Multichannel PCM (LPCM) on S912

[Adam86]

Morning all,

Hopefully one of you kind people can help me as I am pulling my hair out.

I've got a S905X and a S912 Mini M8S Pro Android Box, have used it for a few years on CoreElec - have recently got into the Moonlight Game Streaming from my PC in the other room. All is great execpt i have just recently upgraded my surround sound system and now the Android Box is directly connected to the AVR, this means I can now pass through all the main formats and that works fine even when booted into the Android ROM.

However, I am really struggling to get Multichannel PCM working on all of these boxes (even have a S905X3 as my main CoreElec install now and thats the same). All I get is two channel PCM. Moonlight Game Streaming fully supports 5.1 surround sound and this is passed as uncompressed LPCM - but for some reason the Android OS only passes this through as LPCM 2.0. I know the functionality works fine on Moonlight because if i plug my Fire TV 4K Stick in directly to my amp it works perfectly, so does plugging my laptop in over HDMI and doing a sound test, so I know my AVR is fully capable of it.

Is there a way to get LPCM multichannel 5.1 working on any of these boxes whilst booted into Android? Or a ROM that supports it?

Cheers

[ReaperMan]

I have not tested surround sound on my system...so a shot in the dark.
Minix has(had) s912-h for output to surround sound via licensed codecs(?). Their s812-h was extra hardware based output.


Do a little research into Viper4Android. I'm not sure if surround is emulated or assists proper pass through.
(I did see info about adding lines to build.prop to activate Dolby sound.)


Dolby DD+ decoder option
#this prop to for videoplayer display the DD+/DD icon when playback
ro.platform.support.dolby=true
#DTS decoder option
#display dts icon when playback
ro.platform.support.dts=true
#DTS-HD support prop
#ro.platform.support.dtstrans=true
#ro.platform.support.dtsmulasset=true
#DTS-HD prop end
# Enable player buildin
media.amplayer.seekkeyframe=true
media.amsuperplayer.enable=true
media.amplayer.enable-acodecs=ac3,eac3,rm,dts
media.amplayer.enable=true
media.amsuperplayer.m4aplayer=STAGEFRIGHT_PLAYER
media.amsuperplayer.defplayer=PV_PLAYER
media.amplayer.thumbnail=true
media.amplayer.dsource4local=1
media.amplayer.dropwaitxms=100


Sorry can't be more helpful. I'm sure several prominent members tested surround sound...to what result...I never found out.

[Adam86]

Hello ReaperMan,

Your post is most helpful, however my understanding is that LPCM is not a licensed format as this is merely uncompressed audio that is passed straight to the amp, therefore not bitstreamed in any manner.

So DD or DTS is not part of the equation, I can confirm that by installing Android KODI and enabling passthrough of DD/DTS etc and that works fine. It is merely anything higher than 2.0 LPCM does not get passed to the amp :-(

[ReaperMan]

I forget...some mention of surround only passing via S/PDIF port to surround sound system. In combination with HDMI output?

If you figure it out...start a new info topic to help others.

[RiCkLaR_atvX]

It has been awhile since I faced a similar problem, I can't remember the exact solution to fix LPCM audio, but when I had surround-sound audio issues before running Amlogic w/ Android 7.0 and multi-channel audio it turned out to be that the problem was not LPCM by itself it was actually multi-channel AAC that wasn't getting converted to LPCM (Android default is for AAC to get converted to PCM) before transmitting to TV over HDMI or to surround sound system via SPDIF.

For Android 6 and 7, I believe this was the solution that worked:

# edit /system/build.prop insert this line
media.aac_51_output_enabled=true

And for Android 8 and 9, not too positive on this, but I believe you have to add "vendor" for it to work in newer Android, so you can try this:

# edit /vendor/build.prop insert this line
vendor.media.aac_51_output_enabled=true

WARNING: If you never modified a build.prop before, thoroughly read a few tutorials on doing so, one mistake and you will brick your device.

Also, another thing to try, if there is the setting to select AUDIO via SPDIF and you don't have SPDIF connected, device is only connected with HDMI cable, then try selecting SPDIF and test the surround sound. This trick worked for an Allwinner device connected via HDMI to convert AAC to PCM because I wasn't getting any sound from video files with 5.1_AAC. Not a perfect solution because I believe that in this scenario audio was only 2.0 PCM still, but was happy because at least I could watch my movies on that particular stupid box with sound finally.

[ReaperMan]

Inquisitive and inventive.
We need more testers/ pioneers to report their experiences and solutions.

[Adam86]

It has been awhile since I faced a similar problem, I can't remember the exact solution to fix LPCM audio, but when I had surround-sound audio issues before running Amlogic w/ Android 7.0 and multi-channel audio it turned out to be that the problem was not LPCM by itself it was actually multi-channel AAC that wasn't getting converted to LPCM (Android default is for AAC to get converted to PCM) before transmitting to TV over HDMI or to surround sound system via SPDIF.

For Android 6 and 7, I believe this was the solution that worked:

# edit /system/build.prop insert this line
media.aac_51_output_enabled=true

And for Android 8 and 9, not too positive on this, but I believe you have to add "vendor" for it to work in newer Android, so you can try this:

# edit /vendor/build.prop insert this line
vendor.media.aac_51_output_enabled=true

WARNING: If you never modified a build.prop before, thoroughly read a few tutorials on doing so, one mistake and you will brick your device.

Also, another thing to try, if there is the setting to select AUDIO via SPDIF and you don't have SPDIF connected, device is only connected with HDMI cable, then try selecting SPDIF and test the surround sound. This trick worked for an Allwinner device connected via HDMI to convert AAC to PCM because I wasn't getting any sound from video files with 5.1_AAC. Not a perfect solution because I believe that in this scenario audio was only 2.0 PCM still, but was happy because at least I could watch my movies on that particular stupid box with sound finally.

Thanks for this really descriptive post.

I tried it last night with the buil.prop variables and neither made any difference unfortunately :-(

[ReaperMan]

It might be a limitation to the current Android version on your China Box?
Again, others would have more testing experience to guide you.