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hello all,


i've got my nvidia nforce motherboard with spdif/ encoding hooked up to my linux box with the delta 410. i'm trying to get 5.1 sound over to linux, but failing miserably. i think i need dolby digital encoding on to get all 5 channels, but i dont even know if alsa can understand the dolby digital system.


even when i have dolby digital off, only outputting digital signal, playing only a stereo signal i still get tons of clipping and distortion. its pretty damned ugly. alsa 0.9.8.


add the other channels in and the signal gets crappier and crappier. still there, just really distorted.


nvidia states digital output defualts to 48khz 24 bit samples of pcm. envy24control is set to int 48000. i've tried all the different Master Clocks, 96khz works just about as well as 48khz, and the other frequencies leave a little skew. spdif is just a garbage... thats the kicker.


the other big nut kicker is that dolby digital encoding is off. turning it will often garbage to spew out of the delta 410. DAC volume, toying with router, nothing fixes the output, you hve to reboot to return it to sanity. this is what scares me the most.


i think some audio processor is meant to divide the channels again. i would DRASTICALLY like to avoid this, if at all possible. well, its not really a possiblity at all. my delta410 drives a power amp straight, as it used to do on my windows box. i need dolby digital decoding somehow.



i havent really figured out how to configure the alsa setup... envy24control is the only alsa thing i've gotten to work. alsaplayer and xmms both fail to open the alsa drivers, and my attempts to get jack working have met equal failure. there's some beautiful looking /usr/share/alsa/pcm files that look pre-generated for my sound card, however i have no idea how to use them, and they only deal with sound out, not input.


the two good pieces of news: digital input kind of works! woot. second, i can play through analog out on my nvidia nad my delta 410 plays vaguely syncronized. finally multiple speakers in one room.


theres a chance it could be my cable. its a crap hackjob. the spdif headers are literally pins on the motherbaord i put a jumper onto (with wire out the back... two pin speaker style, red and black). i think that explains some of the distortion, but not all. and i dont see how some noisy dolby digital encoding would cause the sound card to flip its **** and start spewing trash no matter what you do to try and fix it.


the last thing of note about the cable isthat the mobo has a vcc pin output next to spdif/output. i ignored it: ground on the outter shell of the rca, and spdif/out on the center pin of the rca. it could be weird spdif juju i've just got wrong...



sorry this is so long. i've heard this card recommended again and again as a linux solution, and i really hope its digital capbilities arent completely dead in linux. :'-(


thanks

Myren
 

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The first thing to do is to make sure that you use envy24control to set the card to use the incoming spdif signal as the master. If you are using an internal clock of any sort, you'll get dropouts and interruptions in the signal. Once you set the clock properly, you should be able to get 2-channel pcm input via spdif. I don't have a 410, but I have a delta 1010 and a delta 66 and use the spdif input from my cd/dvd player all the time and it works fine.


On the dolby digital front, though, there is no easy answer that I'm aware of. I don't know of any utility that will actually accept a DD encoded signal over spdif and decode it back to the analog outs. This "shouldn't" be too hard and there might be something out there, but I've never seen it.
 
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