Decent q on the CoreELEC team

#1

I am living with CoreELEC every day, it is part of my life, I thank the team for their expended work, I would have had one small request, I’ll explain what: I’m a fan of
the stereo music and cereelec transfers the music in a very high-quality resolution of just me there a little bit missing the absence transfer of the LFE channel. I found the possibility of the solutions on this page:
https://github.com/osmc/osmc/blob/master/package/mediacenter-osmc/patches/all-113-add-support-to-mix-LFE.patch
and I want to You ask whether you could not incorporate into the future developmen of this option as well. Thank you so much for your understanding.

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#2

This only seems to be a patch, when multi-channel sound is downmixed to stereo.
It has nothing to do with adding an LFE channel, when the source is only 2.0 stereo (that would be a 2.1 upmix instead).
Your AVR already takes care of using your subwoofer for deep bass sounds, although it’s not a dedicated channel.

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#3

Do you think that if I buy a newer stereo amplifier so I will then play the bottom of the LFE channel in 2.1?
I have in mind this: I have a recording in the music in DTS 5.1.mkv and I want to listen to over CoreELEC in the stereo receiver in 2.1 is it possible without problem?

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#4

Sure, just configure “2.1” as your output format in “Settings > System > Audio”.

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#5

Thank you so much for the reply, I am pleased. I wish You a nice day.

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#6

Hello mr. relkai,
I’m sorry I yesterday probably poorly expressed. I will write as I think.
I have ordered this STEREO AMPLIFIER" https://www.pioneer-audiovisual.eu/eu/products/50da but this stereo amplifier has no HDMI input only has S/PDIF input a can only accept STEREO PCM 2.0 via S/PDIF.
I have a large collection .mkv in the more-channel file for example in DTS 5.1 and the like.
Therefore I want to ask whether it will not be a problem with the lower sound from multi in DTS 5.1 to two channels to S/PDIFif it can CoreELEC downgrading. Thank you.

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#7

Aaah, I see.
So, you indeed need the downmix option from e.g. 5.1 to 2.0.
To my knowledge this shouldn’t be a problem and I use it for myself in the bedroom.
Therefore you should configure 2.0 output in your settings and I don’t expect any problems.

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#8

Super, I was worried that CoreELEC cannot downmixo ption from e.g. 5.1 to 2.0 but thank you for the pleasant information that it can handle. Thank you so much for the reply.

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#9

Hello mr. relkai,
sorry but here I am again with the answer. I already have the new stereo amplifier and
I have to say that downmix from DTS 5.1 to stereo through the S/PDIF-option and played everything well, very I like it but I found even one little trifle that was the one sound absolutely perfect. As I suspected when I enjoy the “music.mkv” in DTS 5.1 and I set in kodi to 2.0 output makes it the perfect downmix in stereo over S/PDIF-option but if I set on the kodi to output at 2.1 do also downmix in the stereo but doesn’t make downmix and to the subwoofer.
This is the only little thing that is missing to perfect the transmission of audio via kodi via S/PDIF - option.
I would very much You asked could not be still on this piece and it is downmix the transmission of the LFE channel through the via S/PDIF-optioin to improve?
I mean please only add the ability to down from the DTS 5.1 over the transmission of S/PDIF-option to stereo 2.1 for the subwoofer.

Thank you so much.

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#10

Could you please describe your setup in detail?
As far as I understood, you connected the CE box via SPDIF (TOSlink) to your new Pioneer Amp, which has two speakers (L&R) connected. How is your subwoofer connected to this setup?

According to the Pioneer manual, the SPDIF input can only handle PCM input (=uncompressed), which limits the transmission to stereo (2.0)
A downmix to 2.1 will result in compressed data, which your amp cannot not handle at all.

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#11

I have a lot of music in the mkv file in more channel transfer in DTS 5.1 on HDD disk and I playing through my chinese player Scishion V88 pro over S/PDIF-option to my stereo amplifier.
I would like to have whether it is not possible to do this in coreelec/kodi to know to do downmix through the S/PDIF-option on 2.1 so that was downmix and to the subwoofer. Coreelec/kodi will do good down to 2.0 stereo but is missing me there the lower the transfer to the LFE channel over S/PDIF-option. So, if it was possible please.

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#12

Still not answered…

Assuming your subwoofer is connected to the same Amp as second speaker pair. In this case, you have to configure “2.0” as your output format in “Settings > System > Audio”. This is the only format your Amp can handle. What is the problem then?
Does the subwoofer keep quiet?
Are some LFE effects missing (in this case it could be a potential 5.1 > 2.0 downmix issue)?

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#13

Hello,
Yes, exactly I have connected the subwoofer to the same Amp as a second speaker pair.
And also I have in Settings/System/Audio I set to 2.0 and the subwoofer doesn’t give the lower bass sounds.
I think that is a problem in the transmission of the LFE channel through the S/PDIF-option when doing the downmix 5.1 > 2.0.
That the downmix 5.1 > 2.0 will not process the transfer of the LFE channel through the S/PDIF-option.
Thanks.

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#14

Yes, you are right.
Had a look on the code, and it seems to be the same issue like on Kodi17.

Kodi18 drops the LFE channel completely in 2.0 downmix - which is the correct default behaviour (!) for Bassmanagement:

https://www.dolby.com/uploadedFiles/Assets/US/Doc/Professional/18_Metadata.Guide.pdf#page=14
“…In all downmixes, the LFE channel is not included…”

LF should already be present in L/R channels, and add. LFE may overstress speakers.
But FFMPEG is prepared to do a LFE downmix to L/R channels:
https://www.ffmpeg.org/doxygen/2.4/rematrix_8c_source.html#l00288
This is controlled by factor “lfe_mix_level”
ActiveAE runs on top of FFMPEG, but doesn’t init “lfe_mix_level”, so it will be 0 => no downmix.

So the patch https://github.com/osmc/osmc/blob/master/package/mediacenter-osmc/patches/all-113-add-support-to-mix-LFE.patch needs to be adapted for Kodi18, but should still work.
I would appreciate if CE team would add this to the next release.

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#15

rho-bot…
“I would appreciate if CE team would add this to the next release.”

Thank you for your information. It would be amazing if the CE team applied the files to the next CE release. For me it would be the most beautiful experience.

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#16

+1 this look like “a must” patch - not everyone could notice, that LR are stressed more than they should be. 2.0 is often use for TV, which doesnt support 5.1 input. And you couldnt do much with TV speaker, when something goes wrong.

@rho-bot’s post makes sense, for me it seems that Issue should be adressed to Kodi also (as its using FFMPEG wrong way).

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#17

I doubt it is a wrong handling by Kodi, it looks more like to protect speakers for overload condition. L/R channels should already contain LFE frequency range if encoding is properly done.
But they could have implemented an option menu to allow users to enable add. LFE downmix in case L/R speakers can handle this.

@adamg What’s your opinion on this issue? Would it be possible to add the patch for upcoming new stable 9.0.2 Build?

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