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