modules/stream_out/langfromtelx.c

   1 /*****************************************************************************
   2  * langfromtelx.c: dynamic language setting from telx
   3  *****************************************************************************
   4  * Copyright © 2009-2011 VLC authors and VideoLAN
   5  * $Id$
   6  *
   7  * Authors: Christophe Massiot <massiot@via.ecp.fr>
   8  *
   9  * This program is free software; you can redistribute it and/or modify it
  10  * under the terms of the GNU Lesser General Public License as published by
  11  * the Free Software Foundation; either version 2.1 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  17  * GNU Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public License
  20  * along with this program; if not, write to the Free Software Foundation,
  21  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  22  *****************************************************************************/
  23
  24 /*****************************************************************************
  25  * Preamble
  26  *****************************************************************************/
  27 #ifdef HAVE_CONFIG_H
  28 # include "config.h"
  29 #endif
  30
  31 #include <ctype.h>
  32
  33 #include <vlc_common.h>
  34 #include <vlc_plugin.h>
  35 #include <vlc_sout.h>
  36 #include <vlc_block.h>
  37
  38 /*****************************************************************************
  39  * Module descriptor
  40  *****************************************************************************/
  41
  42 #define ID_TEXT N_("Elementary Stream ID")
  43 #define ID_LONGTEXT N_( \
  44     "Specify an identifier integer for this elementary stream to change" )
  45 #define MAGAZINE_TEXT N_("Magazine")
  46 #define MAGAZINE_LONGTEXT N_( \
  47     "Specify the magazine containing the language page" )
  48 #define PAGE_TEXT N_("Page")
  49 #define PAGE_LONGTEXT N_( \
  50     "Specify the page containing the language" )
  51 #define ROW_TEXT N_("Row")
  52 #define ROW_LONGTEXT N_( \
  53     "Specify the row containing the language" )
  54
  55 static int  Open    ( vlc_object_t * );
  56 static void Close   ( vlc_object_t * );
  57
  58 #define SOUT_CFG_PREFIX "sout-langfromtelx-"
  59
  60 vlc_module_begin()
  61     set_shortname( N_("Lang From Telx"))
  62     set_description( N_("Dynamic language setting from teletext"))
  63     set_capability( "sout stream", 50 )
  64     add_shortcut( "langfromtelx" )
  65     set_category( CAT_SOUT )
  66     set_subcategory( SUBCAT_SOUT_STREAM )
  67
  68     set_callbacks( Open, Close )
  69     add_integer( SOUT_CFG_PREFIX "id", 0, ID_TEXT, ID_LONGTEXT,
  70                  false )
  71     add_integer( SOUT_CFG_PREFIX "magazine", 7, MAGAZINE_TEXT,
  72                  MAGAZINE_LONGTEXT, false )
  73     add_integer( SOUT_CFG_PREFIX "page", 0x99, PAGE_TEXT, PAGE_LONGTEXT,
  74                  false )
  75     add_integer( SOUT_CFG_PREFIX "row", 1, ROW_TEXT, ROW_LONGTEXT,
  76                  false )
  77 vlc_module_end();
  78
  79
  80 /*****************************************************************************
  81  * Local prototypes
  82  *****************************************************************************/
  83 static const char *ppsz_sout_options[] = {
  84     "id", "magazine", "page", "row", NULL
  85 };
  86
  87 static sout_stream_id_sys_t *Add   ( sout_stream_t *, es_format_t * );
  88 static int               Del   ( sout_stream_t *, sout_stream_id_sys_t * );
  89 static int               Send  ( sout_stream_t *, sout_stream_id_sys_t *, block_t * );
  90
  91 struct sout_stream_sys_t
  92 {
  93     int i_id, i_magazine, i_page, i_row;
  94     char *psz_language, *psz_old_language;
  95     sout_stream_id_sys_t *p_id, *p_telx;
  96     int i_current_page;
  97 };
  98
  99 /*****************************************************************************
 100  * Open:
 101  *****************************************************************************/
 102 static int Open( vlc_object_t *p_this )
 103 {
 104     sout_stream_t     *p_stream = (sout_stream_t*)p_this;
 105     sout_stream_sys_t *p_sys;
 106
 107     if( !p_stream->p_next )
 108     {
 109         msg_Err( p_stream, "cannot create chain" );
 110         return VLC_EGENERIC;
 111     }
 112
 113     p_sys = malloc( sizeof( sout_stream_sys_t ) );
 114     if( unlikely( !p_sys ) )
 115         return VLC_ENOMEM;
 116
 117     config_ChainParse( p_stream, SOUT_CFG_PREFIX, ppsz_sout_options,
 118                        p_stream->p_cfg );
 119
 120     p_sys->i_id       = var_GetInteger( p_stream, SOUT_CFG_PREFIX "id" );
 121     p_sys->i_magazine = var_GetInteger( p_stream, SOUT_CFG_PREFIX "magazine" );
 122     p_sys->i_page     = var_GetInteger( p_stream, SOUT_CFG_PREFIX "page" );
 123     p_sys->i_row      = var_GetInteger( p_stream, SOUT_CFG_PREFIX "row" );
 124
 125     p_stream->pf_add  = Add;
 126     p_stream->pf_del  = Del;
 127     p_stream->pf_send = Send;
 128
 129     p_stream->p_sys   = p_sys;
 130
 131     return VLC_SUCCESS;
 132 }
 133
 134 /*****************************************************************************
 135  * Close:
 136  *****************************************************************************/
 137 static void Close( vlc_object_t * p_this )
 138 {
 139     sout_stream_t     *p_stream = (sout_stream_t*)p_this;
 140     sout_stream_sys_t *p_sys = (sout_stream_sys_t *)p_stream->p_sys;
 141
 142     free( p_sys->psz_old_language );
 143     free( p_sys );
 144 }
 145
 146 static sout_stream_id_sys_t * Add( sout_stream_t *p_stream, es_format_t *p_fmt )
 147 {
 148     sout_stream_sys_t *p_sys = (sout_stream_sys_t *)p_stream->p_sys;
 149
 150     if ( p_fmt->i_id == p_sys->i_id )
 151     {
 152         p_sys->psz_old_language = p_fmt->psz_language;
 153         msg_Dbg( p_stream,
 154                  "changing language of ID %d (magazine %d page %x row %d)",
 155                  p_sys->i_id, p_sys->i_magazine, p_sys->i_page, p_sys->i_row );
 156         p_sys->psz_language = p_fmt->psz_language = malloc(4);
 157         if ( p_sys->psz_old_language != NULL )
 158             strncpy( p_fmt->psz_language, p_sys->psz_old_language, 3 );
 159         else
 160             strcpy( p_fmt->psz_language, "unk" );
 161         p_fmt->psz_language[3] = '\0';
 162
 163         p_sys->p_id = p_stream->p_next->pf_add( p_stream->p_next, p_fmt );
 164         return p_sys->p_id;
 165     }
 166
 167     if ( p_fmt->i_codec == VLC_CODEC_TELETEXT )
 168     {
 169         p_sys->p_telx = p_stream->p_next->pf_add( p_stream->p_next, p_fmt );
 170         return p_sys->p_telx;
 171     }
 172
 173     return p_stream->p_next->pf_add( p_stream->p_next, p_fmt );
 174 }
 175
 176 static int Del( sout_stream_t *p_stream, sout_stream_id_sys_t *id )
 177 {
 178     sout_stream_sys_t *p_sys = (sout_stream_sys_t *)p_stream->p_sys;
 179
 180     if ( id == p_sys->p_id ) p_sys->p_id = NULL;
 181     if ( id == p_sys->p_telx ) p_sys->p_telx = NULL;
 182
 183     return p_stream->p_next->pf_del( p_stream->p_next, id );
 184 }
 185
 186 static void SetLanguage( sout_stream_t *p_stream, char *psz_language )
 187 {
 188     sout_stream_sys_t *p_sys = (sout_stream_sys_t *)p_stream->p_sys;
 189
 190     if ( strncmp( p_sys->psz_language, psz_language, 3 ) )
 191         msg_Dbg( p_stream, "changing language to %s", psz_language );
 192
 193     strncpy( p_sys->psz_language, (const char *)psz_language, 3 );
 194 }
 195
 196 /*****************************************************************************
 197  * Teletext stuff
 198  *****************************************************************************/
 199 static uint8_t bytereverse( int n )
 200 {
 201     n = (((n >> 1) & 0x55) | ((n << 1) & 0xaa));
 202     n = (((n >> 2) & 0x33) | ((n << 2) & 0xcc));
 203     n = (((n >> 4) & 0x0f) | ((n << 4) & 0xf0));
 204     return n;
 205 }
 206
 207 static int hamming_8_4( int a )
 208 {
 209     switch (a) {
 210     case 0xA8:
 211         return 0;
 212     case 0x0B:
 213         return 1;
 214     case 0x26:
 215         return 2;
 216     case 0x85:
 217         return 3;
 218     case 0x92:
 219         return 4;
 220     case 0x31:
 221         return 5;
 222     case 0x1C:
 223         return 6;
 224     case 0xBF:
 225         return 7;
 226     case 0x40:
 227         return 8;
 228     case 0xE3:
 229         return 9;
 230     case 0xCE:
 231         return 10;
 232     case 0x6D:
 233         return 11;
 234     case 0x7A:
 235         return 12;
 236     case 0xD9:
 237         return 13;
 238     case 0xF4:
 239         return 14;
 240     case 0x57:
 241         return 15;
 242     default:
 243         return -1;     // decoding error , not yet corrected
 244     }
 245 }
 246
 247 static void decode_string( char *res, uint8_t *packet, int len )
 248 {
 249     for ( int i = 0; i < len; i++ )
 250         res[i] = bytereverse( packet[i] ) & 0x7f;
 251
 252     res[len] = '\0';
 253 }
 254
 255 static void HandleTelx( sout_stream_t *p_stream, block_t *p_block )
 256 {
 257     sout_stream_sys_t *p_sys = (sout_stream_sys_t *)p_stream->p_sys;
 258     int len = p_block->i_buffer;
 259
 260     for ( int offset = 1; offset + 46 <= len; offset += 46 )
 261     {
 262         uint8_t * packet = (uint8_t *) p_block->p_buffer+offset;
 263         if ( packet[0] == 0xFF )
 264             continue;
 265
 266         int mpag = (hamming_8_4( packet[4] ) << 4) | hamming_8_4( packet[5] );
 267         int i_row, i_magazine;
 268         if ( mpag < 0 )
 269         {
 270             /* decode error */
 271             continue;
 272         }
 273
 274         i_row = 0xFF & bytereverse(mpag);
 275         i_magazine = (7 & i_row) == 0 ? 8 : (7 & i_row);
 276         i_row >>= 3;
 277
 278         if ( i_magazine != p_sys->i_magazine )
 279             continue;
 280
 281         if ( i_row == 0 )
 282         {
 283             /* row 0 : flags and header line */
 284             p_sys->i_current_page =
 285                 (0xF0 & bytereverse( hamming_8_4(packet[7]) )) |
 286                 (0xF & (bytereverse( hamming_8_4(packet[6]) ) >> 4) );
 287         }
 288         if ( p_sys->i_current_page != p_sys->i_page ) continue;
 289         if ( i_row == p_sys->i_row )
 290         {
 291             /* row 1-23 : normal lines */
 292             char psz_line[41];
 293             decode_string( psz_line, packet + 6, 40 );
 294             psz_line[0] = tolower(psz_line[0]);
 295             psz_line[1] = tolower(psz_line[1]);
 296             psz_line[2] = tolower(psz_line[2]);
 297             psz_line[3] = '\0';
 298             SetLanguage( p_stream, psz_line );
 299         }
 300     }
 301 }
 302
 303 /*****************************************************************************
 304  * Send:
 305  *****************************************************************************/
 306 static int Send( sout_stream_t *p_stream, sout_stream_id_sys_t *id,
 307                  block_t *p_buffer )
 308 {
 309     sout_stream_sys_t *p_sys = (sout_stream_sys_t *)p_stream->p_sys;
 310
 311     if ( id == p_sys->p_telx )
 312         HandleTelx( p_stream, p_buffer );
 313
 314     return p_stream->p_next->pf_send( p_stream->p_next, id, p_buffer );
 315 }