00001 /* 00002 * SpanDSP - a series of DSP components for telephony 00003 * 00004 * fax.h - definitions for analogue line ITU T.30 fax processing 00005 * 00006 * Written by Steve Underwood <steveu@coppice.org> 00007 * 00008 * Copyright (C) 2005 Steve Underwood 00009 * 00010 * All rights reserved. 00011 * 00012 * This program is free software; you can redistribute it and/or modify 00013 * it under the terms of the GNU General Public License version 2, as 00014 * published by the Free Software Foundation. 00015 * 00016 * This program is distributed in the hope that it will be useful, 00017 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00018 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00019 * GNU General Public License for more details. 00020 * 00021 * You should have received a copy of the GNU General Public License 00022 * along with this program; if not, write to the Free Software 00023 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 00024 * 00025 * $Id: fax.h,v 1.24 2007/05/15 13:22:43 steveu Exp $ 00026 */ 00027 00028 /*! \file */ 00029 00030 #if !defined(_SPANDSP_FAX_H_) 00031 #define _SPANDSP_FAX_H_ 00032 00033 /*! \page fax_page FAX over analogue modem handling 00034 00035 \section fax_page_sec_1 What does it do? 00036 00037 \section fax_page_sec_2 How does it work? 00038 */ 00039 00040 typedef struct fax_state_s fax_state_t; 00041 00042 typedef void (fax_flush_handler_t)(fax_state_t *s, void *user_data, int which); 00043 00044 /*! 00045 Analogue line T.30 FAX channel descriptor. This defines the state of a single working 00046 instance of an analogue line soft-FAX machine. 00047 */ 00048 struct fax_state_s 00049 { 00050 /* This must be kept the first thing in the structure, so it can be pointed 00051 to reliably as the structures change over time. */ 00052 t30_state_t t30_state; 00053 00054 /*! TRUE is talker echo protection should be sent for the image modems */ 00055 int use_tep; 00056 00057 fax_flush_handler_t *flush_handler; 00058 void *flush_user_data; 00059 00060 /*! The current receive signal handler */ 00061 span_rx_handler_t *rx_handler; 00062 void *rx_user_data; 00063 00064 /*! The current transmit signal handler */ 00065 span_tx_handler_t *tx_handler; 00066 void *tx_user_data; 00067 int tx_hdlc_preamble_len; 00068 /*! The transmit signal handler to be used when the current one has finished sending. */ 00069 span_tx_handler_t *next_tx_handler; 00070 void *next_tx_user_data; 00071 00072 /*! If TRUE, transmission is in progress */ 00073 int transmit; 00074 00075 /*! If TRUE, transmit silence when there is nothing else to transmit. If FALSE return only 00076 the actual generated audio. Note that this only affects untimed silences. Timed silences 00077 (e.g. the 75ms silence between V.21 and a high speed modem) will alway be transmitted as 00078 silent audio. */ 00079 int transmit_on_idle; 00080 00081 /*! \brief A tone generator context used to generate supervisory tones during 00082 FAX handling. */ 00083 tone_gen_state_t tone_gen; 00084 /*! \brief An HDLC context used when receiving HDLC over V.21 messages. */ 00085 hdlc_rx_state_t hdlcrx; 00086 /*! \brief An HDLC context used when transmitting HDLC over V.21 messages. */ 00087 hdlc_tx_state_t hdlctx; 00088 /*! \brief A V.21 FSK modem context used when transmitting HDLC over V.21 00089 messages. */ 00090 fsk_tx_state_t v21tx; 00091 /*! \brief A V.21 FSK modem context used when receiving HDLC over V.21 00092 messages. */ 00093 fsk_rx_state_t v21rx; 00094 /*! \brief A V.17 modem context used when sending FAXes at 7200bps, 9600bps 00095 12000bps or 14400bps*/ 00096 v17_tx_state_t v17tx; 00097 /*! \brief A V.29 modem context used when receiving FAXes at 7200bps, 9600bps 00098 12000bps or 14400bps*/ 00099 v17_rx_state_t v17rx; 00100 /*! \brief A V.27ter modem context used when sending FAXes at 2400bps or 00101 4800bps */ 00102 v27ter_tx_state_t v27ter_tx; 00103 /*! \brief A V.27ter modem context used when receiving FAXes at 2400bps or 00104 4800bps */ 00105 v27ter_rx_state_t v27ter_rx; 00106 /*! \brief A V.29 modem context used when sending FAXes at 7200bps or 00107 9600bps */ 00108 v29_tx_state_t v29tx; 00109 /*! \brief A V.29 modem context used when receiving FAXes at 7200bps or 00110 9600bps */ 00111 v29_rx_state_t v29rx; 00112 /*! \brief Used to insert timed silences. */ 00113 silence_gen_state_t silence_gen; 00114 /*! \brief */ 00115 dc_restore_state_t dc_restore; 00116 00117 /*! \brief TRUE is the short training sequence should be used. */ 00118 int short_train; 00119 00120 /*! The currently select receiver type */ 00121 int current_rx_type; 00122 /*! The currently select transmitter type */ 00123 int current_tx_type; 00124 00125 int first_tx_hdlc_frame; 00126 00127 /*! Audio logging file handles */ 00128 int fax_audio_rx_log; 00129 int fax_audio_tx_log; 00130 /*! \brief Error and flow logging control */ 00131 logging_state_t logging; 00132 }; 00133 00134 #if defined(__cplusplus) 00135 extern "C" 00136 { 00137 #endif 00138 00139 /*! Apply T.30 receive processing to a block of audio samples. 00140 \brief Apply T.30 receive processing to a block of audio samples. 00141 \param s The FAX context. 00142 \param amp The audio sample buffer. 00143 \param len The number of samples in the buffer. 00144 \return The number of samples unprocessed. This should only be non-zero if 00145 the software has reached the end of the FAX call. 00146 */ 00147 int fax_rx(fax_state_t *s, int16_t *amp, int len); 00148 00149 /*! Apply T.30 transmit processing to generate a block of audio samples. 00150 \brief Apply T.30 transmit processing to generate a block of audio samples. 00151 \param s The FAX context. 00152 \param amp The audio sample buffer. 00153 \param max_len The number of samples to be generated. 00154 \return The number of samples actually generated. This will be zero when 00155 there is nothing to send. 00156 */ 00157 int fax_tx(fax_state_t *s, int16_t *amp, int max_len); 00158 00159 void fax_set_flush_handler(fax_state_t *s, fax_flush_handler_t *handler, void *user_data); 00160 00161 /*! Select whether silent audio will be sent when FAX transmit is idle. 00162 \brief Select whether silent audio will be sent when FAX transmit is idle. 00163 \param s The FAX context. 00164 \param transmit_on_idle TRUE if silent audio should be output when the FAX transmitter is 00165 idle. FALSE to transmit zero length audio when the FAX transmitter is idle. The default 00166 behaviour is FALSE. 00167 */ 00168 void fax_set_transmit_on_idle(fax_state_t *s, int transmit_on_idle); 00169 00170 /*! Select whether talker echo protection tone will be sent for the image modems. 00171 \brief Select whether TEP will be sent for the image modems. 00172 \param s The FAX context. 00173 \param use_tep TRUE if TEP should be sent. 00174 */ 00175 void fax_set_tep_mode(fax_state_t *s, int use_tep); 00176 00177 /*! Initialise a FAX context. 00178 \brief Initialise a FAX context. 00179 \param s The FAX context. 00180 \param calling_party TRUE if the context is for a calling party. FALSE if the 00181 context is for an answering party. 00182 \return A pointer to the FAX context, or NULL if there was a problem. 00183 */ 00184 fax_state_t *fax_init(fax_state_t *s, int calling_party); 00185 00186 /*! Release a FAX context. 00187 \brief Release a FAX context. 00188 \param s The FAX context. */ 00189 int fax_release(fax_state_t *s); 00190 00191 #if defined(__cplusplus) 00192 } 00193 #endif 00194 00195 #endif 00196 /*- End of file ------------------------------------------------------------*/