Is this the only version of LE on Android S905 that outputs bit perfect sound ?

hundrakg · August 23, 2022 at 12:40 PM

Is this the only version of LE on Android S905 that outputs bit perfect sound ? (24Bits LPCM 5.1 sound), other wise android is limited to only 16 bits

LibreELEC-S905.arm-8.2.5-Chroma.422.10bit.img

I know the above is doing 24 bits in 5.1 sound, but just wanted to know if a newer version offers same ?

And does the LE S905 versions support S905x3 and S905x4 ?

**chewitt** · August 23, 2022 at 3:29 PM

I'm not aware of anything in the upstream codebase that should prevent 24-bit audio being used, but it's not something I can easily validate, so you will need to do some testing. LE11 test images: https://test.libreelec.tv/11.0/Amlogic/box/

There is partial support for S905X3 devices; the OS is stable but hardware decoding is an issue. If you only need 1080p output you can disable hardware decoding and everything works. If you want 4K, not happening. No support for S905X4 at the current time.

hundrakg · August 23, 2022 at 6:57 PM

No way to check easy if output is 16 or 24 bits in LPCM 5.1, amlogic chipset is limited to 16 bit out in LPCM, just wanted to verify if later version LE also did support 24bits LPCM like the

LibreELEC-S905.arm-8.2.5-Chroma.422.10bit.img

24-bit output

You sure? I thought I read a post from wesk05 on the Kodi forum, that all AMlogic devices are limited to 16bit audio when not bitstreamed 😥 Although that…

discourse.osmc.tv

Quote from wrxtasy

And yes the 24bit Kernel HDMI output signalling changes talked about in that thread are in the LE v8.2.5.x versions onwards

**chewitt** · August 24, 2022 at 2:43 AM

LE11 uses upstream (Linux 5.19.y) kernels so there is 0% driver code in-common with the legacy image you found. AFAIK all S905 and later hardware supports 24-bit output (and you claim the image you found does, which would support that). Go test.

hundrakg · August 24, 2022 at 4:48 AM

ok, but does all S905 support 24bits LPCM multichannel output, then why did wrxtasy say: "And yes the 24bit Kernel HDMI output signalling changes talked about in that thread are in the LE v8.2.5.x versions onwards" it seems version below 8.2.5 dont support that..

I always thoght it was HW limited by Android S905 and that LE 8.2.5 was coded to support that anyway.

Its very hard to confirm 24 bit output, you need some analyzer hdmi of some sort, As far as I know there is no Receiver that could show 24 vs 16 bit input via HDMI, so I dont know how to confirm this. Receivers via hdmi can confirm only 48/96/192khz and they can confirm if 2 channel or 5-7 channel, but not 24 or 16 bits.

for example, The Nvidia Shield TV only support 16 bits if LPCM 5.1, and only 2 channel 24 bits.

in this thread, I post a link:

OSMC announced new Vero4k, opinions?

wesk05 says: "All Amlogic devices are limited to 16-bit output. An HDMI analyzer or a HDFury Vertex will show you the maximum word length (bit depth) set in the Channel Status Bits of the HDMI signal. 24-bit doesn't necessarily mean that the output is indeed 24-bit, but if these bits are set to 16-bit (max word length-20), then 24-bit output is completely ruled out and that is what you would see with Amlogic devices."

**chewitt** · August 24, 2022 at 2:56 PM

The i2s encoder (which packs audio frames for HDMI) supports 16/24/32-bit output as can be seen here: https://github.com/torvalds/linux…r-i2s.c#L71-L76

However, it looks like 24 is padded to 32, see: https://github.com/torvalds/linux…r-i2s.c#L48-L59

And it outputs 2-channel or 8-channel, see: https://github.com/torvalds/linux…r-i2s.c#L61-L69

So I would make an educated guess that the hardware supports 24/32 bit output over 2-channels, but only 16-bit in 8-channel mode. This is also hinted in this comment in the code: https://github.com/torvalds/linux…oder-i2s.c#L118

That also aligns with the OSMC forum post, and this alsa conf from the legacy kernel which ensures HDMI is using 16-bit LE packing: https://github.com/LibreELEC/Libr…8AUDIO.conf#L39

So I'm right (24-bit is supported) and so is the other guy (HDMI is 16-bit). Enjoy

hundrakg · August 24, 2022 at 5:10 PM

But the LibreELEC-S905.arm-8.2.5-Chroma.422.10bit.img does multichannel 24bits , dont understand