Multichannel Digital Audio For Quadro Cards

Go to the following link (https://nvidia.custhelp.com/app/answers/detail/a_id/2796/~/which-hdmi-audio-formats-do-nvidia-gpus-support%3F) and you will find what digital audio output is supported by GeForce cards. There is a notable typo where it references the 900 series, calling it Kepler. I assume they mean Maxwell. Note that the 900 series of GeForce cards is said here to support up to 24 bit/192khz digital output.

I have an Nvidia Quadro M4000 for video rendering and editing. It is currently the only video card in my system and I need it to be able to output at least 24 bit/48 khz digital audio to a receiver so that I can do some multichannel sound mixing at a decent quality, but I’ve tried connecting multiple HDMI devices to the GPU and I am only allowed to output 16 bit/48 khz audio on all of these devices. I assume that since the M4000 is Maxwell-based, it should be able to support the same audio output as a GeForce 980 at least on a hardware level. Is this a driver oversight? Has anyone else had issues with digital audio output on Quadro graphics cards?

I’ve sent messages to NVidia support about this to no avail. Despite their “response in 24 hours” automatic emails, they’ve been completely silent.

Hi,

Thanks for pointing out the typo!

Regarding your audio question, the NVIDIA driver will expose the audio formats that are defined in the displays, or in this case the audio receiver EDID information. The EDID is a block of data passed from the display to the graphics card that exposes what display timing and audio formats that the display supports.

The supported formats are exposed in the sound properties of the windows OS. Clicking on advanced will allow you to change the default format to 24bit if it is supported.

Since the M4000 doesn’t have a native HDMI output, you should also make sure you are using a DP to HDMI dongle that supports the audio format. We recommend using a passive (DP++) DP (Type 2) to HDMI dongle.

Thanks,

Ryan Park

I am currently using an active DP to HDMI dongle that supports HDMI 2.0a and HDCP 2.2. But I’ve tried connecting three different HDMI devices and my only option for audio output is 16bit/48khz. One of them was a high end receiver that I know is able to decode up to 192khz digital audio.

What is the difference between a passive or active dongle? Shouldn’t any that support HDMI 2.0a output be able to get up to 24/192 audio signals or is that not necessarily true?

Passive adaptor means the adaptor follows the DP++ dual-mode standard so the graphics card will treat the display as a native HDMI device. With this adaptor the NVIDIA driver sends native HDMI signals over the Display Port connector and the dongle adjusts these to the correct level for HDMI.

An Active adaptor means the adaptor actively converts the Display Port signal to HDMI. It is the adaptor that is creating the HDMI signals not the graphics card. So the adaptor is responsible for correctly supporting the audio format.

For 24bit audio to work the receiver needs to advertise that it supports 24 bit audio via the EDID. This is the EDID from our engineer’s BenQ monitor. As you can see it supports 24bit audio.

In the Win 10 audio properties it shows:

He can select the 24bit rate under the advanced tab:

Try to investigate your DP to HDMI adaptor first and then investigate that the receiver correctly exposes the 24 bit audio format. The screen shots above are used whilst connected using a passive DP to HDMI adaptor.

I see. So far any devices (3 so far) I’ve tried to connect have been limited only to 16 bit, 48000 Hz (CD Quality). The encoded format options of the receiving device are consistently detected and different depending on device though. So given the uniformity of the issue it makes sense that the active adapter may be downsampling digital audio to 16 bit/48 Khz. It was a seemingly great value so that must have been where they cut costs.

I’ll try a passive adapter, now that I know that my card supports DP++. And I’ll follow up on this forum whether or not it worked.

Thank you for the help and the information!

Just following up - I don’t know if this was resolved. I don’t think there is a solution. I have tried active and passive adapters, nothing works. The EDID on my Arcam AVR 850 [AVR6] is advertising higher sample rates just fine, and if I plug Displayport into onboard Intel UHD 630 again no issues. This is a driver issue from NVIDIA, and it still doesn’t work in their June 2020 drivers.

I suspect I have to sell my P1000 now. It’s a paperweight with no fix for this. Really frustrating. It was the perfects solution for a low profile card in a SFF PC.