[linux-dvb] Re: latest CVS version

[Klaus Schmidinger <Klaus.Schmidinger@cadsoft.de>]

Ralph Metzler wrote:
> 
> Hi,
> 
> in the latest CVS version there are some changes in the driver
> behavior.
> 
> - I changed the syncing in the ARM code which removes the
>   "jerking" problem during playback.
>   I already spent quite some time testing this but I would
>   like to know if it also works for you and if anybody
>   experiences any long time problems with syncing during
>   playback with this new code.

Looks like the "jerking" problem is gone now. However, from
time to time I get a small picture distortion ("Klötzchen", sorry,
don't know an English word for this) or a short but loud and sharp
"twirping" sound. When I replay the same sequence again, the problem is
either gone or at a different place, which would indicate that the
recording is ok. I am currently rewriting the replay code in VDR
and have tried this with my new cRingBuffer which has two separate
threads for reading and writing, so I would believe that VDR is delivering
the data fast enough to avoid any buffer underrun.

I will continue working on this tomorrow and over the weekend,
just thought I'd let you know - maybe you have an idea if this
could possibly be a driver problem.

Or could this have to do with the fact that VDR installs several
filters for reading the EIT data, and these are also active while
replaying?

> - All transfer to and from the card is now done with PES packets
>   with a maximum size of 2KB.
>   The driver contains a filter which splits larger incoming PES
>   into 2KB PES packets. This does not include PCM PES packets.
>   So programs which create such PCM PES (like DVD playback
>   software) will have to reduce the max. size they use.
>   The 2KB is counted including the headers.
>   Playback of e.g. PCM DVDs is not affected since DVDs always have
>   PES with a max. 2KB length.
> 
> The reason for using smaller packets for the transfer to/from the
> ARM is that this way the dual ported RAM can be used more
> efficiently than with the previous packet size (max. 7KB)
> which only allowed transfers in one direction (DPRAM size is 8KB).
> After all, the DPRAM is dual ported. So, why not use both ports
> at the same time, right?
> 
> Now I can start implementing things like double buffering
> for higher throughput in one direction or use one buffer for
> recording and one for playback (time shifting) ...

Wow, that sound like a dream come true :-)
Will this also work with the "old" Siemens DVB-S card?
Could this also help avoiding the picture distortions when using the OSD?

Klaus
-- 
_______________________________________________________________

Klaus Schmidinger                       Phone: +49-8635-6989-10
CadSoft Computer GmbH                   Fax:   +49-8635-6989-40
Hofmark 2                               Email:   kls@cadsoft.de
D-84568 Pleiskirchen, Germany           URL:     www.cadsoft.de
_______________________________________________________________


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