[linux-dvb] Re: Trying to get a ``polished'' MPEG stream from DVB

[Martin Kenny <marty@kennymoy.com.au>]

Hi,

Jim Darby wrote:

> I can't be the only one trying to transcode DVB output. What does
> everyone else do?
>  
I had something similar with replex. I'd get a whole series of these 
errors, followed by something like:
 ringbuffer overflow 132<184 629145
 ring buffer overflow 629145

My workaround was to use mencoder something like:
 cat /dev/dvb/adapter0/dvr0 | mencoder -of mpeg -ovc copy -oac copy - 
-o ps.mpg

This worked well, except when the cat received errors from the dvr 
device -- this would stop my recording, as cat would exit. I worked 
around that by writing a small C program, imaginatively called dvrcat, 
that simply logged the errors to stderr, and ignored them. This setup 
has been working for me for a couple of months, producing program 
streams that work well with mplayer, VideoLAN and WinDVD.

I've recently added -tskeepbroken to the mencoder command-line, as I had 
a problem once, where mencoder got confused and quit before it's stdin 
had been closed.


Chris Chatfield wrote:

> I'm trying to write one in my spare time. It's going a bit slowly at the
> moment  :( 
That was my grand plan a couple of months ago too, but since the 
mencoder thing has been working for me, it got put on hold.

Cheers,
Marty.

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

unsigned char buffer[188 * 10000];

int main(int argc, char *argv[])
{
 FILE *err = fdopen(STDERR_FILENO, "w");
 if (argc < 2)
 {
   fprintf(err, "Usage: dvrcat <dvr-device>\n");
   return 1;
 }

 int dvrFd = open(argv[1], O_RDONLY);
 if (dvrFd == -1)
 {
   fprintf(err, "Error: %s: %s\n", argv[1], strerror(errno));
   return 2;
 }

 while (1)
 {
   int bytesRead = read(dvrFd, buffer, sizeof buffer);
   if (bytesRead == -1)
   {
     fprintf(err, "Warning: %s: %s\n", argv[1], strerror(errno));
     continue;
   }
   if (bytesRead == 0)
     break;

   int bytesWritten = write(STDOUT_FILENO, buffer, bytesRead);
   if (bytesWritten != bytesRead)
   {
     if (bytesWritten == -1)
       fprintf(err, "Error copying to output: %s: %s\n", argv[1], 
strerror(errno));
     else
       fprintf(err, "Bytes written != bytes read: %s (%d, %d)\n", 
argv[1], bytesWritten, bytesRead);
   }
 }

 return 0;
}



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