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2014-05-28, 23:56
(This post was last modified: 2014-05-30, 13:03 by da-anda.)
I've upgraded from Frodo to Gotham but now I can't find how to boost the center channel. I have my raspberry hooked to my tv (no avr) and the voices in movies sound very low compared to Frodo, where I could select "boost center channel when downmixing" and it worked really well. I have tried checking "Normalize levels on downmix" but I can't get it to work like it did in Frodo.
Can anyone help me?
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2014-05-29, 00:36
(This post was last modified: 2014-05-29, 00:43 by Fraludio.)
I'm using it in four pi's (my house, my parents', my girlfriend's and her parents') and it makes a really good difference to the point I bought the pi just because of this. Today i upgraded to gotham and the first movie we tried (Thor 2) my girlfriend and me went "wtf, it sounds awful, the voices are barely audible".
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2014-05-29, 21:05
(This post was last modified: 2014-05-29, 21:07 by DBMandrake.)
I would second the need for this.
XBMC (all platforms) really does need a boost centre channel volume during downmix option. (as distinct from volume amplification, which is really just a gain increase for all channels with a peak limiter, which doesn't solve the problem of recessed dialogue in the centre channel on many files)
Either that or a way to adjust the down mix matrix from advancedsettings.xml, so those of us that care enough can do something to adjust it without having to recompile. Kind of strange that the audio engine was rewritten so entirely without any thought to making the down mix matrix user adjustable in any way.
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da-anda
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2014-05-30, 11:32
(This post was last modified: 2014-05-30, 11:35 by da-anda.)
I just had a little chat with FernetMenta, because I had the feeling that we do the boost of the center channel on downmix by default now and thus removed that setting. And he confirmed. So, we do it by default UNLESS you enabled "normalize levels on downmix" (which is to be expected). So disable normalization and you should be good to go again. Note that this requires more CPU on the PI because of additional checks for audio clipping.
edit: I dared to change this issue and mark it as solved. Feel free to change it back if it doesn't work for you
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2014-05-30, 12:11
(This post was last modified: 2014-05-30, 12:11 by FernetMenta.)
We use ffmpeg's default mixing matrix. Some channels which are in the input stream but not in the audio configuration get mixed into those available. i.e. when playing 5.1 on a 2.0 setup the center channel gets mixed 0.5 into FL and 0.5 into FR. Default is that we normalize levels on downmix because this protects from clipping and keeps the result closest to the original. Not applying normalization, formally known as "boost volume on downmix" tries to keep the overall volume of the source. In particular this is desired when watching tv where the stream often switches from 5.1 to 2.0 and back.
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da-anda
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well then, this sounds like an option good enough for core and not just PI specific, or, if we can, we could just do it by default for video playback (not music downmix)
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Milhouse
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I agree multichannel music is rare but I've got some examples that play well on the Pi and if centre channel boosting is ever added to core it should take multichannel music into consideration (ie no boost).
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2014-05-30, 14:17
(This post was last modified: 2014-05-30, 14:22 by DBMandrake.)
Come to think of it, rather than having an advancedsetting option to adjust the amount of boost for all videos and a global on/off in settings, it would make a lot of sense to add a "centre channel boost" (or similar) option in the onscreen audio controls which can be saved as a default and also adjusted individually for different movies, just like the volume amplification setting can be - because not all videos require the centre channel boosting. (This also solves the problem of not accidentally applying it to multichannel music files)
So basically like the volume amplification setting but ONLY for the centre channel, and applied on top of any other correction like volume amplification. The only problem I can see with implementing this is would it need skin support to add it to the OSD overlay UI ?
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Kodi 18.3 - Vero4k, Raspberry Pi 2. OSMC.