# HDMI Audio - how it works?



## suraswami (Dec 18, 2019)

Hi,

I have a basic question (pardon my ignorance).  How does HDMI audio pass through work?  Does it use the audio chip on the motherboard or video cards comes with its own audio decoder chip and it uses it output Audio?

I have an Old Asus motherboard that has onboard Via Audio chipset, it has all the analog outputs and digital optical output.  For video I use NVidia GT 210.  TV is connected to the Video card through HDMI cable and audio is connected from the optical output on the TV to the Audio Receiver.

I had used Diamond XS71 Cmedia chip based audio card before.  With windows 10, drivers are not that good, either audio works or it works with some clicking noise.  This card was awesome with good amount of Bass when system was running with Windows 7.

With Via chipset, Bass sucks.  So wondering if HDMI is using onboard Via chipset to stream audio.

I tried optical output from the board and the Bass still sucks.

I have other spare boards which are Realtek chipset based, I can swap it out and see if it's better.  Or spend extra money to find a sound card and try that out.


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## biffzinker (Dec 18, 2019)

suraswami said:


> Does it use the audio chip on the motherboard or video cards comes with its own audio decoder chip and it uses it output Audio?


The video card's on die audio controller is used to output the audio over HDMI, DVI, and DisplayPort. It can be pass-through or decoded by the audio controller.


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## Jetster (Dec 18, 2019)

There an audio chip that used the GPU processing power on the GPU. Its digital and far superior to useing the chip on the motherboard because of the way the GPU processor works


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## biffzinker (Dec 18, 2019)

Jetster said:


> There an audio chip that used the GPU processing power on the GPU.


AMD's TrueAudio works that way but there's still a discrete audio controller on die. Otherwise there wouldn't be a need to install a driver for HDMI Audio Controller.


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## hat (Dec 18, 2019)

HDMI, like optical, is digital. Rather then decoding the digital signal to analog within the onboard audio system (or the sound card), it's passing the raw digital signal along to the endpoint device (in this case, seems to be the receiver) where it is then decoded into an analog signal and passed to the speakers. Usually, the DACs in a receiver would be better than anything you'd ever find on a computer motherbord, or even a sound card. I wonder if you didn't have some audio enhancement feature like some bass boost active before that isn't now.

It's worth a try connecting your optical directly to the receiver from the PC if you have an optical output, or connecting HDMI to the receiver and passing video along to the TV with one of the receiver's HDMI outputs. Or connecting analog directly to the receiver from the PC. Either way, try to eliminate the TV from the audio setup.


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## INSTG8R (Dec 18, 2019)

biffzinker said:


> AMD's TrueAudio works that way but there's still a discrete audio controller on die. Otherwise there wouldn't be a need to install a driver for HDMI Audio Controller.





Jetster said:


> There an audio chip that used the GPU processing power on the GPU. Its digital and far superior to useing the chip on the motherboard because of the way the GPU processor works


Both great examples why Using your GPU HDMI for audio is a great solution. It can just be used as lossless passthrough or use GPU options for processing signals. It will handle digital formats.
Edit: I wasn’t paying attention you were just connecting to a TV. Regardless it’s the”best”  solution as a “single cable” audio connection. Hooking it to your receiver if possible is the ideal connection


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## btarunr (Dec 18, 2019)

Your GPU has an on-die HDA controller that only puts out digital audio, through its HDMI and DP ports. Your CPU processes its stack like any other HDA device in your machine. The DAC that turns this digital audio stream into usable analog audio is inside your monitor/TV/receiver. So next time you find that the "audio quality" of your $1200 RTX 2080 Ti is shit, it's the DAC in your monitor that's actually shit. So avoid plugging in your headset/spreakers to the 3.5 mm jack of your monitor.


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## hat (Dec 18, 2019)

I'm wondering if the tv isn't screwing with it in some way because it's running through the tv to the receiver...


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## INSTG8R (Dec 18, 2019)

hat said:


> I'm wondering if the tv isn't screwing with it in some way because it's running through the tv to the receiver...


If he had a ARC port it wouldn't "matter" so much but that's me injecting my own TV and usage. But I have stuff running both ways in my setup. ARC HDMI to my receiver for my streaming services audio, All other HDMI sources(STB, PS4) go into my receiver and back to the TV for video


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## suraswami (Dec 18, 2019)

Thanks all for the valuable inputs.

My receiver is an old Denon 7.1 Receiver which doesn't have HDMI inputs.  TV is Samsung 65", 8 series curved TV.  It has this unique Input brick which also has the Optical output which is connected to the Receiver.

To eliminate the brick loosing some sound quality, I have connected Optical output from the motherboard directly to the Receiver.  To me sound seems to be of same quality.

I played the same movie, same sequence using stand alone Sony Blu-ray player which is connected using HDMI through the input brick and Optical cable, better Bass.  Blu-ray player route was not that great and hence I went with PC + sound card route.  Stupid sound card's lack of Windows 10 drivers is giving me headache.


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## INSTG8R (Dec 18, 2019)

Well while optical can’t carry as much bandwidth the way you have it connected, unless you’ve done anything it is just pure digital pass through any change in sound quality will be through adjustment on your receiver. It for the most part would be the same via HDMI. Heres a quick article explaining the differences.








						HDMI vs. Optical: Which Digital Audio Connection to Use?
					

When hooking up an audio system or sound bar, you generally have to choose an HDMI or optical digital audio connection. Find out which one is better and why.




					www.cnet.com


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## londiste (Dec 18, 2019)

INSTG8R said:


> Well while optical can’t carry as much bandwidth the way you have it connected,


Bandwidth does not matter for stereo but is an important difference between HDMI audio passthrough and optical for 5.1 sound. HDMI passthrough has enough bandwidth to fit 5.1 channels of uncompressed PCM, optical does not. To fit 5.1 into optical it needs to be compressed. Commonly DTS, DD or some other Dolby codec which is not something all audio cards support on computer side or other devices like TVs are necessarily able to pass through or process.

Probably irrelevant to the question in this thread but something to keep in mind.


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## INSTG8R (Dec 18, 2019)

londiste said:


> Bandwidth does not matter for stereo but is an important difference between HDMI audio passthrough and optical for 5.1 sound. HDMI passthrough has enough bandwidth to fit 5.1 channels of uncompressed PCM, optical does not. To fit 5.1 into optical it needs to be compressed. Commonly DTS, DD or some other Dolby codec which is not something all audio cards support on computer side or other devices like TVs are necessarily able to pass through or process.
> 
> Probably irrelevant to the question in this thread but something to keep in mind.


Oh I agree why I posted the link to save getting too deep into the limitations/semantic. with plugging optical into his motherboard without using something like DTS Connect DD Live on the MoBo side it’s most likely just sending straight stereo pass through.
Even my SB Z is very specific at what it will or won't do via Optical


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## suraswami (Dec 18, 2019)

Looks like I might need new Receiver that has HDMI inputs so it can decode directly instead of passing thru from the TV.

Last night I was testing with Netflix, looks like the TV does a better job with video and audio than the PC's video card.  And if I want to watch 4k content, my video card doesn't support it.  Need to spend more.

Whole point of this build is to salvage old parts and see if I can extend its life making it usable.  Looks like TV by itself has replaced everything.  So instead of going more in this route will save my time and energy and start clearing lots of old hardware so someone else can find use for it.

Thanks all.  Good learning.


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## INSTG8R (Dec 18, 2019)

suraswami said:


> Looks like I might need new Receiver that has HDMI inputs so it can decode directly instead of passing thru from the TV.
> 
> Last night I was testing with Netflix, looks like the TV does a better job with video and audio than the PC's video card.  And if I want to watch 4k content, my video card doesn't support it.  Need to spend more.
> 
> ...


Yeah Netflix and 4K on PC has a lot of hoops and restrictions and required hardware to function that make it a hassle.
If you already have a Smart TV that can run it. If you’re considering a newer receiver it’s worth checking if your TV has an ARC HDMI port(Audio Return Channel) which means you can get 5.1 audio from Netflix back to your receiver setup and get the most out of your entire setup.


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## suraswami (Dec 18, 2019)

INSTG8R said:


> Yeah Netflix and 4K on PC has a lot of hoops and restrictions and required hardware to function that make it a hassle.
> If you already have a Smart TV that can run it. If you’re considering a newer receiver it’s worth checking if your TV has an ARC HDMI port(Audio Return Channel) which means you can get 5.1 audio from Netflix back to your receiver setup and get the most out of your entire setup.


The TV is modern and I love it, another friend also bought it based on my recommendation.

The TV is capable of ARC.  Right now through the HDMI input brick, it also sends out 7.1 channel through the Optical out to the Receiver.  So I can watch Netflix with all the surround sound.


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## INSTG8R (Dec 18, 2019)

suraswami said:


> The TV is modern and I love it, another friend also bought it based on my recommendation.
> 
> The TV is capable of ARC.  Right now through the HDMI input brick, it also sends out 7.1 channel through the Optical out to the Receiver.  So I can watch Netflix with all the surround sound.


Yeah depending on your TV the ARC channel can carry DTS-MA DD-HD and some are even capable of ATMOS. Mine can only do pretty much what Optical standards can with DD Plus being my limitation. But it is handy to have a “1 cable” for everythIng.


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## suraswami (Dec 25, 2019)

Finally found the Driver on CMedia website, installed it and using the GUI I have to enable Digital output, voila back in business.  Sound through dedicated sound card is so much better than HDMI or Onboard Via crap.

PC is for now at least useful to Watch Blu-ray movies.


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