View Full Version : Decode AND passthru AC3 audio
Minotaur
2006-02-17, 09:42
howdy
i'd love to see an option in xbmc that allows simultaneous passthru to optical and decode to analog of ac3 sound. such a setup would allow me to use my amp to decode ac3, but still allow the tv at the other end of an av sender in my bedroom to play decoded ac3 audio :)
jmarshall
2006-02-17, 11:51
not possible. xbox cannot send different signals to the analog and digital outputs.
Minotaur
2006-02-17, 12:00
hmm i thought the dvd player in the ms dash did so... when i have dolby digital enabled in the dash i definately get audio out on the analog output as well as the digital one.
edit: my amp detects the incoming signal on the optical lead as dolby digital in this instance...
jmarshall
2006-02-17, 12:23
it doesn't pass the ac3 through. what you are hearing is on the fly encoding to ac3 (ie the same signal is being sent to both outputs).
when we pass through ac3, then it's padded to pcm - you do not want this sent to the analog out (it'd be white noise).
Is it possible to put an option in for this?
My setup sends modulated RF around the house for simple kitchen and playroom viewing of xbmc, it also has digital out going to the amplifier in the lounge. Since passthrough has become default, ac-3 encoded avis don't have sound in the RF rooms. I'd like to take the processor/quality hit of decoding/recoding (especially as I've now gone analog completely in order to get sound in other rooms).
AC3/DTS passtrough: () on () decode/encode
I'm sure I'm not the only one.
maybe you didnt see the earlier reply from jmarshall?
not possible. xbox cannot send different signals to the analog and digital outputs.
all you can do is disable ac3 passthrough.
I think that's what I meant, but hasn't the option to disable passthru been removed?
well, if you disable ac3 cabable reciever, it will downmix to dolby surround (stereo). Thus you wont' get full 5.1 out of your speakers.
it would be possible to not allow passthrough but still let the xbox output 5.1, and output the two front channels of the 5.1 to the analog ports. but I doubt anybody is intertested in implement it, as it causes much worse quality from the 5.1 output. (ie not supported as it is now)
well, if you disable ac3 cabable reciever, it will downmix to dolby surround (stereo). Thus you wont' get full 5.1 out of your speakers.
it would be possible to not allow passthrough but still let the xbox output 5.1, and output the two front channels of the 5.1 to the analog ports. but I doubt anybody is intertested in implement it, as it causes much worse quality from the 5.1 output. (ie not supported as it is now)
Was I just never playing sources with AC3, or was this the setup previously? I used never have issues with the analog feed differing from the digital, but recently quite a few video files have that issue.
I guess my next best solution is a quick and easy switch between digital and analog so it can be turned over easily when needed? Something I can keymap? Is that possible at the moment?
ultrabrutal
2007-03-15, 21:41
I guess my next best solution is a quick and easy switch between digital and analog so it can be turned over easily when needed? Something I can keymap? Is that possible at the moment?
I was wondering this too because going through the menu every time is alittle annoying not to mention teaching a wife to do it ;)
The option is in osd now atleast. Suppose we could add an option to disable passthrough of ac3/dts and always decode then reencode to ac3. will be worse quality and a waste of cpu power, but if people really want it.
ultrabrutal
2007-03-16, 17:50
No you misunderstand. We just want it easier to switch between analog and digital audio instead of having to go through menus. I would no use an option that would give worse soundquality when using amp.
Wife wants to use the speakers in the TV set, where man wants to use the amp with surround sound. Man forgets to set audio back to analog and wive gets mad. Same as with toilet seats hehe... But if she could just push a button and then there would be sound
we won't give you a shortcut to the one-way-to-fried-eeprom's paradise. sorry.
? spiff.. switchin analog / digital doesn't modify eprom...
Hey Ultrabrutal, have you tried to change wife ?
sorry, I couldn't resist ;)
ultrabrutal
2007-03-17, 00:45
Lol finas, to be honest I was asking for a friend. I do not use analog output and digital in the same room, but I agree it's a needed feature
andyjayh
2007-12-09, 22:03
When I watch movies I use digital for surround and when I watch TV stuff I just use the TV audio. However I can't leave xbmc setup so it will work on both with no user interaction, I think.
If I leave the audio settings on digital then the sound won't work on the TV. If I leave it on analogue then it will only work on Pro Logic on the surround processor, obviously.
Is there a way that I can get xbmc to work with both without user interaction?
Cheers,
Andy