foo_dsp_xfeed, Crossfeed Options

[xnor]

Heya,

this is the discussion thread for foo_dsp_xfeed, a Crossfeed DSP component.
For those who don't know what that is: it enables a more relaxed and natural listening experience with headphones. A more detailed explanation why and how it works is given below.

Download

Usage
1) Install the downloaded zip file using the Components preferences page.
2) Add "Crossfeed" to the list of active DSPs (Playback - DSP Manager preferences page).
3) Configure it.

Explanation
Let's take a look at the image below.



When listening with headphones, the left ear only hears sound coming from the left speaker (LL) and the right ear only the sound coming from the right speaker (RR). This often results in unnatural stereo separation or spaciousness and can cause listening fatigue.

When listening with speakers, sound from the right speaker also arrives at the left ear (RL), with a small time delay though. This time delay is known as interaural time difference (ITD). Additionally, there's a difference in level known as interaural level difference (ILD). In the image above, line thickness indicates these level differences.

In reality, things aren't that simple. The level difference, for example, is not constant because the head obstructs higher frequencies a lot better than low frequencies (aka head shadow). While at low frequencies the attenuation can be as low as and even lower than 3 dB, it can reach up to about 20 dB at high frequencies.
To make things more complex, both the ITD and ILD change depending on the angle of the speakers.

As the delay and level differences are reduced to zero, the left and right speakers merge into a single center speaker (effectively mono).

How is this DSP component different from ...
Compared to simple crossfeed effects, this implementation does not only crossfeed bass and lower mids but all frequencies up to Fs/2.
By configuring crossfeed levels for both low and high frequencies, this DSP can be set up to mimic the acoustic shadow of your own head.
-> For example, hi-hat sounds panned hard to the left/right on a recording can be moved "out of the head" coherently with all the other instruments.

The configuration dialog looks like this:


Please give it a try and let me know what you think, thanks.

This post has been edited by xnor: Sep 19 2011, 22:58

[extrabigmehdi]

Thanks, I found this component very easy to tweak , and the explanations quite good.
I compared with the redline monitor vst, it's not as straightforward and couldn't achieve the same result.
The tb iso prone sound too much like a reverb, and I hate that it reset itself when I use it with the vst adapter.
And for a reverb, I rather use good stereo IR with my favorite vst.

The default settings were too much for me.
Using :
ILD low : -5.5 db
ILD high: -19 db
ITD : 85 us

I don't know to which speaker position this would correspond, but that's nice & enough subtle .


I know a free vst "head-fit" that seems similar , but that introduces more settings, I copy/paste:

ILD LF means interaural level difference at low frequencies

ITD LF time is for interaural delay between ears at low frequencies in ms

ILD HF interaural level difference at high frequencies

ITD HF time is interaural delay between ears at high frequencies

F central is used to adjust the frequency between lows and highs

Unfortunately I didn't manage to make it work inside foobar.

[xnor]

Thanks, I found this component very easy to tweak , and the explanations quite good.

Hey, glad you enjoy it as much as I do.

I don't know to which speaker position this would correspond, but that's nice & enough subtle .

Well that's hard to say. Those ILD values are an indication of a wide angle, the ITD on the other hand corresponds to about 10° if I'm not mistaken. But since the ILD dominates with your settings I guess the ITD value doesn't matter very much.

I know a free vst "head-fit" that seems similar , but that introduces more settings, I copy/paste:

I also know that one. More settings are great but for lower frequencies our ear mainly evaluates time differences and above ~1.6 kHz mainly level differences are evaluated so being able to configure a different ITD for high frequencies doesn't seem important.

But I've noted it down on my todo/look into list.

[extrabigmehdi]

Well that's hard to say. Those ILD values are an indication of a wide angle, the ITD on the other hand corresponds to about 10° if I'm not mistaken. But since the ILD dominates with your settings I guess the ITD value doesn't matter very much.

Well, I still notice the effects of ITD despite my ILD settings. Anyway, I wasn't looking for a "speaker like" soundstage when adjusting the settings, just something relaxing and enjoyable.