dvbsub.c

video linux conference

        bs_write( s, 16, 10 + 6 + (b_text ? 2 : 0) ); /* Segment length */
        bs_write( s, 8, i_region );
        bs_write( s, 4, p_sys->i_region_ver++ );

        /* Region attributes */
        bs_write( s, 1, i_bg < i_entries ); /* Fill */
        bs_write( s, 3, 0 ); /* Reserved */
        bs_write( s, 16, p_sys->p_regions[i_region].i_width );
        bs_write( s, 16, p_sys->p_regions[i_region].i_height );
        bs_write( s, 3, i_depth );  /* Region level of compatibility */
        bs_write( s, 3, i_depth  ); /* Region depth */
        bs_write( s, 2, 0 ); /* Reserved */
        bs_write( s, 8, 1 ); /* Clut id */
        bs_write( s, 8, i_bg ); /* region 8bit pixel code */
        bs_write( s, 4, i_bg ); /* region 4bit pixel code */
        bs_write( s, 2, i_bg ); /* region 2bit pixel code */
        bs_write( s, 2, 0 ); /* Reserved */

        /* In our implementation we only have 1 object per region */
        bs_write( s, 16, i_region );
        bs_write( s, 2, b_text ? DVBSUB_OT_BASIC_CHAR:DVBSUB_OT_BASIC_BITMAP );
        bs_write( s, 2, 0 ); /* object provider flag */
        bs_write( s, 12, 0 ); /* object horizontal position */
        bs_write( s, 4, 0 ); /* Reserved */
        bs_write( s, 12, 0 ); /* object vertical position */

        if( b_text )
        {
            bs_write( s, 8, 1 ); /* foreground pixel code */
            bs_write( s, 8, 0 ); /* background pixel code */
        }
    }
}

static void encode_pixel_data( encoder_t *p_enc, bs_t *s,
                               subpicture_region_t *p_region,
                               vlc_bool_t b_top );

static void encode_object( encoder_t *p_enc, bs_t *s, subpicture_t *p_subpic )
{
    encoder_sys_t *p_sys = p_enc->p_sys;
    subpicture_region_t *p_region;
    int i_region;

    int i_length_pos, i_update_pos, i_pixel_data_pos;

    for( i_region = 0, p_region = p_subpic->p_region; p_region;
         p_region = p_region->p_next, i_region++ )
    {
        bs_write( s, 8, 0x0f ); /* Sync byte */
        bs_write( s, 8, DVBSUB_ST_OBJECT_DATA ); /* Segment type */
        bs_write( s, 16, 1 ); /* Page id */

        i_length_pos = bs_pos( s );
        bs_write( s, 16, 0 ); /* Segment length */
        bs_write( s, 16, i_region ); /* Object id */
        bs_write( s, 4, p_sys->i_region_ver++ );

        /* object coding method */
        switch( p_region->fmt.i_chroma )
        {
        case VLC_FOURCC( 'Y','U','V','P' ):
            bs_write( s, 2, 0 );
            break;
        case VLC_FOURCC( 'T','E','X','T' ):
            bs_write( s, 2, 1 );
            break;
        }

        bs_write( s, 1, 0 ); /* non modifying color flag */
        bs_write( s, 1, 0 ); /* Reserved */

        if( p_region->fmt.i_chroma == VLC_FOURCC( 'T','E','X','T' ) )
        {
            int i_size, i;

            if( !p_region->psz_text ) continue;

            i_size = __MIN( strlen( p_region->psz_text ), 256 );

            bs_write( s, 8, i_size ); /* number of characters in string */
            for( i = 0; i < i_size; i++ )
            {
                bs_write( s, 16, p_region->psz_text[i] );
            }     

            /* Update segment length */
            SetWBE( &s->p_start[i_length_pos/8],
                    (bs_pos(s) - i_length_pos)/8 -2 );
            continue;
        }

        /* Coding of a bitmap object */

        i_update_pos = bs_pos( s );
        bs_write( s, 16, 0 ); /* topfield data block length */
        bs_write( s, 16, 0 ); /* bottomfield data block length */

        /* Top field */
        i_pixel_data_pos = bs_pos( s );
        encode_pixel_data( p_enc, s, p_region, VLC_TRUE );
        i_pixel_data_pos = ( bs_pos( s ) - i_pixel_data_pos ) / 8;
        SetWBE( &s->p_start[i_update_pos/8], i_pixel_data_pos );

        /* Bottom field */
        i_pixel_data_pos = bs_pos( s );
        encode_pixel_data( p_enc, s, p_region, VLC_FALSE );
        i_pixel_data_pos = ( bs_pos( s ) - i_pixel_data_pos ) / 8;
        SetWBE( &s->p_start[i_update_pos/8+2], i_pixel_data_pos );

        /* Stuffing for word alignment */
        bs_align_0( s );
        if( bs_pos( s ) % 16 ) bs_write( s, 8, 0 );

        /* Update segment length */
        SetWBE( &s->p_start[i_length_pos/8], (bs_pos(s) - i_length_pos)/8 -2 );
    }
}

static void encode_pixel_line_2bp( encoder_t *p_enc, bs_t *s,
                                   subpicture_region_t *p_region,
                                   int i_line );
static void encode_pixel_line_4bp( encoder_t *p_enc, bs_t *s,
                                   subpicture_region_t *p_region,
                                   int i_line );
static void encode_pixel_line_8bp( encoder_t *p_enc, bs_t *s,
                                   subpicture_region_t *p_region,
                                   int i_line );
static void encode_pixel_data( encoder_t *p_enc, bs_t *s,
                               subpicture_region_t *p_region,
                               vlc_bool_t b_top )
{
    unsigned int i_line;

    /* Sanity check */
    if( p_region->fmt.i_chroma != VLC_FOURCC('Y','U','V','P') ) return;

    /* Encode line by line */
    for( i_line = !b_top; i_line < p_region->fmt.i_visible_height;
         i_line += 2 )
    {
        switch( p_region->fmt.p_palette->i_entries )
        {
        case 4:
            bs_write( s, 8, 0x10 ); /* 2 bit/pixel code string */
            encode_pixel_line_2bp( p_enc, s, p_region, i_line );
            break;

        case 16:
            bs_write( s, 8, 0x11 ); /* 4 bit/pixel code string */
            encode_pixel_line_4bp( p_enc, s, p_region, i_line );
            break;

        case 256:
            bs_write( s, 8, 0x12 ); /* 8 bit/pixel code string */
            encode_pixel_line_8bp( p_enc, s, p_region, i_line );
            break;

        default:
            msg_Err( p_enc, "subpicture palette (%i) not handled",
                     p_region->fmt.p_palette->i_entries );
            break;
        }

        bs_write( s, 8, 0xf0 ); /* End of object line code */
    }
}

static void encode_pixel_line_2bp( encoder_t *p_enc, bs_t *s,
                                   subpicture_region_t *p_region,
                                   int i_line )
{
    unsigned int i, i_length = 0;
    int i_pitch = p_region->picture.p->i_pitch;
    uint8_t *p_data = &p_region->picture.p->p_pixels[ i_pitch * i_line ];
    int i_last_pixel = p_data[0];

    for( i = 0; i <= p_region->fmt.i_visible_width; i++ )
    {
        if( i != p_region->fmt.i_visible_width &&
            p_data[i] == i_last_pixel && i_length != 284 )
        {
            i_length++;
            continue;
        }

        if( i_length == 1 || i_length == 11 || i_length == 28 )
        {
            /* 2bit/pixel code */
            if( i_last_pixel ) bs_write( s, 2, i_last_pixel );
            else
            {
                bs_write( s, 2, 0 );
                bs_write( s, 1, 0 );
                bs_write( s, 1, 1 ); /* pseudo color 0 */
            }
            i_length--;
        }

        if( i_length == 2 )
        {
            if( i_last_pixel )
            {
                bs_write( s, 2, i_last_pixel );
                bs_write( s, 2, i_last_pixel );
            }
            else
            {
                bs_write( s, 2, 0 );
                bs_write( s, 1, 0 );
                bs_write( s, 1, 0 );
                bs_write( s, 2, 1 ); /* 2 * pseudo color 0 */
            }
        }
        else if( i_length > 2 )
        {
            bs_write( s, 2, 0 );
            if( i_length <= 10 )
            {
                bs_write( s, 1, 1 );
                bs_write( s, 3, i_length - 3 );
                bs_write( s, 2, i_last_pixel );
            }
            else
            {
                bs_write( s, 1, 0 );
                bs_write( s, 1, 0 );

                if( i_length <= 27 )
                {
                    bs_write( s, 2, 2 );
                    bs_write( s, 4, i_length - 12 );
                    bs_write( s, 2, i_last_pixel );
                }
                else
                {
                    bs_write( s, 2, 3 );
                    bs_write( s, 8, i_length - 29 );
                    bs_write( s, 2, i_last_pixel );
                }
            }
        }

        if( i == p_region->fmt.i_visible_width ) break;

        i_last_pixel = p_data[i];
        i_length = 1;
    }

    /* Stop */
    bs_write( s, 2, 0 );
    bs_write( s, 1, 0 );
    bs_write( s, 1, 0 );
    bs_write( s, 2, 0 );

    /* Stuffing */
    bs_align_0( s );
}

static void encode_pixel_line_4bp( encoder_t *p_enc, bs_t *s,
                                   subpicture_region_t *p_region,
                                   int i_line )
{
    unsigned int i, i_length = 0;
    int i_pitch = p_region->picture.p->i_pitch;
    uint8_t *p_data = &p_region->picture.p->p_pixels[ i_pitch * i_line ];
    int i_last_pixel = p_data[0];

    for( i = 0; i <= p_region->fmt.i_visible_width; i++ )
    {
        if( i != p_region->fmt.i_visible_width &&
            p_data[i] == i_last_pixel && i_length != 280 )
        {
            i_length++;
            continue;
        }

        if( i_length == 1 || (i_length == 3 && i_last_pixel) || i_length == 8 )
        {
            /* 4bit/pixel code */
            if( i_last_pixel ) bs_write( s, 4, i_last_pixel );
            else
            {
                bs_write( s, 4, 0 );
                bs_write( s, 1, 1 );
                bs_write( s, 1, 1 );
                bs_write( s, 2, 0 ); /* pseudo color 0 */
            }
            i_length--;
        }

        if( i_length == 2 )
        {
            if( i_last_pixel )
            {
                bs_write( s, 4, i_last_pixel );
                bs_write( s, 4, i_last_pixel );
            }
            else
            {
                bs_write( s, 4, 0 );
                bs_write( s, 1, 1 );
                bs_write( s, 1, 1 );
                bs_write( s, 2, 1 ); /* 2 * pseudo color 0 */
            }
        }
        else if( !i_last_pixel && i_length >= 3 && i_length <= 9 )
        {
            bs_write( s, 4, 0 );
            bs_write( s, 1, 0 );
            bs_write( s, 3, i_length - 2 ); /* (i_length - 2) * color 0 */
        }
        else if( i_length > 2 )
        {
            bs_write( s, 4, 0 );
            bs_write( s, 1, 1 );

            if( i_length <= 7 )
            {
                bs_write( s, 1, 0 );
                bs_write( s, 2, i_length - 4 );
                bs_write( s, 4, i_last_pixel );
            }
            else
            {
                bs_write( s, 1, 1 );

                if( i_length <= 24 )
                {
                    bs_write( s, 2, 2 );
                    bs_write( s, 4, i_length - 9 );
                    bs_write( s, 4, i_last_pixel );
                }
                else
                {
                    bs_write( s, 2, 3 );
                    bs_write( s, 8, i_length - 25 );
                    bs_write( s, 4, i_last_pixel );
                }
            }
        }

        if( i == p_region->fmt.i_visible_width ) break;

        i_last_pixel = p_data[i];
        i_length = 1;
    }

    /* Stop */
    bs_write( s, 8, 0 );

    /* Stuffing */
    bs_align_0( s );
}

static void encode_pixel_line_8bp( encoder_t *p_enc, bs_t *s,
                                   subpicture_region_t *p_region,
                                   int i_line )
{
    unsigned int i, i_length = 0;
    int i_pitch = p_region->picture.p->i_pitch;
    uint8_t *p_data = &p_region->picture.p->p_pixels[ i_pitch * i_line ];
    int i_last_pixel = p_data[0];

    for( i = 0; i <= p_region->fmt.i_visible_width; i++ )
    {
        if( i != p_region->fmt.i_visible_width &&
            p_data[i] == i_last_pixel && i_length != 127 )
        {
            i_length++;
            continue;
        }

        if( i_length == 1 && i_last_pixel )
        {
            /* 8bit/pixel code */
            bs_write( s, 8, i_last_pixel );
        }
        else if( i_length == 2 && i_last_pixel )
        {
            /* 8bit/pixel code */
            bs_write( s, 8, i_last_pixel );
            bs_write( s, 8, i_last_pixel );
        }
        else if( i_length <= 127 )
        {
            bs_write( s, 8, 0 );

            if( !i_last_pixel )
            {
                bs_write( s, 1, 0 );
                bs_write( s, 7, i_length ); /* pseudo color 0 */
            }
            else
            {
                bs_write( s, 1, 1 );
                bs_write( s, 7, i_length );
                bs_write( s, 8, i_last_pixel );
            }
        }

        if( i == p_region->fmt.i_visible_width ) break;

        i_last_pixel = p_data[i];
        i_length = 1;
    }

    /* Stop */
    bs_write( s, 8, 0 );
    bs_write( s, 8, 0 );

    /* Stuffing */
    bs_align_0( s );
}