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greyghost · 2012-01-20, 23:25

ForeverNixNub Wrote:I think the main issue here is this.

On a 5.1 source you have 6 channels.

Left Front
Right Front
Centre
Rear Left
Rear Right
Bass (.1)

What happens with down mixing is it takes Left, and Right and passes it through to the left channel and right channel at 100% volume. However with the main VOICE channel it seems to reduce the volume by 50% and send half to the left and half to the right; as some kind of rudimentary way of normalizing the audio. When in fact it should be taking the centre channel (normally voice/dialogue) and putting out at 100% on both sides.

Then in the moments of a film when you hit music/sound effects its blaring loud because these effects come through at DOUBLE the volume of the voice channel that you've probably adjusted your volume too.

Does this make sense to anyone else?

Yes it does, very clearly discribes my own observations (different computers soundcards OS) .

The constant need to change volume between conversation and action scenes, a slide in the audio options screen to in or decrease impact of the center channel would already be great.

evilspoons · 2012-02-07, 06:23

Same problem. I'd like to see independent channel volume levels pre-mixdown to whatever number of channels it's outputting. I want to turn the center up for my 2.0 bookshelf system.

~~Ned Scott~~ · 2012-02-07, 06:55

evilspoons Wrote:Same problem. I'd like to see independent channel volume levels pre-mixdown to whatever number of channels it's outputting. I want to turn the center up for my 2.0 bookshelf system.

a 2.0 system has no center...

in any case, that's something that has to be handled at an OS level.

DDDamian · 2012-02-07, 07:43

Ned Scott Wrote:a 2.0 system has no center...

in any case, that's something that has to be handled at an OS level.

It's a fairly easy patch, but to make it as a patch means updating it with each release. That and the fact that there is no "correct" level, it'll vary by movie, by system and by user.

How it's mixed now is mathmatically sound, i.e. mixing the channels without clipping by adding the RMS value of each channel mixed and taking the root. There's no more "sound" way to do it.

The algorithm's are the same in the new AE as well.

There's only one way to make people happy on this (well, besides buying them 5.1 systems) is to have the mix-levels definable in advancedsettings.xml. That adds some more code, and another wiki page, but it is quite easily do-able - just not worth doing if it didn't get merged to trunk. Patches just aren't sustainable.

StinDaWg · 2012-04-08, 09:32

For anyone using Windows 7/8, it already has dynamic range compression built in. Microsoft licensed Waves DSP technology. It is under audio settings-enhancements-loudness equalization. It is not perfect, as I find it tends to lower loud explosions a little too much for my liking, and is a little slow regaining, but it definitely normalizes volume between people talking and loud noises so you don't have to constantly play with the remote during the movie.

Personally I use the SRS TruVolume feature on my soundbar for normalization but you should give the Windows option a try if you have it.

Nadu · 2012-04-09, 09:40

(2012-04-08, 09:32)StinDaWg Wrote: For anyone using Windows 7/8, it already has dynamic range compression built in. Microsoft licensed Waves DSP technology. It is under audio settings-enhancements-loudness equalization. It is not perfect, as I find it tends to lower loud explosions a little too much for my liking, and is a little slow regaining, but it definitely normalizes volume between people talking and loud noises so you don't have to constantly play with the remote during the movie.

I have tested something similar once with a Creative X-Fi soundcard and the result was a bit annoying. The loudness changes were just to obvious and harsh.

Nonetheless yesterday I gave the Windows 7 built-in solution a try and watched 3 episodes of a tv show with DTS audio tracks. Previously I had to keep my fingers on the volume control buttons all the time, but now it wasn't necessary to change the volume once! Furthermore loudness changes were not really detectable, so this is really an amazing result. I will keep using the Windows 7 volume normalization, it seems to be a really nice solution for me.

So thanks a lot StinDaWg for suggesting it!

StinDaWg · 2012-04-09, 10:34

Yes, it's very good. If you have a 2.0/2.1 soundbar I recommend setting xbmc audio to 5.1 and do not check boost audio on downmix. This way your sound card downmixes the signal rather than xbmc and with loudness equalization turned on everything should sound fairly even.

krusade · 2012-05-20, 10:41

(2012-02-07, 07:43)DDDamian Wrote: There's only one way to make people happy on this (well, besides buying them 5.1 systems) is to have the mix-levels definable in advancedsettings.xml. That adds some more code, and another wiki page, but it is quite easily do-able - just not worth doing if it didn't get merged to trunk. Patches just aren't sustainable.

Yes, DDDamian, thank you! Please do that. It's what we've been asking for from the beginning. A setting where users can tweak channel volume individually before downmixing. I know it can be a bit inconvenient to implement, but it's the only way to do it right. After all this time we've been reporting this bug and described it in detail so that you guys can aknowledge it, it really saddens me to see we speak again of "something that has to be handled at an OS level". No man, that's not something you should mess with your driver settings for. It happens in XBMC and it's reasonable it should be dealt with there. We know every movie is different, we're not asking for a permanent downmixing solution that is perfect for all cases. We only need a way of changing volume channels separately before downmixing on a case by case method. I don't mind adjusting this setting before I watch a movie. It's a hell of a lot better than doing remote control jockeying with volume levels for 2 hours.

So please, guys, add this in the advanced settings, merge it to the trunk, we will really appreaciate it. It would elegantly solve this problem once and for all and make the XBMC experience that much better!

digitaltomj · 2012-05-20, 14:49

You may want to try manipulating the file outside of xbmc, save it and then just use the new file in place of the old

krusade · 2012-05-24, 21:25

Let's hope they will place some slider controls in the interface, though. To make it more friendly for a case by case tweaking.

DDDamian · 2012-05-24, 21:41

No promises on when, but I do see it happening some time this summer.

~~Ned Scott~~ · 2012-05-24, 23:48

DDDamian · 2012-05-25, 00:04

@NedScott - damn - you do pick 'em lol. An all-time classic and that image is my fanart for it Tongue

**Martijn** · (This post was last modified: 2012-05-25, 00:57 by Martijn.)

(2012-05-24, 23:48)Ned Scott Wrote:

Damn funny Big Grin

tomtastic · (This post was last modified: 2012-06-04, 22:16 by tomtastic.)

I have this problem too, the downmix from 5.1 to 2 chan makes the center (commonly voice) channel almost inaudible.
I'd guess that a lot of AppleTV users dont have 5.1 decoders, and would dearly love to see a center channel downmix slider appear soon.

I've got two ATV2s, one with an old 5.1 decoder amp, and one running HDMI audio straight to the TV's built in speakers, the latter just isn't worth watching 5.1 audio films through no matter what I've set the 'System > Audio Output' settings to as other channels totally drown out the centre (voice).

In summary,
XBMC(IOS) + 5.1input + decoder = great!
XBMC(IOS) + 5.1input + no-decoder = very bad.

(org.xbmc.xbmc-atv2 11.0-3)