[vdr] Re: what causes cTS2PES errors?

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

Rene Bartsch wrote:
> 
> Am Mon, 2003-05-26 um 23.10 schrieb Klaus Schmidinger:
> 
> >
> > I don't believe its the task of the application to do the CRC checking.
> > This should (if not already) be done in the driver.
> >
> > > > I believe there's some CRC32 checking code in mpegtools (
> > > > http://www.metzlerbros.org/dvb/index.html ) maybe that can be used.
> > > >
> > > > If at all, it should only be done on recording as transfering to say an
> > > > av7110 or dxr3 they have their own means of dealing with broken streams in
> > > > a less interruptive manner than just throwing the packet away? But then
> > > > again broken reception crashes the decoder after a while more often than
> > > > not. On full cards in live mode not a lot vdr can do against it?
> >
> > There's _nothing_ VDR can do about this in live mode.
> >
> 
> Yes - it can enable it! ;o)

Did you actually read that posting? See comment below...

> Post from Holger Waechtler on linux-dvb:-ML:
> 
> ------------------------- snip -----------------------------------------
> 
> Rene Bartsch wrote:
> Am Mon, 2003-05-26 um 19.23 schrieb Holger Waechtler:
> 
> Rene Bartsch wrote:
> 
> Hi,
> 
> As subject says, which CRC-code is used in TS of DVB?
> 
> I think I've read CRC32 somewhere - is that correct?
> 
> it's CRC32, the decoder model is described in ITU-T H.222.0, Annex A.
> 
> Is there any chance that CRC32 will be added to DVB-driver for
> low-budgets?
> 
> It's implemented. Set the DMX_CHECK_CRC flag in the
> dmx_sct_filter_params struct if you want only receive sections that
> passed the CRC32 check.

...this is about _sections_ that VDR would receive. Ok, it could set that
flag, but then again libdtv does CRC checking on section data.

I believe the original question was about TS packets of audio/video data,
or am I missing something?

During live TV these packets don't get into application space, so I'd
say there still is nothing VDR could to.

If DMX_CHECK_CRC can also be used on dmx_pes_filter_params, then VDR could set
it in case of recordings or Transfer Mode (but I'm not sure DMX_CHECK_CRC
really applies to dmx_pes_filter_params). But even then I believe it
makes no difference for live TV on a full featured card, since there the data
stays _on_ the card and doesn't get into the driver, let alone the application.

Aren't the 188 byte sized TS packets the application receives from the driver
already the result of several stages of error correction? I don't see any CRC
information in these packets' headers...

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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