/src/vlc/modules/codec/cc.h

Source
/*****************************************************************************
 * cc.h
 *****************************************************************************
 * Copyright (C) 2007 Laurent Aimar
 *
 * Authors: Laurent Aimar <fenrir@via.ecp.fr>
 *
 * 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.
 *****************************************************************************/

#ifndef VLC_CC_H_
#define VLC_CC_H_

#include <vlc_bits.h>

#define CC_PKT_BYTE0(field) (0xFC | (0x03 & field))

/* CC have a maximum rate of 9600 bit/s (per field?) */
#define CC_MAX_DATA_SIZE (2 * 3*600)
enum cc_payload_type_e
{
    CC_PAYLOAD_NONE,
    CC_PAYLOAD_RAW,
    CC_PAYLOAD_GA94,
    CC_PAYLOAD_DVD,
    CC_PAYLOAD_REPLAYTV,
    CC_PAYLOAD_SCTE20,
    CC_PAYLOAD_CDP,
};
typedef struct
{
    /* Which channel are present */
    uint64_t i_708channels;
    uint8_t  i_608channels;

    /* */
    bool b_reorder;
    struct
    {
        uint8_t pktsize;
        uint8_t seq;
        uint8_t sid_bs;
        enum
        {
            CEA708_PKT_END,
            CEA708_PKT_WAIT_BLOCK_HEADER,
            CEA708_PKT_WAIT_EXT_BLOCK_HEADER,
            CEA708_PKT_IN_BLOCK,
        } state;
    } cea708;

    /* */
    enum cc_payload_type_e i_payload_type;
    int i_payload_other_count;

    /* CC data per field
     *  byte[x+0]: field (0/1)
     *  byte[x+1]: cc data 1
     *  byte[x+2]: cc data 2
     */
    size_t  i_data;
    uint8_t p_data[CC_MAX_DATA_SIZE];
} cc_data_t;

static inline void cc_Init( cc_data_t *c )
{
    c->i_608channels = 0;
    c->i_708channels = 0;
    c->i_data = 0;
    c->b_reorder = false;
    c->cea708.pktsize = 0;
    c->cea708.seq = 0;
    c->cea708.sid_bs = 0;
    c->cea708.state = CEA708_PKT_END;
    c->i_payload_type = CC_PAYLOAD_NONE;
    c->i_payload_other_count = 0;
}
static inline void cc_Exit( cc_data_t *c )
{
    VLC_UNUSED(c);
    return;
}
static inline void cc_Flush( cc_data_t *c )
{
    c->i_data = 0;
    c->cea708.state = CEA708_PKT_END;
}

static inline void cc_ProbeCEA708OneByte( cc_data_t *c, bool b_start, const uint8_t cc )
{
    if( b_start )
    {
        const uint8_t i_pkt_sequence = cc >> 6;
        if( i_pkt_sequence > 0 && ((c->cea708.seq + 1) % 4) != i_pkt_sequence )
        {
            c->cea708.pktsize = 0;
            c->cea708.seq = i_pkt_sequence;
            c->cea708.state = CEA708_PKT_END;
        }
        else
        {
            c->cea708.seq = i_pkt_sequence;
            c->cea708.pktsize = cc & 63;
            if( c->cea708.pktsize == 0 )
                c->cea708.pktsize = 127;
            else
                c->cea708.pktsize = c->cea708.pktsize * 2 - 1;
            c->cea708.state = CEA708_PKT_WAIT_BLOCK_HEADER;
        }
    }
    else if( c->cea708.pktsize == 0 ) /* empty pkt reading service blocks */
    {
        c->cea708.state = CEA708_PKT_END;
    }
    else if( c->cea708.state != CEA708_PKT_END )
    {
        switch( c->cea708.state )
        {
            case CEA708_PKT_WAIT_BLOCK_HEADER: /* Byte is service block header */
            {
                uint8_t i_sid = cc >> 5;
                c->cea708.sid_bs = cc & 0x1F;
                if( i_sid != 0x00 && c->cea708.sid_bs != 0 )
                {
                    if( i_sid != 0x07 )
                    {
                        const uint8_t mask = (1 << --i_sid);
                        c->i_708channels |= (mask + (mask - 1));
                        c->cea708.state = CEA708_PKT_IN_BLOCK;
                    }
                    else if( c->cea708.sid_bs < 2 )
                    {
                        c->cea708.state = CEA708_PKT_END;
                    }
                    else
                    {
                        /* need to look up next byte in next pkt */
                        c->cea708.state = CEA708_PKT_WAIT_EXT_BLOCK_HEADER;
                    }
                }
                else c->cea708.state = CEA708_PKT_END;
            } break;

            case CEA708_PKT_WAIT_EXT_BLOCK_HEADER:
            {
                uint8_t i_extsid = cc & 0x3F;
                if( i_extsid >= 0x07 )
                {
                    const uint64_t mask = (INT64_C(1) << --i_extsid);
                    c->i_708channels |= (mask + (mask - 1));
                }
                if( c->cea708.sid_bs == 0 )
                    c->cea708.state = CEA708_PKT_WAIT_BLOCK_HEADER;
                else
                    c->cea708.state = CEA708_PKT_IN_BLOCK;
            } break;

            case CEA708_PKT_IN_BLOCK:
            {
                c->cea708.sid_bs--;
                if( c->cea708.sid_bs == 0 )
                    c->cea708.state = CEA708_PKT_WAIT_BLOCK_HEADER;
            } break;

            default:
                vlc_assert_unreachable();
                break;
        }
        c->cea708.pktsize--;

        if(c->cea708.pktsize == 0)
            c->cea708.state = CEA708_PKT_END;
    }
}

static inline void cc_ProbeCEA708( cc_data_t *c, uint8_t i_field, const uint8_t cc[2] )
{
    if( i_field == 3 ) /* DTVCC_PACKET_START */
        cc_ProbeCEA708OneByte( c, true,  cc[0] );
    else /* DTVCC_PACKET_DATA */
        cc_ProbeCEA708OneByte( c, false, cc[0] );
    cc_ProbeCEA708OneByte( c, false, cc[1] );
}

static inline bool cc_AppendData( cc_data_t *c, uint8_t cc_preamble, const uint8_t cc[2] )
{
    if (c->i_data + 3 > ARRAY_SIZE(c->p_data))
        return false;

    const uint8_t i_field = cc_preamble & 0x03;
    if( i_field == 0 || i_field == 1 ) /* NTSC_CC_FIELD_1 NTSC_CC_FIELD_2 */
    {
        c->i_608channels |= (3 << (2 * i_field));
    }
    else
    {
        cc_ProbeCEA708( c, i_field, cc );
        /* By default enable at least channel 1 */
        c->i_708channels |= 1;
    }

    c->p_data[c->i_data++] = cc_preamble;
    c->p_data[c->i_data++] = cc[0];
    c->p_data[c->i_data++] = cc[1];
    return true;
}

static inline void cc_Extract( cc_data_t *c, enum cc_payload_type_e i_payload_type,
                               bool b_top_field_first, const uint8_t *p_src, int i_src )
{
    if( c->i_payload_type != CC_PAYLOAD_NONE && c->i_payload_type != i_payload_type )
    {
        c->i_payload_other_count++;
        if( c->i_payload_other_count < 50 )
            return;
    }
    c->i_payload_type        = i_payload_type;
    c->i_payload_other_count = 0;

    if( i_payload_type == CC_PAYLOAD_RAW )
    {
        for( int i = 0; i + 2 < i_src; i += 3 )
        {
            const uint8_t *cc = &p_src[i];
            if (!cc_AppendData( c, cc[0], &cc[1] ))
                break;
        }
        c->b_reorder = true;
    }
    else if( i_payload_type == CC_PAYLOAD_GA94 )
    {
        /* cc_data()
         *          u1 reserved(1)
         *          u1 process_cc_data_flag
         *          u1 additional_data_flag
         *          u5 cc_count
         *          u8 reserved(1111 1111)
         *          for cc_count
         *              u5 marker bit(1111 1)
         *              u1 cc_valid
         *              u2 cc_type
         *              u8 cc_data_1
         *              u8 cc_data_2
         *          u8 marker bit(1111 1111)
         *          if additional_data_flag
         *              unknown
         */
        /* cc_type:
         *  0x00: field 1
         *  0x01: field 2
         */
        if(i_src < 1)
            return;
        const uint8_t *cc = &p_src[0];
        const int i_count_cc = cc[0]&0x1f;
        int i;

        if( !(cc[0]&0x40) ) // process flag
            return;
        if( i_src < 1+1 + i_count_cc*3 + 1)  // broken packet
            return;
        if( i_count_cc <= 0 )   // no cc present
            return;
        if( cc[2+i_count_cc * 3] != 0xff )  // marker absent
            return;
        cc += 2;

        for( i = 0; i < i_count_cc; i++, cc += 3 )
        {
            if (!cc_AppendData( c, cc[0], &cc[1] ))
                break;
        }
        c->b_reorder = true;
    }
    else if( i_payload_type == CC_PAYLOAD_DVD )
    {
        /* user_data
         *          (u32 stripped earlier)
         *          u32 (0x43 0x43 0x01 0xf8)
         *          u1 caption_odd_field_first (CC1/CC2)
         *          u1 caption_filler
         *          u5 cc_block_count  (== cc_count / 2)
         *          u1 caption_extra_field_added (because odd cc_count)
         *          for cc_block_count * 2 + caption_extra_field_added
         *              u7 cc_filler_1
         *              u1 cc_field_is_odd
         *              u8 cc_data_1
         *              u8 cc_data_2
         */
        if(i_src < 6)
            return;
        const int b_truncate = p_src[4] & 0x01;
        const int i_count_cc2 = ((p_src[4] >> 1) & 0x1f);
        const uint8_t *cc = &p_src[5];
        i_src -= 5;
        int i;

#define CC_ALIGNMENT_TEST   (0x7f)

        for( i = 0; i < 2*i_count_cc2 + b_truncate && i_src >= 3; i++, cc+=3 )
        {
            if( (cc[0] >> 1) == CC_ALIGNMENT_TEST )
            {
                const bool even_field = (cc[0] & 0x01) ? 0 : 1;
                if (!cc_AppendData( c, CC_PKT_BYTE0(even_field), &cc[1] ))
                    break;
            }
            i_src -= 3;
        }
        c->b_reorder = false;
    }
    else if( i_payload_type == CC_PAYLOAD_REPLAYTV )
    {
        if(i_src < 1)
            return;
        const uint8_t *cc = &p_src[0];
        for( int i_cc_count = i_src >> 2; i_cc_count > 0;
             i_cc_count--, cc += 4 )
        {
            uint8_t i_field = (cc[0] & 0x02) >> 1;
            if (!cc_AppendData( c, CC_PKT_BYTE0(i_field), &cc[2] ))
                return;
        }
        c->b_reorder = false;
    }
    else if( i_payload_type == CC_PAYLOAD_SCTE20 )
    {
        /* user_data(2)
         *          (u32 stripped earlier)
         *          u16 p_cc_scte20
         *          u5 cc_count
         *          for cc_count
         *              u2 cc_priority
         *              u2 cc_field_num
         *              u5 cc_line_offset
         *              u8 cc_data_1[1:8]
         *              u8 cc_data_2[1:8]
         *              u1 marker bit
         *          un additional_realtimevideodata
         *          un reserved
         */
        if(i_src < 2)
            return;
        bs_t s;
        bs_init( &s, &p_src[2], i_src - 2 );
        const int i_cc_count = bs_read( &s, 5 );
        for( int i = 0; i < i_cc_count; i++ )
        {
            bs_skip( &s, 2 );
            const int i_field_idx = bs_read( &s, 2 );
            bs_skip( &s, 5 );
            uint8_t cc[2];
            for( int j = 0; j < 2; j++ )
            {
                cc[j] = 0;
                for( int k = 0; k < 8; k++ )
                    cc[j] |= bs_read( &s, 1 ) << k;
            }
            bs_skip( &s, 1 );

            if( i_field_idx == 0 )
                continue;

            /* 1,2,3 -> 0,1,0. I.E. repeated field 3 is merged with field 1 */
            int i_field = ((i_field_idx - 1) & 1);
            if (!b_top_field_first)
                i_field ^= 1;

            if (!cc_AppendData( c, CC_PKT_BYTE0(i_field), &cc[0] ))
                continue;
        }
        c->b_reorder = true;
    }
    else // CC_PAYLOAD_CDP
    {
#       define CDP_FLAG_TIME_CODE_PRESENT  (1<<7)
#       define CDP_FLAG_CC_DATA_PRESENT    (1<<6)
#       define CDP_FLAG_SVC_INFO_PRESENT   (1<<5)
#       define CDP_FLAG_SVC_INFO_START     (1<<4)
#       define CDP_FLAG_SVC_INFO_CHANGE    (1<<3)
#       define CDP_FLAG_SVC_INFO_COMPLETE  (1<<2)
#       define CDP_FLAG_CAPTION_SVC_ACTIVE (1<<1)

        if(i_src < 7)
            return;

        /* ST334-2 5.2 cdp_header() */
        uint8_t cdp_length = p_src[2];
        if(cdp_length < 8 || cdp_length > i_src)
            return;
        uint8_t cdp_flags = p_src[4];

        /* skip header */
        p_src += 7; i_src -= 7;

        /* 5.3 time_code_section() */
        if( cdp_flags & CDP_FLAG_TIME_CODE_PRESENT )
        {
            if( i_src < 5 ) // Shall be 5 bytes
                return;
            p_src += 5; i_src -= 5;
        }
        /* 5.4 ccdata_section */
        if( cdp_flags & CDP_FLAG_CC_DATA_PRESENT )
        {
            /* ccdata_section()
             *      u8 0x72
             *      u3 marker bits(111)
             *      u5 cc_count
             *      for cc_count
             *          u5 marker bits(1111 1)
             *          u1 cc_valid
             *          u2 cc_type
             *          u8 cc_data_1
             *          u8 cc_data_2
             */
            if( i_src < 2 || p_src[0] != 0x72 ) // marker
                return;

            const uint8_t *cc = &p_src[1];
            const int i_count_cc = cc[0]&0x1f;

            if( i_src - 2 < i_count_cc*3 )  // broken packet
                return;
            cc += 1;
            for( int i = 0; i < i_count_cc; i++, cc += 3 )
            {
                if (!cc_AppendData( c, cc[0], &cc[1] ))
                    break;
            }
        }
        /* remaining data */
        c->b_reorder = false;
    }
}


static inline void cc_ProbeAndExtract( cc_data_t *c, bool b_top_field_first, const uint8_t *p_src, int i_src )
{
    static const uint8_t p_cc_ga94[4] = { 0x47, 0x41, 0x39, 0x34 };
    static const uint8_t p_cc_dvd[4] = { 0x43, 0x43, 0x01, 0xf8 }; /* ascii 'CC', type_code, cc_block_size */
    static const uint8_t p_cc_replaytv4a[2] = { 0xbb, 0x02 };/* RTV4K, BB02xxxxCC02 */
    static const uint8_t p_cc_replaytv4b[2] = { 0xcc, 0x02 };/* see DVR-ClosedCaption in samples */
    static const uint8_t p_cc_replaytv5a[2] = { 0x99, 0x02 };/* RTV5K, 9902xxxxAA02 */
    static const uint8_t p_cc_replaytv5b[2] = { 0xaa, 0x02 };/* see DVR-ClosedCaption in samples */
    static const uint8_t p_cc_scte20[2] = { 0x03, 0x81 };    /* user_data_type_code, SCTE 20 */
    static const uint8_t p_cc_scte20_old[2] = { 0x03, 0x01 };/* user_data_type_code, old, Note 1 */

    if( i_src < 4 )
        return;

    enum cc_payload_type_e i_payload_type;
    if( !memcmp( p_cc_ga94, p_src, 4 ) && i_src >= 5+1+1+1 && p_src[4] == 0x03 )
    {
        /* CC from DVB/ATSC TS */
        i_payload_type = CC_PAYLOAD_GA94;
        i_src -= 5;
        p_src += 5;
    }
    else if( !memcmp( p_cc_dvd, p_src, 4 ) && i_src > 4+1 )
    {
        i_payload_type = CC_PAYLOAD_DVD;
    }
    else if( i_src >= 2+2 + 2+2 &&
             ( ( !memcmp( p_cc_replaytv4a, &p_src[0], 2 ) && !memcmp( p_cc_replaytv4b, &p_src[4], 2 ) ) ||
               ( !memcmp( p_cc_replaytv5a, &p_src[0], 2 ) && !memcmp( p_cc_replaytv5b, &p_src[4], 2 ) ) ) )
    {
        i_payload_type = CC_PAYLOAD_REPLAYTV;
    }
    else if( ( !memcmp( p_cc_scte20, p_src, 2 ) ||
               !memcmp( p_cc_scte20_old, p_src, 2 ) ) && i_src > 2 )
    {
        i_payload_type = CC_PAYLOAD_SCTE20;
    }
    else if (p_src[0] == 0x03 && p_src[1] == i_src - 2) /* DIRECTV */
    {
        i_payload_type = CC_PAYLOAD_GA94;
        i_src -= 2;
        p_src += 2;
    }
    else if (p_src[0] == 0x96 && p_src[1] == 0x69) /* CDP */
    {
        i_payload_type = CC_PAYLOAD_CDP;
    }
    else
    {
#if 0
#define V(x) ( ( x < 0x20 || x >= 0x7f ) ? '?' : x )
        fprintf( stderr, "-------------- unknown user data " );
        for( int i = 0; i < i_src; i++ )
            fprintf( stderr, "%2.2x ", p_src[i] );
        for( int i = 0; i < i_src; i++ )
            fprintf( stderr, "%c ", V(p_src[i]) );
        fprintf( stderr, "\n" );
#undef V
#endif
        return;
    }

    cc_Extract( c, i_payload_type, b_top_field_first, p_src, i_src );
}

#endif /* _CC_H */


Coverage Report

Created: 2026-05-30 08:50