Topic: 5.1 from TV Optical only 2 channels.

Hi there,

I have an LG TV (C1 model)
and
RME Fireface UCX II

I'm connecting via optical from the TV output to the RME optical input. I am testing 5.1 movies via Netflix and Amazon.

TV has the audio options of: PCM, Auto, and Pass Through.

When I choose Auto or Pass Through, I hear static noise only.

The only option that works to give audio is PCM.

That's fine and all, however, I only receive a 2 channel signal. Even when I pick the options that output static noise, I only see the RME total FX software receiving channels 1/2 ADAT.

I'm wondering if anyone might know how I can get 5.1 channels?

LG says on their site that the optical outputs up to 5.1. Here is the article I've checked:
https://www.lg.com/ca_en/support/produc … 7136302910

Any ideas?

Thanks!
Dave

Re: 5.1 from TV Optical only 2 channels.

The static noise is a Dolby Digital/DTS/atmos or similar signal. It contains all the channel information in an encoded state  At full signal its usually just lobs around -7 / -8 db on the meters in TotalMix. You have to route that signal to a decoder. That decoder would be a home theater reciever.

Playing movies from a computer a program like VLC could break that signal down to 5.1, 7.2 or whatever is encoded for output to UCXII analog out. Here VLC does the decoding. It would not be optimal since the channel delays(speaker placement/room size) and so forth are set post-decoding in the HT reciever. UCXII cant do that, you would get audio information only.

UCXII or any other RME device cannot decode a surround signal on its own. It can be routed though. You have to keep the signal at full strenght, 0db and output to HT reciever with DD, DTS or Atmos capability.

So: UCXII can only take the 2 channel PCM out from your TV for output to speakers. For surround sound youll need a HT reciever  to decode to 5.1 analog and further processing for a full SS setup.

RME ADI2 DAC fs. Digiface USB FF UCXII. HEGEL H80. KEF Ls50. FOSTEX T50RP + alots of other gear.

Re: 5.1 from TV Optical only 2 channels.

Happy_amateur wrote:

The static noise is a Dolby Digital/DTS/atmos or similar signal. It contains all the channel information in an encoded state  At full signal its usually just lobs around -7 / -8 db on the meters in TotalMix. You have to route that signal to a decoder. That decoder would be a home theater reciever.

Playing movies from a computer a program like VLC could break that signal down to 5.1, 7.2 or whatever is encoded for output to UCXII analog out. Here VLC does the decoding. It would not be optimal since the channel delays(speaker placement/room size) and so forth are set post-decoding in the HT reciever. UCXII cant do that, you would get audio information only.

UCXII or any other RME device cannot decode a surround signal on its own. It can be routed though. You have to keep the signal at full strenght, 0db and output to HT reciever with DD, DTS or Atmos capability.

So: UCXII can only take the 2 channel PCM out from your TV for output to speakers. For surround sound youll need a HT reciever  to decode to 5.1 analog and further processing for a full SS setup.

What do you think about me getting this device for decoding? :

https://www.amazon.com/gp/product/B0979 … &psc=1

Re: 5.1 from TV Optical only 2 channels.

This is good for taking out a stereo signal out of the surround.
You will receive two channels for recording.

M1-BigSur, Madiface Pro, Digiface USB, Babyface silver

Re: 5.1 from TV Optical only 2 channels.

waedi wrote:

This is good for taking out a stereo signal out of the surround.
You will receive two channels for recording.

But it says it will output more than just stereo. Here is a direct quote from the product:

"▶TV mode will copy TV resolution, output audio to 3.5mm and SPDIF port. ▶2.0 mode will output audio to 3.5mm and SPDIF port, both are PCM 2.0 audio format. ▶5.1 mode only output audio to SPDIF port. ▶7.1 mode only output audio to HDMI AUDIO ONLY port."

Re: 5.1 from TV Optical only 2 channels.

I was refering to this :
HDMI 7.1 Audio-Extractor – HDMI-Splitter unterstützt HDMI 7.1 CH Atmos, alle 5.1 CH, PCM 2.0 Audio-Ausgang, die sich mit Ihrem Soundbar/Verstärker/AV-Receiver verbinden und mehr verbinden kann, genießen Sie Stereo-Ausgang und unkomprimiertes und komprimiertes Audio.

...enjoy stereo output.

your quote above says the same, always stereo.

M1-BigSur, Madiface Pro, Digiface USB, Babyface silver

Re: 5.1 from TV Optical only 2 channels.

waedi wrote:

I was refering to this :
HDMI 7.1 Audio-Extractor – HDMI-Splitter unterstützt HDMI 7.1 CH Atmos, alle 5.1 CH, PCM 2.0 Audio-Ausgang, die sich mit Ihrem Soundbar/Verstärker/AV-Receiver verbinden und mehr verbinden kann, genießen Sie Stereo-Ausgang und unkomprimiertes und komprimiertes Audio.

...enjoy stereo output.

your quote above says the same, always stereo.

I think the description is actually confusing. It lists other bullet points which seem contradictory.

I looked up other units like this one and they have many reviews, and some users mention that they have extracted surround sound. I do believe these units and those like it are extracting more than just  stereo channels.

Anyway, I'm getting it shipped and I'll let you all know.

Thanks!

8

Re: 5.1 from TV Optical only 2 channels.

This unit doesn't change anything. You still need a home theater AVR to decode Dolby Digital or DTS.

Regards
Matthias Carstens
RME

9 (edited by mrd777 2021-09-06 23:24:10)

Re: 5.1 from TV Optical only 2 channels.

MC wrote:

This unit doesn't change anything. You still need a home theater AVR to decode Dolby Digital or DTS.

All the AV receivers I looked into are basically only taking RCA inputs. I have my speakers setup on the RME with TRS/XLR cables to my satellites and sub.

Of course I can switch all my wiring out to RCA wires, but I really wouldn't want to go that route.

I was able to get sound from the following device into the ADAT input on the RME:

https://www.amazon.com/gp/product/B0979 … &psc=1

However, for some reason I'm only receiving the left and right channels on the adat. RME shows no incoming signal for the other channels.

I'm pretty sure the unit is indeed trying to send 5.1 channels because I'm only hearing Left and Right, no center dialogue, and no other channels. You can tell this is 5.1 audio being sent. Watching a film, I hear only music, and some sound effects.

Re: 5.1 from TV Optical only 2 channels.

I understand, I might still need something to do decoding. Perhaps I need to buy this instead:

https://www.amazon.com/Surround-Lossles … mp;sr=1-14

Thoughts?

Re: 5.1 from TV Optical only 2 channels.

It will provide you the same as you had before.
SPDIF stereo made of left and right front channels.
There is no adat.
You can combine it with an adat converter Octamic for example or cheaper ADA8200.
lots of cabling and too much digital converting.
Look out for software solution inside Windows PC. windows probably has already a surround solution for this ?

M1-BigSur, Madiface Pro, Digiface USB, Babyface silver

Re: 5.1 from TV Optical only 2 channels.

IF you want all convert in digital, this is best way for signal convert:
LPCM(Audio in HDMI)->IIS(Standard Internal Audio Signal)->ADAT(for UCX to handle).
For the first step, the chip in audio extractor will do this, some can convert HDMI audio to IIS or SPDIF.
For the second step, ADAT encode chip could do this, such as ALESIS AL1401A.
BUT, there won't have any product combine this two part into one product, as I have search a lot about this in internet.