INTERACT FORUM

Please login or register.

Login with username, password and session length
Advanced search  
Pages: [1]   Go Down

Author Topic: Gain structure confusion when using volume levelling  (Read 1413 times)

mattkhan

  • MC Beta Team
  • Citizen of the Universe
  • *****
  • Posts: 4216
Gain structure confusion when using volume levelling
« on: January 26, 2014, 04:52:21 am »

I am using the current stable JRiver build and all tracks are analysed. I have read up on volume levelling and adaptive volume and concluded that volume levelling only seems like the right approach, at least in part because I have an RTi remote which is not yet programmed to drive the PC. The appears to work as intended except it seems to result in having to crank my amp up way too high producing an small but audible uptick in the noise floor in the room. For example, moderate evening music listening now requires an amp level in the region of +2 or so even with all volumes controls (jriver interval volume, saffire mixcontrol volume, hardware pot on the saffire pro 24) at 100%. My previous, non htpc based setup, would hit similar volumes at -20 or so for reference.

My DSP setup is currently

* output format = 5.1, upsample to 96kHz, no mixing
* volume levelling on
* adaptive volume off
* room correction off
* convolution on with normalise filter volume on

I have looked at contents of my library and can see the R128 peak level varies from -11.8 to +4.2 but I have no idea what, if anything, I can do with this information.

I have seen some threads that refer to the filter being used for convolution resulting in large cuts. The filter I have (R channel in a 2.1 setup shown) is not "done" yet (see attached) but my thinking is that I currently have typically -10 coming from volume levelling, -6 from the convolution "normalize filter volume", maybe another -10 or so from the filter itself (just looking at levels in the amplitude chart). The only one of those that is obviously under my control is the filter itself but that will inevitably involve some boosting (for the sub) so seems a minor contributing factor in total.

One thing I haven't done is the "reference level calibration" in room correction as I can't work out how to add room correction when convolution is active (it forces the sub not to play as far as I can see). I thought that setting room correction after convolution and marking the channels as full range would therefore leave the per channel routing (done in convolver) intact but I don't think it worked.

Thanks
Matt
Logged

mattkhan

  • MC Beta Team
  • Citizen of the Universe
  • *****
  • Posts: 4216
Re: Gain structure confusion when using volume levelling
« Reply #1 on: January 27, 2014, 06:32:54 pm »

I think this problem is basically solved by being more careful in the filter creation (so that it reduces the gain change it provides itself) which then lets me turn off the "normalise filter volume" option.
Logged

mwillems

  • MC Beta Team
  • Citizen of the Universe
  • *****
  • Posts: 5233
  • "Linux Merit Badge" Recipient
Re: Gain structure confusion when using volume levelling
« Reply #2 on: January 27, 2014, 07:03:11 pm »

I think this problem is basically solved by being more careful in the filter creation (so that it reduces the gain change it provides itself) which then lets me turn off the "normalise filter volume" option.

My understanding is that the volume normalization option is only necessary if your filter applies boost; it just reduces the effective volume by 6 dB: http://yabb.jriver.com/interact/index.php?topic=74139.0  My filters are all neutral or cut, and I've never used the normalize function and never had any difficulties.  

Your mileage may vary on that, but your filter looks like an all cut filter (everything below 0dBFS); with a filter like that and volume leveling on you shouldn't have any difficulties with running out of headroom even with normalization off (you've got between 10 and 20 dB of headroom already).  

Volume leveling is probably applying more than 10 dB of cut in many cases by itself, about 65% of my music library needs more than 10 dB of volume leveling, and some of it quite a bit more.  Peak level isn't what determines the leveling reduction, "Volume Level (R128)" is what determines it.

Reference level calibration wouldn't affect your problem, it only affects how the "loudness" compensation function works, it doesn't affect volume/gain structure.

Sounds like you got it sorted though.
Logged

dean70

  • Citizen of the Universe
  • *****
  • Posts: 508
Re: Gain structure confusion when using volume levelling
« Reply #3 on: January 27, 2014, 09:47:42 pm »

I have found the normalize option to cut too much. I ended up using the Adjust volume PEQ filter option to cut by -4db, which gives the same level with convolution filters as without any eq in the path.
Logged

mattkhan

  • MC Beta Team
  • Citizen of the Universe
  • *****
  • Posts: 4216
Re: Gain structure confusion when using volume levelling
« Reply #4 on: January 28, 2014, 03:03:43 am »

My understanding is that the volume normalization option is only necessary if your filter applies boost; it just reduces the effective volume by 6 dB: http://yabb.jriver.com/interact/index.php?topic=74139.0  My filters are all neutral or cut, and I've never used the normalize function and never had any difficulties. 

Your mileage may vary on that, but your filter looks like an all cut filter (everything below 0dBFS); with a filter like that and volume leveling on you shouldn't have any difficulties with running out of headroom even with normalization off (you've got between 10 and 20 dB of headroom already). 
ah ok, good to know it is based on volume level not peak level. The solution in this case was rebalancing the filter between the sub and mains so while there was no boost as such before, there sub was relatively higher than the mains (and the gain on the sub amp too low) meaning that everything sounded a bit too quiet. Changing this (as per attached) and turning off normalisation has bought things to normal (amp) levels.
Logged
Pages: [1]   Go Up