codecs/ilbc/filter.h

   1
   2 /******************************************************************
   3
   4     iLBC Speech Coder ANSI-C Source Code
   5
   6     filter.h
   7
   8     Copyright (C) The Internet Society (2004).
   9     All Rights Reserved.
  10
  11 ******************************************************************/
  12
  13 #ifndef __iLBC_FILTER_H
  14 #define __iLBC_FILTER_H
  15
  16 void AllPoleFilter(
  17     float *InOut,   /* (i/o) on entrance InOut[-orderCoef] to
  18                            InOut[-1] contain the state of the
  19                            filter (delayed samples). InOut[0] to
  20                            InOut[lengthInOut-1] contain the filter
  21                            input, on en exit InOut[-orderCoef] to
  22                            InOut[-1] is unchanged and InOut[0] to
  23                            InOut[lengthInOut-1] contain filtered
  24                            samples */
  25     float *Coef,/* (i) filter coefficients, Coef[0] is assumed
  26                            to be 1.0 */
  27     int lengthInOut,/* (i) number of input/output samples */
  28     int orderCoef   /* (i) number of filter coefficients */
  29 );
  30
  31
  32
  33 void AllZeroFilter(
  34     float *In,      /* (i) In[0] to In[lengthInOut-1] contain
  35                            filter input samples */
  36     float *Coef,/* (i) filter coefficients (Coef[0] is assumed
  37                            to be 1.0) */
  38     int lengthInOut,/* (i) number of input/output samples */
  39     int orderCoef,  /* (i) number of filter coefficients */
  40     float *Out      /* (i/o) on entrance Out[-orderCoef] to Out[-1]
  41                            contain the filter state, on exit Out[0]
  42                            to Out[lengthInOut-1] contain filtered
  43                            samples */
  44 );
  45
  46 void ZeroPoleFilter(
  47     float *In,      /* (i) In[0] to In[lengthInOut-1] contain filter
  48                            input samples In[-orderCoef] to In[-1]
  49                            contain state of all-zero section */
  50     float *ZeroCoef,/* (i) filter coefficients for all-zero
  51                            section (ZeroCoef[0] is assumed to
  52                            be 1.0) */
  53     float *PoleCoef,/* (i) filter coefficients for all-pole section
  54                            (ZeroCoef[0] is assumed to be 1.0) */
  55     int lengthInOut,/* (i) number of input/output samples */
  56     int orderCoef,  /* (i) number of filter coefficients */
  57     float *Out      /* (i/o) on entrance Out[-orderCoef] to Out[-1]
  58                            contain state of all-pole section. On
  59                            exit Out[0] to Out[lengthInOut-1]
  60                            contain filtered samples */
  61 );
  62
  63 void DownSample (
  64     float  *In,     /* (i) input samples */
  65     float  *Coef,   /* (i) filter coefficients */
  66     int lengthIn,   /* (i) number of input samples */
  67     float  *state,  /* (i) filter state */
  68     float  *Out     /* (o) downsampled output */
  69 );
  70
  71 #endif
  72
  73