5. sdt (service description table) class

이 장에서는 SDT (Service Description Table)에 대해서 알아보고, 구현 클래스를 살펴본다.

SDT는 MPEG-2 Part 2의 규격 사항은 아니다. MPEG System의 구성은 기본 골격은 MPEG에서 출발하고

세부적인 사항은 ATSC, DVB, ISDB의 형태로 나누어진다. SDT는 DVB에 해당하는 규격이고

요즘은 ATSC도 같이 보고 있지만 기존에 계속 DVB만해서 익숙한 것 위주로 구현해 본다.

SDT는 현재 방송되고 있는 방송사업자 정보나 방송 채널 이름 같은 정보를 얻어올 수 있다.

좀 세부적으로 들어가면 PAT에 있는 프로그램 갯수가 정말 정확할까? 이런 문제들이 속출하게된다.

테스트 코드에서 볼 수 있듯이 PMT를 parsing하기 위해서는 PAT가 먼저 parsing이 되어야 한다.

하지만 SDT의 경우에는 테스트 코드에서도 볼 수 있지만 PAT와 상관없이 바로 Section PID를 알고 있으므로

바로 PAT와 상관없이 Parsing할 수 있다.

여기서 복합적으로 성능을 올릴 수 있는 방법을 고민해 볼 수 있다. Chip의 특성을 잘 파악한다면

여러가지 복합적으로 생각해 볼 수 있다.

또한 SDT는 CI+와 직접적인 연관이 있다. 업체마다 구현은 다르겠지만 ...

상세하게 여기 기술하기에는 한계가 있다. 정보 유출로 걸릴까 무섭다.

1. 소스 트리

├── CMakeLists.txt

├── psi_glob.h

├── remove.sh

├── sdt.cpp

├── sdt.h

├── section.cpp

├── section.h

├── test.cpp

└── types.h

2. 헤더 파일

#ifndef __SDT_H__ #define __SDT_H__ #include <cstdio> #include <iostream> #include <string> #include <memory> #include <forward_list> #include "types.h" #include "psi_glob.h" /* ------------------------------------------------------------------------------------------------------------------- declare define ------------------------------------------------------------------------------------------------------------------- */ #define SDT_HEADER_SIZE 11 //#define PRINT_SDT_SECSION_HEADER #ifdef PRINT_SDT_SECSION_HEADER #define PRINT_SDT_INFO(x) std::printf("%30s = %10d [%#10x]\n", #x, x, x); #else #define PRINT_SDT_INFO(x) #endif #define SDT_ACTUAL_PID 0x11 #define SDT_ACTUAL_TABLE_ID 0x42 /* ------------------------------------------------------------------------------------------------------------------- declare class data ------------------------------------------------------------------------------------------------------------------- */ typedef struct { UINT8 version; UINT8 section_number; UINT16 program_number; bool EIT_schedule_flag; bool EIT_present_following_flag; UINT8 running_status; bool free_CA_mode; std::string servicProvideeName; std::string serviceName; } SDT_INFO_T; class SDT { public : SDT(); ~SDT(); RESULT_T parsingSDTSection(UINT8* pData); bool isSDTSecton(UINT16 pid); bool isExistSdt(UINT8 version_number, UINT8 section_number, UINT16 program_number); void printSDTList(void); RESULT_T parsingServiceDescriptor(SDT_INFO_T* sdtInfo, UINT8 *pData); private : UINT32 NumOfService; std::forward_list<SDT_INFO_T> sdt_info_list; }; #endif

3. 본체

/** This is free and unencumbered software released into the public domain. Anyone is free to copy, modify, publish, use, compile, sell, or distribute this software, either in source code form or as a compiled binary, for any purpose, commercial or non-commercial, and by any means. In jurisdictions that recognize copyright laws, the author or authors of this software dedicate any and all copyright interest in the software to the public domain. We make this dedication for the benefit of the public at large and to the detriment of our heirs and successors. We intend this dedication to be an overt act of relinquishment in perpetuity of all present and future rights to this software under copyright law. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. For more information, please refer to <http://unlicense.org> */ /** -------------------------------------------------------------------- file : sdt.cpp parsing service description table version : 1.0 data : 2016.06.01 author : HeeSoon Kim(chipmaker0304@gmail.com) -----------------------------------------------------------------------*/ /* service_description_section(){ table_id 8 uimsbf section_syntax_indicator 1 bslbf reserved_future_use 1 bslbf reserved 2 bslbf section_length 12 uimsbf transport_stream_id 16 uimsbf reserved 2 bslbf version_number 5 uimsbf current_next_indicator 1 bslbf section_number 8 uimsbf last_section_number 8 uimsbf original_network_id 16 uimsbf reserved_future_use 8 bslbf for (i=0;i<N;i++){ service_id 16 uimsbf reserved_future_use 6 bslbf EIT_schedule_flag 1 bslbf EIT_present_following_flag 1 bslbf running_status 3 uimsbf free_CA_mode 1 bslbf descriptors_loop_length 12 uimsbf for (j=0;j<N;j++){ descriptor() } } CRC_32 32 rpchof } */ #include "sdt.h" SDT::SDT() { NumOfService = 0; std::cout << __FUNCTION__ << std::endl; } SDT::~SDT() { NumOfService = 0; sdt_info_list.clear(); std::cout << __FUNCTION__ << std::endl; } bool SDT::isSDTSecton(UINT16 pid) { if(pid == SDT_ACTUAL_PID) return true; else return false; } bool SDT::isExistSdt(UINT8 version_number, UINT8 section_number, UINT16 program_number) { for(auto list : sdt_info_list) { if(list.version == version_number && list.section_number == section_number && list.program_number == program_number) { return true; } } return false; } void SDT::printSDTList(void) { int i = 0; sdt_info_list.sort([](SDT_INFO_T& prog1, SDT_INFO_T& prog2) -> bool { return prog1.program_number < prog2.program_number; }); for(auto list : sdt_info_list) { std::printf("%3d] SDT version = %2d, Section = %2d, service_id = %3d \n" \ , i, list.version, list.section_number, list.program_number); std::printf("%3c %30s : %5d \n", '-', "EIT_schedule_flag", list.EIT_schedule_flag); std::printf("%3c %30s : %5d \n", '-', "EIT_present_following_flag", list.EIT_present_following_flag); std::printf("%3c %30s : %#5x \n", '-', "running_status", list.running_status); std::printf("%3c %30s : %5d \n", '-', "free_CA_mode", list.free_CA_mode); std::printf("%3c %30s : %s \n", '-', "service Provide Name", list.servicProvideeName.data()); std::printf("%3c %30s : %s \n", '-', "service Name", list.serviceName.data()); i++; } } #include <cstring> RESULT_T SDT::parsingServiceDescriptor(SDT_INFO_T* sdtInfo, UINT8 *pData) { UINT8 descriptor_tag; UINT8 descriptor_length; UINT8 service_type; UINT8 service_provider_name_length; UINT8 service_name_length; descriptor_tag = pData[0]; descriptor_length = pData[1]; service_type = pData[2]; service_provider_name_length = pData[3]; sdtInfo->servicProvideeName.assign((char*)pData+4, service_provider_name_length); pData = pData + 3 + service_provider_name_length + 1; service_name_length = pData[0]; sdtInfo->serviceName.assign((char*)pData+1, service_name_length + 1); } RESULT_T SDT::parsingSDTSection(UINT8 *pData) { bool EIT_schedule_flag; bool EIT_present_following_flag; bool free_CA_mode; UINT8 *pSection; UINT8 point_field; UINT8 table_id; UINT8 version_number; UINT8 section_number; UINT8 last_section_number; UINT8 running_status; UINT16 section_length; UINT16 transport_stream_id; UINT16 original_network_id; UINT16 service_id; UINT16 descriptors_loop_length; point_field = pData[0]; PRINT_SDT_INFO(point_field); pSection = pData + point_field + 1; table_id = pSection[0]; PRINT_SDT_INFO(table_id); if(table_id != SDT_ACTUAL_TABLE_ID) { return RESULT_NOTOK; } section_length = ((pSection[1] & 0x0f) << 8) | pSection[2]; PRINT_SDT_INFO(section_length); transport_stream_id = (pSection[3] << 8) | pSection[4]; PRINT_SDT_INFO(transport_stream_id); version_number = (pSection[5] >> 1) & 0x1f; PRINT_SDT_INFO(version_number); section_number = pSection[6]; PRINT_SDT_INFO(section_number); last_section_number = pSection[7]; PRINT_SDT_INFO(last_section_number); original_network_id = (pSection[8] << 8) | pSection[9]; PRINT_SDT_INFO(original_network_id); pSection = pData + point_field + SDT_HEADER_SIZE + 1; section_length -= SDT_HEADER_SIZE + 1; while(section_length > 0) { SDT_INFO_T sdtInfo = {0, }; service_id = (pSection[0] << 8) | pSection[1]; PRINT_SDT_INFO(service_id); if(isExistSdt(version_number, section_number, service_id) == true) return RESULT_OK; EIT_schedule_flag = (pSection[2] >> 1) & 0x01; PRINT_SDT_INFO(EIT_schedule_flag); EIT_present_following_flag = pSection[2] & 0x01; PRINT_SDT_INFO(EIT_present_following_flag); running_status = (pSection[3] >> 5) & 0x07; PRINT_SDT_INFO(running_status); free_CA_mode = (pSection[3] >> 4) & 0x01; PRINT_SDT_INFO(free_CA_mode); descriptors_loop_length = ((pSection[3] & 0x0f) << 8) | pSection[4]; PRINT_SDT_INFO(descriptors_loop_length); sdtInfo.version = version_number; sdtInfo.section_number = section_number; sdtInfo.program_number = service_id; sdtInfo.EIT_schedule_flag = EIT_schedule_flag; sdtInfo.EIT_present_following_flag = EIT_present_following_flag; sdtInfo.running_status = running_status; sdtInfo.free_CA_mode = free_CA_mode; parsingServiceDescriptor(&sdtInfo, pSection+5); //sdtInfo.serviceName.copy(0, pSection[]) sdt_info_list.push_front(sdtInfo); pSection += (5 + descriptors_loop_length); section_length -= (5 + descriptors_loop_length); } return RESULT_OK; }

4. 테스트 소스

#include <thread> #include "section.h" #include "sdt.h" int main(int argc, char* argv[]) { SECTION_INFO_T sec; CSection* section = new CSection(); SDT* sdt = new SDT(); // open media test, media is file section->openMedia("file://SGP.ts"); // create task to read continously std::thread tr = std::thread([&]() { while(1) { if(section->readMedia(&sec) == RESULT_NOTOK) break; // check SDT section if(sdt->isSDTSecton(sec.pid) == true) { sdt->parsingSDTSection((UINT8*)sec.section); } } }); tr.join(); sdt->printSDTList(); delete section; delete sdt; return 0; }

5. 실행 결과

CSectionSDT current media type : FILE  mediaInPath : SGP.ts No Data !!    0] SDT version =  1, Section =  0, service_id = 208    -              EIT_schedule_flag :     0     -     EIT_present_following_flag :     1     -                 running_status :   0x4    -                   free_CA_mode :     0     -           service Provide Name : MediaCorp TV      -                   service Name : TV1_SD      1] SDT version =  1, Section =  0, service_id = 209    -              EIT_schedule_flag :     0     -     EIT_present_following_flag :     1     -                 running_status :   0x4    -                   free_CA_mode :     0     -           service Provide Name : MediaCorp TV      -                   service Name : TV2_SD      2] SDT version =  1, Section =  0, service_id = 210    -              EIT_schedule_flag :     0     -     EIT_present_following_flag :     1     -                 running_status :   0x4    -                   free_CA_mode :     0     -           service Provide Name : MediaCorp TV      -                   service Name : TV3_HD      3] SDT version =  1, Section =  0, service_id = 211    -              EIT_schedule_flag :     0     -     EIT_present_following_flag :     1     -                 running_status :   0x4    -                   free_CA_mode :     0     -           service Provide Name : MediaCorp TV      -                   service Name : TV4_HD      4] SDT version =  1, Section =  0, service_id = 212    -              EIT_schedule_flag :     0     -     EIT_present_following_flag :     1     -                 running_status :   0x4    -                   free_CA_mode :     0     -           service Provide Name : MediaCorp TV      -                   service Name : TV5_Radio      5] SDT version =  1, Section =  0, service_id = 213    -              EIT_schedule_flag :     0     -     EIT_present_following_flag :     1     -                 running_status :   0x4    -                   free_CA_mode :     0     -           service Provide Name : MediaCorp TV      -                   service Name : TV6_Rad    ~CSection ~SDT

6. 전체 소스 (github link)

소스 코드는 여기 있는 부분과 다를 수 있다. 중간에 버그나 수정이 필요하면 다시 올리기 때문에 git에서 받는게 가장 최신임.

https://github.com/heesoon/mpeg/tree/master/test/sdt