telx.c

uclinux 下的vlc播放器源代码

/*****************************************************************************
 * telx.c : Minimalistic Teletext subtitles decoder
 *****************************************************************************
 * Copyright (C) 2007 Vincent Penne
 * Some code converted from ProjectX java dvb decoder (c) 2001-2005 by dvb.matt
 * $Id: telx.c 19719 2007-04-06 18:03:48Z massiot $
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
 *****************************************************************************/
/*****************************************************************************
 * 
 * information on teletext format can be found here : 
 * http://pdc.ro.nu/teletext.html
 *
 *****************************************************************************/
#include <vlc/vlc.h>
#include <assert.h>
#include <stdint.h>

#include <vlc/vout.h>
#include <vlc/decoder.h>
#include "vlc_bits.h"

/* #define TELX_DEBUG */
#ifdef TELX_DEBUG
#   define dbg( a ) msg_Dbg a 
#else
#   define dbg( a )
#endif

/*****************************************************************************
 * Module descriptor.
 *****************************************************************************/
static int  Open ( vlc_object_t * );
static void Close( vlc_object_t * );
static subpicture_t *Decode( decoder_t *, block_t ** );

#define OVERRIDE_PAGE_TEXT N_("Override page")
#define OVERRIDE_PAGE_LONGTEXT N_("Override the indicated page, try this if " \
        "your subtitles don't appear (-1 = autodetect from TS, " \
        "0 = autodetect from teletext, " \
        ">0 = actual page number, usually 888 or 889).")

#define IGNORE_SUB_FLAG_TEXT N_("Ignore subtitle flag")
#define IGNORE_SUB_FLAG_LONGTEXT N_("Ignore the subtitle flag, try this if " \
        "your subtitles don't appear.")

#define FRENCH_WORKAROUND_TEXT N_("Workaround for France")
#define FRENCH_WORKAROUND_LONGTEXT N_("Some French channels do not flag " \
        "their subtitling pages correctly due to a historical " \
        "interpretation mistake. Try using this wrong interpretation if " \
        "your subtitles don't appear.")

vlc_module_begin();
    set_description( _("Teletext subtitles decoder") );
    set_shortname( "Teletext" );
    set_capability( "decoder", 50 );
    set_category( CAT_INPUT );
    set_subcategory( SUBCAT_INPUT_SCODEC );
    set_callbacks( Open, Close );

    add_integer( "telx-override-page", -1, NULL,
                 OVERRIDE_PAGE_TEXT, OVERRIDE_PAGE_LONGTEXT, VLC_TRUE );
    add_bool( "telx-ignore-subtitle-flag", 0, NULL,
              IGNORE_SUB_FLAG_TEXT, IGNORE_SUB_FLAG_LONGTEXT, VLC_TRUE );
    add_bool( "telx-french-workaround", 0, NULL,
              FRENCH_WORKAROUND_TEXT, FRENCH_WORKAROUND_LONGTEXT, VLC_TRUE );

vlc_module_end();

/****************************************************************************
 * Local structures
 ****************************************************************************/

struct decoder_sys_t
{
  int         i_align;
  vlc_bool_t  b_is_subtitle[9];
  char        ppsz_lines[32][128];
  char        psz_prev_text[512];
  mtime_t     prev_pts;
  int         i_page[9];
  vlc_bool_t  b_erase[9];
  uint16_t *  pi_active_national_set[9];
  int         i_wanted_page, i_wanted_magazine;
  vlc_bool_t  b_ignore_sub_flag;
};

/****************************************************************************
 * Local data
 ****************************************************************************/

/*
 * My doc only mentions 13 national characters, but experiments show there 
 * are more, in france for example I already found two more (0x9 and 0xb).
 *
 * Conversion is in this order :
 *
 * 0x23 0x24 0x40 0x5b 0x5c 0x5d 0x5e 0x5f 0x60 0x7b 0x7c 0x7d 0x7e
 * (these are the standard ones)
 * 0x08 0x09 0x0a 0x0b 0x0c 0x0d (apparently a control character) 0x0e 0x0f
 */

static uint16_t ppi_national_subsets[][20] =
{
  { 0x00a3, 0x0024, 0x0040, 0x00ab, 0x00bd, 0x00bb, 0x005e, 0x0023, 
    0x002d, 0x00bc, 0x00a6, 0x00be, 0x00f7 }, /* english ,000 */

  { 0x00e9, 0x00ef, 0x00e0, 0x00eb, 0x00ea, 0x00f9, 0x00ee, 0x0023,
    0x00e8, 0x00e2, 0x00f4, 0x00fb, 0x00e7, 0, 0x00eb, 0, 0x00ef }, /* french  ,001 */

  { 0x0023, 0x00a4, 0x00c9, 0x00c4, 0x00d6, 0x00c5, 0x00dc, 0x005f, 
    0x00e9, 0x00e4, 0x00f6, 0x00e5, 0x00fc }, /* swedish,finnish,hungarian ,010 */

  { 0x0023, 0x016f, 0x010d, 0x0165, 0x017e, 0x00fd, 0x00ed, 0x0159, 
    0x00e9, 0x00e1, 0x0115, 0x00fa, 0x0161 }, /* czech,slovak  ,011 */

  { 0x0023, 0x0024, 0x00a7, 0x00c4, 0x00d6, 0x00dc, 0x005e, 0x005f, 
    0x00b0, 0x00e4, 0x00f6, 0x00fc, 0x00df }, /* german ,100 */

  { 0x00e7, 0x0024, 0x00a1, 0x00e1, 0x00e9, 0x00ed, 0x00f3, 0x00fa, 
    0x00bf, 0x00fc, 0x00f1, 0x00e8, 0x00e0 }, /* portuguese,spanish ,101 */

  { 0x00a3, 0x0024, 0x00e9, 0x00b0, 0x00e7, 0x00bb, 0x005e, 0x0023, 
    0x00f9, 0x00e0, 0x00f2, 0x00e8, 0x00ec }, /* italian  ,110 */

  { 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 */

  { 0x0023, 0x0144, 0x0105, 0x005a, 0x015a, 0x0141, 0x0107, 0x00f3, 
    0x0119, 0x017c, 0x015b, 0x0142, 0x017a }, /* polish,  1001 */

  { 0x0023, 0x00cb, 0x010c, 0x0106, 0x017d, 0x0110, 0x0160, 0x00eb, 
    0x010d, 0x0107, 0x017e, 0x0111, 0x0161 }, /* serbian,croatian,slovenian, 1010 */

  { 0x0023, 0x00f5, 0x0160, 0x00c4, 0x00d6, 0x017e, 0x00dc, 0x00d5, 
    0x0161, 0x00e4, 0x00f6, 0x017e, 0x00fc }, /* estonian  ,1011 */

  { 0x0054, 0x011f, 0x0130, 0x015e, 0x00d6, 0x00c7, 0x00dc, 0x011e, 
    0x0131, 0x015f, 0x00f6, 0x00e7, 0x00fc }, /* turkish  ,1100 */
};


/*****************************************************************************
 * Open: probe the decoder and return score
 *****************************************************************************
 * Tries to launch a decoder and return score so that the interface is able
 * to chose.
 *****************************************************************************/
static int Open( vlc_object_t *p_this )
{
    decoder_t     *p_dec = (decoder_t *) p_this;
    decoder_sys_t *p_sys = NULL;
    vlc_value_t    val;
    int            i;

    if( p_dec->fmt_in.i_codec != VLC_FOURCC('t','e','l','x'))
    {
        return VLC_EGENERIC;
    }

    p_dec->pf_decode_sub = Decode;
    p_sys = p_dec->p_sys = malloc( sizeof(decoder_sys_t) );
    if( p_sys == NULL )
    {
        msg_Err( p_dec, "out of memory" );
        return VLC_ENOMEM;
    }


    memset( p_sys, 0, sizeof(decoder_sys_t) );

    p_sys->i_align = 0;
    for ( i = 0; i < 9; i++ )
        p_sys->pi_active_national_set[i] = ppi_national_subsets[1];

    var_Create( p_dec, "telx-override-page",
                VLC_VAR_BOOL | VLC_VAR_DOINHERIT );
    var_Get( p_dec, "telx-override-page", &val );
    if( val.i_int == -1 && p_dec->fmt_in.subs.dvb.i_id != -1 )
    {
        p_sys->i_wanted_magazine = p_dec->fmt_in.subs.dvb.i_id >> 16;
        if( p_sys->i_wanted_magazine == 0 )
            p_sys->i_wanted_magazine = 8;
        p_sys->i_wanted_page = p_dec->fmt_in.subs.dvb.i_id & 0xff;

        var_Create( p_dec, "telx-french-workaround",
                    VLC_VAR_BOOL | VLC_VAR_DOINHERIT );
        var_Get( p_dec, "telx-french-workaround", &val );
        if( p_sys->i_wanted_page < 100 &&
              (val.b_bool || (p_sys->i_wanted_page % 16) >= 10))
        {
            /* See http://www.nada.kth.se/~ragge/vdr/ttxtsubs/TROUBLESHOOTING.txt
             * paragraph about French channels - they mix up decimal and
             * hexadecimal */
            p_sys->i_wanted_page = (p_sys->i_wanted_page / 10) * 16 +
                                   (p_sys->i_wanted_page % 10);
        }
    }
    else if( val.i_int <= 0 )
    {
        p_sys->i_wanted_magazine = -1;
        p_sys->i_wanted_page = -1;
    }
    else
    {
        p_sys->i_wanted_magazine = val.i_int / 100;
        p_sys->i_wanted_page = (((val.i_int % 100) / 10) << 4)
                                | ((val.i_int % 100) % 10);
    }
    var_Create( p_dec, "telx-ignore-subtitle-flag",
                VLC_VAR_BOOL | VLC_VAR_DOINHERIT );
    var_Get( p_dec, "telx-ignore-subtitle-flag", &val );
    p_sys->b_ignore_sub_flag = val.b_bool;

    msg_Dbg( p_dec, "starting telx on magazine %d page %x flag %d",
             p_sys->i_wanted_magazine, p_sys->i_wanted_page,
             p_sys->b_ignore_sub_flag );

    return VLC_SUCCESS;

/*  error: */
/*     if (p_sys) { */
/*       free(p_sys); */
/*       p_sys = NULL; */
/*     } */
/*     return VLC_EGENERIC; */
}

/*****************************************************************************
 * Close:
 *****************************************************************************/
static void Close( vlc_object_t *p_this )
{
    decoder_t     *p_dec = (decoder_t*) p_this;
    decoder_sys_t *p_sys = p_dec->p_sys;

    free( p_sys );
}

/**************************
 * change bits endianness *
 **************************/
static uint8_t bytereverse( int n )
{
    n = (((n >> 1) & 0x55) | ((n << 1) & 0xaa));
    n = (((n >> 2) & 0x33) | ((n << 2) & 0xcc));
    n = (((n >> 4) & 0x0f) | ((n << 4) & 0xf0));
    return n;
}

static int hamming_8_4( int a )
{
    switch (a) {
    case 0xA8: 
        return 0;
    case 0x0B: 
        return 1;
    case 0x26: 
        return 2;
    case 0x85: 
        return 3;
    case 0x92: 
        return 4;
    case 0x31: 
        return 5;
    case 0x1C: 
        return 6;
    case 0xBF: 
        return 7;
    case 0x40: 
        return 8;
    case 0xE3: 
        return 9;
    case 0xCE: 
        return 10;
    case 0x6D: 
        return 11;
    case 0x7A: 
        return 12;
    case 0xD9: 
        return 13;
    case 0xF4: 
        return 14;
    case 0x57: 
        return 15;
    default: 
        return -1;     // decoding error , not yet corrected
    }
}

// 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 )
    {
        if( ch >= 0x800 )
        {
            res[0] = (ch >> 12) | 0xE0;
            res[1] = ((ch >> 6) & 0x3F) | 0x80;
            res[2] = (ch & 0x3F) | 0x80;
            res[3] = 0;
        }
        else
        {
            res[0] = (ch >> 6) | 0xC0;
            res[1] = (ch & 0x3F) | 0x80;
            res[2] = 0;
        }
    }
    else
    {
        res[0] = ch;
        res[1] = 0;
    }
}

static void decode_string( char * res, int res_len, 
                           decoder_sys_t *p_sys, int magazine, 
                           uint8_t * packet, int len )
{
    char utf8[7];
    char * pt = res;
    int i;

    for ( i = 0; i < len; i++ )
    {
        int in = bytereverse( packet[i] ) & 0x7f;
        uint16_t out = 32;
        size_t l;

        switch ( in )
        {
        /* special national characters */
        case 0x23:
            out = p_sys->pi_active_national_set[magazine][0]; 
            break; 
        case 0x24:
            out = p_sys->pi_active_national_set[magazine][1]; 
            break; 
        case 0x40:
            out = p_sys->pi_active_national_set[magazine][2]; 
            break; 
        case 0x5b:
            out = p_sys->pi_active_national_set[magazine][3]; 
            break; 
        case 0x5c:
            out = p_sys->pi_active_national_set[magazine][4]; 
            break; 
        case 0x5d:
            out = p_sys->pi_active_national_set[magazine][5]; 
            break;