Tue Aug 20 16:35:04 2013

Asterisk developer's documentation


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>

Go to the source code of this file.

Data Structures

struct  fft_data
struct  pitchshift_data

Defines

#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 (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 struct ast_datastore_info pitchshift_datastore

Detailed Description

Pitch Shift Audio Effect.

Author:
David Vossel <dvossel@digium.com>

Definition in file func_pitchshift.c.


Define Documentation

#define HIGH   1.25

Definition at line 122 of file func_pitchshift.c.

Referenced by pitchshift_helper().

#define HIGHER   1.5

Definition at line 121 of file func_pitchshift.c.

Referenced by pitchshift_helper().

#define HIGHEST   2

Definition at line 120 of file func_pitchshift.c.

Referenced by pitchshift_helper().

#define LOW   .85

Definition at line 123 of file func_pitchshift.c.

Referenced by pitchshift_helper().

#define LOWER   .7

Definition at line 124 of file func_pitchshift.c.

Referenced by pitchshift_helper().

#define LOWEST   .5

Definition at line 125 of file func_pitchshift.c.

Referenced by pitchshift_helper().

#define M_PI   3.14159265358979323846
#define MAX_FRAME_LENGTH   256

Definition at line 118 of file func_pitchshift.c.

Referenced by pitch_shift().


Function Documentation

AST_MODULE_INFO_STANDARD ( ASTERISK_GPL_KEY  ,
"Audio Effects Dialplan Functions"   
)
static void destroy_callback ( void *  data  )  [static]

Definition at line 153 of file func_pitchshift.c.

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

00154 {
00155    struct pitchshift_data *shift = data;
00156 
00157    ast_audiohook_destroy(&shift->audiohook);
00158    ast_free(shift);
00159 };

static int load_module ( void   )  [static]
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_rate(), ast_frame_subclass::codec, ast_frame::data, MAX_FRAME_LENGTH, ast_frame::ptr, ast_frame::samples, smb_pitch_shift(), and ast_frame::subclass.

Referenced by pitchshift_cb().

00479 {
00480    int16_t *fun = (int16_t *) f->data.ptr;
00481    int samples;
00482 
00483    /* an amount of 1 has no effect */
00484    if (!amount || amount == 1 || !fun || (f->samples % 32)) {
00485       return 0;
00486    }
00487    for (samples = 0; samples < f->samples; samples += 32) {
00488       smb_pitch_shift(amount, 32, MAX_FRAME_LENGTH, 32, ast_format_rate(f->subclass.codec), fun+samples, fun+samples, fft);
00489    }
00490 
00491    return 0;
00492 }

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 166 of file func_pitchshift.c.

References AST_AUDIOHOOK_DIRECTION_WRITE, AST_AUDIOHOOK_STATUS_DONE, ast_channel_datastore_find(), AST_FORMAT_SLINEAR, AST_FORMAT_SLINEAR16, AST_FRAME_VOICE, ast_frame_subclass::codec, ast_datastore::data, ast_frame::frametype, pitch_shift(), pitchshift_data::rx, fft_data::shift_amount, ast_audiohook::status, ast_frame::subclass, and pitchshift_data::tx.

Referenced by pitchshift_helper().

00167 {
00168    struct ast_datastore *datastore = NULL;
00169    struct pitchshift_data *shift = NULL;
00170 
00171 
00172    if (!f) {
00173       return 0;
00174    }
00175    if ((audiohook->status == AST_AUDIOHOOK_STATUS_DONE) ||
00176       (f->frametype != AST_FRAME_VOICE) ||
00177       ((f->subclass.codec != AST_FORMAT_SLINEAR) &&
00178       (f->subclass.codec != AST_FORMAT_SLINEAR16))) {
00179       return -1;
00180    }
00181 
00182    if (!(datastore = ast_channel_datastore_find(chan, &pitchshift_datastore, NULL))) {
00183       return -1;
00184    }
00185 
00186    shift = datastore->data;
00187 
00188    if (direction == AST_AUDIOHOOK_DIRECTION_WRITE) {
00189       pitch_shift(f, shift->tx.shift_amount, &shift->tx);
00190    } else {
00191       pitch_shift(f, shift->rx.shift_amount, &shift->rx);
00192    }
00193 
00194    return 0;
00195 }

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

Definition at line 197 of file func_pitchshift.c.

References ast_audiohook_attach(), ast_audiohook_init(), 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, LOW, LOWER, LOWEST, ast_audiohook::manipulate_callback, pitchshift_cb(), pitchshift_data::rx, fft_data::shift_amount, and pitchshift_data::tx.

00198 {
00199    struct ast_datastore *datastore = NULL;
00200    struct pitchshift_data *shift = NULL;
00201    int new = 0;
00202    float amount = 0;
00203 
00204    ast_channel_lock(chan);
00205    if (!(datastore = ast_channel_datastore_find(chan, &pitchshift_datastore, NULL))) {
00206       ast_channel_unlock(chan);
00207 
00208       if (!(datastore = ast_datastore_alloc(&pitchshift_datastore, NULL))) {
00209          return 0;
00210       }
00211       if (!(shift = ast_calloc(1, sizeof(*shift)))) {
00212          ast_datastore_free(datastore);
00213          return 0;
00214       }
00215 
00216       ast_audiohook_init(&shift->audiohook, AST_AUDIOHOOK_TYPE_MANIPULATE, "pitch_shift");
00217       shift->audiohook.manipulate_callback = pitchshift_cb;
00218       datastore->data = shift;
00219       new = 1;
00220    } else {
00221       ast_channel_unlock(chan);
00222       shift = datastore->data;
00223    }
00224 
00225 
00226    if (!strcasecmp(value, "highest")) {
00227       amount = HIGHEST;
00228    } else if (!strcasecmp(value, "higher")) {
00229       amount = HIGHER;
00230    } else if (!strcasecmp(value, "high")) {
00231       amount = HIGH;
00232    } else if (!strcasecmp(value, "lowest")) {
00233       amount = LOWEST;
00234    } else if (!strcasecmp(value, "lower")) {
00235       amount = LOWER;
00236    } else if (!strcasecmp(value, "low")) {
00237       amount = LOW;
00238    } else {
00239       if (!sscanf(value, "%30f", &amount) || (amount <= 0) || (amount > 4)) {
00240          goto cleanup_error;
00241       }
00242    }
00243 
00244    if (!strcasecmp(data, "rx")) {
00245       shift->rx.shift_amount = amount;
00246    } else if (!strcasecmp(data, "tx")) {
00247       shift->tx.shift_amount = amount;
00248    } else if (!strcasecmp(data, "both")) {
00249       shift->rx.shift_amount = amount;
00250       shift->tx.shift_amount = amount;
00251    } else {
00252       goto cleanup_error;
00253    }
00254 
00255    if (new) {
00256       ast_channel_lock(chan);
00257       ast_channel_datastore_add(chan, datastore);
00258       ast_channel_unlock(chan);
00259       ast_audiohook_attach(chan, &shift->audiohook);
00260    }
00261 
00262    return 0;
00263 
00264 cleanup_error:
00265 
00266    ast_log(LOG_ERROR, "Invalid argument provided to the %s function\n", cmd);
00267    if (new) {
00268       ast_datastore_free(datastore);
00269    }
00270    return -1;
00271 }

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().

00274 {
00275    float wr, wi, arg, *p1, *p2, temp;
00276    float tr, ti, ur, ui, *p1r, *p1i, *p2r, *p2i;
00277    long i, bitm, j, le, le2, k;
00278 
00279    for (i = 2; i < 2 * fft_frame_size - 2; i += 2) {
00280       for (bitm = 2, j = 0; bitm < 2 * fft_frame_size; bitm <<= 1) {
00281          if (i & bitm) {
00282             j++;
00283          }
00284          j <<= 1;
00285       }
00286       if (i < j) {
00287          p1 = fft_buffer + i; p2 = fft_buffer + j;
00288          temp = *p1; *(p1++) = *p2;
00289          *(p2++) = temp; temp = *p1;
00290          *p1 = *p2; *p2 = temp;
00291       }
00292    }
00293    for (k = 0, le = 2; k < (long) (log(fft_frame_size) / log(2.) + .5); k++) {
00294       le <<= 1;
00295       le2 = le>>1;
00296       ur = 1.0;
00297       ui = 0.0;
00298       arg = M_PI / (le2>>1);
00299       wr = cos(arg);
00300       wi = sign * sin(arg);
00301       for (j = 0; j < le2; j += 2) {
00302          p1r = fft_buffer+j; p1i = p1r + 1;
00303          p2r = p1r + le2; p2i = p2r + 1;
00304          for (i = j; i < 2 * fft_frame_size; i += le) {
00305             tr = *p2r * ur - *p2i * ui;
00306             ti = *p2r * ui + *p2i * ur;
00307             *p2r = *p1r - tr; *p2i = *p1i - ti;
00308             *p1r += tr; *p1i += ti;
00309             p1r += le; p1i += le;
00310             p2r += le; p2i += le;
00311          }
00312          tr = ur * wr - ui * wi;
00313          ui = ur * wi + ui * wr;
00314          ur = tr;
00315       }
00316    }
00317 }

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, and fft_data::sys_magn.

Referenced by pitch_shift().

00320 {
00321    float *in_fifo = fft_data->in_fifo;
00322    float *out_fifo = fft_data->out_fifo;
00323    float *fft_worksp = fft_data->fft_worksp;
00324    float *last_phase = fft_data->last_phase;
00325    float *sum_phase = fft_data->sum_phase;
00326    float *output_accum = fft_data->output_accum;
00327    float *ana_freq = fft_data->ana_freq;
00328    float *ana_magn = fft_data->ana_magn;
00329    float *syn_freq = fft_data->syn_freq;
00330    float *sys_magn = fft_data->sys_magn;
00331 
00332    double magn, phase, tmp, window, real, imag;
00333    double freq_per_bin, expct;
00334    long i,k, qpd, index, in_fifo_latency, step_size, fft_frame_size2;
00335 
00336    /* set up some handy variables */
00337    fft_frame_size2 = fft_frame_size / 2;
00338    step_size = fft_frame_size / osamp;
00339    freq_per_bin = sample_rate / (double) fft_frame_size;
00340    expct = 2. * M_PI * (double) step_size / (double) fft_frame_size;
00341    in_fifo_latency = fft_frame_size-step_size;
00342 
00343    if (fft_data->gRover == 0) {
00344       fft_data->gRover = in_fifo_latency;
00345    }
00346 
00347    /* main processing loop */
00348    for (i = 0; i < num_samps_to_process; i++){
00349 
00350       /* As long as we have not yet collected enough data just read in */
00351       in_fifo[fft_data->gRover] = indata[i];
00352       outdata[i] = out_fifo[fft_data->gRover - in_fifo_latency];
00353       fft_data->gRover++;
00354 
00355       /* now we have enough data for processing */
00356       if (fft_data->gRover >= fft_frame_size) {
00357          fft_data->gRover = in_fifo_latency;
00358 
00359          /* do windowing and re,im interleave */
00360          for (k = 0; k < fft_frame_size;k++) {
00361             window = -.5 * cos(2. * M_PI * (double) k / (double) fft_frame_size) + .5;
00362             fft_worksp[2*k] = in_fifo[k] * window;
00363             fft_worksp[2*k+1] = 0.;
00364          }
00365 
00366          /* ***************** ANALYSIS ******************* */
00367          /* do transform */
00368          smb_fft(fft_worksp, fft_frame_size, -1);
00369 
00370          /* this is the analysis step */
00371          for (k = 0; k <= fft_frame_size2; k++) {
00372 
00373             /* de-interlace FFT buffer */
00374             real = fft_worksp[2*k];
00375             imag = fft_worksp[2*k+1];
00376 
00377             /* compute magnitude and phase */
00378             magn = 2. * sqrt(real * real + imag * imag);
00379             phase = atan2(imag, real);
00380 
00381             /* compute phase difference */
00382             tmp = phase - last_phase[k];
00383             last_phase[k] = phase;
00384 
00385             /* subtract expected phase difference */
00386             tmp -= (double) k * expct;
00387 
00388             /* map delta phase into +/- Pi interval */
00389             qpd = tmp / M_PI;
00390             if (qpd >= 0) {
00391                qpd += qpd & 1;
00392             } else {
00393                qpd -= qpd & 1;
00394             }
00395             tmp -= M_PI * (double) qpd;
00396 
00397             /* get deviation from bin frequency from the +/- Pi interval */
00398             tmp = osamp * tmp / (2. * M_PI);
00399 
00400             /* compute the k-th partials' true frequency */
00401             tmp = (double) k * freq_per_bin + tmp * freq_per_bin;
00402 
00403             /* store magnitude and true frequency in analysis arrays */
00404             ana_magn[k] = magn;
00405             ana_freq[k] = tmp;
00406 
00407          }
00408 
00409          /* ***************** PROCESSING ******************* */
00410          /* this does the actual pitch shifting */
00411          memset(sys_magn, 0, fft_frame_size * sizeof(float));
00412          memset(syn_freq, 0, fft_frame_size * sizeof(float));
00413          for (k = 0; k <= fft_frame_size2; k++) {
00414             index = k * pitchShift;
00415             if (index <= fft_frame_size2) {
00416                sys_magn[index] += ana_magn[k];
00417                syn_freq[index] = ana_freq[k] * pitchShift;
00418             }
00419          }
00420 
00421          /* ***************** SYNTHESIS ******************* */
00422          /* this is the synthesis step */
00423          for (k = 0; k <= fft_frame_size2; k++) {
00424 
00425             /* get magnitude and true frequency from synthesis arrays */
00426             magn = sys_magn[k];
00427             tmp = syn_freq[k];
00428 
00429             /* subtract bin mid frequency */
00430             tmp -= (double) k * freq_per_bin;
00431 
00432             /* get bin deviation from freq deviation */
00433             tmp /= freq_per_bin;
00434 
00435             /* take osamp into account */
00436             tmp = 2. * M_PI * tmp / osamp;
00437 
00438             /* add the overlap phase advance back in */
00439             tmp += (double) k * expct;
00440 
00441             /* accumulate delta phase to get bin phase */
00442             sum_phase[k] += tmp;
00443             phase = sum_phase[k];
00444 
00445             /* get real and imag part and re-interleave */
00446             fft_worksp[2*k] = magn * cos(phase);
00447             fft_worksp[2*k+1] = magn * sin(phase);
00448          }
00449 
00450          /* zero negative frequencies */
00451          for (k = fft_frame_size + 2; k < 2 * fft_frame_size; k++) {
00452             fft_worksp[k] = 0.;
00453          }
00454 
00455          /* do inverse transform */
00456          smb_fft(fft_worksp, fft_frame_size, 1);
00457 
00458          /* do windowing and add to output accumulator */
00459          for (k = 0; k < fft_frame_size; k++) {
00460             window = -.5 * cos(2. * M_PI * (double) k / (double) fft_frame_size) + .5;
00461             output_accum[k] += 2. * window * fft_worksp[2*k] / (fft_frame_size2 * osamp);
00462          }
00463          for (k = 0; k < step_size; k++) {
00464             out_fifo[k] = output_accum[k];
00465          }
00466 
00467          /* shift accumulator */
00468          memmove(output_accum, output_accum+step_size, fft_frame_size * sizeof(float));
00469 
00470          /* move input FIFO */
00471          for (k = 0; k < in_fifo_latency; k++) {
00472             in_fifo[k] = in_fifo[k+step_size];
00473          }
00474       }
00475    }
00476 }

static int unload_module ( void   )  [static]

Definition at line 499 of file func_pitchshift.c.

References ast_custom_function_unregister().

00500 {
00501    return ast_custom_function_unregister(&pitch_shift_function);
00502 }


Variable Documentation

Initial value:
 {
   .name = "PITCH_SHIFT",
   .write = pitchshift_helper,
}

Definition at line 494 of file func_pitchshift.c.

Initial value:
 {
   .type = "pitchshift",
   .destroy = destroy_callback
}

Definition at line 161 of file func_pitchshift.c.


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