73.  
  74. NOTE
  75.      G.722 algorithm was developed for sampling rate of 16 kHz.  If sampling
  76.      rate is less than 16 kHz, the algorithm still works, except the upper
  77.      bits contains less useful information.
  78.  
  79.  
  80. SSSSEEEEEEEE AAAALLLLSSSSOOOO
  81.      dmG722DecoderCreate(3dm), dmG722DecoderDestroy(3dm), dmG722Encode(3dm),
  82.      ITU Recommendations G.722.
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  129.                                                                         PPPPaaaaggggeeee 2222
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