[vdr] Re: bitstreamout-0.48pre2

["Dr. Werner Fink" <werner@suse.de>]

On Wed, Oct 22, 2003 at 09:15:56PM +0200, Sven Goethel wrote:
> On Wednesday 22 October 2003 17:18, Dr. Werner Fink wrote:
> > On Wed, Oct 22, 2003 at 05:05:30PM +0200, Gregoire Favre wrote:
> > > On Wed, Oct 22, 2003 at 04:44:36PM +0200, Sven Goethel wrote:
> > > > well - he can just switch bitstreamout off ;-)
> > > > via the main menu
> > >
> > > That's not very convenient :-(
> > >
> > > > i guess thats ok
> > >
> > > Well, is there any reason to do it?
> >
> > AFAIK Svens onboard sound do not provide a S/P-DIF in connector
> > but only a S/P-DIF out connector.
> 
> hmm .. so DVB's S/P-DIF out provides PCM 
> if you play MP2 or PCM itself using PlayVideo ?

Exactly this how it works with my VDR configuration:

    +-----------------------------+          +---------------------+
    | DVB card                    |          | Sound card/chip     |
    |            +--> [J2 Pin 4]--o----------o-[S/P-DIF in]        |
    |            |                |          |    v                |
    |       [HW decoder]          |     +------[mixer]>-+          |
    |                             |     |    |    ^     |          |
    | [PCI]   [I2C]               |     |    |    |   [SP-DIF out]-o--- A/V
    +---|-------I-----------------+     |    +----|----------------+
        |       I                       |         |
        |       I        [         +{mute.sh}]    |
      [PCI]<->(driver)<->[VDR->{bitstreamout}]    |
                         [         |         ]    |
                                   +--> ... --> [PCI]

> 
> looks like ?!

MP2 will be decoded by the DVB card and the result is given on the
S/P-DIF out on Jumper 2 on pin number 4.  This pin is connected
to the S/P-DIF in of the onboard sound chip.

The default mixer configuration is: loop through the S/P-DIF in to
S/P-DIF out.  Now if bitstreamout receives data it opens the
sound card/chip interface and establish a data transfer tp the
S/P-DIF out.  And it bitstreamout closes the sound card/chip interface
the old configurtion will restored.

With the mute.sh script the default configuration is set: `mute.sh off'.
... This could be done also by hand with amixer or alsamixer or
any other mixer for alsa.  Only muting is a further feature of that
script:  It smply disables the SP-DIF out of the sound chip.

... or in short: just simply good sound.
And if you own a high end sound card which is able to skip its
own quart for timings but use the S/P-DIF in signal rate for
that you'll get perfect sound. In this manner e.g. a SB
is _not_ a good sound card.

> 
> >
> > > I don't hear any sound quality improvement in doing so, I just lost my
> > > system sound :-(
> >
> > For owners of a onboard sound chip or sound card with S/P-DIF in
> > connector it is not an improvment because the synchronization done
> > by the DVB card is not doable in sw.  This was the reason why I
> > never add support for MP2 within bitstreamout plugin.  And therefore
> > I'd like to see a compile and runtime configuration.
> 
> ja - please have a look into the pts.h cPTS::process method,
> which should take action if outta sync.
> 
> so now .. the function just evaluates a delta delay of zero ;-),
> which is good, just to know whatis a zero delay.
> 
> well - i guess to calculate a real pts diff, we need the video stream
> as well - and just use the av pts async ..

The problem is: AFAIK if you receive the TS stream of
the video data of the current channel you loose live TV.


       Werner


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