src/usr.bin/aucat/dsp.h - diff

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Diff for /src/usr.bin/aucat/dsp.h between version 1.5 and 1.6

-version 1.5, 2016/06/08 04:36:48
+version 1.6, 2021/01/11 14:45:51
 Line 92
 Line 92
 Line 92
  #endif
  /*
+  * The FIR is sampled and stored in a table of fixed-point numbers
+  * with 23 fractional bits. For convenience, we use the same fixed-point
+  * numbers to represent time and to walk through the table.
+  */
+ #define RESAMP_BITS             23
+ #define RESAMP_UNIT             (1 << RESAMP_BITS)
+ /*
+  * Filter window length (the time unit is RESAMP_UNIT)
+  */
+ #define RESAMP_LENGTH           (8 * RESAMP_UNIT)
+ /*
+  * Time between samples of the FIR (the time unit is RESAMP_UNIT)
+  */
+ #define RESAMP_STEP_BITS        (RESAMP_BITS - 6)
+ #define RESAMP_STEP             (1 << RESAMP_STEP_BITS)
+ /*
+  * Maximum downsample/upsample ratio we support, must be a power of two.
+  * The ratio between the max and the min sample rates is 192kHz / 4kHz = 48,
+  * so we can use 64
+  */
+ #define RESAMP_RATIO            64
+ /*
   * Maximum size of the encording string (the longest possible
   * encoding is ``s24le3msb'').
   */
-Line 111
+Line 137
 Line 111
 Line 137
  };
  struct resamp {
- #define RESAMP_NCTX     2
+ #define RESAMP_NCTX     (RESAMP_LENGTH / RESAMP_UNIT * RESAMP_RATIO)
          unsigned int ctx_start;
          adata_t ctx[NCHAN_MAX * RESAMP_NCTX];
+         int filt_cutoff, filt_step;
          unsigned int iblksz, oblksz;
          int diff;
          int nch;