Using convolver universally in HTPC

[pdroyer]

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 , 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?

[Wayne A. Pflughaupt]

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

[antani]

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.

[antani]

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.

[clubfoot]

How about some REW before and after EQs, so we can see the effects? This sounds very interesting.

[pdroyer]

Wayne A. Pflughaupt wrote:

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!

[antani]

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 .

What you cannot see is the phase correction, but believe me you can easily hear it!

[antani]

Another example.



Waterfalls, before and after.

[pdroyer]

antani wrote:

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.

Were you able to get Console to run in the background (as a service)? This will be important for the WAF.

[antani]

Unfortunately no. I start Console when Windows starts and is a little bit annoying having it in the task bar.

[nsiltala]

Hi Antani,

I am trying to use convolver with Blu-ray movies. It seems the best way to make it work for this and other purposes is to have universal convolver setup.

The problem is that I would need a bit more detailed instructions what are the necessary HW and SW and especially the parameters.

Could you kindly explain in a bit more details what is your setup and parameters (screenshots etc.)?

Thanks a lot

BR,
ns

antani wrote:

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.

[antani]

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.

[nsiltala]

I have Power DVD 7.3 that can playback the bluray audio. I have also ordered the Audiotrak Prodigy 7.1 HiFi card:

http://www.esi-audiotechnik.com/down...Fi-English.pdf

Mainly I need help how to connect the Power DVD audio output to convolver.

Thanks

[antani]

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 .

This is another example of final result, amplitude graph is slightly decreasing because I set the target curve in this way:

[nsiltala]

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

[antani]

CPU is not relevant (unless you get to 100% usage). Latency depends on audio card and plug-in used.

I'm currently having a latency of less than 512 samples. At 48 KHz is 10 milliseconds. One frame at 24fps (blu ray) is 41 milliseconds.

No way you can notice it .

[GollyJer]

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.

[GollyJer]

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.

[antani]

GollyJer wrote:

...do I need a Audiotrak Prodigy 7.1 HiFi card to get this working correctly?...

Yes, or an ESI audio card.

GollyJer wrote:

...If so, is it because of the simplification the Audiotrak drivers provide in regards to Directwire functionality?...

Yes

GollyJer wrote:

... 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.

[GollyJer]

antani wrote:

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.

By component I meant SPDIF; sorry for the confusion. My receiver calls SPDIF it's "component" audio input. I think it makes sense that the analog outputs need to be used when using the PC as an EQ. Thanks.

When you say HD audio streams can't go through SPDIF I'm not sure I understand? Currently DD5.1 & DTS are passed fine through SPDIF when watching HDTV or DVD's. The receiver auto-detects the signal and switches between Dolby Pro Logic (for SDTV), DD & DTS. The only thing I have to switch to myself is Stereo mode when playing .flac files.

[EDIT]
Never mind. I see now that HD Audio is different than the signal that comes across with HDTV. You're talking Blu-ray disc audio (which I have no experience with yet). HD Audio Explained. From what I understand with a little more reading is the SPDIF connection doesn't have enough bandwidth to pass an HD Audio signal.
[/EDIT]

[EDIT 2]
Here's a great link to an explanation of HD Audio technologies. I would have never guessed that Dolby Digital is a lossy, compressed, format.
[/EDIT 2]

[antani]

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.

[nsiltala]

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?

[antani]

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

[nsiltala]

ok thanks, I will receive the audiocard probably by Friday.