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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) #define ISNAN(x) ((x)== NAN)
#endif #endif
/* Number of points for beep detection */ /*! Number of points for beep detection */
#define POINTS 32 #define POINTS 32
/* Number of valid points required for beep detection */ /*! Number of valid points required for beep detection */
#define VALID 22 #define VALID 22
/* Maximum number of invalid points /*! Maximum number of invalid points to declare beep has stopped */
* to declare beep has stopped */
#define MAX_CHIRP 22 #define MAX_CHIRP 22
/* Minimum time for a beep */ /*! Minimum time for a beep */
#define MIN_TIME 8000 #define MIN_TIME 8000
/* Minimum amplitude of the signal */ /*! Minimum amplitude of the signal */
#define MIN_AMPL 0.10 #define MIN_AMPL 0.10
/* Minimum beep frequency */ /*! Minimum beep frequency */
#define MIN_FREQ (600) #define MIN_FREQ (600)
/* Maximum beep frequency */ /*! Maximum beep frequency */
#define MAX_FREQ (1100) #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]) #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) #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)) #define TO_HZ(f) ((F * f) / (2.0 * M_PI))
/* Number of points in discreet energy separation */ /* Number of points in discreet energy separation */
@ -91,22 +96,22 @@
* DEPRECATED */ * DEPRECATED */
#define ADJUST_MAX (65536) #define ADJUST_MAX (65536)
/* Discreet energy separation tolerance to error */ /*! Discreet energy separation tolerance to error */
#define TOLERANCE (0.20) #define TOLERANCE (0.20)
/* Maximum value within tolerance */ /*! Maximum value within tolerance */
#define TOLERANCE_T(m) (m + (m * TOLERANCE)) #define TOLERANCE_T(m) (m + (m * TOLERANCE))
/* Minimum value within tolerance */ /*! Minimum value within tolerance */
#define TOLERANCE_B(m) (m - (m * TOLERANCE)) #define TOLERANCE_B(m) (m - (m * TOLERANCE))
/* Syntax of the API call */ /*! Syntax of the API call */
#define VMD_SYNTAX "<uuid> <command>" #define VMD_SYNTAX "<uuid> <command>"
/* Number of expected parameters in api call */ /*! Number of expected parameters in api call */
#define VMD_PARAMS 2 #define VMD_PARAMS 2
/* FreeSWITCH CUSTOM event type */ /*! FreeSWITCH CUSTOM event type */
#define VMD_EVENT_BEEP "vmd::beep" #define VMD_EVENT_BEEP "vmd::beep"
/* Prototypes */ /* Prototypes */
@ -117,39 +122,39 @@ SWITCH_MODULE_LOAD_FUNCTION(mod_vmd_load);
SWITCH_MODULE_DEFINITION(mod_vmd, mod_vmd_load, NULL, NULL); SWITCH_MODULE_DEFINITION(mod_vmd, mod_vmd_load, NULL, NULL);
SWITCH_STANDARD_APP(vmd_start_function); 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 { typedef enum vmd_state {
BEEP_DETECTED, BEEP_NOT_DETECTED BEEP_DETECTED, BEEP_NOT_DETECTED
} vmd_state_t; } 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 { typedef struct vmd_point {
double freq; double freq;
double ampl; double ampl;
} vmd_point_t; } vmd_point_t;
/* Type that holds codec information */ /*! Type that holds codec information */
typedef struct vmd_codec_info { typedef struct vmd_codec_info {
int rate; int rate;
int channels; int channels;
} vmd_codec_info_t; } 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 { typedef struct vmd_session_info {
/* State of the session */ /*! State of the session */
vmd_state_t state; vmd_state_t state;
/* Snapshot of DESA samples */ /*! Snapshot of DESA samples */
vmd_point_t points[POINTS]; vmd_point_t points[POINTS];
/* Internal FreeSWITCH session */ /*! Internal FreeSWITCH session */
switch_core_session_t *session; switch_core_session_t *session;
/* Codec information for the session */ /*! Codec information for the session */
vmd_codec_info_t vmd_codec; vmd_codec_info_t vmd_codec;
/* Current position in the snapshot */ /*! Current position in the snapshot */
unsigned int pos; unsigned int pos;
/* Frequency aproximation of a detected beep */ /*! Frequency aproximation of a detected beep */
double beep_freq; double beep_freq;
/* A count of how long a distinct beep was detected by /*! A count of how long a distinct beep was detected by
* by the discreet energy separation algorithm */ * by the discreet energy separation algorithm */
switch_size_t timestamp; switch_size_t timestamp;
} vmd_session_info_t; } 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; 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) static switch_bool_t process_data(vmd_session_info_t * vmd_info, switch_frame_t * frame)
{ {
uint32_t i; 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; return SWITCH_TRUE;
} }
/*! Find voicemail beep in the audio stream */
static void find_beep(vmd_session_info_t * vmd_info, switch_frame_t * frame) static void find_beep(vmd_session_info_t * vmd_info, switch_frame_t * frame)
{ {
int i; 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) static double median(double *m, int n)
{ {
int i; int i;
@ -411,17 +418,20 @@ static double median(double *m, int n)
return mingtguess; 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) static void convert_pts(int16_t * i_pts, double *d_pts, int16_t max)
{ {
int i; int i;
for (i = 0; i < P; 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; 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 ampl_estimator(double *x)
{ {
double freq_sq; double freq_sq;
@ -432,7 +442,15 @@ double ampl_estimator(double *x)
return sqrt(PSI(x) / sin(freq_sq)); 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) double freq_estimator(double *x)
{ {
return 0.5 * acos((((x[2] * x[2]) - (x[0] * x[4])) 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_MODULE_LOAD_FUNCTION(mod_vmd_load)
{ {
switch_application_interface_t *app_interface; switch_application_interface_t *app_interface;
@ -461,7 +479,7 @@ SWITCH_MODULE_LOAD_FUNCTION(mod_vmd_load)
return SWITCH_STATUS_SUCCESS; return SWITCH_STATUS_SUCCESS;
} }
/* Same as api function see it for comments */ /*! FreeSWITCH application handler function */
SWITCH_STANDARD_APP(vmd_start_function) SWITCH_STANDARD_APP(vmd_start_function)
{ {
switch_media_bug_t *bug; 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_MODULE_SHUTDOWN_FUNCTION(mod_vmd_shutdown)
{ {
switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_NOTICE, "Voicemail detection disabled\n"); 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; return SWITCH_STATUS_SUCCESS;
} }
/*! FreeSWITCH API handler function */
SWITCH_STANDARD_API(vmd_api_main) SWITCH_STANDARD_API(vmd_api_main)
{ {
switch_core_session_t *vmd_session; switch_core_session_t *vmd_session;