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Using convolver universally in HTPC

57K views 142 replies 28 participants last post by  adolfotregosa 
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#1 ·
I've been reading the forums for a while now, but I can't find an exact answer here or anywhere else. I'm trying to setup my HTPC to do software room correction for anything that comes out of the soundcard. This thread is the closest thing to an answer I've found:

http://www.hometheatershack.com/forums/rew-forum/3589-rew-w-software-eq.html


Is anybody successfully doing this? I'm still working on assigning filters for my sub's impulse response. However, I won't know if I did it right unless I find a way to measure the corrected response.

Here's my plan:
1. Choose 'Virtual Audio Cable'- VAC (shareware) as the output for REW.
2. Use ConvolverVST (free) in VSTHost (also free). I should be able to select VAC as the input and my soundcard (SB Audigy 4Pro) as the output.
3. Verify my REW filters and tweak as necessary.
4. Once I'm satisfied with the room correction, I'd set all of my applications and Windows to output to VAC--> ConvolverVST in VSTHost--> Soundcard.

You'd think someone has already done something like this. It seems like the most eloquent solution, since:
  • it's possible to apply filters to the full frequency range
  • I'd be able to use room correction for streaming audio, DVD-A :bigsmile:, etc. instead of just Zoomplayer and JRMC.
  • It would be cheaper than a hardware solution and could be used in a car pc setup as well

Can anyone help?
 
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#6 ·

What kind of help are you looking for? Looks like you pretty much have a handle on it already. I guess what your “before” and “after” REW graphs look like will tell you if you’re successful.

Regards,
Wayne
I wanted to get feedback on the programs I'm using. Antani brought up 'Reaper' which is free and new to me, so I might try it before I try VAC. And yes, I will need help assessing my success on the "before" and "after". Thanks Wayne!
 
#3 ·
I did very recently exactly what you are trying to do.

I am now applying 6 convolved filters, 6 parametric equalizers, 4 delays and a bass manager to whatever goes out of my sound card and whatever is the sw player.

The result is astonishing and does not require any external hw.

I'm now in the hurry, I'll post more details later on.
 
#4 · (Edited)
Here I am.

I'm running an AMD 4200+ dual core, an audio card Terratec Auron Space 7.1 flashed as Audiotrak Prodigy and Vista.

As VST shell I'm using Console working in ASIO. The VST plug-ins are Spinaudio SpinEQ as parametric equalizer, Voxengo Pristine Space as convolution engine, Voxengo BMS as Bass manager, Voxengo Audio Delay to introduce delays for multichannel reproduction.

I'm generating the impulse response files with REW (1 M sweep), then I create the filters with DRC. DRC goes much further than frequency equalization because it works also in the time domain.

The trickiest part of the process is intercepting the audio stream from the sw players. I tried first Reaper, but I couldn’t manage to make it work in Vista. Then I tried VAC. It was working but only in stereo and it cannot route the streams to ASIO, and I wanted low latency.
Then I chose the easiest way: I bought an used Terratec audio card, compatible with Audiotrak drivers. Audiotrak/ESI drivers offer a unique feature, Directwire, capable of intercepting and routing audio streams from and to ASIO.

What you can get at the end of this is probably the most sophisticated audio equalization around. I’m using it in two different installations, stereo and multichannel, and I can tell you that it’s now very difficult for me to listen music and movies without it.
 
#7 ·
This is the result. I realized after measuring that I was not using the mic calibration file, so now the result is slightly better in the high frequency range. Equalization was done automatically by DRC. I only used the parametric equalizer to correct a couple of spikes in the very low range.



I don't have to tell you what line is before and what is after :D.

What you cannot see is the phase correction, but believe me you can easily hear it!
 
#12 ·
Setting up Convolver is the easiest part.

The problem is that at the moment there is no blu ray sw player where you can use it. Powerdvd and Arcsoft cannot apply audio post processing.

The only way I managed to equalize blu ray is using the Directwire functionality of ESI/Audiotrak sound cards. But first of all you need an ESI/Audiotrak soundcard.
 
#14 ·
You need to set up Directwire in this way:

It will route the audio streams from a WMD program like Powerdvd towards ASIO.
Then you need a VST host such as Console. You should create an Asio project.
The project should look like this:

The 5.1 channels will be processed in this way, from left to right:
- a convolution engine, Voxengo Pristine Space but you can use Convolver as well
- a parametric equalizer (SpinEQ)
- a time delay, to adjust speakers distance (Voxengo Audio Delay)
- a bass manager (Kelly Industries) to boost LFE channel by 10 Db and to route bass frequencies towards the subwoofer.

I doubt you can get a more sophisticated sound elaboration :dumbcrazy:.

This is another example of final result, amplitude graph is slightly decreasing because I set the target curve in this way:
 
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#27 ·
Hi,
Can you explain how I define in bass manager which channel is LFE? In your diagram I guess it is the channel 8. The bass manager user interface shows 8 channels (basic view) but it does not show any channel numbers next to the settings. Is the LFE fixed to rightmost (channel 8?) controls?
BR,
Ns
 
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#15 ·
Excellent, I really appreciate you took time to prepare the instructions.

Now I just need to wait for Audiotrak to arrive. I will post then how it goes.

By the way, is the lip sync any issue? The audio processing takes some time so audio may lag a bit behind video. My PC is 3.0 Ghz dualcore E6850.

BR,
Ns
 
#17 ·
This is great information antani. Since I'm also using an HTPC exclusively as my AV source, this may be the next configuration I look at implementing. Thanks for posting.
 
#18 ·
I'm a little unsure, do I need a Audiotrak Prodigy 7.1 HiFi card to get this working correctly? If so, is it because of the simplification the Audiotrak drivers provide in regards to Directwire functionality? And does any of this apply if I'm simply pushing the signal out of the HTPC via component audio to my receiver?

That's 3!
17 more to go. :nerd:
 
#19 ·
...do I need a Audiotrak Prodigy 7.1 HiFi card to get this working correctly?...
Yes, or an ESI audio card.
...If so, is it because of the simplification the Audiotrak drivers provide in regards to Directwire functionality?...
Yes
... And does any of this apply if I'm simply pushing the signal out of the HTPC via component audio to my receiver?...
I don't understand exactly what you mean by "component". In order to use the HTPC as an equalizer you need to use the analog 7.1 outputs of the audio card. You cannot use the spdif. By the way HD audio streams cannot go through the spdif and currently there is no audio card with HDMI 7.1 outputs.
 
#21 ·
SPIDF can carry DD and DTS, but not the new HD audio streams such as PCM 5.1 or Dolby TrueHD.

In any case the equalization process requires to use the analog outputs of the audio card. The audio decoding must be done by the sw player.

If you select spdif as output you will bypass the equalization.
 
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#22 · (Edited)
Please ignore blow, I realized the example is for 5.1 config. Still one question: How do you know what channel numbers in "Prodigy IN" correspond to which channel (center etc.)?


Hi Antani,

I can see only 6 channels wired in the picture. Is it used for 7.1 sound?

Can you explain what is channel number for front left, center, right, subwoofer etc?

Should the front center and subwoofer lines be visible in directwire and console pictures?
 
#23 ·
There are only 6 wires because I have 5.1 speakers. If you want 7.1 you should wire all the 8 channels.

You can find the explanation of inputs and outputs in the instruction of your audio card. If I remember well:
1 front left
2 front right
3 surround left
4 surround right
5 central
6 sub
7 back surround left
8 back surround right
 
#28 ·
I'm using the Adobe Premiere version from Kelly Industries because I had problem with the standard one.
In this version you can choose the sequence of the channels by clicking in the bottom left corner (L R Ls Rs C LFE or L R C LFE Ls Rs).
.

In my sound card LFE is channel 6, but with a 5.1 setup.

In any case it should not be difficult to identify the LFE with some trials.
 
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#29 ·
Thanks,

Another question: As the bass manager is located AFTER the eq/room correction (pristine space) for me it looks like the room equalization can't be applied for the side channel's low frequencies routed to bass management sub channel. Or the correction is not correct if it is made based on side channel signal measurements.

Can you explain how this is handled? Are you using bass management also for measurement signal when recording the impulse response for side channels (i.e. actually sub channel is recorded/corrected for low frequencies of side channels)?
 
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#31 · (Edited)
Console is not officially supported with Vista. Seems to work in some level but when I create an ASIO project with Prodigy it freezes. Do you know any other alternative plugin host for this setup with Vista?

UPDATE: Now I got it working - not sure what was the reason but when I created other parts first and added prodigy last then it didn't freeze anymore.

Now I can get the sound through test config in attached picture. However if I turn dry adjustment to minimum I don't get almost any sound. if I understand correctly the convolved signal is adjusted via "wet" level adjustments and by pass signal via "dry". Therefore it looks to me that the convolved audio path is not working.

Could you share screenshot from your prisitne space settings? Should the dry path be disabled fully?
Thanks
 

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#32 ·
It should look similar to this:


Each wav mono filter should have a slot, each channel should refer to a different slot. If you are using stereo wav filters you will use only 4 slots.

Dry is not important, as you said is a bypass, and should be muted. You should only take care of the wet. Each channel's wet level should be adjusted manually. You might want to try A-gain.
 
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#33 ·
Thanks a lot again.

I forgot to say that I use audiolense for creating filters http://www.juicehifi.com/index.html.

With Audiolense I can select the speaker config and it creates filter with needed amount of channels. So I assume that then I should use only one slot in Pristine Space for all channels.

Anyway there is no sound even from channel one in wet mode, so there is some other problem. Need to study a bit more.
 
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