func_pitchshift.c File Reference

Pitch Shift Audio Effect. More...

#include "asterisk.h"
#include "asterisk/module.h"
#include "asterisk/channel.h"
#include "asterisk/pbx.h"
#include "asterisk/utils.h"
#include "asterisk/audiohook.h"
#include <math.h>

Include dependency graph for func_pitchshift.c:

Go to the source code of this file.

Data Structures
struct	fft_data
struct	pitchshift_data

Macros
#define	HIGH   1.25
#define	HIGHER   1.5
#define	HIGHEST   2
#define	LOW   .85
#define	LOWER   .7
#define	LOWEST   .5
#define	M_PI   3.14159265358979323846
#define	MAX_FRAME_LENGTH   256

Functions
	AST_MODULE_INFO_STANDARD_EXTENDED (ASTERISK_GPL_KEY, "Audio Effects Dialplan Functions")
static void	destroy_callback (void *data)
static int	load_module (void)
static int	pitch_shift (struct ast_frame *f, float amount, struct fft_data *fft_data)
static int	pitchshift_cb (struct ast_audiohook *audiohook, struct ast_channel *chan, struct ast_frame *f, enum ast_audiohook_direction direction)
static int	pitchshift_helper (struct ast_channel *chan, const char *cmd, char *data, const char *value)
static void	smb_fft (float *fft_buffer, long fft_frame_size, long sign)
static void	smb_pitch_shift (float pitchShift, long num_samps_to_process, long fft_frame_size, long osamp, float sample_rate, int16_t *indata, int16_t *outdata, struct fft_data *fft_data)
static int	unload_module (void)

Variables
static struct ast_custom_function	pitch_shift_function
static const struct ast_datastore_info	pitchshift_datastore

Detailed Description

Pitch Shift Audio Effect.

Author

David Vossel dvoss.nosp@m.el@d.nosp@m.igium.nosp@m..com

Definition in file func_pitchshift.c.

Macro Definition Documentation

HIGH

#define HIGH   1.25

Definition at line 120 of file func_pitchshift.c.

Referenced by pitchshift_helper().

HIGHER

#define HIGHER   1.5

Definition at line 119 of file func_pitchshift.c.

Referenced by pitchshift_helper().

HIGHEST

#define HIGHEST   2

Definition at line 118 of file func_pitchshift.c.

Referenced by pitchshift_helper().

LOW

#define LOW   .85

Definition at line 121 of file func_pitchshift.c.

Referenced by pitchshift_helper().

LOWER

#define LOWER   .7

Definition at line 122 of file func_pitchshift.c.

Referenced by pitchshift_helper().

LOWEST

#define LOWEST   .5

Definition at line 123 of file func_pitchshift.c.

Referenced by pitchshift_helper().

M_PI

#define M_PI   3.14159265358979323846

Definition at line 114 of file func_pitchshift.c.

Referenced by smb_fft(), and smb_pitch_shift().

MAX_FRAME_LENGTH

#define MAX_FRAME_LENGTH   256

Definition at line 116 of file func_pitchshift.c.

Referenced by pitch_shift().

Function Documentation

AST_MODULE_INFO_STANDARD_EXTENDED()

AST_MODULE_INFO_STANDARD_EXTENDED	(	ASTERISK_GPL_KEY	,
		"Audio Effects Dialplan Functions"
	)

Referenced by load_module().

destroy_callback()

static void destroy_callback ( void *  data )

static

Definition at line 151 of file func_pitchshift.c.

References ast_audiohook_destroy(), ast_free, and pitchshift_data::audiohook.

{
   struct pitchshift_data *shift = data;

   ast_audiohook_destroy(&shift->audiohook);
   ast_free(shift);
};

load_module()

static int load_module ( void  )

static

Definition at line 504 of file func_pitchshift.c.

References ast_custom_function_register, AST_MODULE_INFO_STANDARD_EXTENDED(), AST_MODULE_LOAD_DECLINE, AST_MODULE_LOAD_SUCCESS, and ASTERISK_GPL_KEY.

{
   int res = ast_custom_function_register(&pitch_shift_function);
   return res ? AST_MODULE_LOAD_DECLINE : AST_MODULE_LOAD_SUCCESS;
}

pitch_shift()

static int pitch_shift ( struct ast_frame *  f, float  amount, struct fft_data *  fft_data  )

static

Definition at line 478 of file func_pitchshift.c.

References ast_format_get_sample_rate(), ast_frame::data, ast_frame_subclass::format, if(), MAX_FRAME_LENGTH, ast_frame::ptr, ast_frame::samples, smb_pitch_shift(), and ast_frame::subclass.

Referenced by pitchshift_cb().

{
   int16_t *fun = (int16_t *) f->data.ptr;
   int samples;

   /* an amount of 1 has no effect */
   if (!amount || amount == 1 || !fun || (f->samples % 32)) {
      return 0;
   }
   for (samples = 0; samples < f->samples; samples += 32) {
      smb_pitch_shift(amount, 32, MAX_FRAME_LENGTH, 32, ast_format_get_sample_rate(f->subclass.format), fun+samples, fun+samples, fft);
   }

   return 0;
}

pitchshift_cb()

static int pitchshift_cb ( struct ast_audiohook *  audiohook, struct ast_channel *  chan, struct ast_frame *  f, enum ast_audiohook_direction  direction  )

static

Definition at line 164 of file func_pitchshift.c.

References AST_AUDIOHOOK_DIRECTION_WRITE, AST_AUDIOHOOK_STATUS_DONE, ast_channel_datastore_find(), ast_datastore::data, NULL, pitch_shift(), pitchshift_data::rx, fft_data::shift_amount, ast_audiohook::status, and pitchshift_data::tx.

Referenced by pitchshift_helper().

{
   struct ast_datastore *datastore = NULL;
   struct pitchshift_data *shift = NULL;


   if (!f) {
      return 0;
   }
   if (audiohook->status == AST_AUDIOHOOK_STATUS_DONE) {
      return -1;
   }

   if (!(datastore = ast_channel_datastore_find(chan, &pitchshift_datastore, NULL))) {
      return -1;
   }

   shift = datastore->data;

   if (direction == AST_AUDIOHOOK_DIRECTION_WRITE) {
      pitch_shift(f, shift->tx.shift_amount, &shift->tx);
   } else {
      pitch_shift(f, shift->rx.shift_amount, &shift->rx);
   }

   return 0;
}

pitchshift_helper()

static int pitchshift_helper ( struct ast_channel *  chan, const char *  cmd, char *  data, const char *  value  )

static

Definition at line 192 of file func_pitchshift.c.

References ast_audiohook_attach(), ast_audiohook_init(), AST_AUDIOHOOK_MANIPULATE_ALL_RATES, AST_AUDIOHOOK_TYPE_MANIPULATE, ast_calloc, ast_channel_datastore_add(), ast_channel_datastore_find(), ast_channel_lock, ast_channel_unlock, ast_datastore_alloc, ast_datastore_free(), ast_log, pitchshift_data::audiohook, ast_datastore::data, HIGH, HIGHER, HIGHEST, LOG_ERROR, LOG_WARNING, LOW, LOWER, LOWEST, ast_audiohook::manipulate_callback, NULL, pitchshift_cb(), pitchshift_data::rx, fft_data::shift_amount, and pitchshift_data::tx.

{
   struct ast_datastore *datastore = NULL;
   struct pitchshift_data *shift = NULL;
   int new = 0;
   float amount = 0;

   if (!chan) {
      ast_log(LOG_WARNING, "No channel was provided to %s function.\n", cmd);
      return -1;
   }

   ast_channel_lock(chan);
   if (!(datastore = ast_channel_datastore_find(chan, &pitchshift_datastore, NULL))) {
      ast_channel_unlock(chan);

      if (!(datastore = ast_datastore_alloc(&pitchshift_datastore, NULL))) {
         return 0;
      }
      if (!(shift = ast_calloc(1, sizeof(*shift)))) {
         ast_datastore_free(datastore);
         return 0;
      }

      ast_audiohook_init(&shift->audiohook, AST_AUDIOHOOK_TYPE_MANIPULATE, "pitch_shift", AST_AUDIOHOOK_MANIPULATE_ALL_RATES);
      shift->audiohook.manipulate_callback = pitchshift_cb;
      datastore->data = shift;
      new = 1;
   } else {
      ast_channel_unlock(chan);
      shift = datastore->data;
   }


   if (!strcasecmp(value, "highest")) {
      amount = HIGHEST;
   } else if (!strcasecmp(value, "higher")) {
      amount = HIGHER;
   } else if (!strcasecmp(value, "high")) {
      amount = HIGH;
   } else if (!strcasecmp(value, "lowest")) {
      amount = LOWEST;
   } else if (!strcasecmp(value, "lower")) {
      amount = LOWER;
   } else if (!strcasecmp(value, "low")) {
      amount = LOW;
   } else {
      if (!sscanf(value, "%30f", &amount) || (amount <= 0) || (amount > 4)) {
         goto cleanup_error;
      }
   }

   if (!strcasecmp(data, "rx")) {
      shift->rx.shift_amount = amount;
   } else if (!strcasecmp(data, "tx")) {
      shift->tx.shift_amount = amount;
   } else if (!strcasecmp(data, "both")) {
      shift->rx.shift_amount = amount;
      shift->tx.shift_amount = amount;
   } else {
      goto cleanup_error;
   }

   if (new) {
      ast_channel_lock(chan);
      ast_channel_datastore_add(chan, datastore);
      ast_channel_unlock(chan);
      ast_audiohook_attach(chan, &shift->audiohook);
   }

   return 0;

cleanup_error:

   ast_log(LOG_ERROR, "Invalid argument provided to the %s function\n", cmd);
   if (new) {
      ast_datastore_free(datastore);
   }
   return -1;
}

smb_fft()

static void smb_fft ( float *  fft_buffer, long  fft_frame_size, long  sign  )

static

Definition at line 273 of file func_pitchshift.c.

References cos, and M_PI.

Referenced by smb_pitch_shift().

{
   float wr, wi, arg, *p1, *p2, temp;
   float tr, ti, ur, ui, *p1r, *p1i, *p2r, *p2i;
   long i, bitm, j, le, le2, k;

   for (i = 2; i < 2 * fft_frame_size - 2; i += 2) {
      for (bitm = 2, j = 0; bitm < 2 * fft_frame_size; bitm <<= 1) {
         if (i & bitm) {
            j++;
         }
         j <<= 1;
      }
      if (i < j) {
         p1 = fft_buffer + i; p2 = fft_buffer + j;
         temp = *p1; *(p1++) = *p2;
         *(p2++) = temp; temp = *p1;
         *p1 = *p2; *p2 = temp;
      }
   }
   for (k = 0, le = 2; k < (long) (log(fft_frame_size) / log(2.) + .5); k++) {
      le <<= 1;
      le2 = le>>1;
      ur = 1.0;
      ui = 0.0;
      arg = M_PI / (le2>>1);
      wr = cos(arg);
      wi = sign * sin(arg);
      for (j = 0; j < le2; j += 2) {
         p1r = fft_buffer+j; p1i = p1r + 1;
         p2r = p1r + le2; p2i = p2r + 1;
         for (i = j; i < 2 * fft_frame_size; i += le) {
            tr = *p2r * ur - *p2i * ui;
            ti = *p2r * ui + *p2i * ur;
            *p2r = *p1r - tr; *p2i = *p1i - ti;
            *p1r += tr; *p1i += ti;
            p1r += le; p1i += le;
            p2r += le; p2i += le;
         }
         tr = ur * wr - ui * wi;
         ui = ur * wi + ui * wr;
         ur = tr;
      }
   }
}

smb_pitch_shift()

static void smb_pitch_shift ( float  pitchShift, long  num_samps_to_process, long  fft_frame_size, long  osamp, float  sample_rate, int16_t *  indata, int16_t *  outdata, struct fft_data *  fft_data  )

static

Definition at line 319 of file func_pitchshift.c.

References fft_data::ana_freq, fft_data::ana_magn, cos, fft_data::fft_worksp, fft_data::gRover, fft_data::in_fifo, fft_data::last_phase, M_PI, fft_data::out_fifo, fft_data::output_accum, smb_fft(), step_size(), fft_data::sum_phase, fft_data::syn_freq, fft_data::sys_magn, tmp(), and window.

Referenced by pitch_shift().

{
   float *in_fifo = fft_data->in_fifo;
   float *out_fifo = fft_data->out_fifo;
   float *fft_worksp = fft_data->fft_worksp;
   float *last_phase = fft_data->last_phase;
   float *sum_phase = fft_data->sum_phase;
   float *output_accum = fft_data->output_accum;
   float *ana_freq = fft_data->ana_freq;
   float *ana_magn = fft_data->ana_magn;
   float *syn_freq = fft_data->syn_freq;
   float *sys_magn = fft_data->sys_magn;

   double magn, phase, tmp, window, real, imag;
   double freq_per_bin, expct;
   long i,k, qpd, index, in_fifo_latency, step_size, fft_frame_size2;

   /* set up some handy variables */
   fft_frame_size2 = fft_frame_size / 2;
   step_size = fft_frame_size / osamp;
   freq_per_bin = sample_rate / (double) fft_frame_size;
   expct = 2. * M_PI * (double) step_size / (double) fft_frame_size;
   in_fifo_latency = fft_frame_size-step_size;

   if (fft_data->gRover == 0) {
      fft_data->gRover = in_fifo_latency;
   }

   /* main processing loop */
   for (i = 0; i < num_samps_to_process; i++){

      /* As long as we have not yet collected enough data just read in */
      in_fifo[fft_data->gRover] = indata[i];
      outdata[i] = out_fifo[fft_data->gRover - in_fifo_latency];
      fft_data->gRover++;

      /* now we have enough data for processing */
      if (fft_data->gRover >= fft_frame_size) {
         fft_data->gRover = in_fifo_latency;

         /* do windowing and re,im interleave */
         for (k = 0; k < fft_frame_size;k++) {
            window = -.5 * cos(2. * M_PI * (double) k / (double) fft_frame_size) + .5;
            fft_worksp[2*k] = in_fifo[k] * window;
            fft_worksp[2*k+1] = 0.;
         }

         /* ***************** ANALYSIS ******************* */
         /* do transform */
         smb_fft(fft_worksp, fft_frame_size, -1);

         /* this is the analysis step */
         for (k = 0; k <= fft_frame_size2; k++) {

            /* de-interlace FFT buffer */
            real = fft_worksp[2*k];
            imag = fft_worksp[2*k+1];

            /* compute magnitude and phase */
            magn = 2. * sqrt(real * real + imag * imag);
            phase = atan2(imag, real);

            /* compute phase difference */
            tmp = phase - last_phase[k];
            last_phase[k] = phase;

            /* subtract expected phase difference */
            tmp -= (double) k * expct;

            /* map delta phase into +/- Pi interval */
            qpd = tmp / M_PI;
            if (qpd >= 0) {
               qpd += qpd & 1;
            } else {
               qpd -= qpd & 1;
            }
            tmp -= M_PI * (double) qpd;

            /* get deviation from bin frequency from the +/- Pi interval */
            tmp = osamp * tmp / (2. * M_PI);

            /* compute the k-th partials' true frequency */
            tmp = (double) k * freq_per_bin + tmp * freq_per_bin;

            /* store magnitude and true frequency in analysis arrays */
            ana_magn[k] = magn;
            ana_freq[k] = tmp;

         }

         /* ***************** PROCESSING ******************* */
         /* this does the actual pitch shifting */
         memset(sys_magn, 0, fft_frame_size * sizeof(float));
         memset(syn_freq, 0, fft_frame_size * sizeof(float));
         for (k = 0; k <= fft_frame_size2; k++) {
            index = k * pitchShift;
            if (index <= fft_frame_size2) {
               sys_magn[index] += ana_magn[k];
               syn_freq[index] = ana_freq[k] * pitchShift;
            }
         }

         /* ***************** SYNTHESIS ******************* */
         /* this is the synthesis step */
         for (k = 0; k <= fft_frame_size2; k++) {

            /* get magnitude and true frequency from synthesis arrays */
            magn = sys_magn[k];
            tmp = syn_freq[k];

            /* subtract bin mid frequency */
            tmp -= (double) k * freq_per_bin;

            /* get bin deviation from freq deviation */
            tmp /= freq_per_bin;

            /* take osamp into account */
            tmp = 2. * M_PI * tmp / osamp;

            /* add the overlap phase advance back in */
            tmp += (double) k * expct;

            /* accumulate delta phase to get bin phase */
            sum_phase[k] += tmp;
            phase = sum_phase[k];

            /* get real and imag part and re-interleave */
            fft_worksp[2*k] = magn * cos(phase);
            fft_worksp[2*k+1] = magn * sin(phase);
         }

         /* zero negative frequencies */
         for (k = fft_frame_size + 2; k < 2 * fft_frame_size; k++) {
            fft_worksp[k] = 0.;
         }

         /* do inverse transform */
         smb_fft(fft_worksp, fft_frame_size, 1);

         /* do windowing and add to output accumulator */
         for (k = 0; k < fft_frame_size; k++) {
            window = -.5 * cos(2. * M_PI * (double) k / (double) fft_frame_size) + .5;
            output_accum[k] += 2. * window * fft_worksp[2*k] / (fft_frame_size2 * osamp);
         }
         for (k = 0; k < step_size; k++) {
            out_fifo[k] = output_accum[k];
         }

         /* shift accumulator */
         memmove(output_accum, output_accum+step_size, fft_frame_size * sizeof(float));

         /* move input FIFO */
         for (k = 0; k < in_fifo_latency; k++) {
            in_fifo[k] = in_fifo[k+step_size];
         }
      }
   }
}

unload_module()

static int unload_module ( void  )

static

Definition at line 499 of file func_pitchshift.c.

References ast_custom_function_unregister().

{
   return ast_custom_function_unregister(&pitch_shift_function);
}

Variable Documentation

pitch_shift_function

struct ast_custom_function pitch_shift_function

static

Initial value:

= {
   .name = "PITCH_SHIFT",
   .write = pitchshift_helper,
}

Definition at line 494 of file func_pitchshift.c.

pitchshift_datastore

const struct ast_datastore_info pitchshift_datastore

static

Initial value:

= {
   .type = "pitchshift",
   .destroy = destroy_callback
}

Definition at line 159 of file func_pitchshift.c.