[vdr] Re: bitstreamout vs. AC3overDVB

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

On Sat, Nov 13, 2004 at 08:58:07AM +0100, hm@seneca.muc.de wrote:
> Dr. Werner Fink <werner@suse.de> wrote:
> > Exactly.  Beside this my bitstreamout plugin works perfectly for
> > most AV receivers if the sound card clock is a few ppm faster
> 
> Why is it that the data format of AC3overDVB differs from the one sent by
> bitstreamout? I would like to understand the technical reason. 

The only difference is that most sound cards are able to send
non-audio marked S/P-DIF transport stream whereas the DVB card
can not do that.  The 16 bit PCM payload in the 32 bit S/P-DIF
words of the bitstreamout plugin and den AC3overDVB patch
(and also with the AC3overDVB replaying firmware) are exactly
the same (ISO/IEC61937) ... the advantage of the AC3overDVB path
is simply that the audio stream can be synchonized with the
video stream during replay whereas the bitstreamout plugin
try this at startup.  This because you can not hold the
buffer of sound chip or speedup the clock of the sound chip.

For more information you may read the file Description
within the source tar ball of the bitstreamout plugin.


         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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