Mercurial > hg > audiostuff

comparison spandsp-0.0.3/spandsp-0.0.3/src/spandsp/t38_gateway.h @ 5:f762bf195c4b

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
import spandsp-0.0.3
author Peter Meerwald <pmeerw@cosy.sbg.ac.at>
date Fri, 25 Jun 2010 16:00:21 +0200
parents
children
comparison
equal deleted inserted replaced
4:26cd8f1ef0b1 5:f762bf195c4b
1 /*
2 * SpanDSP - a series of DSP components for telephony
3 *
4 * t38_gateway.h - An implementation of T.38, less the packet exchange part
5 *
6 * Written by Steve Underwood <steveu@coppice.org>
7 *
8 * Copyright (C) 2005 Steve Underwood
9 *
10 * All rights reserved.
11 *
12 * This program is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU General Public License version 2, as
14 * published by the Free Software Foundation.
15 *
16 * This program is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 * GNU General Public License for more details.
20 *
21 * You should have received a copy of the GNU General Public License
22 * along with this program; if not, write to the Free Software
23 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24 *
25 * $Id: t38_gateway.h,v 1.17 2006/12/07 13:22:26 steveu Exp $
26 */
27
28 /*! \file */
29
30 #if !defined(_T38_GATEWAY_H_)
31 #define _T38_GATEWAY_H_
32
33 /*! \page t38_gateway_page T.38 real time FAX over IP PSTN gateway
34 \section t38_gateway_page_sec_1 What does it do?
35
36 The T.38 gateway facility provides a robust interface between T.38 IP packet streams and
37 and 8k samples/second audio streams. It provides the buffering and flow control features needed
38 to maximum the tolerance of jitter and packet loss on the IP network.
39
40 \section t38_gateway_page_sec_2 How does it work?
41 */
42
43 #define T38_RX_BUF_LEN 2048
44 #define T38_TX_BUF_LEN 16384
45
46 #define T38_TX_HDLC_BUFS 256
47
48 /* Make sure the HDLC frame buffers are big enough for ECM frames. */
49 #define T38_MAX_HDLC_LEN 260
50
51 typedef struct
52 {
53 t38_core_state_t t38;
54
55 int ecm_allowed;
56
57 /*! \brief HDLC message buffers. */
58 uint8_t hdlc_buf[T38_TX_HDLC_BUFS][T38_MAX_HDLC_LEN];
59 /*! \brief HDLC message lengths. */
60 int hdlc_len[T38_TX_HDLC_BUFS];
61 /*! \brief HDLC message status flags. */
62 int hdlc_flags[T38_TX_HDLC_BUFS];
63 /*! \brief HDLC buffer contents. */
64 int hdlc_contents[T38_TX_HDLC_BUFS];
65 /*! \brief HDLC buffer number for input. */
66 int hdlc_in;
67 /*! \brief HDLC buffer number for output. */
68 int hdlc_out;
69
70 /*! \brief Progressively calculated CRC for HDLC messaging received from a modem. */
71 uint16_t crc;
72
73 /*! \brief non-ECM modem receive data buffer */
74 uint8_t rx_data[T38_RX_BUF_LEN];
75 int rx_data_ptr;
76
77 /*! \brief non-ECM modem transmit data buffer */
78 uint8_t non_ecm_tx_data[T38_TX_BUF_LEN];
79 int non_ecm_tx_in_ptr;
80 int non_ecm_tx_out_ptr;
81
82 /*! \brief The location of the most recent EOL marker in the non-ECM data buffer */
83 int non_ecm_tx_latest_eol_ptr;
84 unsigned int bit_stream;
85 /*! \brief The non-ECM flow control fill octet (0xFF before the first data, and 0x00
86 once data has started). */
87 uint8_t non_ecm_flow_control_fill_octet;
88 /*! \brief TRUE if we are in the initial all ones part of non-ECM transmission. */
89 int non_ecm_at_initial_all_ones;
90 /*! \brief TRUE is the end of non-ECM data indication has been received. */
91 int non_ecm_data_finished;
92 /*! \brief The current octet being sent as non-ECM data. */
93 int current_non_ecm_octet;
94 /*! \brief The current bit number in the current non-ECM octet. */
95 int non_ecm_bit_no;
96 /*! \brief A count of the number of non-ECM fill octets generated for flow control control
97 purposes. */
98 int non_ecm_flow_control_fill_octets;
99
100 int current_rx_data_type;
101 int current_rx_field_type;
102 int current_rx_field_class;
103 int in_progress_rx_indicator;
104
105 /*! \brief The current T.38 data type being sent. */
106 int current_tx_data_type;
107
108 /*! \brief TRUE if we are in error correcting (ECM) mode */
109 int ecm_mode;
110 /*! \brief The current bit rate for the fast modem. */
111 int fast_bit_rate;
112 /*! \brief The current fast modem type. */
113 int fast_modem;
114 /*! \brief Use talker echo protection when transmitting. */
115 int use_tep;
116 /*! \brief TRUE if a carrier is present. Otherwise FALSE. */
117 int rx_signal_present;
118 /*! \brief TRUE if a modem has trained correctly. */
119 int rx_trained;
120
121 /*! \brief A tone generator context used to generate supervisory tones during
122 FAX handling. */
123 tone_gen_state_t tone_gen;
124 /*! \brief An HDLC context used when receiving HDLC messages. */
125 hdlc_rx_state_t hdlcrx;
126
127 /*! \brief HDLC data used when transmitting HDLC messages. */
128 hdlc_tx_state_t hdlctx;
129
130 /*! \brief A V.21 FSK modem context used when transmitting HDLC over V.21
131 messages. */
132 fsk_tx_state_t v21tx;
133 /*! \brief A V.21 FSK modem context used when receiving HDLC over V.21
134 messages. */
135 fsk_rx_state_t v21rx;
136
137 #if defined(ENABLE_V17)
138 /*! \brief A V.17 modem context used when sending FAXes at 7200bps, 9600bps
139 12000bps or 14400bps*/
140 v17_tx_state_t v17tx;
141 /*! \brief A V.29 modem context used when receiving FAXes at 7200bps, 9600bps
142 12000bps or 14400bps*/
143 v17_rx_state_t v17rx;
144 #endif
145
146 /*! \brief A V.29 modem context used when sending FAXes at 7200bps or
147 9600bps */
148 v29_tx_state_t v29tx;
149 /*! \brief A V.29 modem context used when receiving FAXes at 7200bps or
150 9600bps */
151 v29_rx_state_t v29rx;
152
153 /*! \brief A V.27ter modem context used when sending FAXes at 2400bps or
154 4800bps */
155 v27ter_tx_state_t v27ter_tx;
156 /*! \brief A V.27ter modem context used when receiving FAXes at 2400bps or
157 4800bps */
158 v27ter_rx_state_t v27ter_rx;
159
160 /*! \brief Used to insert timed silences. */
161 silence_gen_state_t silence_gen;
162
163 /*! The current receive signal handler */
164 span_rx_handler_t *rx_handler;
165 void *rx_user_data;
166
167 /*! The current transmit signal handler */
168 span_tx_handler_t *tx_handler;
169 void *tx_user_data;
170 /*! The transmit signal handler to be used when the current one has finished sending. */
171 span_tx_handler_t *next_tx_handler;
172 void *next_tx_user_data;
173
174 /*! The number of octets to send in each image packet (non-ECM or ECM) at the current
175 rate and the current specified packet interval. */
176 int octets_per_data_packet;
177
178 int v21_rx_active;
179 int fast_rx_active;
180 int samples_since_last_tx_packet;
181 int octets_since_last_tx_packet;
182 int short_train;
183
184 /*! \brief TRUE if we need to corrupt the HDLC frame in progress, so the receiver cannot
185 interpret it. */
186 int corrupt_the_frame;
187
188 int current_rx_type;
189 int current_tx_type;
190
191 logging_state_t logging;
192 } t38_gateway_state_t;
193
194 #ifdef __cplusplus
195 extern "C" {
196 #endif
197
198 /*! \brief Initialise a gateway mode T.38 context.
199 \param s The T.38 context.
200 \param tx_packet_handler A callback routine to encapsulate and transmit T.38 packets.
201 \param tx_packet_user_data An opaque pointer passed to the tx_packet_handler routine.
202 \return A pointer to the termination mode T.38 context, or NULL if there was a problem. */
203 t38_gateway_state_t *t38_gateway_init(t38_gateway_state_t *s,
204 t38_tx_packet_handler_t *tx_packet_handler,
205 void *tx_packet_user_data);
206
207 /*! Process a block of received FAX audio samples.
208 \brief Process a block of received FAX audio samples.
209 \param s The T.38 context.
210 \param amp The audio sample buffer.
211 \param len The number of samples in the buffer.
212 \return The number of samples unprocessed. */
213 int t38_gateway_rx(t38_gateway_state_t *s, const int16_t *amp, int len);
214
215 /*! Generate a block of FAX audio samples.
216 \brief Generate a block of FAX audio samples.
217 \param s The T.38 context.
218 \param amp The audio sample buffer.
219 \param max_len The number of samples to be generated.
220 \return The number of samples actually generated.
221 */
222 int t38_gateway_tx(t38_gateway_state_t *s, int16_t *amp, int max_len);
223
224 /*! Control whether error correcting mode (ECM) is allowed.
225 \brief Control whether error correcting mode (ECM) is allowed.
226 \param s The T.38 context.
227 \param ecm_allowed TRUE is ECM is to be allowed.
228 */
229 void t38_gateway_ecm_control(t38_gateway_state_t *s, int ecm_allowed);
230
231 #ifdef __cplusplus
232 }
233 #endif
234
235 #endif
236 /*- End of file ------------------------------------------------------------*/

Repositories maintained by Peter Meerwald, pmeerw@pmeerw.net.