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Added useful comments. 

Eric


git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@10720 d0543943-73ff-0310-b7d9-9358b9ac24b2
This commit is contained in:
Eric des Courtis 2008-12-11 22:13:20 +00:00
parent 186c98b6d7
commit 1a4fb0d978
1 changed files with 56 additions and 37 deletions
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93
src/mod/applications/mod_vmd/mod_vmd.c
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@ -50,35 +50,40 @@
#define ISNAN(x) ((x)== NAN)
#endif
/* Number of points for beep detection */
/*! Number of points for beep detection */
#define POINTS 32
/* Number of valid points required for beep detection */
/*! Number of valid points required for beep detection */
#define VALID 22
/* Maximum number of invalid points
* to declare beep has stopped */
/*! Maximum number of invalid points to declare beep has stopped */
#define MAX_CHIRP 22
/* Minimum time for a beep */
/*! Minimum time for a beep */
#define MIN_TIME 8000
/* Minimum amplitude of the signal */
/*! Minimum amplitude of the signal */
#define MIN_AMPL 0.10
/* Minimum beep frequency */
/*! Minimum beep frequency */
#define MIN_FREQ (600)
/* Maximum beep frequency */
/*! Maximum beep frequency */
#define MAX_FREQ (1100)
/* PSI function for amplitude calculation*/
/*! \brief \f$\psi{(x)}\f$ function for amplitude calculation
*
* \f$\psi{(x)} = {x^2_1} - {x_2} {x_0}\f$
*/
#define PSI(x) (x[1]*x[1]-x[2]*x[0])
/* Sample rate */
/*! Sample rate NOTE: this should be dynamic in the future */
#define F (8000)
/* Conversion of frequency to Hz */
/*! \brief Conversion of frequency to Hz
*
* \f$F = \frac{f}{{2}{\pi}}\f$
*/
#define TO_HZ(f) ((F * f) / (2.0 * M_PI))
/* Number of points in discreet energy separation */
@ -91,22 +96,22 @@
* DEPRECATED */
#define ADJUST_MAX (65536)
/* Discreet energy separation tolerance to error */
/*! Discreet energy separation tolerance to error */
#define TOLERANCE (0.20)
/* Maximum value within tolerance */
/*! Maximum value within tolerance */
#define TOLERANCE_T(m) (m + (m * TOLERANCE))
/* Minimum value within tolerance */
/*! Minimum value within tolerance */
#define TOLERANCE_B(m) (m - (m * TOLERANCE))
/* Syntax of the API call */
/*! Syntax of the API call */
#define VMD_SYNTAX "<uuid> <command>"
/* Number of expected parameters in api call */
/*! Number of expected parameters in api call */
#define VMD_PARAMS 2
/* FreeSWITCH CUSTOM event type */
/*! FreeSWITCH CUSTOM event type */
#define VMD_EVENT_BEEP "vmd::beep"
/* Prototypes */
@ -117,39 +122,39 @@ SWITCH_MODULE_LOAD_FUNCTION(mod_vmd_load);
SWITCH_MODULE_DEFINITION(mod_vmd, mod_vmd_load, NULL, NULL);
SWITCH_STANDARD_APP(vmd_start_function);
/* Type that holds state information about the beep */
/*! Type that holds state information about the beep */
typedef enum vmd_state {
BEEP_DETECTED, BEEP_NOT_DETECTED
} vmd_state_t;
/* Type that holds data for 5 points of discreet energy separation */
/*! Type that holds data for 5 points of discreet energy separation */
typedef struct vmd_point {
double freq;
double ampl;
} vmd_point_t;
/* Type that holds codec information */
/*! Type that holds codec information */
typedef struct vmd_codec_info {
int rate;
int channels;
} vmd_codec_info_t;
/* Type that holds session information pertinent to the vmd module */
/*! Type that holds session information pertinent to the vmd module */
typedef struct vmd_session_info {
/* State of the session */
/*! State of the session */
vmd_state_t state;
/* Snapshot of DESA samples */
/*! Snapshot of DESA samples */
vmd_point_t points[POINTS];
/* Internal FreeSWITCH session */
/*! Internal FreeSWITCH session */
switch_core_session_t *session;
/* Codec information for the session */
/*! Codec information for the session */
vmd_codec_info_t vmd_codec;
/* Current position in the snapshot */
/*! Current position in the snapshot */
unsigned int pos;
/* Frequency aproximation of a detected beep */
/*! Frequency aproximation of a detected beep */
double beep_freq;
/* A count of how long a distinct beep was detected by
* by the discreet energy separation algorithm */
/*! A count of how long a distinct beep was detected by
* by the discreet energy separation algorithm */
switch_size_t timestamp;
} vmd_session_info_t;
@ -202,6 +207,7 @@ static switch_bool_t vmd_callback(switch_media_bug_t * bug, void *user_data, swi
return SWITCH_TRUE;
}
/*! Process and convert data to be used by the find_beep() function */
static switch_bool_t process_data(vmd_session_info_t * vmd_info, switch_frame_t * frame)
{
uint32_t i;
@ -253,6 +259,7 @@ static switch_bool_t process_data(vmd_session_info_t * vmd_info, switch_frame_t
return SWITCH_TRUE;
}
/*! Find voicemail beep in the audio stream */
static void find_beep(vmd_session_info_t * vmd_info, switch_frame_t * frame)
{
int i;
@ -347,7 +354,7 @@ static void find_beep(vmd_session_info_t * vmd_info, switch_frame_t * frame)
}
}
/* Find the median of an array of doubles */
/*! Find the median of an array of doubles */
static double median(double *m, int n)
{
int i;
@ -411,17 +418,20 @@ static double median(double *m, int n)
return mingtguess;
}
/* Convert many points for Signed L16 to relative floating point */
/*! Convert many points for Signed L16 to relative floating point */
static void convert_pts(int16_t * i_pts, double *d_pts, int16_t max)
{
int i;
for (i = 0; i < P; i++) {
/* Signed L16 to relative floating point conversion */
/*! Signed L16 to relative floating point conversion */
d_pts[i] = ((((double) (i_pts[i]) + (double) max) / (double) (2 * max)) - 0.5) * 2.0;
}
}
/* Amplitude estimator for DESA-2 */
/*! \brief Amplitude estimator for DESA-2
*
* \f$A = \sqrt{\frac{\psi{(x)}}{\sin{\Omega^2}}}\f$
*/
double ampl_estimator(double *x)
{
double freq_sq;
@ -432,7 +442,15 @@ double ampl_estimator(double *x)
return sqrt(PSI(x) / sin(freq_sq));
}
/* The DESA-2 algorithm */
/*! \brief The DESA-2 algorithm
*
* \f$\frac{1}{2}\arccos{\frac{{{x^2_2} -
* {x_0}{x_4}} - {{x^2_1} -
* {x_0}{x_2}} - {{x^2_3} -
* {x_2}{x_4}}}
* {{2}({x^2_2} - {x_1}{x_3})}}\f$
*
*/
double freq_estimator(double *x)
{
return 0.5 * acos((((x[2] * x[2]) - (x[0] * x[4]))
@ -443,7 +461,7 @@ double freq_estimator(double *x)
);
}
/*! FreeSWITCH module loading function */
SWITCH_MODULE_LOAD_FUNCTION(mod_vmd_load)
{
switch_application_interface_t *app_interface;
@ -461,7 +479,7 @@ SWITCH_MODULE_LOAD_FUNCTION(mod_vmd_load)
return SWITCH_STATUS_SUCCESS;
}
/* Same as api function see it for comments */
/*! FreeSWITCH application handler function */
SWITCH_STANDARD_APP(vmd_start_function)
{
switch_media_bug_t *bug;
@ -518,7 +536,7 @@ SWITCH_STANDARD_APP(vmd_start_function)
}
/* Called when the system shuts down */
/*! Called when the system shuts down */
SWITCH_MODULE_SHUTDOWN_FUNCTION(mod_vmd_shutdown)
{
switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_NOTICE, "Voicemail detection disabled\n");
@ -526,6 +544,7 @@ SWITCH_MODULE_SHUTDOWN_FUNCTION(mod_vmd_shutdown)
return SWITCH_STATUS_SUCCESS;
}
/*! FreeSWITCH API handler function */
SWITCH_STANDARD_API(vmd_api_main)
{
switch_core_session_t *vmd_session;