[mythtv] Mythtv does not set the non-audio bit for ac-3 surround

[Michael T. Dean]

On 03/21/2008 07:59 PM, Bas Wielens wrote:
> i've been trying for days now to get the surround working in mythtv when playing dvd's. I've tried everything i found in google, with no result. My receiver (Sony) does not indicate surround when playing a dvd.
>
> I've set the the passthrough output device to 'Default' (also tried ALSA:iec958, ALSA:iec958{AES0 0x06}, ALSA:iec958{AES0 0x02}, ALSA:spdif, ALSA:surround51, ...) non worked...If i would set the non-audio bit by hand, using the 'iecset audio 0' it actually worked using the 'Default' passthrough device. My receivers blue light comes up and i get full ac-3 surround. The only drawback is that i have to set this manual inside a shell each time i want to play a dvd and i have to set it back manual using 'iecset audio 0' if i want to listen to music. This is really unpractical...
>   

Anytime you specify the bit 0x02 for AES0, you're telling your sound 
card to set the IEC958 status bit to specify non-audio.  Therefore, both 
when you specified ALSA:iec958{AES0 0x06} and ALSA:iec958{AES0 0x02} , 
you were specifying the non-audio bit.

There's likely a misconfiguration of your sound card, and not a bug in 
Myth.  (Though I will admit that there are many ways Myth's ALSA support 
could be improved, all of those ways I'm thinking of are feature 
requests and not bugs.)  Therefore, I recommend you ask on the 
mythtv-users list ( 
http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users ).  Doing so 
also has the nice benefit that more eyes will see your posts, so the 
person who has your answer is more likely to see it.

Mike