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comparison spandsp-0.0.6pre17/src/spandsp/fax.h @ 4:26cd8f1ef0b1

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import spandsp-0.0.6pre17
author Peter Meerwald <pmeerw@cosy.sbg.ac.at>
date Fri, 25 Jun 2010 15:50:58 +0200
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3:c6c5a16ce2f2 4:26cd8f1ef0b1
1 /*
2 * SpanDSP - a series of DSP components for telephony
3 *
4 * fax.h - definitions for analogue line ITU T.30 fax processing
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 Lesser General Public License version 2.1,
14 * as 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 Lesser General Public License for more details.
20 *
21 * You should have received a copy of the GNU Lesser General Public
22 * License along with this program; if not, write to the Free Software
23 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24 *
25 * $Id: fax.h,v 1.39 2009/03/13 12:59:26 steveu Exp $
26 */
27
28 /*! \file */
29
30 #if !defined(_SPANDSP_FAX_H_)
31 #define _SPANDSP_FAX_H_
32
33 /*! \page fax_page FAX over analogue modem handling
34
35 \section fax_page_sec_1 What does it do?
36
37 \section fax_page_sec_2 How does it work?
38 */
39
40 typedef struct fax_state_s fax_state_t;
41
42 #if defined(__cplusplus)
43 extern "C"
44 {
45 #endif
46
47 /*! Apply T.30 receive processing to a block of audio samples.
48 \brief Apply T.30 receive processing to a block of audio samples.
49 \param s The FAX context.
50 \param amp The audio sample buffer.
51 \param len The number of samples in the buffer.
52 \return The number of samples unprocessed. This should only be non-zero if
53 the software has reached the end of the FAX call.
54 */
55 SPAN_DECLARE(int) fax_rx(fax_state_t *s, int16_t *amp, int len);
56
57 /*! Apply fake T.30 receive processing when a block of audio samples is missing (e.g due
58 to packet loss).
59 \brief Apply fake T.30 receive processing.
60 \param s The FAX context.
61 \param len The number of samples to fake.
62 \return The number of samples unprocessed. This should only be non-zero if
63 the software has reached the end of the FAX call.
64 */
65 SPAN_DECLARE(int) fax_rx_fillin(fax_state_t *s, int len);
66
67 /*! Apply T.30 transmit processing to generate a block of audio samples.
68 \brief Apply T.30 transmit processing to generate a block of audio samples.
69 \param s The FAX context.
70 \param amp The audio sample buffer.
71 \param max_len The number of samples to be generated.
72 \return The number of samples actually generated. This will be zero when
73 there is nothing to send.
74 */
75 SPAN_DECLARE(int) fax_tx(fax_state_t *s, int16_t *amp, int max_len);
76
77 /*! Select whether silent audio will be sent when FAX transmit is idle.
78 \brief Select whether silent audio will be sent when FAX transmit is idle.
79 \param s The FAX context.
80 \param transmit_on_idle TRUE if silent audio should be output when the FAX transmitter is
81 idle. FALSE to transmit zero length audio when the FAX transmitter is idle. The default
82 behaviour is FALSE.
83 */
84 SPAN_DECLARE(void) fax_set_transmit_on_idle(fax_state_t *s, int transmit_on_idle);
85
86 /*! Select whether talker echo protection tone will be sent for the image modems.
87 \brief Select whether TEP will be sent for the image modems.
88 \param s The FAX context.
89 \param use_tep TRUE if TEP should be sent.
90 */
91 SPAN_DECLARE(void) fax_set_tep_mode(fax_state_t *s, int use_tep);
92
93 /*! Get a pointer to the T.30 engine associated with a FAX context.
94 \brief Get a pointer to the T.30 engine associated with a FAX context.
95 \param s The FAX context.
96 \return A pointer to the T.30 context, or NULL.
97 */
98 SPAN_DECLARE(t30_state_t *) fax_get_t30_state(fax_state_t *s);
99
100 /*! Get a pointer to the logging context associated with a FAX context.
101 \brief Get a pointer to the logging context associated with a FAX context.
102 \param s The FAX context.
103 \return A pointer to the logging context, or NULL.
104 */
105 SPAN_DECLARE(logging_state_t *) fax_get_logging_state(fax_state_t *s);
106
107 /*! Initialise a FAX context.
108 \brief Initialise a FAX context.
109 \param s The FAX context.
110 \param calling_party TRUE if the context is for a calling party. FALSE if the
111 context is for an answering party.
112 \return A pointer to the FAX context, or NULL if there was a problem.
113 */
114 SPAN_DECLARE(fax_state_t *) fax_init(fax_state_t *s, int calling_party);
115
116 /*! Release a FAX context.
117 \brief Release a FAX context.
118 \param s The FAX context.
119 \return 0 for OK, else -1. */
120 SPAN_DECLARE(int) fax_release(fax_state_t *s);
121
122 /*! Free a FAX context.
123 \brief Free a FAX context.
124 \param s The FAX context.
125 \return 0 for OK, else -1. */
126 SPAN_DECLARE(int) fax_free(fax_state_t *s);
127
128 #if defined(__cplusplus)
129 }
130 #endif
131
132 #endif
133 /*- End of file ------------------------------------------------------------*/

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