Wiring question, digital out

[jernst]

Hi all,

I'm thinking to buy an external receiver (Dolby Digital, Dolby Prologic II) but I have the following questions in order to don't buy things that won't work together...

I have an MSI motherboard with 5:1 analog output (3x mini-jack connectors), coax SPDIF and optical SPDIF. I want to connect my PC to the receiver which will take place near my TV-set, 10 meters away from my PC.

Questions:

1) If I playback sources that can't be decoded by the receiver (mp3, ogg vorbis, etc.), will my PC output the sound to the SPDIF interface(s) ?

2) Will the receiver understands PCM and will the sound be only stereo even if I have 6 channels Vorbis ? / Or do I have to use the analog output(s) and buy myself some more wires (1 for stereo, 3 for 5:1)

3) What wire is the best for 10 meters: optical or coax ?

4) Is the digital coax cable a "normal" coax wire, like the one of TV antennas ?

5) If I playback Dolby prologic II content, will it go trough the digital interface and be understood by the receiver as prologic II content ?

6) Does Prologic II decoder decodes Prologic I as well ?

7) Do I need any dshow filter to achieve all this (more than the AC3 filter for AC3 encodes) ?


I know this is a lot of questions, but I will be very gratefull if someone could answer some of these...


Thank you !
john

[Stalker]

I'll give it a shot =)

Originally posted by jernst
[B]Hi all,
Hi

1) If I playback sources that can't be decoded by the receiver (mp3, ogg vorbis, etc.), will my PC output the sound to the SPDIF interface(s) ?
Most soundchips are able to throughput any mono/stereo source through your SPDIF as 48khz mono or stereo.

2) Will the receiver understands PCM and will the sound be only stereo even if I have 6 channels Vorbis ? / Or do I have to use the analog output(s) and buy myself some more wires (1 for stereo, 3 for 5:1)
Well since you don't have one of those fancy Nforce chipsets with onboard realtime AC3 encoding, then yes, it will only be stereo, unless you use the analog outputs for those sources - at least until someone manages to do a realtime AC3 encoding DirectShow filter that works.

3) What wire is the best for 10 meters: optical or coax ?

That's a matter of opinion, but I use optical.

4) Is the digital coax cable a "normal" coax wire, like the one of TV antennas ?
Don't know that one, since I use optical =)

5) If I playback Dolby prologic II content, will it go trough the digital interface and be understood by the receiver as prologic II content ?
No it will be passed as a PCM stereo source, then the decoder puts the stereo source through a complex matrix and tries to seperate the rear (and the front) channels. If the source has been encoded as DPL II it will seperate the channels to the full extent of it's abilities.

6) Does Prologic II decoder decodes Prologic I as well ?
With DPL II you really have no use for Prologic, since DPL II does the same (and more) - only better.
See DPL II Listening Guide (http://www.dolby.com/ht/co.br.0107.PLIIListenersGuide.html)

7) Do I need any dshow filter to achieve all this (more than the AC3 filter for AC3 encodes) ?
You need the "normal" dshow filters for all the different sound formats you need to decode or passthrough: ogg, mp3, aac, mpg, AC3, DTS, etc.

Hope that helps ;)

[jernst]

With DPL II you really have no use for Prologic, since DPL II does the same (and more) - only better.
Yes I know that, but if I have movies already encoded with DPL I, the DPL II matrix scheme will wor with it as well ?

BTE, to achieve the same quality, do DPLII Vorbis tracks need (much) more space than stereo ones ?

thanks for everything

[Stalker]

Originally posted by jernst
Yes I know that, but if I have movies already encoded with DPL I, the DPL II matrix scheme will wor with it as well ?

Yes, it will. It uses the same principles, although more complex. DPL II will succesfully seperate the surround channel from the front channels, but will not yield much seperation between left and right, at least nothing intended by the source. IMHO normal stereo also sounds better with DPL II.

BTE, to achieve the same quality, do DPLII Vorbis tracks need (much) more space than stereo ones ?

Not as such, but you'll need a bit higher bitrate to retain the DPL encoding. DSPGuru says it's 160 for MP3. Don't know what the equivalent would be in Vorbis - probably 2.0 <-> 2.5.
thanks for everything
You're welcome!