On Wed, Mar 16, 2005 at 01:39:44PM +0100, Roland Praml wrote: > > vdr-1.3.22 + bso-0.80 = Ok! > > > > Slight A/V delay though. Will keep on tweeking tonight. > > I've updated to 0.80, too. Now it works with newer recordings. > > Just for my understanding: > The A/V problem exists because the soundcard clock doesn't know > anything about the DVB-clock respectively timestamp and there's > no way to get the current video-timestamp which is displayed at > the moment. So the only way in my eyes is to use the spdif of > the DVB-card for perfect A/V-sync. > > There are different ways to transfer AC3 over spdif: > - a real AC3 stream (like DVD playes do) > - AC3 embedded in PCM (like AC3overDVB and bso) There are two methods: a 32bit method which is a transport layer similar to S/P-DIF but only for AC3 (you need HW access to the S/P-DIF interface of the soundcard) and the other method is 16bit using a nonlinear PCM stream accordingly to ISO/IEC61937. The later one requrires in the 32bit S/P-DIF transport layer the non-audio status bit. Nevertheless many AV receivers do detected _and_ handle the nonlinear PCM stream within the S/P-DIF transport layer -> http://www.epanorama.net/documents/audio/spdif.html > > bso can set the nonaudio-bit, AC3overDVB can't. > > Why? is this a hardware limitation? Can it theoretically > worked around by some soldering etc? Ask TI, I don't know. > > Long time ago there were so called 'copy-bit killer' > Can I set the nonaudio with a similar circuit. Depends if this circuit works on the payload of the 32bit S/P-DIF transport layer or on the status bits of the transport layer its self ... the later one should be done. > As other mentioned this should also be done by a soundcard > by reading from spdif-in, set the bit, and writing to spdif-out > > (it's definitely a bug in the sony-firmware why my receiver > can't play AC3 over DVB. I've a AC3 and DTS CD, the surround > sound is wrapped in PCM-frames. DTS is played fine, AC3 not. > The behaviour is the same as if replaying AC3 over DVB. > BUT if I skip quickly from an DTS to an AC3 track the receiver > sometimes "hangs" on DTS but plays AC3 WITH SOUND) I don't think its a bug ... it is not specified to play 16 bit nonlinear PCM without marking the 32bit S/P-DIF transport layer as nonlinear. For all the others which can handle this ... it's a nice feature. Werner -- AC3 loop through sound card http://bitstreamout.sourceforge.net/ Howto http://www.vdr-portal.de/board/thread.php?threadid=1958 ------------------------------------------------------------------ "Having a smoking section in a restaurant is like having a peeing section in a swimming pool." -- Edward Burr
