[vdr] Re: Anyone using SoundBlaster cards for AC3?

[Juha <juhis@trinity.is-a-geek.com>]

On Fri, 2003-10-03 at 02:05, Mario Schellenberger wrote:

> J> Now, my question is, do I need to make a connection
> J> between the two cards to test bitstreamout? I've seen some posts on the
> J> web that indicate that the cards need to be connected, but I'm not quite
> J> sure, since all the relevant information seems to be in german, which I
> J> unfortunately don't understand very well.
> 
> So I'll try to make this point clear, even though my englisch is not
> the best;-)

> I have connected my SB to my DolbyDigital receiver via an optical
> connection. In order to watch tv-stations that broadcast in
> dolbydigital i have to use the bitstreamout plugin, which works best
> with the newest alsa-driver (bst-out0.46g and alsa0.9.7). no physical
> connection between dvb and sb is needed in this case (all audio-data
> is transfered via the pci-bus!). in case i want to watch a
> non-dolby-digital channel the data is transfered via my DVB-to-SB-aux
> connection. there is, as far as is know, no way to transfer the
> "normal" audio signal via the pci-bus.
> to sum this up:
> in order to get both audio formats ("normal" and dd) to be send from
> your SB to your receiver you'd have to make _one_ connection from dvb to
> SB (either J2 to SPDIF-In or Audio-Out to Aux-In). for bitstreamout
> alone to work you don't need this connection, but then you have to
> switch your receiver, everytime you want to watch a dd-channel via
> your soundcard (and you'd also have to connect your DVB directly to an
> analog-in of your receiver).
> 

Hi Mario and everyone else,

Thanks for the info, I really appreciate it. Now, before I test this out
just a few clarifying questions that might prevent me from damaging my
hardware. If I understood correctly, audio data in ac3 packages can be
transfered via the pci-bus to the soundcard. But not other kind of audio
data, at least not analog signals, as apparently is your case. What I'd
like to do is transfer the data from the dvb card, via my soundcard to
my amplifier without ever converting it to analog signal. So the data
would be either in the format of the standard spdif data (don't know
what it's called) or ac3 (dolby digital).

So, I now assume I got the previous part straight and need a connecting
cable between the two cards. I've soldered a connector between the dvb
card and soundcard, but I haven't tried it out yet. I connected the J1
pin 4 (spdif) and pin 10 (ground) as seen in the link below, to the
soundcard connector that says "CD SPDIF".

http://www.vdrportal.de/board/portal_vdrinfo.php?site=7&infonr=4&infoln=en&sid=8a18f76e84cca6c6e4a1fc5e3d0d156d

Would this be the correct way to make the connections? Again, I assume
it is. Now, the final thing I have to know is which way to insert the
connector to soundcard, since I have no idea which pin in the soundcard
is for spdif and which is the ground (its a symmetrical two-pin
connector). If I just randomly try it out, do I run at risk of breaking
my hardware? Is there a way to know / measure the way it needs to be
connected? If I have to test it out, I'd like to do it so that I
disconnect the external amplifier so I don't break it, but instead for
example record the signal with arecord, or just play it throug my
computer speakers. Is this possible, what settings in the alsamixer are
essential for doing this?

This ended up not being the most straighforward question. There are just
so many things I'm not sure about. I really appreciate if you can
straighten them out even a little bit. Thanks.

Best regards,

Juha

> J> So do they need to be connected and if so, how? Any pointers to eg.
> J> websites containing preferably english information on this?
> 
> For any further questions reply to the list and i'll try to help (and
> sure others will also help!). Hope you understood my english;-)
> 
> greets,
> schelli
> 
> Mario Schellenberger
> mailto:schelli@gmx.net
> 




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