switch_resample.h

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/* 
 * FreeSWITCH Modular Media Switching Software Library / Soft-Switch Application
 * Copyright (C) 2005-2014, Anthony Minessale II <anthm@freeswitch.org>
 *
 * Version: MPL 1.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is FreeSWITCH Modular Media Switching Software Library / Soft-Switch Application
 *
 * The Initial Developer of the Original Code is
 * Anthony Minessale II <anthm@freeswitch.org>
 * Portions created by the Initial Developer are Copyright (C)
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 * 
 * Anthony Minessale II <anthm@freeswitch.org>
 *
 *
 * switch_caller.h -- Caller Identification
 *
 */
/*! \file switch_resample.h
    \brief Audio Resample Code

        This module implements a generic interface for doing audio resampling it currently uses libresample but can be ported to
        any resample library with a little effort.  I decided against making this interface pluggable because there are not many
        options in terms of resample libraries so it seemed like a waste but I did opt to frontend the interface in case a better 
        way comes along some day. =D
        
*/
#define switch_normalize_volume(x) if (x > 4) x = 4; if (x < -4) x = -4;
#define switch_normalize_volume_granular(x) if (x > 13) x = 13; if (x < -13) x = -13;

#ifndef SWITCH_RESAMPLE_H
#define SWITCH_RESAMPLE_H
#define SWITCH_RESAMPLE_QUALITY 2
#include <switch.h>
SWITCH_BEGIN_EXTERN_C
/*!
  \defgroup resamp Audio Resample Functions
  \ingroup core1
  \{ 
*/
/*! \brief An audio resampling handle */
        typedef struct {
        /*! a pointer to store the resampler object */
        void *resampler;
        /*! the rate to resample from in hz */
        int from_rate;
        /*! the rate to resample to in hz */
        int to_rate;
        /*! the factor to resample by (from / to) */
        double factor;
        double rfactor;
        int16_t *to;
        /*! the size of the to buffer used */
        uint32_t to_len;
        /*! the total size of the to buffer */
        uint32_t to_size;
        /*! the number of channels */
        int channels;

} switch_audio_resampler_t;

/*!
  \brief Prepare a new resampler handle
  \param new_resampler NULL pointer to aim at the new handle
  \param from_rate the rate to transfer from in hz
  \param to_rate the rate to transfer to in hz
  \param quality the quality desired
  \return SWITCH_STATUS_SUCCESS if the handle was created
 */
SWITCH_DECLARE(switch_status_t) switch_resample_perform_create(switch_audio_resampler_t **new_resampler,
                                                                                                                           uint32_t from_rate, uint32_t to_rate, uint32_t to_size,
                                                                                                                           int quality, uint32_t channels, const char *file, const char *func, int line);


#define switch_resample_create(_n, _fr, _tr, _ts, _q, _c) switch_resample_perform_create(_n, _fr, _tr, _ts, _q, _c, __FILE__, __SWITCH_FUNC__, __LINE__)

/*!
  \brief Destroy an existing resampler handle
  \param resampler the resampler handle to destroy
 */
SWITCH_DECLARE(void) switch_resample_destroy(switch_audio_resampler_t **resampler);

/*!
  \brief Resample one float buffer into another using specifications of a given handle
  \param resampler the resample handle
  \param src the source data
  \param srclen the length of the source data
  \return the used size of dst
 */
SWITCH_DECLARE(uint32_t) switch_resample_process(switch_audio_resampler_t *resampler, int16_t *src, uint32_t srclen);


/*!
  \brief Convert an array of floats to an array of shorts
  \param f the float buffer
  \param s the short buffer
  \param len the length of the buffers
  \return the size of the converted buffer
 */
SWITCH_DECLARE(switch_size_t) switch_float_to_short(float *f, short *s, switch_size_t len);

/*!
  \brief Convert an array of chars to an array of floats
  \param c the char buffer
  \param f the float buffer
  \param len the length of the buffers
  \return the size of the converted buffer
 */
SWITCH_DECLARE(int) switch_char_to_float(char *c, float *f, int len);

/*!
  \brief Convert an array of floats to an array of chars
  \param f an array of floats
  \param c an array of chars
  \param len the length of the buffers
  \return the size of the converted buffer
 */
SWITCH_DECLARE(int) switch_float_to_char(float *f, char *c, int len);

/*!
  \brief Convert an array of shorts to an array of floats
  \param s an array of shorts
  \param f an array of floats
  \param len the size of the buffers
  \return the size of the converted buffer
 */
SWITCH_DECLARE(int) switch_short_to_float(short *s, float *f, int len);

/*!
  \brief Perform a byteswap on a buffer of 16 bit samples
  \param buf an array of samples
  \param len the size of the array
 */
SWITCH_DECLARE(void) switch_swap_linear(int16_t *buf, int len);

/*!
  \brief Generate static noise
  \param data the audio data buffer
  \param samples the number of 2 byte samples
  \param divisor the volume factor
 */
SWITCH_DECLARE(void) switch_generate_sln_silence(int16_t *data, uint32_t samples, uint32_t channels, uint32_t divisor);

/*!
  \brief Change the volume of a signed linear audio frame
  \param data the audio data
  \param samples the number of 2 byte samples
  \param vol the volume factor -4 -> 4
 */
SWITCH_DECLARE(void) switch_change_sln_volume(int16_t *data, uint32_t samples, int32_t vol);

/*!
  \brief Change the volume of a signed linear audio frame with more granularity
  \param data the audio data
  \param samples the number of 2 byte samples
  \param vol the volume factor -12 -> 12
 */
SWITCH_DECLARE(void) switch_change_sln_volume_granular(int16_t *data, uint32_t samples, int32_t vol);
///\}

SWITCH_DECLARE(uint32_t) switch_merge_sln(int16_t *data, uint32_t samples, int16_t *other_data, uint32_t other_samples, int channels);
SWITCH_DECLARE(uint32_t) switch_unmerge_sln(int16_t *data, uint32_t samples, int16_t *other_data, uint32_t other_samples, int channels);
SWITCH_DECLARE(void) switch_mux_channels(int16_t *data, switch_size_t samples, uint32_t orig_channels, uint32_t channels);

#define switch_resample_calc_buffer_size(_to, _from, _srclen) ((uint32_t)(((float)_to / (float)_from) * (float)_srclen) * 2)

                                                 
SWITCH_END_EXTERN_C
#endif
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