Subject:Terratec DMX 6 Fire and AC-3

Posted by: miwi21

Date:2/24/2003 4:28:57 PM

Anyone using this card and AC-3 in Acid or Vegas? Do the drivers "expose" the discrete channels necessary to get 5.1 sound?

Subject:RE: Terratec DMX 6 Fire and AC-3

Reply by: SonyNateM

Date:2/26/2003 10:30:22 AM

I took a look through the DMX 6 Fire 24/96 manual here:

ftp://ftp.terratec.net/Audio/DMX6fire2496/Manual/DMX6fire2496_Manual_GB.pdf

and didn't find anything suggesting that they allow discrete access to each of the 3 stereo outputs on the rear of the card. It looks like it may just be another card that does PowerDVD-assisted AC-3 decoding and EAX/DirectSound surround for games. You may want to drop them a note before purchasing this card to make sure it has the features you desire.

Nate

Subject:RE: Terratec DMX 6 Fire and AC-3

Reply by: rique

Date:2/26/2003 12:08:45 PM

The card has three stereo outputs (3.5 mm jacks) for Front, Rear, and Center-LFE (left = center, right =LFE/subwoofer), as shown on page 10 of that manual. Is this not sufficient for true 5.1 playback?

Subject:RE: Terratec DMX 6 Fire and AC-3

Reply by: SonyNateM

Date:3/4/2003 11:06:56 AM

If the drivers/chipset allowed for independent access to each of those outputs, then yes, it would be. However, it looks to me from their driver software/configuration setup that it only allows access to a single stereo output to normal WAVE devices. Only games that use EAX and sofware DVD players that use DirectSound will have access to all the outputs on the card. Unless they provide a driver that allows access to each output as a stereo pair, our software has no way to access the additional outputs.

Nate

Subject:RE: Terratec DMX 6 Fire and AC-3

Reply by: Laurence

Date:3/4/2003 5:09:56 PM

This is such a common issue and I don't really think most people understand it. What's going on is this.

For Acid or Vegas to use the six audio outputs, it would need to be able to directly access all six audio outputs. Unfortunately, must "5.1 surround" soundcards don't let software do this. What they really are is just a stereo card and a hardware Dolby AC-3 decoder bundled together. Audio can be sent to them directly as a stereo wave file only. For surround mode, what they do is take the AC-3 encoded audio stream like the one on a DVD and decode it into six discrete audio channels. This is really cool for playing back movies in 5.1 (which is what most people want) but sucks for authoring 5.1 soundtracks. The only way to use one of these cards would be to encode the audio to 5.1 in real time. CPUs just aren't up to that task yet. This is in no way a limitation of Vegas or Acid. No authoring software can (or will be able to) make use of these extra outs.

Here's another way to look at it: You can play back 5.1 DVD's with a regular stereo sound card with SPDIF out and a 5.1 surround sound decoder. Just connect the SPDIF of your audio card to the SPDIF of the surround sound decoder and use a DVD playback program like Power DVD with a 5.1 to SPDIF audio option. Obviously you wouldn't be able to use this arrangement to author 5.1 soundtracks in Acid or Vegas though. With most "5.1 surround sound" cards, you basically have the same setup.

Laurence Kingston

Subject:RE: Terratec DMX 6 Fire and AC-3

Reply by: rique

Date:3/5/2003 3:51:08 PM

Now I'm really confused so let me ask this way.
I have this Terratec DMX 6 fire card and In Acid4 or Vegas4 I can open a project with 6 tracks and assign each track to a different speaker using surround pan. Under Options/Preferences/Audio I can select "ASIO for DMX 6 Fire 24/96" for audio device type. For "Default Stereo and Front playback device" I can select "FrontLeft/Front Right", for "Default Rear Playback Device" I can select "Rear Left/Rear Right", and for "Default Center and LFE Playback Device" I can select "Center/LFE". The Mixer window shows 3 pairs of stereo indicators Front, Rear, and Center & LFE and I can adjust the volume on each of the 6 sliders during playback. I haven't done a big project yet but have burned test DVDs (played on a set top player through home theater) that had each speaker playing the same sound one at a time in sequence. Are you saying there is someway this is not true 6 channel surround mixing?

Subject:RE: Terratec DMX 6 Fire and AC-3

Reply by: pwppch

Date:3/5/2003 5:34:49 PM

From what you describe, you will be able to rout to the front, rear, center, and LFE directly in ACID 4 or Vegas 4.

Make sure that the routing is correct on the master bus on the mixer page as well.

Peter