ts_demux.cpp

//
// Copyright (c) 2013-2021 Runner365
//
// SPDX-License-Identifier: MIT
//

#include "ts_demux.hpp"
#include "srt_log.hpp"
#include <string.h>

ts_demux::ts_demux():_data_total(0)
    ,_last_pid(0)
    ,_last_dts(0)
    ,_last_pts(0)
{

}

ts_demux::~ts_demux() {

}

int ts_demux::decode_unit(unsigned char* data_p, std::string key_path, TS_DATA_CALLBACK_PTR callback)
{
    int pos = 0;
    int npos = 0;
    ts_header ts_header_info;

    ts_header_info._sync_byte = data_p[pos];
    pos++;

    ts_header_info._transport_error_indicator = (data_p[pos]&0x80)>>7;
    ts_header_info._payload_unit_start_indicator = (data_p[pos]&0x40)>>6;
    ts_header_info._transport_priority = (data_p[pos]&0x20)>>5;
    ts_header_info._PID = ((data_p[pos]<<8)|data_p[pos+1])&0x1FFF;
    pos += 2;
    
    ts_header_info._transport_scrambling_control = (data_p[pos]&0xC0)>>6;
    ts_header_info._adaptation_field_control = (data_p[pos]&0x30)>>4;
    ts_header_info._continuity_counter = (data_p[pos]&0x0F);
    pos++;
    npos = pos;

    adaptation_field* field_p = &(ts_header_info._adaptation_field_info);
    // adaptation field
    // 0x01 No adaptation_field, payload only
    // 0x02 Adaptation_field only, no payload
    // 0x03 Adaptation_field followed by payload
    if( ts_header_info._adaptation_field_control == 2 
        || ts_header_info._adaptation_field_control == 3 ){
        // adaptation_field()
        field_p->_adaptation_field_length = data_p[pos];
        pos++;

        if( field_p->_adaptation_field_length > 0 ){
            field_p->_discontinuity_indicator = (data_p[pos]&0x80)>>7;
            field_p->_random_access_indicator = (data_p[pos]&0x40)>>6;
            field_p->_elementary_stream_priority_indicator = (data_p[pos]&0x20)>>5;
            field_p->_PCR_flag = (data_p[pos]&0x10)>>4;
            field_p->_OPCR_flag = (data_p[pos]&0x08)>>3;
            field_p->_splicing_point_flag = (data_p[pos]&0x04)>>2;
            field_p->_transport_private_data_flag = (data_p[pos]&0x02)>>1;
            field_p->_adaptation_field_extension_flag = (data_p[pos]&0x01);
            pos++;

            if( field_p->_PCR_flag == 1 ) { // PCR info
                //program_clock_reference_base 33 uimsbf
                //reserved 6 bslbf
                //program_clock_reference_extension 9 uimsbf
                pos += 6;
            }
            if( field_p->_OPCR_flag == 1 ) {
                //original_program_clock_reference_base 33 uimsbf
                //reserved 6 bslbf
                //original_program_clock_reference_extension 9 uimsbf
                pos += 6;
            }
            if( field_p->_splicing_point_flag == 1 ) {
                //splice_countdown 8 tcimsbf
                pos++;
            }
            if( field_p->_transport_private_data_flag == 1 ) {
                //transport_private_data_length 8 uimsbf
                field_p->_transport_private_data_length = data_p[pos];
                pos++;
                memcpy(field_p->_private_data_byte, data_p + pos, field_p->_transport_private_data_length);
                pos += field_p->_transport_private_data_length;
            }
            if( field_p->_adaptation_field_extension_flag == 1 ) {
                //adaptation_field_extension_length 8 uimsbf
                field_p->_adaptation_field_extension_length = data_p[pos];
                pos++;
                //ltw_flag 1 bslbf
                field_p->_ltw_flag = (data_p[pos]&0x80)>>7;
                //piecewise_rate_flag 1 bslbf
                field_p->_piecewise_rate_flag = (data_p[pos]&0x40)>>6;
                //seamless_splice_flag 1 bslbf
                field_p->_seamless_splice_flag = (data_p[pos]&0x20)>>5;
                //reserved 5 bslbf
                pos++;
                if (field_p->_ltw_flag == 1) {
                    //ltw_valid_flag 1 bslbf
                    //ltw_offset 15 uimsbf
                    pos += 2;
                }
                if (field_p->_piecewise_rate_flag == 1) {
                    //reserved 2 bslbf
                    //piecewise_rate 22 uimsbf
                    pos += 3;
                }
                if (field_p->_seamless_splice_flag == 1) {
                    //splice_type 4 bslbf
                    //DTS_next_AU[32..30] 3 bslbf
                    //marker_bit 1 bslbf
                    //DTS_next_AU[29..15] 15 bslbf
                    //marker_bit 1 bslbf
                    //DTS_next_AU[14..0] 15 bslbf
                    //marker_bit 1 bslbf
                    pos += 5;
                }
            }
        }
        npos += sizeof(field_p->_adaptation_field_length) + field_p->_adaptation_field_length;
        pos = npos;//must consider the 'stuffing_byte' in adaptation field
    }

    if(ts_header_info._adaptation_field_control == 1 
       || ts_header_info._adaptation_field_control == 3 ) {
        // data_byte with placeholder
        // payload parser
        if(ts_header_info._PID == 0x00){
            // PAT // program association table
            if(ts_header_info._payload_unit_start_indicator) {
                pos++;
            }
            _pat._table_id = data_p[pos];
            pos++;
            _pat._section_syntax_indicator = (data_p[pos]>>7)&0x01;
            // skip 3 bits of 1 zero and 2 reserved
            _pat._section_length = ((data_p[pos]<<8)|data_p[pos+1])&0x0FFF;
            pos += 2;
            _pat._transport_stream_id = (data_p[pos]<<8)|data_p[pos+1];
            pos += 2;
            // reserved 2 bits
            _pat._version_number = (data_p[pos]&0x3E)>>1;
            _pat._current_next_indicator = data_p[pos]&0x01;
            pos++;
            _pat._section_number = data_p[pos];
            pos++;
            _pat._last_section_number = data_p[pos];

            if (_pat._table_id != 0x00) {
                srt_log_error("pat table id(0x%02x) error, it must be 0x00", _pat._table_id);
                return -1;
            }
            // PAT = section_length + 3
            if((188 - npos) <= (_pat._section_length + 3)) {
                srt_log_error("pat _section_length(%d) error, the left len:%d", _pat._section_length, (188 - npos));
                return -1;
            }
            pos++;
            _pat._pid_vec.clear();
            for (;pos+4 <= _pat._section_length-5-4+9 + npos;) { // 4:CRC, 5:follow section_length item  rpos + 4(following unit length) section_length + 9(above field and unit_start_first_byte )
                PID_INFO pid_info;
                //program_number 16 uimsbf
                pid_info._program_number = data_p[pos]<<8|data_p[pos+1];
                pos += 2;
//              reserved 3 bslbf
                
                if (pid_info._program_number == 0) {
//                  // network_PID 13 uimsbf
                    pid_info._network_id = (data_p[pos]<<8|data_p[pos+1])&0x1FFF;
                    pos += 2;
                }
                else {
//                  //     program_map_PID 13 uimsbf
                    pid_info._pid = (data_p[pos]<<8|data_p[pos+1])&0x1FFF;
                    pos += 2;
                }
                _pat._pid_vec.push_back(pid_info);
                // network_PID and program_map_PID save to list
            }
//               CRC_32 use pat to calc crc32, eq
            pos += 4;
        }else if(ts_header_info._PID == 0x01){
            // CAT // conditional access table
        }else if(ts_header_info._PID == 0x02){
            //TSDT  // transport stream description table
        }else if(ts_header_info._PID == 0x03){
            //IPMP // IPMP control information table
            // 0x0004-0x000F Reserved
            // 0x0010-0x1FFE May be assigned as network_PID, Program_map_PID, elementary_PID, or for other purposes
        }else if(ts_header_info._PID == 0x11){
            // SDT // https://en.wikipedia.org/wiki/Service_Description_Table / https://en.wikipedia.org/wiki/MPEG_transport_stream
        }else if(is_pmt(ts_header_info._PID)) {
            if(ts_header_info._payload_unit_start_indicator)
                pos++;
            _pmt._table_id = data_p[pos];
            pos++;
            _pmt._section_syntax_indicator = (data_p[pos]>>7)&0x01;
            // skip 3 bits of 1 zero and 2 reserved
            _pmt._section_length = ((data_p[pos]<<8)|data_p[pos+1])&0x0FFF;
            pos += 2;
            _pmt._program_number = (data_p[pos]<<8)|data_p[pos+1];
            pos += 2;
            // reserved 2 bits
            _pmt._version_number = (data_p[pos]&0x3E)>>1;
            _pmt._current_next_indicator = data_p[pos]&0x01;
            pos++;
            _pmt._section_number = data_p[pos];
            pos++;
            _pmt._last_section_number = data_p[pos];
            pos++;
            // skip 3 bits for reserved 3 bslbf
            _pmt._PCR_PID = ((data_p[pos]<<8)|data_p[pos+1])&0x1FFF; //PCR_PID 13 uimsbf
            pos += 2;

            //reserved 4 bslbf
            _pmt._program_info_length = ((data_p[pos]<<8)|data_p[pos+1])&0x0FFF;//program_info_length 12 uimsbf
            pos += 2;

             //0x02, // TS_program_map_section
            if (_pmt._table_id != 0x02) {
                srt_log_error("pmt tableid(0x%02x) error, it must be 0x02", _pmt._table_id)
                return -1;
            }
            memcpy(_pmt._dscr, data_p+pos, _pmt._program_info_length);
//               for (i = 0; i < N; i++) {
//                   descriptor()
//               }
            pos += _pmt._program_info_length;
            _pmt._stream_pid_vec.clear();
            _pmt._pid2steamtype.clear();

            for (; pos + 5 <= _pmt._section_length + 4 - 4 + npos; ) { // pos(above field length) i+5(following unit length) section_length +3(PMT begin three bytes)+1(payload_unit_start_indicator) -4(crc32)
                STREAM_PID_INFO pid_info;
                pid_info._stream_type = data_p[pos];//stream_type 8 uimsbf  0x1B AVC video stream as defined in ITU-T Rec. H.264 | ISO/IEC 14496-10 Video
                pos++;
                //reserved 3 bslbf
                pid_info._elementary_PID = ((data_p[pos]<<8)|data_p[pos+1])&0x1FFF; //elementary_PID 13 uimsbf
                pos += 2;
                //reserved 4 bslbf
                pid_info._ES_info_length = ((data_p[pos]<<8)|data_p[pos+1])&0x0FFF; //ES_info_length 12 uimsbf
                pos += 2;
                if( pos + pid_info._ES_info_length > _pmt._section_length + 4 - 4 + npos )
                    break;
                int absES_info_length = pos + pid_info._ES_info_length;
                for (; pos< absES_info_length; ) {
                    //descriptor()
                    int descriptor_tag = data_p[pos];
                    (void)descriptor_tag;
                    pos++;
                    int descriptor_length = data_p[pos];
                    pos++;
                    memcpy(pid_info._dscr, data_p + pos, descriptor_length);
                    pos += descriptor_length;
                }
                // save program_number(stream num) elementary_PID(PES PID) stream_type(stream codec)
                _pmt._stream_pid_vec.push_back(pid_info);
                _pmt._pid2steamtype.insert(std::make_pair((unsigned short)pid_info._elementary_PID, pid_info._stream_type));
            }
            pos += 4;//CRC_32
        }else if(ts_header_info._PID == 0x0042){
            // USER
        }else if(ts_header_info._PID == 0x1FFF){
            // Null packet
        }else{//pes packet or pure data packet
            //bool isFound = false;
            for (size_t i = 0; i < _pmt._stream_pid_vec.size(); i++) {
                if(ts_header_info._PID == _pmt._stream_pid_vec[i]._elementary_PID){
                    //isFound = true;
                    if(ts_header_info._payload_unit_start_indicator){
                        unsigned char* ret_data_p = nullptr;
                        size_t ret_size = 0;
                        uint64_t dts = 0;
                        uint64_t pts = 0;
                        
                        //callback last media data in data buffer
                        int err_code = on_callback(callback, _last_pid, key_path, _last_dts, _last_pts);
                        if (err_code != 0)
                            return err_code;

                        int ret = pes_parse(data_p+npos, npos, &ret_data_p, ret_size, dts, pts);
                        if (ret > 188) {
                            srt_log_error("pes length(%d) error", ret);
                            return -1;
                        }

                        _last_pts = pts;
                        _last_dts = (dts == 0) ? pts : dts;

                        if ((ret_data_p != nullptr) && (ret_size > 0)) {
                            insert_into_databuf(ret_data_p, ret_size, key_path, ts_header_info._PID);
                        }
                    }else{
                        //fwrite(p, 1, 188-(npos+pos), pes_info[i].fd);
                        insert_into_databuf(data_p + npos, 188-npos, key_path, ts_header_info._PID);
                    }
                }
            }
        }
    }

    return 0;
}
int ts_demux::decode(SRT_DATA_MSG_PTR data_ptr, TS_DATA_CALLBACK_PTR callback)
{
    int ret = -1;
    std::string path;

    if (!data_ptr || (data_ptr->data_len() < 188) || (data_ptr->data_len()%188 != 0))
    {
        return -1;
    }

    unsigned int count = data_ptr->data_len()/188;
    path = data_ptr->get_path();
    for (unsigned int index = 0; index < count; index++)
    {
        unsigned char* data = data_ptr->get_data() + 188*index;
        if (data[0] != 0x47) {
            continue;
        }
        ret = decode_unit(data, path, callback);
        if (ret != 0) // srs_error_code is positive
        {
            break;
        }
    }
    return ret;
}

void ts_demux::insert_into_databuf(unsigned char* data_p, size_t data_size, std::string key_path, unsigned short pid) {
    _last_pid = pid;
    _data_total += data_size;
    _data_buffer_vec.push_back(std::make_shared<SRT_DATA_MSG>(data_p, data_size, key_path));
    return;
}

int ts_demux::on_callback(TS_DATA_CALLBACK_PTR callback, unsigned short pid, std::string key_path,
                            uint64_t dts, uint64_t pts) {
    if ((_data_total <=0 ) || (_data_buffer_vec.empty())) {
        return 0;
    }

    auto iter = _pmt._pid2steamtype.find(pid);
    if (iter == _pmt._pid2steamtype.end()) {
        return 0;
    }
    unsigned char stream_type = iter->second;
    auto total_data_ptr = std::make_shared<SRT_DATA_MSG>(_data_total, key_path);
    size_t pos = 0;

    for (size_t index = 0; index < _data_buffer_vec.size(); index++) {
        memcpy(total_data_ptr->get_data() + pos, 
            _data_buffer_vec[index]->get_data(),
            _data_buffer_vec[index]->data_len());
        pos += _data_buffer_vec[index]->data_len();
    }
    _data_buffer_vec.clear();
    _data_total = 0;

    return callback->on_data_callback(total_data_ptr, stream_type, dts, pts);
}

bool ts_demux::is_pmt(unsigned short pid) {
    for (size_t index = 0; index < _pat._pid_vec.size(); index++) {
        if (_pat._pid_vec[index]._program_number != 0) {
            if (_pat._pid_vec[index]._pid == pid) {
                return true;
            }
        }
    }
    return false;
}


int ts_demux::pes_parse(unsigned char* p, size_t npos, 
                        unsigned char** ret_pp, size_t& ret_size,
                        uint64_t& dts, uint64_t& pts) {
    int pos = 0;
    int packet_start_code_prefix = (p[pos]<<16)|(p[pos+1]<<8)|p[pos+2];  //packet_start_code_prefix 24 bslbf
    pos += 3;
    int stream_id = p[pos]; //stream_id 8 uimsbf
    pos++;
    
    int PES_packet_length = ((unsigned int)p[pos]<<8)|p[pos+1]; //PES_packet_length 16 uimsbf
    (void)PES_packet_length;
    pos += 2;

    if (0x00000001 != packet_start_code_prefix) {
        srt_log_error("pes packet start code prefix(%06x) error, it must be 0x00 00 01", packet_start_code_prefix);
        return 255;
    }
    if (stream_id != 188//program_stream_map 1011 1100
        && stream_id != 190//padding_stream 1011 1110
        && stream_id != 191//private_stream_2 1011 1111
        && stream_id != 240//ECM 1111 0000
        && stream_id != 241//EMM 1111 0001
        && stream_id != 255//program_stream_directory 1111 1111
        && stream_id != 242//DSMCC_stream 1111 0010
        && stream_id != 248//ITU-T Rec. H.222.1 type E stream 1111 1000
        ) 
    {
        if (0x80 != (p[pos] & 0xc0)) {
            srt_log_error("the first 2 bits:0x%02x error, it must be 0x80.", (p[pos] & 0xc0));
            return 255;
        }
        //skip 2bits//'10' 2 bslbf
        int PES_scrambling_control = (p[pos]&30)>>4; //PES_scrambling_control 2 bslbf
        (void)PES_scrambling_control;
        int PES_priority = (p[pos]&0x08)>>3; //PES_priority 1 bslbf
        (void)PES_priority;
        int data_alignment_indicator = (p[pos]&0x04)>>2;//data_alignment_indicator 1 bslbf
        (void)data_alignment_indicator;
        int copyright = (p[pos]&0x02)>>1; //copyright 1 bslbf
        (void)copyright;
        int original_or_copy = (p[pos]&0x01);//original_or_copy 1 bslbf
        (void)original_or_copy;
        pos++;
        int PTS_DTS_flags = (p[pos]&0xC0)>>6; //PTS_DTS_flags 2 bslbf
        int ESCR_flag = (p[pos]&0x20)>>5; // ESCR_flag 1 bslbf
        int ES_rate_flag = (p[pos]&0x10)>>4;//ES_rate_flag 1 bslbf
        int DSM_trick_mode_flag = (p[pos]&0x08)>>3;//DSM_trick_mode_flag 1 bslbf
        int additional_copy_info_flag = (p[pos]&0x04)>>2; //additional_copy_info_flag 1 bslbf
        int PES_CRC_flag = (p[pos]&0x02)>>1; //PES_CRC_flag 1 bslbf
        int PES_extension_flag = (p[pos]&0x01);//PES_extension_flag 1 bslbf
        pos++;
        int PES_header_data_length = p[pos]; //PES_header_data_length 8 uimsbf
        (void)PES_header_data_length;
        pos++;

        if (PTS_DTS_flags == 2) {
            // skip 4 bits '0010' 4 bslbf
            // PTS [32..30] 3 bslbf
            // marker_bit 1 bslbf
            // PTS [29..15] 15 bslbf
            // marker_bit 1 bslbf
            // PTS [14..0] 15 bslbf
            // marker_bit 1 bslbf
            pts = (((p[pos]>>1)&0x07) << 30) | (p[pos+1]<<22) | (((p[pos+2]>>1)&0x7F)<<15) | (p[pos+3]<<7) | ((p[pos+4]>>1)&0x7F);
            pos += 5;
        }
        if (PTS_DTS_flags == 3) {
            // '0011' 4 bslbf
            // PTS [32..30] 3 bslbf
            // marker_bit 1 bslbf
            //PTS [29..15] 15 bslbf
            //marker_bit 1 bslbf
            // PTS [14..0] 15 bslbf
            // marker_bit 1 bslbf
            pts = (((p[pos]>>1)&0x07) << 30) | (p[pos+1]<<22) | (((p[pos+2]>>1)&0x7F)<<15) | (p[pos+3]<<7) | ((p[pos+4]>>1)&0x7F);
            pos += 5;
            // '0001' 4 bslbf
            // DTS [32..30] 3 bslbf
            // marker_bit 1 bslbf
            // DTS [29..15] 15 bslbf
            // marker_bit 1 bslbf
            // DTS [14..0] 15 bslbf
            // marker_bit 1 bslbf
            dts = (((p[pos]>>1)&0x07) << 30) | (p[pos+1]<<22) | (((p[pos+2]>>1)&0x7F)<<15) | (p[pos+3]<<7) | ((p[pos+4]>>1)&0x7F);
            pos += 5;
        }
        if (ESCR_flag == 1) {
            // reserved 2 bslbf
            // ESCR_base[32..30] 3 bslbf
            // marker_bit 1 bslbf
            // ESCR_base[29..15] 15 bslbf
            // marker_bit 1 bslbf
            // ESCR_base[14..0] 15 bslbf
            // marker_bit 1 bslbf
            // ESCR_extension 9 uimsbf
            // marker_bit 1 bslbf
            uint64_t ESCR_base = ((((uint64_t)p[pos] >> 3) & 0x07) << 30) | (((uint64_t)p[pos] & 0x03) << 28) | ((uint64_t)p[pos + 1] << 20) | ((((uint64_t)p[pos + 2] >> 3) & 0x1F) << 15) | (((uint64_t)p[pos + 2] & 0x3) << 13) | ((uint64_t)p[pos + 3] << 5) | ((p[pos + 4] >> 3) & 0x1F);
            int ESCR_extension = ((p[pos + 4] & 0x03) << 7) | ((p[pos + 5] >> 1) & 0x7F);
            (void)ESCR_base;
            (void)ESCR_extension;
            pos += 6;
        }
        if (ES_rate_flag == 1) {
            // marker_bit 1 bslbf
            // ES_rate 22 uimsbf
            // marker_bit 1 bslbf
            int ES_rate = (p[pos]&0x7F)<<15 | (p[pos+1])<<7 | (p[pos+2]&0x7F)>>1;
            (void)ES_rate;
            pos += 3;
        }
        if (DSM_trick_mode_flag == 1) { // ignore
            int trick_mode_control = (p[pos]&0xE0)>>5;//trick_mode_control 3 uimsbf
            if ( trick_mode_control == 0/*fast_forward*/ ) {
                // field_id 2 bslbf
                // intra_slice_refresh 1 bslbf
                // frequency_truncation 2 bslbf
            }
            else if ( trick_mode_control == 1/*slow_motion*/ ) {
                //rep_cntrl 5 uimsbf
            }
            else if ( trick_mode_control == 2/*freeze_frame*/ ) {
                // field_id 2 uimsbf
                // reserved 3 bslbf
            }
            else if ( trick_mode_control == 3/*fast_reverse*/ ) {
                // field_id 2 bslbf
                // intra_slice_refresh 1 bslbf
                // frequency_truncation 2 bslbf
            }else if ( trick_mode_control == 4/*slow_reverse*/ ) {
                // rep_cntrl 5 uimsbf
            }
            else{
                //reserved 5 bslbf
            }
            pos++;
        }
        if ( additional_copy_info_flag == 1) { // ignore
            // marker_bit 1 bslbf
            // additional_copy_info 7 bslbf
            pos++;
        }
        if ( PES_CRC_flag == 1) { // ignore
            // previous_PES_packet_CRC 16 bslbf
            pos += 2;
        }
        if ( PES_extension_flag == 1) { // ignore
            int PES_private_data_flag = (p[pos]&0x80)>>7;// PES_private_data_flag 1 bslbf
            int pack_header_field_flag = (p[pos]&0x40)>>6;// pack_header_field_flag 1 bslbf
            int program_packet_sequence_counter_flag = (p[pos]&0x20)>>5;// program_packet_sequence_counter_flag 1 bslbf
            int P_STD_buffer_flag = (p[pos]&0x10)>>4; // P-STD_buffer_flag 1 bslbf
            // reserved 3 bslbf
            int PES_extension_flag_2 = (p[pos]&0x01);// PES_extension_flag_2 1 bslbf
            pos++;

            if ( PES_private_data_flag == 1) {
                // PES_private_data 128 bslbf
                pos += 16;
            }
            if (pack_header_field_flag == 1) {
                // pack_field_length 8 uimsbf
                // pack_header()
            }
            if (program_packet_sequence_counter_flag == 1) {
                // marker_bit 1 bslbf
                // program_packet_sequence_counter 7 uimsbf
                // marker_bit 1 bslbf
                // MPEG1_MPEG2_identifier 1 bslbf
                // original_stuff_length 6 uimsbf
                pos += 2;
            }
            if ( P_STD_buffer_flag == 1) {
                // '01' 2 bslbf
                // P-STD_buffer_scale 1 bslbf
                // P-STD_buffer_size 13 uimsbf
                pos += 2;
            }
            if ( PES_extension_flag_2 == 1) {
                // marker_bit 1 bslbf
                int PES_extension_field_length = (p[pos]&0x7F);// PES_extension_field_length 7 uimsbf
                pos++;
                for (int i = 0; i < PES_extension_field_length; i++) {
                    // reserved 8 bslbf
                    pos++;
                }
            }
        }

//        for (int i = 0; i < N1; i++) {
        //stuffing_byte 8 bslbf
//            rpos++;
//        }
//        for (int i = 0; i < N2; i++) {
        //PES_packet_data_byte 8 bslbf
//        rpos++;
//        }
        *ret_pp = p+pos;
        ret_size = 188-(npos+pos);
    }
    else if ( stream_id == 188//program_stream_map 1011 1100 BC
             || stream_id == 191//private_stream_2 1011 1111 BF
             || stream_id == 240//ECM 1111 0000 F0
             || stream_id == 241//EMM 1111 0001 F1
             || stream_id == 255//program_stream_directory 1111 1111 FF
             || stream_id == 242//DSMCC_stream 1111 0010 F2
             || stream_id == 248//ITU-T Rec. H.222.1 type E stream 1111 1000 F8
             ) {
//        for (i = 0; i < PES_packet_length; i++) {
         //PES_packet_data_byte 8 bslbf
//         rpos++;
//        }
        *ret_pp = p+pos;
        ret_size = 188-(npos+pos);
        //fwrite(p, 1, 188-(npos+rpos), fd);
    }
    else if ( stream_id == 190//padding_stream 1011 1110
             ) {
//        for (i = 0; i < PES_packet_length; i++) {
        // padding_byte 8 bslbf
//            rpos++;
        *ret_pp = p+pos;
        ret_size = 188-(npos+pos);
//        }
    }
    
    return pos;
}