t38_gateway.c File Reference

#include <inttypes.h>
#include <stdlib.h>
#include <stdio.h>
#include <fcntl.h>
#include <time.h>
#include <string.h>
#include <tgmath.h>
#include <math.h>
#include "floating_fudge.h"
#include <assert.h>
#include <tiffio.h>
#include "spandsp/telephony.h"
#include "spandsp/logging.h"
#include "spandsp/queue.h"
#include "spandsp/dc_restore.h"
#include "spandsp/bit_operations.h"
#include "spandsp/power_meter.h"
#include "spandsp/complex.h"
#include "spandsp/tone_detect.h"
#include "spandsp/tone_generate.h"
#include "spandsp/async.h"
#include "spandsp/crc.h"
#include "spandsp/hdlc.h"
#include "spandsp/silence_gen.h"
#include "spandsp/fsk.h"
#include "spandsp/v29tx.h"
#include "spandsp/v29rx.h"
#include "spandsp/v27ter_tx.h"
#include "spandsp/v27ter_rx.h"
#include "spandsp/v17tx.h"
#include "spandsp/v17rx.h"
#include "spandsp/super_tone_rx.h"
#include "spandsp/modem_connect_tones.h"
#include "spandsp/t4_rx.h"
#include "spandsp/t4_tx.h"
#include "spandsp/t4_t6_decode.h"
#include "spandsp/t4_t6_encode.h"
#include "spandsp/t30_fcf.h"
#include "spandsp/t35.h"
#include "spandsp/t30.h"
#include "spandsp/t30_logging.h"
#include "spandsp/fax_modems.h"
#include "spandsp/t38_core.h"
#include "spandsp/t38_non_ecm_buffer.h"
#include "spandsp/t38_gateway.h"
#include "spandsp/private/logging.h"
#include "spandsp/private/silence_gen.h"
#include "spandsp/private/fsk.h"
#include "spandsp/private/v17tx.h"
#include "spandsp/private/v17rx.h"
#include "spandsp/private/v27ter_tx.h"
#include "spandsp/private/v27ter_rx.h"
#include "spandsp/private/v29tx.h"
#include "spandsp/private/v29rx.h"
#include "spandsp/private/modem_connect_tones.h"
#include "spandsp/private/hdlc.h"
#include "spandsp/private/fax_modems.h"
#include "spandsp/private/t4_t6_decode.h"
#include "spandsp/private/t4_t6_encode.h"
#include "spandsp/private/t4_rx.h"
#include "spandsp/private/t4_tx.h"
#include "spandsp/private/t30.h"
#include "spandsp/private/t38_core.h"
#include "spandsp/private/t38_non_ecm_buffer.h"
#include "spandsp/private/t38_gateway.h"

Defines

#define DEFAULT_MS_PER_TX_CHUNK   30
#define HDLC_START_BUFFER_LEVEL   8
#define INDICATOR_TX_COUNT   3
#define DATA_TX_COUNT   1
#define DATA_END_TX_COUNT   3
#define MAX_NSX_SUPPRESSION   10
#define HDLC_FRAMING_OK_THRESHOLD   5

Enumerations

enum  {
  DISBIT1 = 0x01, DISBIT2 = 0x02, DISBIT3 = 0x04, DISBIT4 = 0x08,
  DISBIT5 = 0x10, DISBIT6 = 0x20, DISBIT7 = 0x40, DISBIT8 = 0x80
}
enum  { T38_NONE, T38_V27TER_RX, T38_V29_RX, T38_V17_RX }
enum  { HDLC_FLAG_FINISHED = 0x01, HDLC_FLAG_CORRUPT_CRC = 0x02, HDLC_FLAG_PROCEED_WITH_OUTPUT = 0x04, HDLC_FLAG_MISSING_DATA = 0x08 }
enum  { FLAG_INDICATOR = 0x100, FLAG_DATA = 0x200 }
enum  {
  TIMED_MODE_STARTUP = 0, TIMED_MODE_IDLE, TIMED_MODE_TCF_PREDICTABLE_MODEM_START_FAST_MODEM_ANNOUNCED, TIMED_MODE_TCF_PREDICTABLE_MODEM_START_FAST_MODEM_SEEN,
  TIMED_MODE_TCF_PREDICTABLE_MODEM_START_PAST_V21_MODEM, TIMED_MODE_TCF_PREDICTABLE_MODEM_START_BEGIN
}

Functions

 SPAN_DECLARE_NONSTD (int)
 Get the next bit of a transmitted serial bit stream.
void t38_gateway_get_transfer_statistics (t38_gateway_state_t *s, t38_stats_t *t)
 Get the current transfer statistics.
t38_core_state_tt38_gateway_get_t38_core_state (t38_gateway_state_t *s)
 Get a pointer to the T.38 core IFP packet engine associated with a T.38 context.
logging_state_tt38_gateway_get_logging_state (t38_gateway_state_t *s)
 Get a pointer to the logging context associated with a T.38 context.
void t38_gateway_set_ecm_capability (t38_gateway_state_t *s, int ecm_allowed)
 Control whether error correcting mode (ECM) is allowed.
void t38_gateway_set_transmit_on_idle (t38_gateway_state_t *s, int transmit_on_idle)
 Select whether silent audio will be sent when transmit is idle.
void t38_gateway_set_supported_modems (t38_gateway_state_t *s, int supported_modems)
 Specify supported modems.
void t38_gateway_set_nsx_suppression (t38_gateway_state_t *s, const uint8_t *from_t38, int from_t38_len, const uint8_t *from_modem, int from_modem_len)
 Select whether NSC, NSF, and NSS should be suppressed.
void t38_gateway_set_tep_mode (t38_gateway_state_t *s, int use_tep)
 Select whether TEP will be sent for the image modems.
void t38_gateway_set_fill_bit_removal (t38_gateway_state_t *s, int remove)
 Select whether non-ECM fill bits are to be removed during transmission.
void t38_gateway_set_real_time_frame_handler (t38_gateway_state_t *s, t38_gateway_real_time_frame_handler_t *handler, void *user_data)
 Set a callback function for T.30 frame exchange monitoring.
t38_gateway_state_tt38_gateway_init (t38_gateway_state_t *s, t38_tx_packet_handler_t *tx_packet_handler, void *tx_packet_user_data)
 Initialise a gateway mode T.38 context.
int t38_gateway_release (t38_gateway_state_t *s)
 Release a T.38 context.
int t38_gateway_free (t38_gateway_state_t *s)
 Free a T.38 context.

Detailed Description


Define Documentation

#define DATA_END_TX_COUNT   3

The number of transmissions of terminating data IFP packets

#define DATA_TX_COUNT   1

The number of transmissions of data IFP packets

#define DEFAULT_MS_PER_TX_CHUNK   30

The default number of milliseconds per transmitted IFP when sending bulk T.38 data

Referenced by t38_terminal_set_config().

#define HDLC_FRAMING_OK_THRESHOLD   5

The number of consecutive flags to declare HDLC framing is OK.

#define HDLC_START_BUFFER_LEVEL   8

The number of bytes which must be in the audio to T.38 HDLC buffer before we start outputting them as IFP messages.

#define INDICATOR_TX_COUNT   3

The number of transmissions of indicator IFP packets

#define MAX_NSX_SUPPRESSION   10

The maximum number of bytes to be zapped, in order to corrupt NSF, NSS and NSC messages, so the receiver does not recognise them.

Referenced by t38_gateway_set_nsx_suppression().


Function Documentation

SPAN_DECLARE_NONSTD ( int   ) 

Get the next bit of a transmitted serial bit stream.

Get the next bit of data from a T.38 rate adapting non-ECM buffer context.

Get a bit of received non-ECM image data.

Get the next bit of a transmitted serial bit stream.

Parameters:
user_data An opaque point which must point to a transmitter context.
Returns:
the next bit, or PUTBIT_END_OF_DATA to indicate the data stream has ended.

Get the next bit of a transmitted serial bit stream.

Process a block of received V.8 audio samples.

Fake processing of a missing block of received V.29 modem audio samples.

Fake processing of a missing block of received V.27ter modem audio samples.

Generate a block of V.22bis modem audio samples.

Fake processing of a missing block of received V.22bis modem audio samples.

Process a block of received V.18 audio samples.

Fake processing of a missing block of received V.17 modem audio samples.

Generate a block of FAX audio samples.

Apply fake received audio processing.

Generate a block of T.31 modem audio samples.

Fake processing of a missing block of received T.31 modem audio samples.

Dummy receive fillin callback.

Dummy receive callback.

Process a block of samples through an instance of the modem connect tones detector.

Get the next sequence of bytes for transmission.

Get the next byte for transmission.

Fake processing of a missing block of received FSK modem audio samples.

Process a block of received FSK modem audio samples.

Apply T.30 transmit processing to generate a block of audio samples.

Apply fake T.30 receive processing when a block of audio samples is missing (e.g due to packet loss).

Parameters:
s The FAX context.
len The number of samples to fake.
Returns:
The number of samples unprocessed. This should only be non-zero if the software has reached the end of the FAX call.

Apply T.30 transmit processing to generate a block of audio samples.

Parameters:
s The FAX context.
amp The audio sample buffer.
max_len The number of samples to be generated.
Returns:
The number of samples actually generated. This will be zero when there is nothing to send.

Process a block of received FSK modem audio samples.

Parameters:
s The modem context.
amp The audio sample buffer.
len The number of samples in the buffer.
Returns:
The number of samples unprocessed.

Fake processing of a missing block of received FSK modem audio samples (e.g due to packet loss).

Parameters:
s The modem context.
len The number of samples to fake.
Returns:
The number of samples unprocessed.
Parameters:
s A pointer to an HDLC transmitter context.
Returns:
The next byte for transmission.
Parameters:
s A pointer to an HDLC transmitter context.
buf The buffer for the data.
max_len The number of bytes to get.
Returns:
The number of bytes actually got.
Parameters:
s The context.
amp An array of signal samples.
len The number of samples in the array.
Returns:
The number of unprocessed samples.

A dummy routine to use as a receive callback, when we aren't really trying to process what is received. It just absorbs and ignores the data.

Parameters:
user_data The context.
amp The signal.buffer
len The length of the signal buffer
Returns:
0.

A dummy routine to use as a receive fillin callback, when we aren't really trying to process what is received. It just absorbs and ignores the request.

Parameters:
user_data The context.
len The length of the signal buffer
Returns:
0.

Fake processing of a missing block of received T.31 modem audio samples (e.g due to packet loss).

Parameters:
s The T.31 modem context.
len The number of samples to fake.
Returns:
The number of samples unprocessed.

Generate a block of T.31 modem audio samples.

Parameters:
s The T.31 modem context.
amp The audio sample buffer.
max_len The number of samples to be generated.
Returns:
The number of samples actually generated.

Apply fake processing when a block of audio samples is missing (e.g due to packet loss).

Parameters:
s The T.38 context.
len The number of samples to fake.
Returns:
The number of samples unprocessed. This should only be non-zero if the software has reached the end of the FAX call.

Generate a block of FAX audio samples.

Parameters:
s The T.38 context.
amp The audio sample buffer.
max_len The number of samples to be generated.
Returns:
The number of samples actually generated.

Fake processing of a missing block of received V.17 modem audio samples. (e.g due to packet loss).

Parameters:
s The modem context.
len The number of samples to fake.
Returns:
The number of samples unprocessed.

Process a block of received V.18 audio samples.

Parameters:
s The V.18 context.
amp The audio sample buffer.
len The number of samples in the buffer.

Fake processing of a missing block of received V.22bis modem audio samples. (e.g due to packet loss).

Parameters:
s The modem context.
len The number of samples to fake.
Returns:
The number of samples unprocessed.

Generate a block of V.22bis modem audio samples.

Parameters:
s The modem context.
amp The audio sample buffer.
len The number of samples to be generated.
Returns:
The number of samples actually generated.

Fake processing of a missing block of received V.27ter modem audio samples. (e.g due to packet loss).

Parameters:
s The modem context.
len The number of samples to fake.
Returns:
The number of samples unprocessed.

Fake processing of a missing block of received V.29 modem audio samples. (e.g due to packet loss).

Parameters:
s The modem context.
len The number of samples to fake.
Returns:
The number of samples unprocessed.

Process a block of received V.8 audio samples.

Parameters:
s The V.8 context.
amp The audio sample buffer.
len The number of samples in the buffer.

Get the next bit of a transmitted serial bit stream.

Apply T.30 transmit processing to generate a block of audio samples.

Apply fake T.30 receive processing.

Apply T.30 receive processing to a block of audio samples.

Parameters:
s The FAX context.
amp The audio sample buffer.
len The number of samples in the buffer.
Returns:
The number of samples unprocessed. This should only be non-zero if the software has reached the end of the FAX call.

Apply fake T.30 receive processing when a block of audio samples is missing (e.g due to packet loss).

Parameters:
s The FAX context.
len The number of samples to fake.
Returns:
The number of samples unprocessed. This should only be non-zero if the software has reached the end of the FAX call.

Apply T.30 transmit processing to generate a block of audio samples.

Parameters:
s The FAX context.
amp The audio sample buffer.
max_len The number of samples to be generated.
Returns:
The number of samples actually generated. This will be zero when there is nothing to send.

Get the next bit of a transmitted serial bit stream.

Fake processing of a missing block of received FSK modem audio samples.

Process a block of received FSK modem audio samples.

Generate a block of FSK modem audio samples.

Parameters:
s The modem context.
amp The audio sample buffer.
len The number of samples to be generated.
Returns:
The number of samples actually generated.

Process a block of received FSK modem audio samples.

Parameters:
s The modem context.
amp The audio sample buffer.
len The number of samples in the buffer.
Returns:
The number of samples unprocessed.

Fake processing of a missing block of received FSK modem audio samples (e.g due to packet loss).

Parameters:
s The modem context.
len The number of samples to fake.
Returns:
The number of samples unprocessed.

Get the next bit of a transmitted serial bit stream.

Get the next sequence of bytes for transmission.

Get the next byte for transmission.

Parameters:
s A pointer to an HDLC transmitter context.
Returns:
The next bit for transmission.
Parameters:
s A pointer to an HDLC transmitter context.
Returns:
The next byte for transmission.
Parameters:
s A pointer to an HDLC transmitter context.
buf The buffer for the data.
max_len The number of bytes to get.
Returns:
The number of bytes actually got.

Get the next bit of a transmitted serial bit stream.

Process a block of samples through an instance of the modem connect tones detector.

Parameters:
s The context.
amp An array of signal samples.
len The number of samples to generate.
Returns:
The number of samples generated.
Parameters:
s The context.
amp An array of signal samples.
len The number of samples in the array.
Returns:
The number of unprocessed samples.

Get the next bit of a transmitted serial bit stream.

Dummy receive fillin callback.

Dummy receive callback.

Generate a block of silent audio samples.

Parameters:
s The silence generator context.
amp The audio sample buffer.
max_len The number of samples to be generated.
Returns:
The number of samples actually generated. This will be zero when there is nothing to send.

A dummy routine to use as a receive callback, when we aren't really trying to process what is received. It just absorbs and ignores the data.

Parameters:
user_data The context.
amp The signal.buffer
len The length of the signal buffer
Returns:
0.

A dummy routine to use as a receive fillin callback, when we aren't really trying to process what is received. It just absorbs and ignores the request.

Parameters:
user_data The context.
len The length of the signal buffer
Returns:
0.

Get the next bit of a transmitted serial bit stream.

Generate a block of T.31 modem audio samples.

Fake processing of a missing block of received T.31 modem audio samples.

Process a block of received T.31 modem audio samples.

Parameters:
s The T.31 modem context.
amp The audio sample buffer.
len The number of samples in the buffer.
Returns:
The number of samples unprocessed.

Fake processing of a missing block of received T.31 modem audio samples (e.g due to packet loss).

Parameters:
s The T.31 modem context.
len The number of samples to fake.
Returns:
The number of samples unprocessed.

Generate a block of T.31 modem audio samples.

Parameters:
s The T.31 modem context.
amp The audio sample buffer.
max_len The number of samples to be generated.
Returns:
The number of samples actually generated.

Get the next bit of a transmitted serial bit stream.

Generate a block of FAX audio samples.

Apply fake received audio processing.

Process a block of received FAX audio samples.

Parameters:
s The T.38 context.
amp The audio sample buffer.
len The number of samples in the buffer.
Returns:
The number of samples unprocessed.

Apply fake processing when a block of audio samples is missing (e.g due to packet loss).

Parameters:
s The T.38 context.
len The number of samples to fake.
Returns:
The number of samples unprocessed. This should only be non-zero if the software has reached the end of the FAX call.

Generate a block of FAX audio samples.

Parameters:
s The T.38 context.
amp The audio sample buffer.
max_len The number of samples to be generated.
Returns:
The number of samples actually generated.

Get the next bit of a transmitted serial bit stream.

Fake processing of a missing block of received V.17 modem audio samples.

Process a block of received V.17 modem audio samples.

Parameters:
s The modem context.
amp The audio sample buffer.
len The number of samples in the buffer.
Returns:
The number of samples unprocessed.

Fake processing of a missing block of received V.17 modem audio samples. (e.g due to packet loss).

Parameters:
s The modem context.
len The number of samples to fake.
Returns:
The number of samples unprocessed.

Get the next bit of a transmitted serial bit stream.

Generate a block of V.17 modem audio samples.

Parameters:
s The modem context.
amp The audio sample buffer.
len The number of samples to be generated.
Returns:
The number of samples actually generated.

Get the next bit of a transmitted serial bit stream.

Process a block of received V.18 audio samples.

Generate a block of V.18 audio samples.

Parameters:
s The V.18 context.
amp The audio sample buffer.
max_len The number of samples to be generated.
Returns:
The number of samples actually generated.

Process a block of received V.18 audio samples.

Parameters:
s The V.18 context.
amp The audio sample buffer.
len The number of samples in the buffer.

Get the next bit of a transmitted serial bit stream.

Generate a block of V.22bis modem audio samples.

Fake processing of a missing block of received V.22bis modem audio samples.

Process a block of received V.22bis modem audio samples.

Parameters:
s The modem context.
amp The audio sample buffer.
len The number of samples in the buffer.
Returns:
The number of samples unprocessed.

Fake processing of a missing block of received V.22bis modem audio samples. (e.g due to packet loss).

Parameters:
s The modem context.
len The number of samples to fake.
Returns:
The number of samples unprocessed.

Generate a block of V.22bis modem audio samples.

Parameters:
s The modem context.
amp The audio sample buffer.
len The number of samples to be generated.
Returns:
The number of samples actually generated.

Get the next bit of a transmitted serial bit stream.

Fake processing of a missing block of received V.27ter modem audio samples.

Process a block of received V.27ter modem audio samples.

Parameters:
s The modem context.
amp The audio sample buffer.
len The number of samples in the buffer.
Returns:
The number of samples unprocessed.

Fake processing of a missing block of received V.27ter modem audio samples. (e.g due to packet loss).

Parameters:
s The modem context.
len The number of samples to fake.
Returns:
The number of samples unprocessed.

Get the next bit of a transmitted serial bit stream.

Generate a block of V.27ter modem audio samples.

Parameters:
s The modem context.
amp The audio sample buffer.
len The number of samples to be generated.
Returns:
The number of samples actually generated.

Get the next bit of a transmitted serial bit stream.

Fake processing of a missing block of received V.29 modem audio samples.

Process a block of received V.29 modem audio samples.

Parameters:
s The modem context.
amp The audio sample buffer.
len The number of samples in the buffer.
Returns:
The number of samples unprocessed.

Fake processing of a missing block of received V.29 modem audio samples. (e.g due to packet loss).

Parameters:
s The modem context.
len The number of samples to fake.
Returns:
The number of samples unprocessed.

Get the next bit of a transmitted serial bit stream.

Generate a block of V.29 modem audio samples.

Parameters:
s The modem context.
amp The audio sample buffer.
len The number of samples to be generated.
Returns:
The number of samples actually generated.

Get the next bit of a transmitted serial bit stream.

Process a block of received V.8 audio samples.

Generate a block of V.8 audio samples.

Parameters:
s The V.8 context.
amp The audio sample buffer.
max_len The number of samples to be generated.
Returns:
The number of samples actually generated.

Process a block of received V.8 audio samples.

Parameters:
s The V.8 context.
amp The audio sample buffer.
len The number of samples in the buffer.

References silence_gen_set().

int t38_gateway_free ( t38_gateway_state_t s  ) 

Free a T.38 context.

Free a gateway mode T.38 context.

Parameters:
s The T.38 context.
Returns:
0 for OK, else -1.
logging_state_t* t38_gateway_get_logging_state ( t38_gateway_state_t s  ) 

Get a pointer to the logging context associated with a T.38 context.

Get a pointer to the logging context associated with a T.38 context.

Parameters:
s The T.38 context.
Returns:
A pointer to the logging context, or NULL.
t38_core_state_t* t38_gateway_get_t38_core_state ( t38_gateway_state_t s  ) 

Get a pointer to the T.38 core IFP packet engine associated with a T.38 context.

Get a pointer to the T.38 core IFP packet engine associated with a gateway mode T.38 context.

Parameters:
s The T.38 context.
Returns:
A pointer to the T.38 core context, or NULL.
void t38_gateway_get_transfer_statistics ( t38_gateway_state_t s,
t38_stats_t t 
)

Get the current transfer statistics.

Get the current transfer statistics for the current T.38 session.

Parameters:
s The T.38 context.
t A pointer to a buffer for the statistics.
t38_gateway_state_t* t38_gateway_init ( t38_gateway_state_t s,
t38_tx_packet_handler_t *  tx_packet_handler,
void *  tx_packet_user_data 
)

Initialise a gateway mode T.38 context.

Parameters:
s The T.38 context.
tx_packet_handler A callback routine to encapsulate and transmit T.38 packets.
tx_packet_user_data An opaque pointer passed to the tx_packet_handler routine.
Returns:
A pointer to the termination mode T.38 context, or NULL if there was a problem.

References T30_SUPPORT_V17, T30_SUPPORT_V27TER, T30_SUPPORT_V29, t38_gateway_set_nsx_suppression(), t38_gateway_set_supported_modems(), and t38_non_ecm_buffer_init().

int t38_gateway_release ( t38_gateway_state_t s  ) 

Release a T.38 context.

Release a gateway mode T.38 context.

Parameters:
s The T.38 context.
Returns:
0 for OK, else -1.
void t38_gateway_set_ecm_capability ( t38_gateway_state_t s,
int  ecm_allowed 
)

Control whether error correcting mode (ECM) is allowed.

Control whether error correcting mode (ECM) is allowed.

Parameters:
s The T.38 context.
ecm_allowed TRUE is ECM is to be allowed.
void t38_gateway_set_fill_bit_removal ( t38_gateway_state_t s,
int  remove 
)

Select whether non-ECM fill bits are to be removed during transmission.

Select whether non-ECM fill bits are to be removed during transmission.

Parameters:
s The T.38 context.
remove TRUE if fill bits are to be removed.
void t38_gateway_set_nsx_suppression ( t38_gateway_state_t s,
const uint8_t *  from_t38,
int  from_t38_len,
const uint8_t *  from_modem,
int  from_modem_len 
)

Select whether NSC, NSF, and NSS should be suppressed.

Select whether NSC, NSF, and NSS should be suppressed. It selected, the contents of these messages are forced to zero for all octets beyond the message type. This makes them look like manufacturer specific messages, from a manufacturer which does not exist.

Parameters:
s The T.38 context.
from_t38 A string of bytes to overwrite the header of any NSC, NSF, and NSS frames passing through the gateway from T.38 the the modem.
from_t38_len The length of the overwrite string.
from_modem A string of bytes to overwrite the header of any NSC, NSF, and NSS frames passing through the gateway from the modem to T.38.
from_modem_len The length of the overwrite string.

References MAX_NSX_SUPPRESSION.

Referenced by t38_gateway_init().

void t38_gateway_set_real_time_frame_handler ( t38_gateway_state_t s,
t38_gateway_real_time_frame_handler_t handler,
void *  user_data 
)

Set a callback function for T.30 frame exchange monitoring.

Set a callback function for T.30 frame exchange monitoring. This is called from the heart of the signal processing, so don't take too long in the handler routine.

Parameters:
s The T.30 context.
handler The callback function.
user_data An opaque pointer passed to the callback function.
void t38_gateway_set_supported_modems ( t38_gateway_state_t s,
int  supported_modems 
)

Specify supported modems.

Specify which modem types are supported by a T.30 context.

Parameters:
s The T.38 context.
supported_modems Bit field list of the supported modems.

References T30_SUPPORT_V17, and T30_SUPPORT_V29.

Referenced by t38_gateway_init().

void t38_gateway_set_tep_mode ( t38_gateway_state_t s,
int  use_tep 
)

Select whether TEP will be sent for the image modems.

Select whether talker echo protection tone will be sent for the image modems.

Parameters:
s The T.38 context.
use_tep TRUE if TEP should be sent.
void t38_gateway_set_transmit_on_idle ( t38_gateway_state_t s,
int  transmit_on_idle 
)

Select whether silent audio will be sent when transmit is idle.

Select whether silent audio will be sent when transmit is idle.

Parameters:
s The T.38 context.
transmit_on_idle TRUE if silent audio should be output when the FAX transmitter is idle. FALSE to transmit zero length audio when the FAX transmitter is idle. The default behaviour is FALSE.

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