Spdif

[ace_87]

Alright guys, quick question..currently i have a 5.1 speaker setup from my PC using the 6 channel connectors, but they are quite short in length and as my PC is not right beside me the connectors just about reach..however i was thinkin that as my mobo has a SPDIF connection to buy a SPDIF cable (as they come in larger lengths) and hook that up to the PC instead. BUT (and here comes the real question) would they still be able to output 5.1 channels?

[Agent]

No you won't, unless you have a card with DICE.

I've covered this a few times before. This should help: Need help getting 5.1 from my Amp Please

[r_j_k_p]

just to make this crystal clear:

1, if i connect via on optical cable from my asus p5k to an amp, if the film im watching is in 5.1, will i get 5.1 on the speakers?

2, if on the same connections i play music which is in stereo, only stereo will play on the speakers.

[ace_87]

Originally Posted by Agent

No you won't, unless you have a card with DICE.

I've covered this a few times before. This should help: Need help getting 5.1 from my Amp Please

I see...very informative, so basically what your saying is that i need a DICE card to encode the signals into 5.1? The speakers ive got are the z680's and they have a in built dolby digital decoder, so they still wouldnt be able to output 5.1?

[Agent]

Originally Posted by r_j_k_p

just to make this crystal clear:

1, if i connect via on optical cable from my asus p5k to an amp, if the film im watching is in 5.1, will i get 5.1 on the speakers?

2, if on the same connections i play music which is in stereo, only stereo will play on the speakers.

Yes and Yes
As for number 2 - Even if the audio is multichannel (Like a surround sound .wav for example) you will still only get 2 channels as its not encoded in a DD or DTS stream

Originally Posted by ace_87

I see...very informative, so basically what your saying is that i need a DICE card to encode the signals into 5.1? The speakers ive got are the z680's and they have a in built dolby digital decoder, so they still wouldnt be able to output 5.1?

Thats correct for a digital connection. For any content that is not currently pre-encoded (Like audio on a DVD), then you must have some hardware to take the audio, encode it into DD or DTS, pass it to the amp which then decodes it.

The speakers will output 5.1 fine if you use analogue to them.

[r_j_k_p]

so i have quite a few files that are films that give me the option of choosing 5.1 on vlc, as well as stereo (such as avi's or mkv's)
is there any way to check whether these are DD/DTS stream or just a multichannel.

[r_j_k_p]

further question
when hooking up from mobo to surround sound 5.1 via optical
say some music is in stereo, i understand the front left and front right will play the sound, but will the bass also be present?
or will the base be tuned to the front left and front right speakers?

[directhex]

Originally Posted by r_j_k_p

further question
when hooking up from mobo to surround sound 5.1 via optical
say some music is in stereo, i understand the front left and front right will play the sound, but will the bass also be present?
or will the base be tuned to the front left and front right speakers?

largely the decision on that front is up to your amp

[Agent]

Originally Posted by r_j_k_p

so i have quite a few files that are films that give me the option of choosing 5.1 on vlc, as well as stereo (such as avi's or mkv's)
is there any way to check whether these are DD/DTS stream or just a multichannel.

The audio properties in any decent player will show you what kind of data the stream is. In VLC (off the top of my head) its Misc->Media info.
It should then show all the data streams within that file. One will obviously be video, the rest will most likely be audio and perhaps subtitles if they have been encoded in that way.
AC3 = Dolby Digital. DTS just says DTS as far as I know, although these are rare on compressed videos as the audio size of DTS is fairly big.

Originally Posted by r_j_k_p

further question
when hooking up from mobo to surround sound 5.1 via optical
say some music is in stereo, i understand the front left and front right will play the sound, but will the bass also be present?
or will the base be tuned to the front left and front right speakers?

Non compressed audio over SPDIF (known as PCM, or IEC-958 Type II id you really want to get technical) is 2 channel. There is no channel in the stream for the bass / .1 bit.
Some amps will have a built in 'crossover'. These look at the audio and attempt to separate the frequencies that are in the bass range and send them to the sub. This depends on the amp and the settings it has.

Most videos will be encoded in AAC though - Its small, more efficient than MP3 and supports multichannel.

At this point its probably a good idea to introduce you to AC3 Filter, as if you do have videos with AC3/DTS streams in, you'll be wanting it.

Apparently AC3Filter can also take a stream and upmix/downmix it and encode it to AC3 now. I've not tried it, but its worth a look If you can get this working as it claims, you should be able to use 5.1 over optical with no extra hardware.
You're on your own with this one though