No Surround Sound from Laptop's HDMI

Shadows1990 · 5 Jan 2010 at 16:15

I've got my laptop connected to the TV via HDMI, and then the audio is passed from the TV to the amp via Optical.

The problem I'm having is that HDMI audio will not output 5.1 to the TV.

Here is a screenshot of what I mean:

As you can see, it's reporting that the maximum amount of channels is 2. Although I'm fairly sure a 9800M GTS can do up to 7.1 Audio via HDMI.

Here is the report from MonInfo:

CE audio data (formats supported)
LPCM 2-channel, 16/20/24 bit depths at 32/44/48 kHz

CE speaker allocation data
Channel configuration.... 2.0
Front left/right......... Yes
Front LFE................ No
Front center............. No
Rear left/right.......... No
Rear center.............. No
Front left/right center.. No
Rear left/right center... No
Rear LFE................. No

CE vendor specific data (VSDB)
IEEE registration number. 0x000C03
CEC physical address..... 0.1.0.0
Supports AI (ACP, ISRC).. Yes
Supports 48bpp........... No
Supports 36bpp........... Yes
Supports 30bpp........... Yes
Supports YCbCr 4:4:4..... Yes
Supports dual-link DVI... No
Maximum TMDS clock....... 225MHz

Does the problem lie with the connection from the HDMI port to the TV, or in the laptop itself (software, configuration etc)?

edit: My TV is a LG325700. I have set the 'Digital Audio Out' to 'Dolby Digital', the only other choice being PCM.

Shadows1990 · 6 Jan 2010 at 13:20

No-One?

[RB] · 6 Jan 2010 at 14:30

Forgive my potential ignorance here but would the TV not be designed to accept two channels via HDMI as this is all it has?

Surely the way to approach this is Laptop -> Amp?

Shadows1990 · 6 Jan 2010 at 14:33

Problem is that the laptop has Digital Coax and HDMI, but the amp/receiver only has optical in.

I guess I was kinda hoping for the TV to do a pass-through of the audio through the optical out

[RB] · 6 Jan 2010 at 15:06

Shadows1990 said:
Problem is that the laptop has Digital Coax and HDMI, but the amp/receiver only has optical in.

I guess I was kinda hoping for the TV to do a pass-through of the audio through the optical out

As I have course to speak to LG regularly I thought I'd check for you.

Unfortunately the lady I've just spoken to didn't seem to grasp what I was trying to explain. (despite being explained in more than 1 way

)

She did say as long as the source was outputting in 5.1 the set should output 5.1, however that's a bit vague

/edit I would side with the idea that the HDMI is detecting two channels and going with this.

Shadows1990 · 6 Jan 2010 at 15:12

Thanks for speaking to LG [RB]

Just to clarify, my laptop is connected to the TV via HDMI. The TV is then outputting the audio via the optical link to the amp/receiver.

It just seems weird that the laptop is reporting that it can only output 2 channels via the HDMI port, when I was told that it can do 5.1.

What I'm trying to determine is whether the problem is at the laptop's end, or at the TV. I've tried using my Compaq Mini 311 (Nvidia ION chipset) to test the HDMI audio out aswell, which is only reporting a maximum of 2 channels.

Participant · 6 Jan 2010 at 15:17

This thread, albeit referring to Panasonics, seems to imply that the problem could potentially be with your TV:

http://www.avforums.com/forums/plas...t-tv-can-pass-through-5-1-surround-sound.html.

I.e. it seems that most TVs probably cannot pass 5.1 through HDMI--> optical.

You may therefore need to buy some more hardware e.g. a new amp or an HMDI / optical converter [EDIT: or a USB sound card with an optical out?]. Either that or find a mate with an HDMI amp and take your laptop round to see how many channels it reports.

[EDIT 2: found another link of relevance in which someone states that very few TVs can pass through 5.1 from an HDMI source: http://forums.cnet.com/5208-13973_102-0.html?threadID=356344]

Shadows1990 · 6 Jan 2010 at 15:20

Hmmm, that thread reminds me of another one that I saw, in which the user reported that the HDMI would input 5.1 with a specific port.

I'll try that now, and report back.

edit: Just tried all three HDMI ports, and each one is reporting a maximum of 2 channels in the HDMI audio properties.

Participant · 6 Jan 2010 at 15:29

This guy sounds just like you. Someone in that thread states that a required limitation (feature?) of HDMI licensing is that it can accept and process a primary signal, but not pass it on.

Shadows1990 · 6 Jan 2010 at 15:35

That sounds very similar to my problem indeed.

AFAIK, it's the EU restriction that is preventing companies from passing audio from the HDMI, through an optical out. If so, I might see if I can source a non-EU based firmware, and see what happens. As it stands, my TV is actually running firmware that was only available on the Polish LG page.

edit: Just noticed on the 32LG5700 specifications page that it has a built in decoder for DD:

Dolby Digital Decoder Yes