[linux-dvb] Re: example program

[Justin Cormack <justin@street-vision.com>]

> 
> Justin Cormack wrote:
> > Has anyone got a short demo bit of code that just reads the transport
> > stream? It would be really helpful. Or even just a sketch. It would be
> > useful in the docs.
> 
> just copy'n'paste the code fragment in szap.c, set_demux() for vdr=1, 
> this sets up the demux to stream a TS out of the dvr device, you can do 
> something simple like
> 
> $ cat /dev/dvb/adapter0/dvr > stream.ts
> 
> to write this into a file. Note that as soon you close the demux file 
> descriptor the stream will stop.

ok thanks, mostly there I think (still trying to sort out my oops of 
yesterday. Basically I cant get dvbstream not to oops on any machine so I
thought I would go back to basics).

I cant get tzap to tune though, with config file set to
BBC-1:50583333:INVERSION_OFF:BANDWIDTH_8_MHZ:FEC_2_3:FEC_NONE:QAM_64:TRANSMISSION_MODE_2K:GUARD_INTERVAL_1_32:HIERARCHY_NONE:600:601
(which I think is right for Crystal Palace) I get
./tzap BBC-1
using '/dev/dvb/adapter0/frontend0' and '/dev/dvb/adapter0/demux0'
tuning to 50583333 Hz
status 01 | signal 2d2d | snr 0000 | ber 0000ffff | unc 00000000 | 
status 01 | signal 2d2d | snr 0000 | ber 0000ffff | unc 00000000 | 
status 01 | signal 2d2d | snr 0000 | ber 0000ffff | unc 00000000 | 
status 01 | signal 2d2d | snr 0000 | ber 0000ffff | unc 00000000 | 


> 
> > Also, none of the dvbtools compile on todays DVB cvs, as all the type names
> > seem to have changed.
> 
> what do you mean by dvbtools? The tools in the DVB/apps/ directory? Or 
> Dave Chapman's dvbstream?

yes dvbstream.

Does below look about right then, minus the missing tuning?

#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#include <errno.h>

#include <linux/dvb/frontend.h>
#include <linux/dvb/dmx.h>

#define FRONTEND "/dev/dvb/adapter0/frontend0"
#define DEMUX "/dev/dvb/adapter0/demux0"
#define DVR "/dev/dvb/adapter0/dvr0"

int main(int argc, char ** argv) {
  struct dvb_frontend_info info;
  struct dvb_frontend_parameters frontend;
  struct dmx_pes_filter_params pesfilter;
  int fd, fdd, fdts;
  uint16_t strength, snr;
  fe_status_t status;
  int buffersize = 64 * 1024;
  char buffer[1024];
  int pid = 0;

  if ((fd = open (FRONTEND, O_RDWR)) < 0) {
    perror ("frontend open failed");
    return -1;
  }
  
  ioctl (fd, FE_GET_INFO, &info);

  fprintf(stderr, "card found: %s\n", info.name);

  if (info.type != FE_OFDM)
    fprintf(stderr, "warning: this program understands DVB-T best\n");

  /* add tuning here */
  /*  printf ("tuning to %i Hz\n", frontend->frequency);
  
  if (ioctl(fd, FE_SET_FRONTEND, &frontend) < 0) {
    PERROR("ioctl FE_SET_FRONTEND failed");
    close(fd);
    return -1;
  }
  */

  ioctl(fd, FE_READ_SIGNAL_STRENGTH, &strength);
  ioctl(fd, FE_READ_SNR, &snr);

  fprintf(stderr, "signal strength %d SNR %d\n", strength, snr);

  ioctl(fd, FE_READ_STATUS, &status);
  if (status & FE_HAS_LOCK)
    fprintf(stderr, "FE_HAS_LOCK");


  if ((fdd = open(DEMUX, O_RDWR)) < 0) {
   perror ("demux open failed");
   return -1;
  }

  if (ioctl(fdd, DMX_SET_BUFFER_SIZE, buffersize) == -1)
    perror("DMX_SET_BUFFER_SIZE failed");

  pesfilter.pid = pid; // ?
  pesfilter.input = DMX_IN_FRONTEND;
  pesfilter.output = DMX_OUT_TS_TAP;
  pesfilter.pes_type = DMX_PES_VIDEO;
  pesfilter.flags = DMX_IMMEDIATE_START;

  if (ioctl(fdd, DMX_SET_PES_FILTER, &pesfilter) == -1) {
    fprintf(stderr, "DMX_SET_PES_FILTER failed "
	    "(PID = 0x%04x): %d %m\n", pid, errno);
    return -1;
  }

  if ((fdts = open(DVR, O_RDONLY)) < 0) {
   perror ("dvr open failed");
   return -1;
  }

  while (read(fdts, buffer, 1024) > 0)
    write(STDOUT_FILENO, buffer, 1024);

  return 0;
}


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