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 Workaround for non-ASIO / ASIO "non-DSP" cards 


Joined: 01 Nov 2006
Posts: 15
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Just thought I would post this *latest* method I came up with for running Allocator+Arbitrator using ASIO4ALL and Virtual Audio Cable.

Those who have tried my previous ASIO4ALL / V.A.C. methods might find themselves getting clicks and pops starting 2 to 4 minutes into a track. This is caused by a phenomenon known as "clock skew". It happens when ASIO4ALL attempts to link an input and an output that are driven by two different clock sources, that (usually) operate at ever-so-slightly different clock speeds. The clocks drift more and more out of sync as time goes on, until the clicks and pops finally start.

There is a solution for this, and it's simple, and requires no additional software.

Basically, you need the input and output device selected and "enabled" (green) in ASIO4ALL to be the same device. IN this case, the device will be Virtual Audio Cable. The input device is "Virtual Cable 1" a two channel virtual audio cable, and the output device is "Virtual Audio Cable 2". (Separate cables, yes, but still the same device.

Allocator is used normally, with ASIO4ALL selected as the audio device, and "Virtual Cable 1" inputs 1 and 2 selected and "Virtual Cable 2" outputs 1 through 8 selected.

Now, Allocator streams the output channels into the Virtual Cable 2.

The next step is to take the outputs from Virtual Cable 2 and "re-stream" them into your soundcard. This is done with the handy "Audio Repeater" that is supplied with Virtual Audio Cable. Simply select Virtual Cable 2 for the input device, your 8-channel soundcard for the output device, '24' for bitdepth, '8' for #channels, 4000 for buffersize and press start. This restreams the content of the 8 Virtual Cable 2 channels to 8 channels of your soundcard.

This "solution" is a good thing to try for any time using different devices for input and ouput in ASIO4ALL causes "pops and clicks" to slowly creep into playback.

Note: If you get pops and clicks steadily then you are probably not experiencing "clock skew" but a resource consumption issue, VST resource issue, or IRQ conflict.

Basically, if you have a non-ASIO soundcard, or an ASIO soundcard that lacks software routing (DSP mixing) then ASIO4ALL, Virtual Audio Cable, and the Audio Repeater is a cost effective way to make even the most rudimentary audio cards work with Allocator.

Cheers,
Presto
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 And now for the big ***BUT*** 


Joined: 01 Nov 2006
Posts: 15
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The Audiorepeater I am talking about in the above post is version 1.13 - this utility uses older MME technology, which means that it uses the Windows Kmixer. This means everything that passes in and then out of the Repeater will be converted to 48khz sampling rate and *then* converted again to the sample rate selected by the repeater. Even if Allocator is spitting out 44.1khz and you set the Repeater to 44.1khz as well, kmixer resamples from 44.1 to 48 and 48 back to 44.1.

There is supposed to be a WDM/KS version of the Audio Repeater in the works.

Just wanted to mention this, since for most audiophile applications, any routing via the kmixer is *not* a desirable solution, especially for 44.1 khz Redbook CD wav files. For 48kHz material from DVD-V discs, it's not quite as bad...

For those who can't hear the difference, or simply don't care, this method sounds quite good. I do believe that I can hear a slight brittle quality to the high-end as a result of the additional resampling, but it's not "horrible" by any means.

No more "workaround" or "jerry-rigged" methods from me until after the new audio repeater comes out or a meida file player bridge comes available.

Remeber that the CORRECT way to maximize the potential of the Allocator is to use a soundcard that:

a) Is ASIO compliant
b) has drivers that perform hardware AND SOFTWARE mixing.


My belief is that if the Allocator sounds *this amazingly good* with ASIO4ALL workaround methods, using a proper ASIO hardware solution is only going to sound better yet.


Cheers,
Presto
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Site Admin

Joined: 29 Jan 2006
Posts: 555
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Thanks, Presto for working on this routing issue diligently. I'm sure you gave a lot of folks a solution to a problem of streaming of audio between applications.
It is worthy of noting that the KX mixer is a very coarse tool when it comes to audio quality as admitted by MS programmer on another forum. It uses 16 bit integer math resulting in audible rounding errors. The audio in Vista is supposed to be better, but that remains to be seen. The best way to use Allocator is to stream bit-perfect audio to it, or to use the digital input on the sound card.
Hopefully the VAC will upgrade their algorithms so that bit-perfect audio is passed between apps regardless of operating system.

Jan
View user's profile Find all posts by thuneau Send private message Send e-mail
  


Joined: 06 Apr 2006
Posts: 85
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Presto> Have you tried the latest version of Audio Repeater? (v1.18 I think)
Does this utilise WDM rather than MME and if so, do you find your sound quality improved?

I want to buy a particular sound card (*X-Meridian) but it doesnt have software WDM->ASIO routing, so I want to know if the method you have graciously provided is bitperfect into ASIO with the V1.18 software Smile

(*See Post #190 @ http://www.avsforum.com/avs-vb/showthread.php?t=765317&page=7&pp=190)
(Looks like an awesome card for a good price. And moddable to be better Smile

EDIT: Presto> does your method also mute the original WDM/MME output? Otherwise you will get the XO'd sound + the full range output coming out on output 1 + 2.
View user's profile Find all posts by Iceman_jkh Send private message
  


Joined: 06 Apr 2006
Posts: 85
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Would it be possible for someone with a good quality card (perhaps Jan) to try using Presto's method of VAC + ASIO4all to get Allocator working?

Im very interested to know whether there is any difference in sound quality (and latency/lag) between the VAC + A4a method and the native drivers which your card mftr provided.

Reason: I want to purchase this card (AuzenTech X-Meridian: http://www.auzentech.com/site/products/x-meridian.php) and it doesnt have native WDM->ASIO capture drivers (although it does support ASIO2.0).

I realise that AudioRepeater is MME, but that program should not need to be used, as I only need to perform the VAC+A4a chain, I believe.

Thanks
Ice
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