[Jogee]

Sounds a bit like dynamic range compression. It's enabled by default, but should only affect ac3 and dts material. Take a look at the Audio section in advancedsettings.xml.

[Ned Scott]

Download Add-on:XBMC Audio Mixer (wiki) from the Add-on manager. You can boost the volume for Mac OS X using that.

[Zokkel]

Download Add-on:XBMC Audio Mixer (wiki) from the Add-on manager. You can boost the volume for Mac OS X using that.

I'm very glad a pro has come to help us, but that's not our problem. That might be the solution for pecinko, but our audio volume in general is fine. Nothing wrong there. Also Davzie tried that option without succes.

It is the volume in a song itself. I looked it up and it think it might be that Dynamic Range Compression. (The description of DRC is indeed similar to the problem we have)
Like Jogee says, it should only affect ac3 and dts material and I'm talking about mp3-files. Anyway, tonight I will try putting that off in advancedsettings and see if it affects mp3 as well.

The only things that annoys me, is that everyone is saying the previous build doesn't have this problem... So it really should be fixable... sigh...
Sad to here Jmenorton has the same problem on XBMCBuntu, cause that was Davzie's next step to solve it...

Anyway, thanks to everyone that is trying to find a solution here... let's search further

[pecinko]

For what it's worth, sound seems fine with usb output (zeppelin air).

[Zokkel]

Me again...

In my search of the meaning of DRC, I came across something called 'limiting'. Roughly said: an aggressive way of DRC.

http://en.wikipedia.org/wiki/Dynamic_ran...n#Limiting

Then I saw this in the advancedsettingsfile, audio section:

<limiterhold>0.025</limiterhold> <!-- default values for limiter/compressor -->
<limiterrelease>0.1</limiterrelease> <!-- default values for limiter/compressor -->

Can an expert tell me if this is relevant for our problem, and if so, how to put this limiter off... or what values to choose for a better experience

[jmenorton]

After listening to my music for for a few hours now, with the volume at -40db or there abouts, it sounds fine for me now. Just means im limited to how much volume control i have with my xbmc remote. Im using all FLAC files btw, XBMC at -40db, TV at 100% volume, and amp now at about 50%. On the old build 50% on my amp would have been audible at the bottom of the garden, now its comfortable. Sounds fine though tbh, just dont like to think im pushing my amp (Fairly old pioneer) unnecessarily hard.

[Jogee]

Zokkel,

Take a look at this thread - http://forum.xbmc.org/showthread.php?tid=111106. I haven't read through it all, but it does go into more detail. It is a very long thread, be warned.

Ciao.

[Zokkel]

Guys,

Believe it or not, but I think I might have find a solution here. It is my opinion that it is indeed a problem with the default values of that limiter. I read the thread that Jogee suggested... Man, way to technical for me. So I decided to try turn that damn limiter of and set all setting to 0 in the advancedsettings-file. Like this:

Code:

<advancedsettings>
    <audio>
        <headroom>12</headroom>
        <limiterhold>0</limiterhold>
        <limiterrelease>0</limiterrelease>
    </audio>
</advancedsettings>

I put the volume of my mac mini up to ± 90%, I put the volume of XBMC at -20 dB and my amplifier is now up to 30-35%
I know, it's a bit a noobish way to solve things, but for me this worked like a threat!

There is only one remark: I have no idea what I actually did when I put the limiter-numbers to 0, I was just messing around and don't have clue what it means.
So if anyone can explain me in easy-tech-terms what I did and what the consequences are...That would be wonderful...

Try it out and let me know if that worked for you guys.
Grtz

[MassIV]

Found a clue in line 53 in following link:
https://github.com/xbmc/xbmc/blob/master...ttings.cpp

Code:

//default hold time of 25 ms, this allows a 20 hertz sine to pass undistorted
  m_limiterHold = 0.025f;
  m_limiterRelease = 0.1f;

But this only confuses me more as 20Hz = 50ms cycle and f stands for frequency.
Anyway since these are apparently time in ms, i assume this is the "hold time". And if it is, it is meant to prevent the limiter from opening and closing very rapidly causing "chattering" by just keeping it turned on for 25ms every time it is activated. As anticipation of more loud noise.

As for LimiterRelease, the image in Jogee's link leads me to believe this is the "moderate release" part of the "zero attack and moderate release" type Limiter. So how the sine wave continues after it hit the threshold. In this case how fast the limiter pulls his hands off. Fast is good but super fast release times, along with a fast attack time setting, will distort low-frequency sounds.

So it could be that 0ms hold allows instant closing after activation and 0ms release allows instant 'hands off' (meaning it would not do anything).
But i can't be sure that is how the limiter reads that 0ms and i doubt it will actually completely turn it off.

Quote from link: It doesn't work with passthrough, if you want the limiter, disable it.
So enabling passthrough should turn it off.

If i understood correctly the threshold is controlled by / linked to the volume amplification setting you can access during playback.
Increase volume amplification during playback will amplify soft noise as much as loud noise, but loud noise will hit the threshold; bringing them closer together.
For example: Soft voices and loud explosions will be brought to the same level by volume amplification. Then use volume (also from audio menu during play) to lower the general volume of the movie to the desired level. This only changes things for that one movie and doesn't mess up your whole general audio volume settings bla bla.

But is there a threshold when volume amplification is turned off / 0db dunno.

That is what i could make of it, i'm not sure of anything. Do not trust me, I'm not a doctor.

[User 34959]

Guys,

Believe it or not, but I think I might have find a solution here.

Code:

<advancedsettings>
    <audio>
        <headroom>12</headroom>
        <limiterhold>0</limiterhold>
        <limiterrelease>0</limiterrelease>
    </audio>
</advancedsettings>

It seems that these settings help completely get rid of this issue, or help reduce it to a minimum where you can't hear it anymore.

I too read the linked thread but it's still unclear what these settings do. Why on earth would this limiter by enabled by default on music player? According to the another thread it's not supposed to be.

[jawilljr]

Guys,

Believe it or not, but I think I might have find a solution here.

Code:

<advancedsettings>
    <audio>
        <headroom>12</headroom>
        <limiterhold>0</limiterhold>
        <limiterrelease>0</limiterrelease>
    </audio>
</advancedsettings>

It seems that these settings help completely get rid of this issue, or help reduce it to a minimum where you can't hear it anymore.

I too read the linked thread but it's still unclear what these settings do. Why on earth would this limiter by enabled by default on music player? According to the another thread it's not supposed to be.

Those settings also definitely helped my audio quality... definitely a bug or something.

Jerry

[DDDamian]

Found a clue in line 53 in following link:
https://github.com/xbmc/xbmc/blob/master...ttings.cpp

Code:

//default hold time of 25 ms, this allows a 20 hertz sine to pass undistorted
  m_limiterHold = 0.025f;
  m_limiterRelease = 0.1f;

But this only confuses me more as 20Hz = 50ms cycle and f stands for frequency.

This code work is by bobo1on1, so not my code but i can comment a bit:

The headroom value is in decibels - reducing the maximum volume by 12db is the equivilent of reducing the apparent volume to a quarter of 0db. Try changing that value to zero and see what level your output goes to.

BTW, in the comment quoted above and the code snippet - in C++ the f in 0.025f means "float" or a floating-point value, not frequency

[Zokkel]

The headroom value is in decibels - reducing the maximum volume by 12db is the equivilent of reducing the apparent volume to a quarter of 0db. Try changing that value to zero and see what level your output goes to.

Are'nt you saying the opposite of the description given in http://wiki.xbmc.org/index.php?title=Adv...3Caudio.3E ?

"<!-- Amount of headroom XBMC should use above the maximum volume level, in decibels. Defaults to 0, valid values 0, 6, 12. -->"

So putting it to 12, gives you 12 decibels above (so more, right?) the maximum volume level...

Maybe I shouldn't have wrote this in the code-file. It's not by setting "headroom" to 12 that solves this problem, but by putting limiterhold and release to 0. I only thought, putting that to 12 gives me more ... euhm... headroom
So by leaving headroom out of the code, I think this problem will be solved to. But this works fine for me now, so I'm done trying and messing around

When you read the post of Ned Scott in this thread: http://forum.xbmc.org/showthread.php?tid=111106&page=5
It seems that real pro work will not intervene in the near future. So for now, my limiter is set to 0

[DDDamian]

@Zokkel - no, 12db headroom would mean leave 12db free from the max of 0db, adding to it would result in clipping.

As it turns out, we're both wrong - in your case in the definition, and in my case in making the assumption it was still a valid setting. I checked the code and while it is still read into XBMC from the advancedsettings file, it is no longer actually used anywhere! So set it wherever you like

I'm well aware of what Ned refers to in that post - I'm one of the devs helping gnif out with AudioEngine. And Ned's quite right, there's unlikely to be much done with the audio side of things as the new audio code is nearing merge with master. Each dev more or less works on what he wants, so anythings possible, but all the devs are aware that new code is coming.

If you want to stay on top of things for this branch just look for any threads with AudioEngine in the title in the Development section of the forum.

[jmenorton]

How do you edit the Advancedsetting.xml im opening it from xbmcubuntu and it just opening with Chromium web browser.