[vdr] bitstreamout-0.70 and vdr-1.3.21

Dr. Werner Fink werner at suse.de
Fri Mar 11 12:15:44 CET 2005


On Fri, Mar 11, 2005 at 08:33:17AM +0100, Dieter Bloms wrote:
> Hi,
> 
> On Thu, Mar 10, Dr. Werner Fink wrote:
> 
> > > it is in sync, but the pcm headers are wrong with ac3 stream.
> > 
> > What does wrong mean?  IMHO the headers which bitstreamout
> > produce should be correct accordingly to IEC 61937.  This
> > works with AC3, DTS and even with MP2 Audio. Only for the
> > later one my AV receiver has no auto detection which
> > requires switching my AV receiver into MP2 Audio mode by hand.
> 
> The nonaudio bit is not set and my sony amplifier stumble on it.

Then your sound card does not support the nonaudio bit
or you've set the Z680 option to yes, taht means skip
setting of the nonaudio bit.  You may try to set
the Z680 option to `no'.

> > This is what a sound card should do with loop through, that means
> > redirect the data from its S/P-DIF in to its S/P-DIF out _without_
> > modifying (e.g. _NO_ resampling, clipping or so whatever sound
> > `washing' which kill the pure compressed data).
> 
> I know, but I want the soundcard to modifying the pcm data, so that the
> nonaudio bit is set.

Sorry but the nonaudio bit has _nothing_ to do with the PCM
stream its self.  The nonaudio bit is set in the S/P-DIF
data 32bit data word stream which is used to transport the
16bit PCM data word stream.  Within this S/P-DIF 32bit data
words there is a sectionn for a PCM 16bit word and a preamble,
a parity check bit, some more bits, and the so called status
bit.  Within 192 S/P-DIF 32bit data words for each channel
you have 192 status bits. This 192 32bit data words starts
with a special preample in the first 32bit data word.
Now the second bit of the 192 status bits is the nonaudio bit.
If it is raised the S/P-DIF 32bit data stream is marked as
nonlinear.

> My amplifier works great With your bitstreamout plugin, but I can't get
> the sound in sync. And with loopthrough the nonaudiobit isn't set :(
> I use the soundcard "C-Media Electronics Inc CM8738 (rev 10)".

You can not set the nonaudio bit in loop through mode.
AFAIK the ALSA driver does not support that.


          Werner

-- 
AC3 loop through sound card http://bitstreamout.sourceforge.net/
Howto http://www.vdr-portal.de/board/thread.php?threadid=1958
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