Tech Question: Sound through HDMI

[harharhar]

Hello,

I'm just wondering, when you output sound through HDMI from a PC (say, using the motherboard HDMI or the GPU HDMI), instead of the usual sound jacks, how is the quality?

What is processing the sound? Is it still the Realtek sound chip? Or the CPU/GPU? What if you have a sound card installed? (My guess is that the sound card is then as good as useless)

I have tried to google for details but can't seem to find a good answer. If any one knows or have a link to show me, I appreciate it a lot!

Thanks!!

 

[kandinsky]

Interesting question, never thought about it. A few I read seems to say that the onboard audio chip in your GPU processes the audio signal.

If you had a sound card, you would take your audio out from the soundcard right? So it's not useless.

 

[harharhar]

Interesting question, never thought about it. A few I read seems to say that the onboard audio chip in your GPU processes the audio signal.

If you had a sound card, you would take your audio out from the soundcard right? So it's not useless.

What I mean is if you have a sound card but still output your audio from the MB / GPU HDMI, then it's as good as the sound card is not doing anything.

 

[batniss]

What I mean is if you have a sound card but still output your audio from the MB / GPU HDMI, then it's as good as the sound card is not doing anything.

You are probably right, your GPU will handle the audio if you are on HDMI.

 

[Entry Level PC]

Prolly GPU bah.

 

[wwenze]

GPU .

 

[royfrosty]

Its gpu dsp doing the work.

Capable to output dts hd and dolby true hd.

As for mainboard, the sound will still be under realtek digital audio.

At sound settings you can see the audio selection.

If its mobo, it will state that its from realtek.

If from gpu, it will show the device that it is connected to. Such as avr or others.

 

[Entry Level PC]

I tried google before which give better sound quality,
GPU Sound or Onboard Sound chip.
No answer.
My entry level ears also cannot tell any difference.

 

[wwenze]

I tried google before which give better sound quality,
GPU Sound or Onboard Sound chip.
No answer.
My entry level ears also cannot tell any difference.

Because GPU cannot output analogue

And most people on the internet don't know the technical differences between DAC, sound card, and audio controller anyway.

 

[wacko]

my basic understanding is that digital is digital, there is no conversion to analogue signals which is what a sound output device requires (speaker, headphones, etc), and no amplification applied. hence what will affect the final sound quality are the digital to analogue conversion, the amplification applied on the analogue signals, and the sound output device. of which none is a factor when the digital sound signals leave the HDMI port of the GPU.

 

[harharhar]

my basic understanding is that digital is digital, there is no conversion to analogue signals which is what a sound output device requires (speaker, headphones, etc), and no amplification applied. hence what will affect the final sound quality are the digital to analogue conversion, the amplification applied on the analogue signals, and the sound output device. of which none is a factor when the digital sound signals leave the HDMI port of the GPU.

I see... So that means it depends on the digital-to-analogue conversion which is probably at the TV or Monitor (assuming the HDMI output is to a TV or Monitor)?

 

[wacko]

I see... So that means it depends on the digital-to-analogue conversion which is probably at the TV or Monitor (assuming the HDMI output is to a TV or Monitor)?

the way i rationalise it, if one of the 3 factors in determining sound quality is a massive bottleneck (e.g. built-in speakers on TVs/monitors), it doesn't really matter how good the other 2 factors are.

 

[royfrosty]

Sound is a form of analogue signals.

I believe from the GPU, it has a ADC converter to do digitization. It simply takes the analogue signal, amplify twice the frequency, and convert to digital signals before leaving the gpu.

Once it leaves the GPU, it goes to the external source. Lets take AVR as an example.

It takes the digital signals and convert back to analogue signals before leaving to speakers.

 

[kandinsky]

Sound is a form of analogue signals.

I believe from the GPU, it has a ADC converter to do digitization. It simply takes the analogue signal, amplify twice the frequency, and convert to digital signals before leaving the gpu.

You mean the GPU is taking an analog audio signal from the mobo?

 

[royfrosty]

You mean the GPU is taking an analog audio signal from the mobo?

It has to be i guess. Cause it needs to be converted first before going through Hdmi.

Unless the medium transfer mode is not hdmi

 

[wwenze]

Sound is a form of analogue signals.

I believe from the GPU, it has a ADC converter to do digitization. It simply takes the analogue signal, amplify twice the frequency, and convert to digital signals before leaving the gpu.

Once it leaves the GPU, it goes to the external source. Lets take AVR as an example.

It takes the digital signals and convert back to analogue signals before leaving to speakers.

Time to change your belief then.

The GPU contains an integrated audio controller, just like the one built inside a motherboard southbridge or the C-Media chip on a Xonar soundcard (Asus rebranded it as AV200 but whatever)

The audio controller takes digital audio data samples sent from the OS and outputs it into a standard digital audio interface format. Examples of which are HDMI, SPDIF, SPDIF with Dolby compression, AC'97, and Intel HD audio (the latter 2 being standards that also include the audio controller and codec)

 

[wacko]

Sound is a form of analogue signals.

I believe from the GPU, it has a ADC converter to do digitization. It simply takes the analogue signal, amplify twice the frequency, and convert to digital signals before leaving the gpu.

Once it leaves the GPU, it goes to the external source. Lets take AVR as an example.

It takes the digital signals and convert back to analogue signals before leaving to speakers.

hmmm, i think the only time the sound signals are in analogue form in the computer is when the signals are about to leave the computer through the audio out ports (3.5mm, RCA). otherwise it is in digital form. again, this is based on logical determination, not from any sound engineering background.

 

[Kiwi8]

Sound is a form of analogue signals.

I believe from the GPU, it has a ADC converter to do digitization. It simply takes the analogue signal, amplify twice the frequency, and convert to digital signals before leaving the gpu.

Once it leaves the GPU, it goes to the external source. Lets take AVR as an example.

It takes the digital signals and convert back to analogue signals before leaving to speakers.

I dun think the GPU takes in analog sound. It should be taking digital signals from the motherboard onboard chip or sound card (as appropriate).

The only digital-to-analog conversion is after the digital signals leave via the HDMI port to the other side, be it the TV/monitor's speakers.

 

[royfrosty]

Time to change your belief then.

The GPU contains an integrated audio controller, just like the one built inside a motherboard southbridge or the C-Media chip on a Xonar soundcard (Asus rebranded it as AV200 but whatever)

The audio controller takes digital audio data samples sent from the OS and outputs it into a standard digital audio interface format. Examples of which are HDMI, SPDIF, SPDIF with Dolby compression, AC'97, and Intel HD audio (the latter 2 being standards that also include the audio controller and codec)

Ah thanks for the info! Cause im not very sure about how the gpu encode it. May i ask, if thats the case, will audio still be degraded? Since its something different from the mobo. Will sound be affected?

 

[Alphas]

GPU does contain audio controller but it does not encode to Dts or DDL, it merely pass it through as spdif through hdmi. There is no loss of quality since the source is in Dts then it let the channel pass through the hdmi cable for the receiver to decode, there is none encoding at this stage.