spandsp  0.0.6
t4_rx.h
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1 /*
2  * SpanDSP - a series of DSP components for telephony
3  *
4  * t4_rx.h - definitions for T.4 FAX receive processing
5  *
6  * Written by Steve Underwood <steveu@coppice.org>
7  *
8  * Copyright (C) 2003 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 
26 /*! \file */
27 
28 #if !defined(_SPANDSP_T4_RX_H_)
29 #define _SPANDSP_T4_RX_H_
30 
31 /*! \page t4_page T.4 image compression and decompression
32 
33 \section t4_page_sec_1 What does it do?
34 The T.4 image compression and decompression routines implement the 1D and 2D
35 encoding methods defined in ITU specification T.4. They also implement the pure
36 2D encoding method defined in T.6. These are image compression algorithms used
37 for FAX transmission.
38 
39 \section t4_page_sec_1 How does it work?
40 */
41 
42 typedef int (*t4_row_write_handler_t)(void *user_data, const uint8_t buf[], size_t len);
43 
44 /*! Supported compression modes. */
45 typedef enum
46 {
47  /*! No compression */
49  /*! T.1 1D compression */
51  /*! T.4 2D compression */
53  /*! T.6 2D compression */
55  /*! T.85 monochrome JBIG coding with L0 fixed. */
57  /*! T.85 monochrome JBIG coding with L0 variable. */
59  /*! T.43 colour JBIG coding */
61  /*! T.45 run length colour compression */
63  /*! T.42 + T.81 + T.30 Annex E colour JPEG coding */
65  /*! T.42 + T.81 + T.30 Annex K colour sYCC-JPEG coding */
68 
69 /*! Supported X resolutions, in pixels per metre. */
70 typedef enum
71 {
72  T4_X_RESOLUTION_R4 = 4016,
73  T4_X_RESOLUTION_R8 = 8031,
74  T4_X_RESOLUTION_300 = 11811,
75  T4_X_RESOLUTION_R16 = 16063,
76  T4_X_RESOLUTION_600 = 23622,
77  T4_X_RESOLUTION_800 = 31496,
78  T4_X_RESOLUTION_1200 = 47244
80 
81 /*! Supported Y resolutions, in pixels per metre. */
82 typedef enum
83 {
84  T4_Y_RESOLUTION_STANDARD = 3850,
85  T4_Y_RESOLUTION_FINE = 7700,
86  T4_Y_RESOLUTION_300 = 11811,
87  T4_Y_RESOLUTION_SUPERFINE = 15400, /* 400 is 15748 */
88  T4_Y_RESOLUTION_600 = 23622,
89  T4_Y_RESOLUTION_800 = 31496,
90  T4_Y_RESOLUTION_1200 = 47244
92 
93 /*!
94  Exact widths in PELs for the difference resolutions, and page widths.
95  Note:
96  The A4 widths also apply to North American letter and legal.
97  The R4 resolution widths are not supported in recent versions of T.30
98  Only images of exactly these widths are acceptable for FAX transmisson.
99 
100  R4 864 pels/215mm for ISO A4, North American Letter and Legal
101  R4 1024 pels/255mm for ISO B4
102  R4 1216 pels/303mm for ISO A3
103  R8 1728 pels/215mm for ISO A4, North American Letter and Legal
104  R8 2048 pels/255mm for ISO B4
105  R8 2432 pels/303mm for ISO A3
106  R16 3456 pels/215mm for ISO A4, North American Letter and Legal
107  R16 4096 pels/255mm for ISO B4
108  R16 4864 pels/303mm for ISO A3
109 */
110 typedef enum
111 {
112  T4_WIDTH_R4_A4 = 864,
113  T4_WIDTH_R4_B4 = 1024,
114  T4_WIDTH_R4_A3 = 1216,
115  T4_WIDTH_R8_A4 = 1728,
116  T4_WIDTH_R8_B4 = 2048,
117  T4_WIDTH_R8_A3 = 2432,
118  T4_WIDTH_300_A4 = 2592,
119  T4_WIDTH_300_B4 = 3072,
120  T4_WIDTH_300_A3 = 3648,
121  T4_WIDTH_R16_A4 = 3456,
122  T4_WIDTH_R16_B4 = 4096,
123  T4_WIDTH_R16_A3 = 4864,
124  T4_WIDTH_600_A4 = 5184,
125  T4_WIDTH_600_B4 = 6144,
126  T4_WIDTH_600_A3 = 7296,
127  T4_WIDTH_1200_A4 = 10368,
128  T4_WIDTH_1200_B4 = 12288,
129  T4_WIDTH_1200_A3 = 14592
131 
132 /*!
133  Length of the various supported paper sizes, in pixels at the various Y resolutions.
134  Paper sizes are
135  A4 (215mm x 297mm)
136  B4 (255mm x 364mm)
137  A3 (303mm x 418.56mm)
138  North American Letter (215.9mm x 279.4mm)
139  North American Legal (215.9mm x 355.6mm)
140  Unlimited
141 
142  T.4 does not accurately define the maximum number of scan lines in a page. A wide
143  variety of maximum row counts are used in the real world. It is important not to
144  set our sending limit too high, or a receiving machine might split pages. It is
145  important not to set it too low, or we might clip pages.
146 
147  Values seen for standard resolution A4 pages include 1037, 1045, 1109, 1126 and 1143.
148  1109 seems the most-popular. At fine res 2150, 2196, 2200, 2237, 2252-2262, 2264,
149  2286, and 2394 are used. 2255 seems the most popular. We try to use balanced choices
150  here.
151 */
152 typedef enum
153 {
154  /* A4 is 297mm long */
155  T4_LENGTH_STANDARD_A4 = 1143,
156  T4_LENGTH_FINE_A4 = 2286,
157  T4_LENGTH_300_A4 = 4665,
158  T4_LENGTH_SUPERFINE_A4 = 4573,
159  T4_LENGTH_600_A4 = 6998,
160  T4_LENGTH_800_A4 = 9330,
161  T4_LENGTH_1200_A4 = 13996,
162  /* B4 is 364mm long */
163  T4_LENGTH_STANDARD_B4 = 1401,
164  T4_LENGTH_FINE_B4 = 2802,
165  T4_LENGTH_300_B4 = 0,
166  T4_LENGTH_SUPERFINE_B4 = 5605,
167  T4_LENGTH_600_B4 = 0,
168  T4_LENGTH_800_B4 = 0,
169  T4_LENGTH_1200_B4 = 0,
170  /* North American letter is 279.4mm long */
171  T4_LENGTH_STANDARD_US_LETTER = 1075,
172  T4_LENGTH_FINE_US_LETTER = 2151,
173  T4_LENGTH_300_US_LETTER = 0,
174  T4_LENGTH_SUPERFINE_US_LETTER = 4302,
175  T4_LENGTH_600_US_LETTER = 0,
176  T4_LENGTH_800_US_LETTER = 0,
177  T4_LENGTH_1200_US_LETTER = 0,
178  /* North American legal is 355.6mm long */
179  T4_LENGTH_STANDARD_US_LEGAL = 1369,
180  T4_LENGTH_FINE_US_LEGAL = 2738,
181  T4_LENGTH_300_US_LEGAL = 0,
182  T4_LENGTH_SUPERFINE_US_LEGAL = 5476,
183  T4_LENGTH_600_US_LEGAL = 0,
184  T4_LENGTH_800_US_LEGAL = 0,
185  T4_LENGTH_1200_US_LEGAL = 0
187 
188 /*!
189  T.4 FAX compression/decompression descriptor. This defines the working state
190  for a single instance of a T.4 FAX compression or decompression channel.
191 */
192 typedef struct t4_state_s t4_state_t;
193 
194 /*!
195  T.4 FAX compression/decompression statistics.
196 */
197 typedef struct
198 {
199  /*! \brief The number of pages transferred so far. */
201  /*! \brief The number of pages in the file (<0 if unknown). */
203  /*! \brief The number of horizontal pixels in the most recent page. */
204  int width;
205  /*! \brief The number of vertical pixels in the most recent page. */
206  int length;
207  /*! \brief The number of bad pixel rows in the most recent page. */
208  int bad_rows;
209  /*! \brief The largest number of bad pixel rows in a block in the most recent page. */
211  /*! \brief The horizontal resolution of the page in pixels per metre */
213  /*! \brief The vertical resolution of the page in pixels per metre */
215  /*! \brief The type of compression used between the FAX machines */
216  int encoding;
217  /*! \brief The size of the image on the line, in bytes */
219 } t4_stats_t;
220 
221 #if defined(__cplusplus)
222 extern "C" {
223 #endif
224 
225 /*! \brief Prepare for reception of a document.
226  \param s The T.4 context.
227  \param file The name of the file to be received.
228  \param output_encoding The output encoding.
229  \return A pointer to the context, or NULL if there was a problem. */
230 SPAN_DECLARE(t4_state_t *) t4_rx_init(t4_state_t *s, const char *file, int output_encoding);
231 
232 /*! \brief Prepare to receive the next page of the current document.
233  \param s The T.4 context.
234  \return zero for success, -1 for failure. */
235 SPAN_DECLARE(int) t4_rx_start_page(t4_state_t *s);
236 
237 /*! \brief Put a bit of the current document page.
238  \param s The T.4 context.
239  \param bit The data bit.
240  \return TRUE when the bit ends the document page, otherwise FALSE. */
241 SPAN_DECLARE(int) t4_rx_put_bit(t4_state_t *s, int bit);
242 
243 /*! \brief Put a byte of the current document page.
244  \param s The T.4 context.
245  \param byte The data byte.
246  \return TRUE when the byte ends the document page, otherwise FALSE. */
247 SPAN_DECLARE(int) t4_rx_put_byte(t4_state_t *s, uint8_t byte);
248 
249 /*! \brief Put a byte of the current document page.
250  \param s The T.4 context.
251  \param buf The buffer containing the chunk.
252  \param len The length of the chunk.
253  \return TRUE when the byte ends the document page, otherwise FALSE. */
254 SPAN_DECLARE(int) t4_rx_put_chunk(t4_state_t *s, const uint8_t buf[], int len);
255 
256 /*! \brief Complete the reception of a page.
257  \param s The T.4 receive context.
258  \return 0 for success, otherwise -1. */
259 SPAN_DECLARE(int) t4_rx_end_page(t4_state_t *s);
260 
261 /*! \brief End reception of a document. Tidy up and close the file.
262  This should be used to end T.4 reception started with
263  t4_rx_init.
264  \param s The T.4 receive context.
265  \return 0 for success, otherwise -1. */
266 SPAN_DECLARE(int) t4_rx_release(t4_state_t *s);
267 
268 /*! \brief End reception of a document. Tidy up, close the file and
269  free the context. This should be used to end T.4 reception
270  started with t4_rx_init.
271  \param s The T.4 receive context.
272  \return 0 for success, otherwise -1. */
273 SPAN_DECLARE(int) t4_rx_free(t4_state_t *s);
274 
275 /*! \brief Set the row write handler for a T.4 receive context.
276  \param s The T.4 receive context.
277  \param handler A pointer to the handler routine.
278  \param user_data An opaque pointer passed to the handler routine.
279  \return 0 for success, otherwise -1. */
280 SPAN_DECLARE(int) t4_rx_set_row_write_handler(t4_state_t *s, t4_row_write_handler_t handler, void *user_data);
281 
282 /*! \brief Set the encoding for the received data.
283  \param s The T.4 context.
284  \param encoding The encoding. */
285 SPAN_DECLARE(void) t4_rx_set_rx_encoding(t4_state_t *s, int encoding);
286 
287 /*! \brief Set the expected width of the received image, in pixel columns.
288  \param s The T.4 context.
289  \param width The number of pixels across the image. */
290 SPAN_DECLARE(void) t4_rx_set_image_width(t4_state_t *s, int width);
291 
292 /*! \brief Set the row-to-row (y) resolution to expect for a received image.
293  \param s The T.4 context.
294  \param resolution The resolution, in pixels per metre. */
295 SPAN_DECLARE(void) t4_rx_set_y_resolution(t4_state_t *s, int resolution);
296 
297 /*! \brief Set the column-to-column (x) resolution to expect for a received image.
298  \param s The T.4 context.
299  \param resolution The resolution, in pixels per metre. */
300 SPAN_DECLARE(void) t4_rx_set_x_resolution(t4_state_t *s, int resolution);
301 
302 /*! \brief Set the DCS information of the fax, for inclusion in the file.
303  \param s The T.4 context.
304  \param dcs The DCS information, formatted as an ASCII string. */
305 SPAN_DECLARE(void) t4_rx_set_dcs(t4_state_t *s, const char *dcs);
306 
307 /*! \brief Set the sub-address of the fax, for inclusion in the file.
308  \param s The T.4 context.
309  \param sub_address The sub-address string. */
310 SPAN_DECLARE(void) t4_rx_set_sub_address(t4_state_t *s, const char *sub_address);
311 
312 /*! \brief Set the identity of the remote machine, for inclusion in the file.
313  \param s The T.4 context.
314  \param ident The identity string. */
315 SPAN_DECLARE(void) t4_rx_set_far_ident(t4_state_t *s, const char *ident);
316 
317 /*! \brief Set the vendor of the remote machine, for inclusion in the file.
318  \param s The T.4 context.
319  \param vendor The vendor string, or NULL. */
320 SPAN_DECLARE(void) t4_rx_set_vendor(t4_state_t *s, const char *vendor);
321 
322 /*! \brief Set the model of the remote machine, for inclusion in the file.
323  \param s The T.4 context.
324  \param model The model string, or NULL. */
325 SPAN_DECLARE(void) t4_rx_set_model(t4_state_t *s, const char *model);
326 
327 /*! Get the current image transfer statistics.
328  \brief Get the current transfer statistics.
329  \param s The T.4 context.
330  \param t A pointer to a statistics structure. */
331 SPAN_DECLARE(void) t4_rx_get_transfer_statistics(t4_state_t *s, t4_stats_t *t);
332 
333 /*! Get the short text name of an encoding format.
334  \brief Get the short text name of an encoding format.
335  \param encoding The encoding type.
336  \return A pointer to the string. */
337 SPAN_DECLARE(const char *) t4_encoding_to_str(int encoding);
338 
339 #if defined(__cplusplus)
340 }
341 #endif
342 
343 #endif
344 /*- End of file ------------------------------------------------------------*/
int x_resolution
The horizontal resolution of the page in pixels per metre.
Definition: t4_rx.h:212
void t4_rx_set_model(t4_state_t *s, const char *model)
Set the model of the remote machine, for inclusion in the file.
Definition: t4_rx.c:1206
Definition: t4_rx.h:197
void t4_rx_set_rx_encoding(t4_state_t *s, int encoding)
Set the encoding for the received data.
Definition: t4_rx.c:1158
void t4_rx_set_vendor(t4_state_t *s, const char *vendor)
Set the vendor of the remote machine, for inclusion in the file.
Definition: t4_rx.c:1200
const char * t4_encoding_to_str(int encoding)
Get the short text name of an encoding format.
Definition: t4_rx.c:1227
int pages_transferred
The number of pages transferred so far.
Definition: t4_rx.h:200
int line_image_size
The size of the image on the line, in bytes.
Definition: t4_rx.h:218
Definition: t4_rx.h:54
void t4_rx_set_x_resolution(t4_state_t *s, int resolution)
Set the column-to-column (x) resolution to expect for a received image.
Definition: t4_rx.c:1176
void t4_rx_set_image_width(t4_state_t *s, int width)
Set the expected width of the received image, in pixel columns.
Definition: t4_rx.c:1164
Definition: t4_rx.h:60
int t4_rx_start_page(t4_state_t *s)
Prepare to receive the next page of the current document.
Definition: t4_rx.c:1068
Definition: t4_rx.h:52
int t4_rx_free(t4_state_t *s)
End reception of a document. Tidy up, close the file and free the context. This should be used to end...
Definition: t4_rx.c:1148
Definition: t4_rx.h:62
int length
The number of vertical pixels in the most recent page.
Definition: t4_rx.h:206
int t4_rx_set_row_write_handler(t4_state_t *s, t4_row_write_handler_t handler, void *user_data)
Set the row write handler for a T.4 receive context.
Definition: t4_rx.c:1002
t4_image_y_resolution_t
Definition: t4_rx.h:82
Definition: t4_rx.h:58
Definition: t4_rx.h:48
void t4_rx_set_y_resolution(t4_state_t *s, int resolution)
Set the row-to-row (y) resolution to expect for a received image.
Definition: t4_rx.c:1170
Definition: t4_rx.h:50
Definition: t4_rx.h:66
void t4_rx_set_dcs(t4_state_t *s, const char *dcs)
Set the DCS information of the fax, for inclusion in the file.
Definition: t4_rx.c:1182
Definition: t4_rx.h:64
int t4_rx_put_byte(t4_state_t *s, uint8_t byte)
Put a byte of the current document page.
Definition: t4_rx.c:981
int bad_rows
The number of bad pixel rows in the most recent page.
Definition: t4_rx.h:208
int width
The number of horizontal pixels in the most recent page.
Definition: t4_rx.h:204
int t4_rx_end_page(t4_state_t *s)
Complete the reception of a page.
Definition: t4_rx.c:581
t4_image_width_t
Definition: t4_rx.h:110
t4_image_compression_t
Definition: t4_rx.h:45
int y_resolution
The vertical resolution of the page in pixels per metre.
Definition: t4_rx.h:214
t4_image_length_t
Definition: t4_rx.h:152
void t4_rx_set_sub_address(t4_state_t *s, const char *sub_address)
Set the sub-address of the fax, for inclusion in the file.
Definition: t4_rx.c:1188
int t4_rx_put_bit(t4_state_t *s, int bit)
Put a bit of the current document page.
Definition: t4_rx.c:975
int pages_in_file
The number of pages in the file (<0 if unknown).
Definition: t4_rx.h:202
t4_image_x_resolution_t
Definition: t4_rx.h:70
int t4_rx_put_chunk(t4_state_t *s, const uint8_t buf[], int len)
Put a byte of the current document page.
Definition: t4_rx.c:987
int encoding
The type of compression used between the FAX machines.
Definition: t4_rx.h:216
Definition: t4_rx.h:56
t4_state_t * t4_rx_init(t4_state_t *s, const char *file, int output_encoding)
Prepare for reception of a document.
Definition: t4_rx.c:1010
Definition: private/t4_tx.h:33
int longest_bad_row_run
The largest number of bad pixel rows in a block in the most recent page.
Definition: t4_rx.h:210
int t4_rx_release(t4_state_t *s)
End reception of a document. Tidy up and close the file. This should be used to end T...
Definition: t4_rx.c:1137
void t4_rx_set_far_ident(t4_state_t *s, const char *ident)
Set the identity of the remote machine, for inclusion in the file.
Definition: t4_rx.c:1194
void t4_rx_get_transfer_statistics(t4_state_t *s, t4_stats_t *t)
Get the current transfer statistics.
Definition: t4_rx.c:1212