AC3 in Australia (Was Re: [mythtv] DVB 3.4 report)

Mark Anderson markjanderson at mail.com
Fri Jan 7 03:21:56 EST 2005


On Fri, 7 Jan 2005 06:54 pm, Tj wrote:
> Mark Anderson wrote:
> >nly got back onto it last night after a week away camping and wake
> >boarding.
> >
> >I am basically back at where we left off last year with big dvb 3.2. The
> >problems as they stand:
> >
> >1. I don't really understand what the changes to mpeg.c do, it should work
> >without them but doesn't.
>
> I'm not sure but I think Marcus may have fixed this in transport.c..
> Will try his code once (if) I get 10.1 Official installed and myth
> working later today.
>
> If you're at home now, try his patch and restore mpeg.c and see if you
> got DD.
>
Which patch are you referring to?

> >2. Still can't change between stream types AC3->PCM or PCM->AC3, I am
> > tracking this one down and understand why it is happening, just need to
> > work out how to fix it. Streams from the previous channel are still in
> > the list of available streams and so it chooses it instead of the correct
> > one. Need to clear them out when the channels change.
>
> Ah!! So that's the problem, what files and functions are you looking at?
>
Actually, I was wrong. It only adds new stream types as they are found. So 
typically you have twp streams, PCM and AC3 after selecting an AC3 channel 
and then a PCM channel. However, the audio is not re-initialised when you 
change between streams... still looking.  I am looking at 
autoSelectAudioTrack, mainly when it is being called.

> >3. The biggest problem is that the audio stutters every 5-10 seconds, my
> >decoder only displays "Dolby digital..." when the stream first starts and
> > I see this displayed when it stutters. I'd be interested to see if it
> > happens for anyone else to eliminiate my setup.
>
> I only tested it for like 10 seconds on my amp. When I use an AC3 APID,
> the dolby digital signal lights up, but the decoder used is still dolby
> pro logic II (presumably becoz the audio is 2ch, but from what I read
> you can still use pro logic II for surround effects). I did a recording
> of CSI (which is supposedly surround sound), but the same thing still
> happens. Like you, I also got audio stutter, and wierd audio
> positioning. The problem of that stutter I suspect is due to the hacked
> mpeg.c (Probably not all private streams packets are AC3 audio, but the
> hacked mpeg.c treats every private stream as such)..
>
That's the best explanation so far, I think you might be right.

> Anyway, will learn more tonight.


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