[linux-dvb] Re: Any need for gszap?

[Roberto Ragusa <r.ragusa@libero.it>]

On Mon, 05 Jan 2004 09:53:51 +0100
Holger Waechtler <holger@convergence.de> wrote:

> Niklas Peinecke wrote:
> > 
> > I've seen the EOF problem also. I got the impression that it is speed 
> > related, i.e. if there is heavy load on the machine EOF occurs more 
> > frequently. Nevertheless if you pipe the stream to a file and then 
> > replay, there are no problems. Maybe the driver replays values <0 
> > through /dev/dvb/adapter0/dvr0 (don't know if this is possible)?
> 
> no, it's not. You get the raw unmodified data from air through the dvr 
> device. Data is only lost in case of buffer overflows, but the MPEG 
> decoder should be able to tolerate corrupted MPEG packets silently.
> 

Are you saying that a buffer overflow would only cause skipped packets?

I'm quite sure I used to get an error number 75 (EOVERFLOW) when the
buffer overflows.
Just grep for EOVERFLOW in dmxdev.c.

In the same file, function dvb_dvr_do_ioctl() there is a disappointing

        switch (cmd) {
        case DMX_SET_BUFFER_SIZE:
                // FIXME: implement
                ret=0;
                break;

so the limit can't be even raised. The default is 10*1024*188 bytes
(which is only one second with HDTV at 15Mbit/s).

Am I wrong?
-- 
   Roberto Ragusa    r.ragusa at libero.it


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