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Author Topic: OT - Possible to output to SPDIF in 5.1 without AC3 Passthru?  (Read 1372 times)

escaflo

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I am currently using Philips Acoustic Edge 5.1 and it is connected to my amplifier via a SPDIF coaxial cable.

Problem is that this only allows it to have 2 output unless I switch it to AC3 passthru. It's not much of a problem playing music, but when it comes to playing games, I guess I still prefer if I had 5.1 channel.

I know that onboard sound like Nvida Nforce 2 have Dolby Digital Encoder that encode any soundstream to Dolby Digital 5.1 format and output it via its SPDIF. I am just wondering if there is any software around that can do this also? Or is there any workaround for this?

Thanks
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bspachman

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Re:OT - Possible to output to SPDIF in 5.1 without AC3 Passthru?
« Reply #1 on: March 06, 2004, 07:27:49 am »

I guess I'm not familiar with this sound card. For me (MAudio Delta Dio), I have it and MC9/10 to use the SPDIF output all the time. If the music is in 2-channel, I get 2 channels of output. If the music is in 5.1, I get 5.1 channels of output.

Can't you just leave your sound card set to 5.1 all the time?

Brad
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Chris Shaw

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Re:OT - Possible to output to SPDIF in 5.1 without AC3 Passthru?
« Reply #2 on: March 06, 2004, 08:45:09 am »

I have a Shuttle SFF PC with the nForce2 chipset, but the AC3 encoder is pretty poor quality. You certainly wouldn't want to listen to music through it.

I found this
http://sourceforge.net/projects/ac3encode
It's an open source, real time AC3 encoder. I don't know enough about DirectShow to know if it would help, though.
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escaflo

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Re:OT - Possible to output to SPDIF in 5.1 without AC3 Passthru?
« Reply #3 on: March 06, 2004, 10:29:53 am »

I guess I'm not familiar with this sound card. For me (MAudio Delta Dio), I have it and MC9/10 to use the SPDIF output all the time. If the music is in 2-channel, I get 2 channels of output. If the music is in 5.1, I get 5.1 channels of output.

Can't you just leave your sound card set to 5.1 all the time?

Brad

It ain't really possible for this soundcard because I only get to choose the following for output to SPDIF.

Front Left and Right Channel
Rear Left and Right Channel
Center and LFE Channel
Dolby Digital AC3 Passthru

As such, its only possible for me to listen to music in Front Left and Right Channel and when I want to watch DVD, I would have to manually change it to Dolby Digital AC3 passthru, which is  irritating if not troublesome.

Anyway, thanks for all your tips. I am currently looking at the AC3 Encode.

Edit: After reading the website of AC3 Encode, I think it only encodes 16bit wave file? Which most possibly mean it is not possible to do encoding like how Nforce2 soundcard does it.

Thanks anyway for the link.
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loraan

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Re:OT - Possible to output to SPDIF in 5.1 without AC3 Passthru?
« Reply #4 on: March 07, 2004, 12:09:10 pm »

I know that onboard sound like Nvida Nforce 2 have Dolby Digital Encoder that encode any soundstream to Dolby Digital 5.1 format and output it via its SPDIF. I am just wondering if there is any software around that can do this also? Or is there any workaround for this?

My understanding, from readings at avsforum.com, is that currently ONLY the Nvidia SoundStorm motherboards support real-time encoding to dolby digital 5.1. That means that with any other soundcard on the market, you either get 5.1 passthrough over digital (for 5.1 sources), 2ch stereo over digital (for stereo sources), or 5.1 playback over analog (for either 5.1 or stereo sources).

In other words, non-Nvidia cards can create virtual 5.1 sound out of stereo sources, but they can only output that sound over analog outputs. They can't simultaneously create virtual 5.1 and encode to dolby digital 5.1. Nvidia SoundStorm has the unique ability to take analog output from an app--either stereo or 5.1--and encode that sound to DD 5.1 in realtime.
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