static int check_pes(uint8_t *p, uint8_t *end){
    int pes1;
    int pes2=      (p[3] & 0xC0) == 0x80
                && (p[4] & 0xC0) != 0x40
                &&((p[4] & 0xC0) == 0x00 || (p[4]&0xC0)>>2 == (p[6]&0xF0));

    for(p+=3; p<end && *p == 0xFF; p++);
    if((*p&0xC0) == 0x40) p+=2;
    if((*p&0xF0) == 0x20){
        pes1= p[0]&p[2]&p[4]&1;
    }else if((*p&0xF0) == 0x30){
        pes1= p[0]&p[2]&p[4]&p[5]&p[7]&p[9]&1;
    }else
        pes1 = *p == 0x0F;

    return pes1||pes2;
}