vlc/modules/codec/substtml.c

/*****************************************************************************
 * substtml.c : TTML subtitles decoder
 *****************************************************************************
 * Copyright (C) 2015 VLC authors and VideoLAN
 *
 * Authors: Hugo Beauzée-Luyssen <hugo@beauzee.fr>
 *          Sushma Reddy <sushma.reddy@research.iiit.ac.in>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser 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.
 *****************************************************************************/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#include <vlc_common.h>
#include <vlc_plugin.h>
#include <vlc_modules.h>
#include <vlc_codec.h>

#include "substext.h"

#define ALIGN_TEXT N_("Subtitle justification")
#define ALIGN_LONGTEXT N_("Set the justification of subtitles")

/*****************************************************************************
 * Module descriptor.
 *****************************************************************************/
static int  OpenDecoder   ( vlc_object_t * );
static void CloseDecoder  ( vlc_object_t * );

vlc_module_begin ()
    set_capability( "decoder", 10 )
    set_shortname( N_("TTML decoder"))
    set_description( N_("TTML subtitles decoder") )
    set_callbacks( OpenDecoder, CloseDecoder )
    set_category( CAT_INPUT )
    set_subcategory( SUBCAT_INPUT_SCODEC )
    add_integer( "ttml-align", 0, ALIGN_TEXT, ALIGN_LONGTEXT, false )
vlc_module_end ();


/*****************************************************************************
 * Local prototypes
 *****************************************************************************/

struct decoder_sys_t
{
    int i_align;
};

static subpicture_t *ParseText( decoder_t *p_dec, block_t *p_block )
{
    decoder_sys_t *p_sys = p_dec->p_sys;
    subpicture_t *p_spu = NULL;
    char *psz_subtitle = NULL;

    /* We cannot display a subpicture with no date */
    if( p_block->i_pts <= VLC_TS_INVALID )
    {
        msg_Warn( p_dec, "subtitle without a date" );
        return NULL;
    }

    /* Check validity of packet data */
    /* An "empty" line containing only \0 can be used to force
       and ephemer picture from the screen */

    if( p_block->i_buffer < 1 )
    {
        msg_Warn( p_dec, "no subtitle data" );
        return NULL;
    }

    psz_subtitle = malloc( p_block->i_buffer );
    if ( unlikely( psz_subtitle == NULL ) )
        return NULL;
    memcpy( psz_subtitle, p_block->p_buffer, p_block->i_buffer );

    /* Create the subpicture unit */
    p_spu = decoder_NewSubpictureText( p_dec );
    if( !p_spu )
    {
        free( psz_subtitle );
        return NULL;
    }
    p_spu->i_start    = p_block->i_pts;
    p_spu->i_stop     = p_block->i_pts + p_block->i_length;
    p_spu->b_ephemer  = (p_block->i_length == 0);
    p_spu->b_absolute = false;
    subpicture_updater_sys_t *p_spu_sys = p_spu->updater.p_sys;

    p_spu_sys->align = SUBPICTURE_ALIGN_BOTTOM | p_sys->i_align;
    p_spu_sys->text  = psz_subtitle;

    return p_spu;
}

/****************************************************************************
 * DecodeBlock: the whole thing
 ****************************************************************************/
static subpicture_t *DecodeBlock( decoder_t *p_dec, block_t **pp_block )
{
    if( !pp_block || *pp_block == NULL )
        return NULL;

    block_t* p_block = *pp_block;
    subpicture_t *p_spu = ParseText( p_dec, p_block );

    block_Release( p_block );
    *pp_block = NULL;

    return p_spu;
}

/*****************************************************************************
 * OpenDecoder: probe the decoder and return score
 *****************************************************************************/
static int OpenDecoder( vlc_object_t *p_this )
{
    decoder_t *p_dec = (decoder_t*)p_this;
    decoder_sys_t *p_sys;

    if ( p_dec->fmt_in.i_codec != VLC_CODEC_TTML )
    {
        return VLC_EGENERIC;
    }

    /* Allocate the memory needed to store the decoder's structure */
    p_dec->p_sys = p_sys = calloc( 1, sizeof( *p_sys ) );
    if( unlikely( p_sys == NULL ) )
    {
        return VLC_ENOMEM;
    }

    p_dec->pf_decode_sub = DecodeBlock;
    p_dec->fmt_out.i_cat = SPU_ES;
    p_sys->i_align = var_InheritInteger( p_dec, "ttml-align" );
    return VLC_SUCCESS;
}

/*****************************************************************************
 * CloseDecoder: clean up the decoder
 *****************************************************************************/
static void CloseDecoder( vlc_object_t *p_this )
{
    /* Cleanup here */
    decoder_t *p_dec = (decoder_t *)p_this;
    decoder_sys_t *p_sys = p_dec->p_sys;

    free( p_sys );
}