Mpeg2/ts acquiring a PCR PID method

A simple function to get the PCR PID from the specified mpeg2/ts file,

The head structure of the PMT has a PCR PID, we first get the PMT PID, and then analyze the PMT package, you can get the PCR pid.

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

Make_pid:

#define MAKE_PID (P) (((p[0]<<8) + p[1]) & 0X1FFF)

[HTML]  View Plain  copy ushort getpcrpid (const char* filename)    {   #define  TSPACKET_SIZE     188        ushort pid,  pmtpid, pcrpid = 0;       uchar buf[TSPACKET_SIZE];        uchar* p = buf;       file*   fp;              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)  {                fprintf (stderr,  "Adaptation field  exist\n ");               p +=  1 + p[0];  // p[0] is Adaptation field length,  1 for length field             }              // p[0]  for   Point field length,  1 to point field           p  += 1 + p[0];              // 8   Offset for pcr pid in PMT header            p += 8;               //  Pcr pid If it's 0x1fff,   will need to continue to fetch            pcrpid = make_pid (p);