[vdr] play-ac3 patch for use with STDIN / ac3dec without downmixing - how?

[Günter Niedermeier <guenter.niedermeier@ncs-online.de>]

Hello to all,

I've read in a lot of mails about ac3dec
to stream ac3 data from vdr to the DSP device
to get the S/PDIF output working.

I have tested this with several versions of ac3dec
and a52dec written by Aaron. But in every case i get
only one result out of my SBLive!/DXR3 card.
It's Dolby ProLogic.
None of the tests resulted in a Dolby Digital signal.

If i use play-ac3 (included in the emu10k1 package)
to stream the data from vdr to DSP i get a wonderfull
DD 5.1 signal out of the S/PDIF of my SBLive!/DXR3 card.

In some of these mails i've also read that
ac3dec ac3play or play-ac3 do the same. But i think
this could not be correct.

Now my question:

What do I make false with ac3dec?
Is there a special command/option to call ac3dec / a52dec
to use streaming only without any downmixing or something
else?

BTW:

I've also read in some mails about problems using
play-ac3 in combination with vdr. I had the same
problems, but i found a patched version in the WEB
which is able to play ac3 streams from STDIN to DSP,
and it works really good with my both cards.

I used several kinds of starting vdr with play-ac3
and every result was the same. (directly, with FIFO
device, with a shellscript...)

Simply use ./vdr -a 'play-ac3 -' and it works.

The only bug in this version is that it never exit's
when the ac3 stream is broken.
When this occurs vdr starts a new (second, third...) play-ac3
process without exiting the older one.
The result is a unavailable DSP device, the older play-ac3
processes become zombie's and at least you must exit/kill
vdr to release them.
This effect is reproducable if you replay a DVD via vdr
and you jump from one chapter to another and so on.

I had contact with Bert de Bruijn who has written this
patch, and i told him about this problem, but he said
he is unable to correct this because of very less knowledge
about C-programming.

Parhaps somebody who reads this mail is able to correct
this problem in the patch.

Here now the URL:

http://bert.debruijn.be/linuxstuff.html
http://bert.debruijn.be/linux-stuff/play-ac3.c
http://bert.debruijn.be/linux-stuff/play-ac3.patch-v1.2


Regards

Guenter Niedermeier