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Surround Sound in Vegas
I am trying to monitor 5.1 sound from Vegas Pro 10 to a Creative Audigy card using SPDIF to a Yamaha 5.1 amplifier. Although the “supported formats” test checks out, – I can hear each speaker separately – I can only monintor stereo audio whilst in Vegas. Is this a limitation of Vegas? I seem to remember it worked normally when using analogue outs..
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7 Replies
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Do you have the Stereo Downmix button selected? It’s just above the mixer. Clicking it will toggle between 5.1 surround, Stereo and Mono.
Daniel Hughes
Amateur Writer, Director,
Director of Photography
United Kingdom -
Did you set Vegas up to route each channel to a different set of speakers? By default they all go to channels 1 & 2. Go into Options | Preferences | Audio Device and make sure that “Default stereo and front playback device”, “Default rear playback device”, and “Default center and LFE playback device” are pointing to your 6 outputs for 5.1 Surround.
I’ve never used SPDIF but this is what I use for my M-Audio Firewire 410 via ASIO.
~jr
http://www.johnrofrano.com
http://www.vasst.com -
I haven’t looked into this subject in a while, so maybe some new developments are out there…
But, if you were to output “surround” or “multichannel” via spdif it would have to be Dolby AC3 or DTS, and to my knowledge, Vegas (or any other program) does not do this on the fly.
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“…the “supported formats” test checks out…”
What is this exactly? Is this a function of Vegas? Or a soundcard app?
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Thank you all for your thoughts which will help a lot; Jon – the test is within Windows 7 and linked to the card: it just proves that windows can output 5.1 to my amp.
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Far as I know, Vegas will only output decoded audio. S/PDIF (IEC60958) is not fast enough for 5.1 channel uncompressed audio. It was originally engineered for stereo only, then the IEC61937 standard defined how compressed multichannel audio, AC-3 or DTS usually, could be sent via the same protocol. As far as I know, you can’t get Vegas to compress to AC-3 on the fly.
If I look at the setup in my system, the S/PDIF output (which I’m not using…) indicates compressed types it’ll pass on: AC-3 and DTS. Clearly, DVD/Blu-ray software is capable of sending pre-encoded bitstreams to a decoding amplifier this way, so there’s a Windows standard of some kind for this interface. But it’s not going to do the AC-3 encoding for me.
It’s technically possible someone could make a “fake” audio device, which shows up as a 6 channel uncompressed output, but does the conversion to AC-3 and pipes to S/PDIF on the fly. Modern PCs are plenty fast enough to do this, but I’ve not heard of it actually being done.
-Dave
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Thanks, Dave. interesting.
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