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Crossfeed, Different software implementations (bs2b, rockbox)
Northpack
post Apr 20 2010, 19:10
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I'm using the bs2b crossfeed plugin with foobar2000 for quite a while now and I'd like to adapt my favourite settings to the rockbox crossfeed. The parameters of the latter are very different however. bs2b has the following parameters:

- Crossfeed db (1 - 15db)
- Crossfeed hz/ms (300hz/620ms - 2000hz/90ms)

Rockbox seems to have the same parameters as the crossfeed VST from blogohl:
QUOTE
Ipsilateral : signal from one channel going to the corresponding (same) ear.
Contralateral : signal from one channel going to the opposite ear.
Hi Loss contra : high frequency are more attenuated by the head than lows, so attenuation value is between 0 and - 40 dB (default is - 10dB).

Now we've got three setting where bs2b has only one. I guess all three values are somehow correlated and adjusted alltogether in bs2b, but I'd really like to know in which way... It's evident from the bs2b concept page that the HF of the contralateral channel is attenuated, but I can't figure out by which amout. And what about the ipsilateral gain?
QUOTE
F is frequency cutoff of the Hi shelf contralateral filter : value ajustable between 500 and 2000 Hz (default is 700 Hz)
Delay is the time delay between the ipsilateral signal and the contralateral one.

In bs2b frequency cutoff and delay are correlated, which makes sense to me as both are are dependent on the virtual speaker's azimuth. Contrary to the VST however, rockbox omits the delay setting. I guess it's a fixed value. So does it even make any sense to alter the cutoff frequency here?

This post has been edited by Northpack: Apr 20 2010, 19:25
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Northpack
post Apr 22 2010, 23:31
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jlohl, thanks for your explanation (and for commiting the rockbox crossfeed, it really made my day smile.gif)
Could you comment on what the HF Loss parameter exactly does? Af fair as I have understood, HF needs to be attenuated not only to mimic the damping effect of the human head but also in order to prevent possible comb effects caused by the delay. I experimented with this setting on my Sansa and noticed that HF content actually seems to increase when the attenuation is highered... so -24db gives considerably more clear HF than -6db. Or, to put it more precisely, especially the center signals seem to sound deteriorated with HF Loss set to -6db, while uncorrelated signals are kept intact. The higher the setting, the more natural those signals appear to me, with no more noticeable difference above -18 or -20db. Is this observation coherent with theory or am I hearing placebos? Do you know which amout of HF attenuation the bs2b design uses?

This post has been edited by Northpack: Apr 22 2010, 23:33
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