t4_rx.h

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00001 /*
00002  * SpanDSP - a series of DSP components for telephony
00003  *
00004  * t4_rx.h - definitions for T.4 FAX receive processing
00005  *
00006  * Written by Steve Underwood <steveu@coppice.org>
00007  *
00008  * Copyright (C) 2003 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 Lesser General Public License version 2.1,
00014  * as 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 Lesser General Public License for more details.
00020  *
00021  * You should have received a copy of the GNU Lesser General Public
00022  * License along with this program; if not, write to the Free Software
00023  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
00024  */
00025 
00026 /*! \file */
00027 
00028 #if !defined(_SPANDSP_T4_RX_H_)
00029 #define _SPANDSP_T4_RX_H_
00030 
00031 /*! \page t4_page T.4 image compression and decompression
00032 
00033 \section t4_page_sec_1 What does it do?
00034 The T.4 image compression and decompression routines implement the 1D and 2D
00035 encoding methods defined in ITU specification T.4. They also implement the pure
00036 2D encoding method defined in T.6. These are image compression algorithms used
00037 for FAX transmission.
00038 
00039 \section t4_page_sec_1 How does it work?
00040 */
00041 
00042 typedef int (*t4_row_write_handler_t)(void *user_data, const uint8_t buf[], size_t len);
00043 
00044 /*! Supported compression modes. */
00045 typedef enum
00046 {
00047     /*! No compression */
00048     T4_COMPRESSION_NONE = 0,
00049     /*! T.1 1D compression */
00050     T4_COMPRESSION_ITU_T4_1D = 1,
00051     /*! T.4 2D compression */
00052     T4_COMPRESSION_ITU_T4_2D = 2,
00053     /*! T.6 2D compression */
00054     T4_COMPRESSION_ITU_T6 = 3,
00055     /*! T.85 monochrome JBIG coding with L0 fixed. */
00056     T4_COMPRESSION_ITU_T85 = 4,
00057     /*! T.85 monochrome JBIG coding with L0 variable. */
00058     T4_COMPRESSION_ITU_T85_L0 = 5,
00059     /*! T.43 colour JBIG coding */
00060     T4_COMPRESSION_ITU_T43 = 6,
00061     /*! T.45 run length colour compression */
00062     T4_COMPRESSION_ITU_T45 = 7,
00063     /*! T.42 + T.81 + T.30 Annex E colour JPEG coding */
00064     T4_COMPRESSION_ITU_T42 = 8,
00065     /*! T.42 + T.81 + T.30 Annex K colour sYCC-JPEG coding */
00066     T4_COMPRESSION_ITU_SYCC_T42 = 9
00067 } t4_image_compression_t;
00068 
00069 /*! Supported X resolutions, in pixels per metre. */
00070 typedef enum
00071 {
00072     T4_X_RESOLUTION_R4 = 4016,
00073     T4_X_RESOLUTION_R8 = 8031,
00074     T4_X_RESOLUTION_300 = 11811,
00075     T4_X_RESOLUTION_R16 = 16063,
00076     T4_X_RESOLUTION_600 = 23622,
00077     T4_X_RESOLUTION_800 = 31496,
00078     T4_X_RESOLUTION_1200 = 47244
00079 } t4_image_x_resolution_t;
00080 
00081 /*! Supported Y resolutions, in pixels per metre. */
00082 typedef enum
00083 {
00084     T4_Y_RESOLUTION_STANDARD = 3850,
00085     T4_Y_RESOLUTION_FINE = 7700,
00086     T4_Y_RESOLUTION_300 = 11811,
00087     T4_Y_RESOLUTION_SUPERFINE = 15400,  /* 400 is 15748 */
00088     T4_Y_RESOLUTION_600 = 23622,
00089     T4_Y_RESOLUTION_800 = 31496,
00090     T4_Y_RESOLUTION_1200 = 47244
00091 } t4_image_y_resolution_t;
00092 
00093 /*!
00094     Exact widths in PELs for the difference resolutions, and page widths.
00095     Note:
00096         The A4 widths also apply to North American letter and legal.
00097         The R4 resolution widths are not supported in recent versions of T.30
00098         Only images of exactly these widths are acceptable for FAX transmisson.
00099 
00100     R4    864 pels/215mm for ISO A4, North American Letter and Legal
00101     R4   1024 pels/255mm for ISO B4
00102     R4   1216 pels/303mm for ISO A3
00103     R8   1728 pels/215mm for ISO A4, North American Letter and Legal
00104     R8   2048 pels/255mm for ISO B4
00105     R8   2432 pels/303mm for ISO A3
00106     R16  3456 pels/215mm for ISO A4, North American Letter and Legal
00107     R16  4096 pels/255mm for ISO B4
00108     R16  4864 pels/303mm for ISO A3
00109 */
00110 typedef enum
00111 {
00112     T4_WIDTH_R4_A4 = 864,
00113     T4_WIDTH_R4_B4 = 1024,
00114     T4_WIDTH_R4_A3 = 1216,
00115     T4_WIDTH_R8_A4 = 1728,
00116     T4_WIDTH_R8_B4 = 2048,
00117     T4_WIDTH_R8_A3 = 2432,
00118     T4_WIDTH_300_A4 = 2592,
00119     T4_WIDTH_300_B4 = 3072,
00120     T4_WIDTH_300_A3 = 3648,
00121     T4_WIDTH_R16_A4 = 3456,
00122     T4_WIDTH_R16_B4 = 4096,
00123     T4_WIDTH_R16_A3 = 4864,
00124     T4_WIDTH_600_A4 = 5184,
00125     T4_WIDTH_600_B4 = 6144,
00126     T4_WIDTH_600_A3 = 7296,
00127     T4_WIDTH_1200_A4 = 10368,
00128     T4_WIDTH_1200_B4 = 12288,
00129     T4_WIDTH_1200_A3 = 14592
00130 } t4_image_width_t;
00131 
00132 /*!
00133     Length of the various supported paper sizes, in pixels at the various Y resolutions.
00134     Paper sizes are
00135         A4 (215mm x 297mm)
00136         B4 (255mm x 364mm)
00137         A3 (303mm x 418.56mm)
00138         North American Letter (215.9mm x 279.4mm)
00139         North American Legal (215.9mm x 355.6mm)
00140         Unlimited
00141 
00142     T.4 does not accurately define the maximum number of scan lines in a page. A wide
00143     variety of maximum row counts are used in the real world. It is important not to
00144     set our sending limit too high, or a receiving machine might split pages. It is
00145     important not to set it too low, or we might clip pages.
00146 
00147     Values seen for standard resolution A4 pages include 1037, 1045, 1109, 1126 and 1143.
00148     1109 seems the most-popular.  At fine res 2150, 2196, 2200, 2237, 2252-2262, 2264,
00149     2286, and 2394 are used. 2255 seems the most popular. We try to use balanced choices
00150     here.
00151 */
00152 typedef enum
00153 {
00154     /* A4 is 297mm long */
00155     T4_LENGTH_STANDARD_A4 = 1143,
00156     T4_LENGTH_FINE_A4 = 2286,
00157     T4_LENGTH_300_A4 = 4665,
00158     T4_LENGTH_SUPERFINE_A4 = 4573,
00159     T4_LENGTH_600_A4 = 6998,
00160     T4_LENGTH_800_A4 = 9330,
00161     T4_LENGTH_1200_A4 = 13996,
00162     /* B4 is 364mm long */
00163     T4_LENGTH_STANDARD_B4 = 1401,
00164     T4_LENGTH_FINE_B4 = 2802,
00165     T4_LENGTH_300_B4 = 0,
00166     T4_LENGTH_SUPERFINE_B4 = 5605,
00167     T4_LENGTH_600_B4 = 0,
00168     T4_LENGTH_800_B4 = 0,
00169     T4_LENGTH_1200_B4 = 0,
00170     /* North American letter is 279.4mm long */
00171     T4_LENGTH_STANDARD_US_LETTER = 1075,
00172     T4_LENGTH_FINE_US_LETTER = 2151,
00173     T4_LENGTH_300_US_LETTER = 0,
00174     T4_LENGTH_SUPERFINE_US_LETTER = 4302,
00175     T4_LENGTH_600_US_LETTER = 0,
00176     T4_LENGTH_800_US_LETTER = 0,
00177     T4_LENGTH_1200_US_LETTER = 0,
00178     /* North American legal is 355.6mm long */
00179     T4_LENGTH_STANDARD_US_LEGAL = 1369,
00180     T4_LENGTH_FINE_US_LEGAL = 2738,
00181     T4_LENGTH_300_US_LEGAL = 0,
00182     T4_LENGTH_SUPERFINE_US_LEGAL = 5476,
00183     T4_LENGTH_600_US_LEGAL = 0,
00184     T4_LENGTH_800_US_LEGAL = 0,
00185     T4_LENGTH_1200_US_LEGAL = 0
00186 } t4_image_length_t;
00187 
00188 /*!
00189     T.4 FAX compression/decompression descriptor. This defines the working state
00190     for a single instance of a T.4 FAX compression or decompression channel.
00191 */
00192 typedef struct t4_state_s t4_state_t;
00193 
00194 /*!
00195     T.4 FAX compression/decompression statistics.
00196 */
00197 typedef struct
00198 {
00199     /*! \brief The number of pages transferred so far. */
00200     int pages_transferred;
00201     /*! \brief The number of pages in the file (<0 if unknown). */
00202     int pages_in_file;
00203     /*! \brief The number of horizontal pixels in the most recent page. */
00204     int width;
00205     /*! \brief The number of vertical pixels in the most recent page. */
00206     int length;
00207     /*! \brief The number of bad pixel rows in the most recent page. */
00208     int bad_rows;
00209     /*! \brief The largest number of bad pixel rows in a block in the most recent page. */
00210     int longest_bad_row_run;
00211     /*! \brief The horizontal resolution of the page in pixels per metre */
00212     int x_resolution;
00213     /*! \brief The vertical resolution of the page in pixels per metre */
00214     int y_resolution;
00215     /*! \brief The type of compression used between the FAX machines */
00216     int encoding;
00217     /*! \brief The size of the image on the line, in bytes */
00218     int line_image_size;
00219 } t4_stats_t;
00220     
00221 #if defined(__cplusplus)
00222 extern "C" {
00223 #endif
00224 
00225 /*! \brief Prepare for reception of a document.
00226     \param s The T.4 context.
00227     \param file The name of the file to be received.
00228     \param output_encoding The output encoding.
00229     \return A pointer to the context, or NULL if there was a problem. */
00230 SPAN_DECLARE(t4_state_t *) t4_rx_init(t4_state_t *s, const char *file, int output_encoding);
00231 
00232 /*! \brief Prepare to receive the next page of the current document.
00233     \param s The T.4 context.
00234     \return zero for success, -1 for failure. */
00235 SPAN_DECLARE(int) t4_rx_start_page(t4_state_t *s);
00236 
00237 /*! \brief Put a bit of the current document page.
00238     \param s The T.4 context.
00239     \param bit The data bit.
00240     \return TRUE when the bit ends the document page, otherwise FALSE. */
00241 SPAN_DECLARE(int) t4_rx_put_bit(t4_state_t *s, int bit);
00242 
00243 /*! \brief Put a byte of the current document page.
00244     \param s The T.4 context.
00245     \param byte The data byte.
00246     \return TRUE when the byte ends the document page, otherwise FALSE. */
00247 SPAN_DECLARE(int) t4_rx_put_byte(t4_state_t *s, uint8_t byte);
00248 
00249 /*! \brief Put a byte of the current document page.
00250     \param s The T.4 context.
00251     \param buf The buffer containing the chunk.
00252     \param len The length of the chunk.
00253     \return TRUE when the byte ends the document page, otherwise FALSE. */
00254 SPAN_DECLARE(int) t4_rx_put_chunk(t4_state_t *s, const uint8_t buf[], int len);
00255 
00256 /*! \brief Complete the reception of a page.
00257     \param s The T.4 receive context.
00258     \return 0 for success, otherwise -1. */
00259 SPAN_DECLARE(int) t4_rx_end_page(t4_state_t *s);
00260 
00261 /*! \brief End reception of a document. Tidy up and close the file.
00262            This should be used to end T.4 reception started with
00263            t4_rx_init.
00264     \param s The T.4 receive context.
00265     \return 0 for success, otherwise -1. */
00266 SPAN_DECLARE(int) t4_rx_release(t4_state_t *s);
00267 
00268 /*! \brief End reception of a document. Tidy up, close the file and
00269            free the context. This should be used to end T.4 reception
00270            started with t4_rx_init.
00271     \param s The T.4 receive context.
00272     \return 0 for success, otherwise -1. */
00273 SPAN_DECLARE(int) t4_rx_free(t4_state_t *s);
00274 
00275 /*! \brief Set the row write handler for a T.4 receive context.
00276     \param s The T.4 receive context.
00277     \param handler A pointer to the handler routine.
00278     \param user_data An opaque pointer passed to the handler routine.
00279     \return 0 for success, otherwise -1. */
00280 SPAN_DECLARE(int) t4_rx_set_row_write_handler(t4_state_t *s, t4_row_write_handler_t handler, void *user_data);
00281 
00282 /*! \brief Set the encoding for the received data.
00283     \param s The T.4 context.
00284     \param encoding The encoding. */
00285 SPAN_DECLARE(void) t4_rx_set_rx_encoding(t4_state_t *s, int encoding);
00286 
00287 /*! \brief Set the expected width of the received image, in pixel columns.
00288     \param s The T.4 context.
00289     \param width The number of pixels across the image. */
00290 SPAN_DECLARE(void) t4_rx_set_image_width(t4_state_t *s, int width);
00291 
00292 /*! \brief Set the row-to-row (y) resolution to expect for a received image.
00293     \param s The T.4 context.
00294     \param resolution The resolution, in pixels per metre. */
00295 SPAN_DECLARE(void) t4_rx_set_y_resolution(t4_state_t *s, int resolution);
00296 
00297 /*! \brief Set the column-to-column (x) resolution to expect for a received image.
00298     \param s The T.4 context.
00299     \param resolution The resolution, in pixels per metre. */
00300 SPAN_DECLARE(void) t4_rx_set_x_resolution(t4_state_t *s, int resolution);
00301 
00302 /*! \brief Set the DCS information of the fax, for inclusion in the file.
00303     \param s The T.4 context.
00304     \param dcs The DCS information, formatted as an ASCII string. */
00305 SPAN_DECLARE(void) t4_rx_set_dcs(t4_state_t *s, const char *dcs);
00306 
00307 /*! \brief Set the sub-address of the fax, for inclusion in the file.
00308     \param s The T.4 context.
00309     \param sub_address The sub-address string. */
00310 SPAN_DECLARE(void) t4_rx_set_sub_address(t4_state_t *s, const char *sub_address);
00311 
00312 /*! \brief Set the identity of the remote machine, for inclusion in the file.
00313     \param s The T.4 context.
00314     \param ident The identity string. */
00315 SPAN_DECLARE(void) t4_rx_set_far_ident(t4_state_t *s, const char *ident);
00316 
00317 /*! \brief Set the vendor of the remote machine, for inclusion in the file.
00318     \param s The T.4 context.
00319     \param vendor The vendor string, or NULL. */
00320 SPAN_DECLARE(void) t4_rx_set_vendor(t4_state_t *s, const char *vendor);
00321 
00322 /*! \brief Set the model of the remote machine, for inclusion in the file.
00323     \param s The T.4 context.
00324     \param model The model string, or NULL. */
00325 SPAN_DECLARE(void) t4_rx_set_model(t4_state_t *s, const char *model);
00326 
00327 /*! Get the current image transfer statistics. 
00328     \brief Get the current transfer statistics.
00329     \param s The T.4 context.
00330     \param t A pointer to a statistics structure. */
00331 SPAN_DECLARE(void) t4_rx_get_transfer_statistics(t4_state_t *s, t4_stats_t *t);
00332 
00333 /*! Get the short text name of an encoding format. 
00334     \brief Get the short text name of an encoding format.
00335     \param encoding The encoding type.
00336     \return A pointer to the string. */
00337 SPAN_DECLARE(const char *) t4_encoding_to_str(int encoding);
00338 
00339 #if defined(__cplusplus)
00340 }
00341 #endif
00342 
00343 #endif
00344 /*- End of file ------------------------------------------------------------*/

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