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/ IRIX Base Documentation 2001 May / SGI IRIX Base Documentation 2001 May.iso / usr / share / catman / p_man / cat3dm / dmedia / dmG728Decode.z / dmG728Decode
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Text File  |  1998-10-20  |  5.2 KB  |  133 lines
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  4. ddddmmmmGGGG777722228888DDDDeeeeccccooooddddeeee((((3333ddddmmmm))))                                            ddddmmmmGGGG777722228888DDDDeeeeccccooooddddeeee((((3333ddddmmmm))))
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  8. NNNNAAAAMMMMEEEE
  9.      dmG728Decode - implements the ITU (International Telecommunication Union)
  10.      Recommendation G.728 decompression (LD-CELP).
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  13. SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS
  14.      ####iiiinnnncccclllluuuuddddeeee <<<<ddddmmmmeeeeddddiiiiaaaa////ddddmmmm____aaaauuuuddddiiiioooouuuuttttiiiillll....hhhh>>>>
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  16.      DDDDMMMMssssttttaaaattttuuuussss ddddmmmmGGGG777722228888DDDDeeeeccccooooddddeeee((((DDDDMMMMGGGG777722228888ddddeeeeccccooooddddeeeerrrr hhhhaaaannnnddddlllleeee,,,,
  17.                           uuuunnnnssssiiiiggggnnnneeeedddd cccchhhhaaaarrrr ****iiiibbbbuuuuffff,,,, sssshhhhoooorrrrtttt ****oooobbbbuuuuffff,,,, iiiinnnntttt nnnnssssaaaammmmpppplllleeeessss))))
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  20. PPPPAAAARRRRAAAAMMMMEEEETTTTEEEERRRR
  21.      _h_a_n_d_l_e    DDDDMMMMGGGG777722228888ddddeeeeccccooooddddeeeerrrr structure, created by ddddmmmmGGGG777722228888DDDDeeeeccccooooddddeeeerrrrCCCCrrrreeeeaaaatttteeee((((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).  This bitstrem buffer must consist of a
  27.                multiple of 10 bytes.
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  30.      _o_b_u_f      pointer to output sample data buffer.  The data format is short
  31.                (16-bit).  The samples are assumed to be two's complement.  The
  32.                sampling rate must be 8 kHz.
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  35.      _n_s_a_m_p_l_e_s  number of sample in the output buffer to be generated. the
  36.                value of nsamples passed to the G.728 decode/decode routines
  37.                must always be a multiple of 40.
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  40. RRRREEEETTTTUUUURRRRNNNNEEEEDDDD VVVVAAAALLLLUUUUEEEE
  41.      Returns DDDDMMMM____FFFFAAAAIIIILLLLUUUURRRREEEE or DDDDMMMM____SSSSUUUUCCCCCCCCEEEESSSSSSSS.
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  44. DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
  45.      ddddmmmmGGGG777722228888DDDDeeeeccccooooddddeeee((((3333ddddmmmm)))) implements the ITU Recommendation G.728 decompression.
  46.      The uncompressed data sampling rate is 8000 Hz.  And the compressed
  47.      bitrate is 16000 bits/s. The mode for decoding operation can be
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  50.      DDDDMMMM____GGGG777722228888____PPPPOOOOSSSSTTTTFFFFIIIILLLLTTTTEEEERRRRIIIINNNNGGGG____YYYYEEEESSSS
  51.      DDDDMMMM____GGGG777722228888____PPPPOOOOSSSSTTTTFFFFIIIILLLLTTTTEEEERRRRIIIINNNNGGGG____NNNNOOOO
  52.  
  53.  
  54.      that selects a decoder with or without postfiltering.  for speech/voice
  55.      signal, postfiltering should be used.  For DTMF tone or music audio, no
  56.      postfiltering should be used.  The mode is set by a call to
  57.      ddddmmmmGGGG777722228888DDDDeeeeccccooooddddeeeerrrrSSSSeeeettttPPPPaaaarrrraaaammmmssss((((3333ddddmmmm)))). Without calling ddddmmmmGGGG777722228888DDDDeeeeccccooooddddeeeerrrrSSSSeeeettttPPPPaaaarrrraaaammmmssss((((3333ddddmmmm)))),
  58.      decoder sets default to DDDDMMMM____GGGG777722228888____PPPPOOOOSSSSTTTTFFFFIIIILLLLTTTTEEEERRRRIIIINNNNGGGG____YYYYEEEESSSS.
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  63.                                                                         PPPPaaaaggggeeee 1111
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  70. ddddmmmmGGGG777722228888DDDDeeeeccccooooddddeeee((((3333ddddmmmm))))                                            ddddmmmmGGGG777722228888DDDDeeeeccccooooddddeeee((((3333ddddmmmm))))
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  74.      see DESCRIPTION in ddddmmmmGGGG777722228888EEEEnnnnccccooooddddeeee((((3333ddddmmmm)))) for the discussion of decompression
  75.      of a part of compressed bit stream beginning in the middle of a
  76.      compressed data file.
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  79. NNNNOOOOTTTTEEEE
  80.      G.728 algorithm was developed for sampling rate of 8 kHz.
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  83. SSSSEEEEEEEE AAAALLLLSSSSOOOO
  84.      dmG728DecoderCreate(3dm), dmG728DecoderDestroy(3dm), dmG728Encode(3dm),
  85.      ITU Recommendations G.728.
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  129.                                                                         PPPPaaaaggggeeee 2222
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