Mpeg2/ts get the video PID

Get the function code of the video PID from the PMT table

Implementation of the GETPMTPID function see: http://blog.csdn.net/myaccella/article/details/6982596

#define MAKE_PID (P) (((p[0]<<8) + p[1]) & 0X1FFF)
#define Make_word (H, L) ((h) << 8) | (l))

Structure definition of Little endian

typedef struct {
unsigned stream_type:8;

unsigned elementary_pid_high:5;
Unsigned:3;

unsigned elementary_pid_low:8;

unsigned es_info_length_high:4;
Unsigned:4;

unsigned es_info_length_low:8;
}mpegpmtstream_t;

typedef struct {
unsigned table_id:8;

unsigned section_length_high:4;
Unsigned:2;
Unsigned:1;
unsigned section_syntax_indicator:1;

unsigned section_length_low:8;

unsigned program_number_high:8;

unsigned program_number_low:8;

unsigned current_next_indicator:1;
unsigned version_number:5;
Unsigned:2;

unsigned section_number:8;

unsigned last_section_number:8;

unsigned pcr_pid_high:5;
Unsigned:3;

unsigned pcr_pid_low:8;

unsigned program_info_length_high:4;
Unsigned:4;

unsigned program_info_length_low:8;
}mpegpmtheader_t;

[HTML]  View Plain  copy ushort getvideopid (const char* filename)    {   # define tspacket_size     188    #define  CRC_SIZE           4       ushort pid,  pmtpid, videopid = 0;       uchar buf[TSPACKET_SIZE];        uchar* p = buf;       mpegpmtheader_ t* header;       MpegPmtStream_t* stream;        FILE*  fp;       int pos = 0;        ushort section_len;               pmtpid = getpmtpid (filename);       if  (pmtpid ==  0)   {           fprintf (stderr,  "Unable to get  pmt pid!\n ");           return 0;       }          fp = fopen (filename,  " RB ");       if  (fp == null)  {            fprintf (stderr,  "failed to open the file %s:  %s\n ",  filename, strerror (errno));           return  0;       }             while   (Fread (BUF,&NBSP;1,&NBSP;TSPACKET_SIZE,&NBSP;FP)  == tspacket_size)  {            if  (Buf[0] != mpeg_ts_sync_byte)  { //  @MPEG_ts_sync_byte = 0x47                fprintf (stderr,  "no sync byte!\n");                break;           }              p = buf;            pid = make_pid ((p+1));            if ( pid != pmtpid )  {                // Not a  PMT packet                continue;            }              //  Payload_unit_start_indicator  must be 1           if  ( BUF[1]&NBSP;&GT;&GT;&NBSP;6&NBSP;&AMP;&NBSP;0X01))  {                fprintf (stderr,  "no payload_unit_start_indicator!\n");                continue;            }               // Skip the TS header           p  += mpeg_ts_header_size; //@MPEG_TS_HEADER_SIZE  = 4               // Adaptation field exist or not            if  ((buf[3] >> 4 &  0x03)  & 0x2)  {