Teletext module patch by Vincent Penne

- the stream provided by thedj containing some kind of VPS informations know works fine (they aren't displayed as subtitles anymore). It also solve the same issue on two examples streams on the vlc file repository (called stream-demux-telx-1.dump and stream-demux-telx-2.dump)

- got rid of a kludge that used to be necessary on the "has-subtitles.ts" example stream to avoid subtitles disapearing too fast in some cases. I don't know exactly why it's not anymore necessary, probably because I handle better the subtitle flag now.

- now the page number is handled independently for each 8 magazines

modules/codec/telx.c

@@ -110,7 +110,7 @@ struct decoder_sys_t
   char        ppsz_lines[32][128];
   char        psz_prev_text[512];
   mtime_t     prev_pts;
-  int         i_page;
+  int         i_page[9];
   vlc_bool_t  b_erase[9];
   uint16_t *  pi_active_national_set[9];
 };
@@ -159,6 +159,7 @@ static uint16_t ppi_national_subsets[][20] =
   { 0x0023, 0x00a4, 0x0162, 0x00c2, 0x015e, 0x0102, 0x00ce, 0x0131, 
     0x0163, 0x00e2, 0x015f, 0x0103, 0x00ee }, /* rumanian ,111 */
 
+  /* I have these tables too, but I don't know how they can be triggered */
   { 0x0023, 0x0024, 0x0160, 0x0117, 0x0119, 0x017d, 0x010d, 0x016b, 
     0x0161, 0x0105, 0x0173, 0x017e, 0x012f }, /* lettish,lithuanian ,1000 */
 
@@ -315,6 +316,7 @@ static int hamming_8_4( int a )
 
 // utc-2 --> utf-8
 // this is not a general function, but it's enough for what we do here
+// the result buffer need to be at least 4 bytes long
 static void to_utf8( char * res, uint16_t ch )
 {
     if( ch >= 0x80 )
@@ -461,13 +463,18 @@ static subpicture_t *Decode( decoder_t *p_dec, block_t **pp_block )
     p_block = *pp_block;
     *pp_block = NULL;
 
+    dbg((p_dec, "start of telx packet with header %2x\n",
+                * (uint8_t *) p_block->p_buffer));
     len = p_block->i_buffer;
     for ( offset = 1; offset + 46 <= len; offset += 46 )
     {
         uint8_t * packet = (uint8_t *) p_block->p_buffer+offset;
+        int vbi = ((0x20 & packet[2]) != 0 ? 0 : 313) + (0x1F & packet[2]);
       
-        /* dbg((p_dec, "header %02x %02x %02x\n", packet[0], packet[1], packet[2])); */
-/*       if (packet[1] != 0x2C) { */
+        dbg((p_dec, "vbi %d header %02x %02x %02x\n", vbi packet[0], packet[1], packet[2]));
+        if ( packet[0] == 0xFF ) continue;
+
+/*      if (packet[1] != 0x2C) { */
 /*         printf("wrong header\n"); */
 /*         //goto error; */
 /*         continue; */
@@ -500,28 +507,37 @@ static subpicture_t *Decode( decoder_t *p_dec, block_t **pp_block )
                           << (a * 4);
             }
 
-            dbg((p_dec, "mag %d flags %x page %x character set %d subtitles %d\n%s\n", magazine, flag, 
-                 //p_sys->i_page, 
-                 (0xF0 & bytereverse(hamming_8_4(packet[7]) )) |
-                 (0xF & bytereverse(hamming_8_4(packet[6]) )>>4 ),
-                 7 & flag>>21, 1 & flag>>15, t));
-
     /*         if (!b_ignore_sub_flag && !(1 & flag>>15)) */
     /*           continue; */
 
-            p_sys->i_page = (0xF0 & bytereverse( hamming_8_4(packet[7]) )) |
+            p_sys->i_page[magazine] = (0xF0 & bytereverse( hamming_8_4(packet[7]) )) |
                              (0xF & (bytereverse( hamming_8_4(packet[6]) ) >> 4) );
 
             decode_string( psz_line, sizeof(psz_line), p_sys, magazine,
                            packet + 14, 40 - 14 );
 
+            dbg((p_dec, "mag %d flags %x page %x character set %d subtitles %d", magazine, flag,
+                 p_sys->i_page[magazine],
+                 7 & flag>>21, 1 & flag>>15, psz_line));
+
             p_sys->pi_active_national_set[magazine] =
                                  ppi_national_subsets[7 & (flag >> 21)];
 
             p_sys->b_is_subtitle[magazine] = b_ignore_sub_flag
-                                              || (1 & (flag >> 15));
-            
-            if ( (i_conf_wanted_page && p_sys->i_page != i_wanted_page)
+                                              || ( (1 & (flag >> 15))
+                                                  && (1 & (flag>>16)) );
+
+            dbg(( p_dec, "FLAGS%s%s%s%s%s%s%s mag_ser %d",
+                  (1 & (flag>>14))? " news" : "",
+                  (1 & (flag>>15))? " subtitle" : "",
+                  (1 & (flag>>7))? " erase" : "",
+                  (1 & (flag>>16))? " suppressed_head" : "",
+                  (1 & (flag>>17))? " update" : "",
+                  (1 & (flag>>18))? " interrupt" : "",
+                  (1 & (flag>>19))? " inhibit" : "",
+                  (1 & (flag>>20)) ));
+           
+            if ( (i_conf_wanted_page && p_sys->i_page[magazine] != i_wanted_page)
                    || !p_sys->b_is_subtitle[magazine] )
                 continue;
 
@@ -531,8 +547,10 @@ static subpicture_t *Decode( decoder_t *p_dec, block_t **pp_block )
             /* kludge here : 
              * we ignore the erase flag if it happens less than 1.5 seconds
              * before last caption
-             *TODO make this time configurable */
-            if ( p_block->i_pts > p_sys->prev_pts + 1500000 && 
+             * TODO   make this time configurable
+             * UPDATE the kludge seems to be no more necessary
+             *        so it's commented out*/
+            if ( /*p_block->i_pts > p_sys->prev_pts + 1500000 && */
                  p_sys->b_erase[magazine] )
             {
                 int i;
@@ -563,8 +581,9 @@ static subpicture_t *Decode( decoder_t *p_dec, block_t **pp_block )
             int i;
             /* row 1-23 : normal lines */
 
-            if ( (i_conf_wanted_page && p_sys->i_page != i_wanted_page)
-                   || !p_sys->b_is_subtitle[magazine] )
+            if ( (i_conf_wanted_page && p_sys->i_page[magazine] != i_wanted_page)
+                   || !p_sys->b_is_subtitle[magazine] 
+                   || (!i_conf_wanted_page && p_sys->i_page[magazine] > 0x99) )
                 continue;
 
             decode_string( psz_line, sizeof(psz_line), p_sys, magazine,
@@ -617,7 +636,7 @@ static subpicture_t *Decode( decoder_t *p_dec, block_t **pp_block )
         else if ( row == 25 )
         {
             /* row 25 : alternate header line */
-            if ( (i_conf_wanted_page && p_sys->i_page != i_wanted_page)
+            if ( (i_conf_wanted_page && p_sys->i_page[magazine] != i_wanted_page)
                    || !p_sys->b_is_subtitle[magazine] )
                 continue;