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[aproc]

I was trying to create a set of filters using Parametric Equalizer of JRiver DSP for custom downmixing of 5.1 to stereo, and observed varying volume levels during the playback (volume going up and down). Even if I try changing the custom coefficients to the standard ones, the problem persists. With JRSS downmixing, there is no such problem.

I am using the following set of filters for downmixing (standard coefficients):

Add Center to Left (-3.0 dB)
Add Center to Right (-3.0 dB)
Add SL to Left (-3.0 dB)
Add SR to Right (-3.0 dB)
Add Sub to Left (+4.0 dB)
Add Sub to Right (+4.0 dB)





 

[mwillems]

I was trying to create a set of filters using Parametric Equalizer of JRiver DSP for custom downmixing of 5.1 to stereo, and observed varying volume levels during the playback (volume going up and down). Even if I try changing the custom coefficients to the standard ones, the problem persists. With JRSS downmixing, there is no such problem.

I am using the following set of filters for downmixing (standard coefficients):

Add Center to Left (-3.0 dB)
Add Center to Right (-3.0 dB)
Add SL to Left (-3.0 dB)
Add SR to Right (-3.0 dB)
Add Sub to Left (+4.0 dB)
Add Sub to Right (+4.0 dB)





 

One way to troubleshoot what's happening is to watch the audio path dialog box during playback and see what's happening.  It sounds like clip protection is engaging for some reason, and if it is, you should see it in the audio path box. 

Do you have JRiver's volume disabled or turned all the way up?  I ask because you're adding significant boost to the left and right when mixing the subs in to them.  If you don't provide "headroom" by lowering the internal volume in JRiver, it may cause clipping protection to engage.  See http://wiki.jriver.com/index.php/Volume#Internal_Volume_Headroom

[aproc]

I am using JRiver's internal volume and the volume is normally set at 85%. Even if I set it to 100%, I don't see clipping protection getting engaged with some videos and the problem manifests. I can see clipping protection getting engaged with other videos though.

[mwillems]

I am using JRiver's internal volume and the volume is normally set at 85%. Even if I set it to 100%, I don't see clipping protection getting engaged with some videos and the problem manifests. I can see clipping protection getting engaged with other videos though.

Interesting, so to be sure I understand: you're experiencing volume fluctuations with some videos and there's nothing showing in the audio path?  Did you have a look at analyzer to see if the signal was at or near clipping?  Regardless, it is peculiar. 

What kind of output settings/devices are you using?  One other though: some audio interfaces have built in "clipping protection" which is sometimes overactive.  For example, some Asus soundcards will automatically turn down the volume when it gets close to clipping unless you bypass the Asus mixer by using WASAPI or ASIO.  Maybe investigate whether your device has something similar, or lower the volume slightly in the windows mixer as well if you're not using a direct output mode?

[aproc]

Interesting, so to be sure I understand: you're experiencing volume fluctuations with some videos and there's nothing showing in the audio path?  

Yes.

Did you have a look at analyzer to see if the signal was at or near clipping?  

The signal doesn't seem to be near clipping. All the spikes are rather below the ceiling.

What kind of output settings/devices are you using?  One other though: some audio interfaces have built in "clipping protection" which is sometimes overactive.  For example, some Asus soundcards will automatically turn down the volume when it gets close to clipping unless you bypass the Asus mixer by using WASAPI or ASIO.  Maybe investigate whether your device has something similar, or lower the volume slightly in the windows mixer as well if you're not using a direct output mode?

I have Creative xfi Surround 5.1 USB soundcard SB1090 [the earlier model, not the Pro one]. In the output settings, I have selected WASAPI exclusive event style with the default 100 ms buffer. I tried lowering the volume in the windows mixer, but it didn't help.

I think I should mention this issue as well that I get a static noise often when the playback starts and sometimes during seeking. During the playback, there is no such noise. However, I don't think that this problem has anything to do with the above problem. Also, when using MPC-HC with ReClock (WASAPI exclusive mode), I don't have any of these problems.

[aproc]

Has anybody any idea if this is a bug in Media Center or my system isn't setup correctly?