Stereo to 5.1 Questions: Hardware and Bidule

[farmer dan]

First of all, Happy and prosperous New Year.

I have resurrected my stereo to 5.1 encoding projects and discovered, again, what a newbie I am. Here's my audio setup: ASUS A7N8X-E mobo with NForce2 capability and a Creative Sound Blaster Audigy2 Platinum-ex with 6.1 speakers. I have the NForce drivers installed, but the speakers are connected to the soundcard.

To learn the encoding, I took an 8 second cut of a series of machine gun bursts and used Daphy's Guide--real basic: file player, Ambiophonic allinone and file recorder--to use Bidule (great guide Daphy, thanks). I used BeSweet to encode the resulting file to AC3. The AC3 file played well, but it had slowed down. (The machine gun sounds like a gattling gun--good gattling gun sound if that's what I wanted.) And I don't have anything, I think, that will play the 5 channel wave sound. I wanted to discover where in the process the slowdown occurred and that's when I discovered my lack of knowlege. If my questions are too newbie or the answers too involved, I would like to know where I can go to research the answers. Here is the first area of questions:

Monitoring Layouts

I would like to hear what my layout is doing. How do I do this? All of the output devices have only two inputs. It seems like I cannot monitor the five-channel wave file I am trying to produce. There are two menus for output devices MME and Windows DirectSound. Each menu contains three devices: one each for nVidia, Audigy and Windows, but they all have only two inputs.

The next bidules I looked at were DUPLEX. I must learn how this works. I can't figure out how to input to these and only the ASIO devices have more than two channels: Nvidia 2-5 channels, Audigy 24/96 6-8 channels and Audigy regular(?) 18-14 channels. How do I use duplex?

I guess I need to learn to walk before I run. My goal right now is to take a simple stereo signal, preferably from a file, and ultimately encode it to 5.1 or surround. I would like to learn how to monitor the layout as I'm processing the file, encode it and save it to disk. I would appreciate any and all answers to these questions or suggestions as to where I can look to do research. Creative, Nvidia, Plogue and Google haven't yet produced any info that I can really use. Thanks.

Dan

[ursamtl]

Hi Dan,

Best wishes to you too for the new year. Given your setup, monitoring your mix is quite simple actually. You need to use one of those ASIO duplex devices you saw. Duplex simple means both input and output at the same time. Bidule implements this as two objects appearing at the same time, one at the top for input and the other underneath for output. The trick is to ignore the top one and simply connect to the bottom one. Think of signal flow in bidule as going from top to bottom. Therefore, connection points on the top of an object are the inputs. The opposite is true for outputs. For example, an audio file player has connection points only on its bottom since the signal is flowing out of the player into the bidule.

As for which device to choose, either of the Audigy ASIOs would be best. If you have a powerful enough CPU, go for the 24/96 version, since this will give you the best quality. However, you must set your Plogue Bidule preferences to a sampling rate of 96,000Hz and your audio file must be converted to 96,000Hz. Don't worry about bit depth since Plogue automatically converts to 32-bit floating-point format. I suspect your slowed down sound may be related to different sampling rates.

Let us know how you make out.

Steve.

[farmer dan]

Thanks very much, Steve. Using the info you provided I was able to listen to the machine gun using the duplex. I suspect your slowed down sound may be related to different sampling rates.
You were absolutely right. I recorded the sound at 96000 (I wasn't paying attention) and had Plogue set for 48000. I reset Plogue for 96k and didn't have a gattling gun any more. Well, at least I learned how to make one :D

I used the basic layout that you generate when you use Daphy's guide and ran a second connection from the output of the "allinone" to input channels on the duplex.

This "bidule stuff" is addicting.

I'm looking for a recommendation now. Do I use Plogue to get the different channel mixes correctly, or would it be better to just generate the basic five channel wave and use BeSweet to generate the surround file?

Additionally, since my ultimate goal is to put these audio files on a DVD, should I do all of my work in 48kHz or work at 96kHz until the end and convert the final file to DVD format when I'm done?

Once again. Thanks for the help, Steve.

Dan

[ursamtl]

On my system (Audigy 2 ZS Platinm) the outputs are as follows:

1: Front Left
2: Front Right
3: Front Left (repeated)
4: Front Right (repeated)
5: Rear Left
6: Rear Right
7: Center
8: LFE
9... (irrelevant for 5.1 systems)

Note that this differs somewhat from the order used in most layouts we've developed on here. In my V.I layouts, for instance, I followed the ITU standard for 5.1 of L, R, C, LFE, rL, rR.

As you wrote, it requires some trial and error. The great thing is that you'll learn a lot from it!

Steve.

[farmer dan]

Thanks again for the info.

Since my last reply, I discovered your V.I layouts--I'm currently experimenting with the one from 041127. I'll rewire according to the info about your Audigy 2 system. I'll bet they're the same--I suppose I could look on the Creative site to see if they're different.

I have been reading this forum on LFE and surround mixing. The question still remains if it's better to apply the standards, like the -31db conversational level and the LFE manipulations that dspguru talks about in one of his posts, in Plogue or to generate the six-channel wave file and do the rest in BeSweet.

Dan

[farmer dan]

I'm posting this if anyone else has an Audigy 2 Platinum-ex and is experimenting with the bidules. The sample inputs are completely different from the ones posted by usramtl above. I discovered this by making a tone generator the input to one of ursamtl's V.I layouts and moving the connector for the FL channel across the input of the Audigy duplexer. Here are my results:[list=1]
FL
FR
rR
rL
FrontCenter
SubWoofer
RearCenter
Not Tested
[/list=1] As a reminder, I have a 6.1 speaker system connecteed.

Dan

[ursamtl]

The difference is interesting. Are you using the latest Creative drivers? I ask this because I assume that the Audigy 2 and Audigy 2 ZS would use the same channel order.

In any case, the method you use is a good lesson to everyone. Simply take a tone or audio file and run it through each output individually to see what you have (assuming you are able to monitor them). I wouldn't recommend connecting the sound source to whatever objects convert from 2 to 5.1 because they often distribute some aspects of the sound to more than one output. Go directly from the sound source to an output, testing each one individually.

[farmer dan]

ursamtl wrote:The difference is interesting. Are you using the latest Creative drivers? I ask this because I assume that the Audigy 2 and Audigy 2 ZS would use the same channel order. I thought so too. But, after I checked for updated drivers and made sure that the tone generator wasn't "bleeding" into any other channels, I re-ran the test and got the same results. Interesting.

By the way, while doing research on how to do all of this, I've seen quite a few posts saying that working with bidules was fun and addicting. Please add my name to that list. :rolleyes: The results are just amazing. Thanks to all of you who have written and maintained the guides, the websites and the installers.

Dan