parse.c

video linux conference

    if( p_sys->i_spu_size > (int)i_index + 1 )
    {
        /* Zero or one padding byte, are quite usual
         * More than one padding byte - this is very strange, but
         * we can deal with it */
        msg_Warn( p_dec, "%i padding bytes, we usually get 0 or 1 of them",
                  p_sys->i_spu_size - i_index );
    }

    /* Successfully parsed ! */
    return VLC_SUCCESS;
}

/*****************************************************************************
 * ParseRLE: parse the RLE part of the subtitle
 *****************************************************************************
 * This part parses the subtitle graphical data and stores it in a more
 * convenient structure for later decoding. For more information on the
 * subtitles format, see http://sam.zoy.org/doc/dvd/subtitles/index.html
 *****************************************************************************/
static int ParseRLE( decoder_t *p_dec, subpicture_t * p_spu,
                     subpicture_data_t *p_spu_data )
{
    decoder_sys_t *p_sys = p_dec->p_sys;
    uint8_t       *p_src = &p_sys->buffer[4];

    unsigned int i_code;

    unsigned int i_width = p_spu->i_width;
    unsigned int i_height = p_spu->i_height;
    unsigned int i_x, i_y;

    uint16_t *p_dest = (uint16_t *)p_spu_data->p_data;

    /* The subtitles are interlaced, we need two offsets */
    unsigned int  i_id = 0;                   /* Start on the even SPU layer */
    unsigned int  pi_table[ 2 ];
    unsigned int *pi_offset;

    /* Cropping */
    vlc_bool_t b_empty_top = VLC_TRUE;
    unsigned int i_skipped_top = 0, i_skipped_bottom = 0;
    unsigned int i_transparent_code = 0;
 
    /* Colormap statistics */
    int i_border = -1;
    int stats[4]; stats[0] = stats[1] = stats[2] = stats[3] = 0;

    pi_table[ 0 ] = p_spu_data->pi_offset[ 0 ] << 1;
    pi_table[ 1 ] = p_spu_data->pi_offset[ 1 ] << 1;

    for( i_y = 0 ; i_y < i_height ; i_y++ )
    {
        pi_offset = pi_table + i_id;

        for( i_x = 0 ; i_x < i_width ; i_x += i_code >> 2 )
        {
            i_code = AddNibble( 0, p_src, pi_offset );

            if( i_code < 0x04 )
            {
                i_code = AddNibble( i_code, p_src, pi_offset );

                if( i_code < 0x10 )
                {
                    i_code = AddNibble( i_code, p_src, pi_offset );

                    if( i_code < 0x040 )
                    {
                        i_code = AddNibble( i_code, p_src, pi_offset );

                        if( i_code < 0x0100 )
                        {
                            /* If the 14 first bits are set to 0, then it's a
                             * new line. We emulate it. */
                            if( i_code < 0x0004 )
                            {
                                i_code |= ( i_width - i_x ) << 2;
                            }
                            else
                            {
                                /* We have a boo boo ! */
                                msg_Err( p_dec, "unknown RLE code "
                                         "0x%.4x", i_code );
                                return VLC_EGENERIC;
                            }
                        }
                    }
                }
            }

            if( ( (i_code >> 2) + i_x + i_y * i_width ) > i_height * i_width )
            {
                msg_Err( p_dec, "out of bounds, %i at (%i,%i) is out of %ix%i",
                         i_code >> 2, i_x, i_y, i_width, i_height );
                return VLC_EGENERIC;
            }

            /* Try to find the border color */
            if( p_spu_data->pi_alpha[ i_code & 0x3 ] != 0x00 )
            {
                i_border = i_code & 0x3;
                stats[i_border] += i_code >> 2;
            }

            /* Auto crop subtitles (a lot more optimized) */
            if( p_spu_data->b_auto_crop )
            {
                if( !i_y )
                {
                    /* We assume that if the first line is transparent, then
                     * it is using the palette index for the
                     * (background) transparent color */
                    if( (i_code >> 2) == i_width &&
                        p_spu_data->pi_alpha[ i_code & 0x3 ] == 0x00 )
                    {
                        i_transparent_code = i_code;
                    }
                    else
                    {
                        p_spu_data->b_auto_crop = VLC_FALSE;
                    }
                }

                if( i_code == i_transparent_code )
                {
                    if( b_empty_top )
                    {
                        /* This is a blank top line, we skip it */
                      i_skipped_top++;
                    }
                    else
                    {
                        /* We can't be sure the current lines will be skipped,
                         * so we store the code just in case. */
                      *p_dest++ = i_code;
                      i_skipped_bottom++;
                    }
                }
                else
                {
                    /* We got a valid code, store it */
                    *p_dest++ = i_code;

                    /* Valid code means no blank line */
                    b_empty_top = VLC_FALSE;
                    i_skipped_bottom = 0;
                }
            }
            else
            {
                *p_dest++ = i_code;
            }
        }

        /* Check that we didn't go too far */
        if( i_x > i_width )
        {
            msg_Err( p_dec, "i_x overflowed, %i > %i", i_x, i_width );
            return VLC_EGENERIC;
        }

        /* Byte-align the stream */
        if( *pi_offset & 0x1 )
        {
            (*pi_offset)++;
        }

        /* Swap fields */
        i_id = ~i_id & 0x1;
    }

    /* We shouldn't get any padding bytes */
    if( i_y < i_height )
    {
        msg_Err( p_dec, "padding bytes found in RLE sequence" );
        msg_Err( p_dec, "send mail to <[e-mail]> if you "
                        "want to help debugging this" );

        /* Skip them just in case */
        while( i_y < i_height )
        {
            *p_dest++ = i_width << 2;
            i_y++;
        }

        return VLC_EGENERIC;
    }

    msg_Dbg( p_dec, "valid subtitle, size: %ix%i, position: %i,%i",
             p_spu->i_width, p_spu->i_height, p_spu->i_x, p_spu->i_y );

    /* Crop if necessary */
    if( i_skipped_top || i_skipped_bottom )
    {
        int i_y = p_spu->i_y + i_skipped_top;
        int i_height = p_spu->i_height - (i_skipped_top + i_skipped_bottom);

        p_spu_data->i_y_top_offset = i_skipped_top;
        p_spu_data->i_y_bottom_offset = i_skipped_bottom;
        msg_Dbg( p_dec, "cropped to: %ix%i, position: %i,%i",
                 p_spu->i_width, i_height, p_spu->i_x, i_y );
    }
 
    /* Handle color if no palette was found */
    if( !p_spu_data->b_palette )
    {
        int i, i_inner = -1, i_shade = -1;

        /* Set the border color */
        p_spu_data->pi_yuv[i_border][0] = 0x00;
        p_spu_data->pi_yuv[i_border][1] = 0x80;
        p_spu_data->pi_yuv[i_border][2] = 0x80;
        stats[i_border] = 0;

        /* Find the inner colors */
        for( i = 0 ; i < 4 && i_inner == -1 ; i++ )
        {
            if( stats[i] )
            {
                i_inner = i;
            }
        }

        for(       ; i < 4 && i_shade == -1 ; i++ )
        {
            if( stats[i] )
            {
                if( stats[i] > stats[i_inner] )
                {
                    i_shade = i_inner;
                    i_inner = i;
                }
                else
                {
                    i_shade = i;
                }
            }
        }

        /* Set the inner color */
        if( i_inner != -1 )
        {
            p_spu_data->pi_yuv[i_inner][0] = 0xff;
            p_spu_data->pi_yuv[i_inner][1] = 0x80;
            p_spu_data->pi_yuv[i_inner][2] = 0x80;
        }

        /* Set the anti-aliasing color */
        if( i_shade != -1 )
        {
            p_spu_data->pi_yuv[i_shade][0] = 0x80;
            p_spu_data->pi_yuv[i_shade][1] = 0x80;
            p_spu_data->pi_yuv[i_shade][2] = 0x80;
        }

        msg_Dbg( p_dec, "using custom palette (border %i, inner %i, shade %i)",
                 i_border, i_inner, i_shade );
    }

    return VLC_SUCCESS;
}

static void Render( decoder_t *p_dec, subpicture_t *p_spu,
                    subpicture_data_t *p_spu_data )
{
    uint8_t *p_p;
    int i_x, i_y, i_len, i_color, i_pitch;
    uint16_t *p_source = (uint16_t *)p_spu_data->p_data;
    video_format_t fmt;

    /* Create a new subpicture region */
    memset( &fmt, 0, sizeof(video_format_t) );
    fmt.i_chroma = VLC_FOURCC('Y','U','V','P');
    fmt.i_aspect = 0; /* 0 means use aspect ratio of background video */
    fmt.i_width = fmt.i_visible_width = p_spu->i_width;
    fmt.i_height = fmt.i_visible_height = p_spu->i_height -
        p_spu_data->i_y_top_offset - p_spu_data->i_y_bottom_offset;
    fmt.i_x_offset = fmt.i_y_offset = 0;
    p_spu->p_region = p_spu->pf_create_region( VLC_OBJECT(p_dec), &fmt );
    if( !p_spu->p_region )
    {
        msg_Err( p_dec, "cannot allocate SPU region" );
        return;
    }

    p_spu->p_region->i_x = 0;
    p_spu->p_region->i_y = p_spu_data->i_y_top_offset;
    p_p = p_spu->p_region->picture.p->p_pixels;
    i_pitch = p_spu->p_region->picture.p->i_pitch;

    /* Build palette */
    fmt.p_palette->i_entries = 4;
    for( i_x = 0; i_x < fmt.p_palette->i_entries; i_x++ )
    {
        fmt.p_palette->palette[i_x][0] = p_spu_data->pi_yuv[i_x][0];
        fmt.p_palette->palette[i_x][1] = p_spu_data->pi_yuv[i_x][1];
        fmt.p_palette->palette[i_x][2] = p_spu_data->pi_yuv[i_x][2];
        fmt.p_palette->palette[i_x][3] =
            p_spu_data->pi_alpha[i_x] == 0xf ? 0xff :
            p_spu_data->pi_alpha[i_x] << 4;
    }

    /* Draw until we reach the bottom of the subtitle */
    for( i_y = 0; i_y < (int)fmt.i_height * i_pitch; i_y += i_pitch )
    {
        /* Draw until we reach the end of the line */
        for( i_x = 0 ; i_x < (int)fmt.i_width; i_x += i_len )
        {
            /* Get the RLE part, then draw the line */
            i_color = *p_source & 0x3;
            i_len = *p_source++ >> 2;
            memset( p_p + i_x + i_y, i_color, i_len );
        }
    }
}