Re: TS discontinuity with TT S-2300

[Oliver Endriss <o.endriss@gmx.de>]

On Sunday 27 June 2010 17:56:06 Marko Ristola wrote:
> 27.06.2010 15:37, Oliver Endriss wrote:
> > Hi,
> >
> > On Sunday 27 June 2010 01:05:57 Jaroslav Klaus wrote:
> >   
> >> Hi,
> >>
> >> I'm loosing TS packets in my dual CAM premium TT S-2300 card (av7110+saa7146).
> >>
> >> I use dvblast to select 4 TV channels (~ 16 PIDs) from multiplex,
> >> descramble them and stream them to network. Dvblast reports TS
> >> discontinuity across all video PIDs only (no audio) usually every
> >> 1-3 minutes ~80 packets. But sometimes it goes well for tens of
> >> minutes (up to 1-2hours). Everything seems to be ok with 3 TV channels.
> >>
> >>     
> > The full-featured cards are not able to deliver the full bandwidth of a
> > transponder. It is a limitaion of the board design, not a firmware or
> > driver issue.
> >   
> I noticed that saa7146 uses dvb_dmx_swfilter_packets().

Yes.

> I planned using of that function too for
> Mantis 16K buffer delivery, but I found out that
> hardware delivers sometimes additional bytes (corrupted partially lost
> packets?)
> between the full sized 204 byte packets:
> 
> Jun 26 16:20:37 koivu kernel: demux: skipped 49 bytes at position 3379
> Jun 26 16:20:37 koivu kernel: demux: skipped 18 bytes at position 9868
> Jun 26 16:20:37 koivu kernel: demux: skipped 30 bytes at position 10090
> Jun 26 16:20:38 koivu kernel: demux: skipped 14 bytes at position 7208
> Jun 26 16:20:38 koivu kernel: demux: skipped 114 bytes at position 7426

Are you sure that Mantis driver delivers garbage, not partial packets?
Please note that the dvb_dmx_swfilter[_204]() routines must accept
partial packets, i.e. the rest of the packet will be dellivered with the
next call.

> So dvb_dmx_swfilter(_204)() is needed to skip
> these unwanted bytes. With simple usage of
> dvb_dmx_swfilter_packets() the rest of the buffer
> would have been lost. I wrote a faster version of these
> functions, also for 188 sized packets today:
> "Re: [PATCH] Avoid unnecessary data copying inside
> dvb_dmx_swfilter_204() function"

dvb_dmx_swfilter_packets() expects complete TS packets from the driver.
The saa7146 does so. It does not deliver garbage data. (Otherwise this
would have been noticed a long time ago. The ttpci drivers are the
oldest DVB drivers and are very well tested.)

CU
Oliver

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