Multi-channel ADC with HDMI output?

[rah]

Hi,

Contemporary AVRs seem to have lost their multi-channel analogue inputs (e.g. Denons, Arcams, etc.) They still include S/PDIF inputs but S/PDIF is limited to 5.1 audio only due to bandwidth constraints.

I'd like to be able to use 7.1 audio, or even higher channel counts, with modern AVRs. Hence, I'm wondering if there is an ADC which will take multi-channel analogue input and spit out an HDMI stream to feed into an AVR?

For similar reasons, is anyone aware of a means of converting multi-channel digital audio to HDMI? For example, a USB sound card that will take 11.2 PCM or a Dolby TrueHD bitstream and spit out an HDMI stream? The closest I've been able to find are USB graphics adapters (example) but they seem to universally use DisplayLink chipsets for which there are no open source drivers on GNU/Linux and that makes them a no-go for me.

Thanks,

rah

 

[MCH]

i think you can do that with a raspberry pi. Hifiberry is selling now a 8 channel ADC for raspberry pi5, or you could use a usb soundcard. I believe it is possible to output 8 channel LPCM over the rpi HDMI. I did it with a raspberry pi4, but ran into trouble with channels swapping. If you are interested, i can point you to the related thread.

 

[rah]

i think you can do that with a raspberry pi. Hifiberry is selling now a 8 channel ADC for raspberry pi5, or you could use a usb soundcard. I believe it is possible to output 8 channel LPCM over the rpi HDMI. I did it with a raspberry pi4, but ran into trouble with channels swapping. If you are interested, i can point you to the related thread.

I'd rather not use a Raspberry Pi because the bootloader requires a non-free binary blob.

Also, for digital audio I'd like to have to ability to output bitstreams and not just PCM. The Rockchip RK3399 requires no binary blobs but it likewise only supports PCM over HDMI at present; the current mainline Linux drivers can't output bitstreams.

More generally, I'd prefer to buy a converter off the shelf if it's available, rather than DIYing something with a computer.

 

[voodooless]

I'd rather not use a Raspberry Pi because the bootloader requires a non-free binary blob.

Whatever else you buy will use non-free binary blobs as well...

 

[rah]

Whatever else you buy will use non-free binary blobs as well...

Firstly, there's no way to determine whether a device whose internals one can't access uses a non-free binary blob. There may be adapters which don't even have an OS.

Secondly, regardless, I'm happy to use an adapter whose internals can't be accessed.

 

[phofman]

he Rockchip RK3399 requires no binary blobs but it likewise only supports PCM over HDMI at present; the current mainline Linux drivers can't output bitstreams.

Apart of your focus on a ready-made device doing 8ch ADC -> HDMI (which IMO will be very difficult to source) - why would you need non-PCM bitstream support for outputting 8ch PCM over HDMI? The non-PCM bitstream would require encoding the PCM from ADCs to the non-PCM stream (HD-DTS etc.). Why this hassle when HDMI can transfer all the 8 channels in PCM 24 bit?

 

[Roland68]

Hi,

Contemporary AVRs seem to have lost their multi-channel analogue inputs (e.g. Denons, Arcams, etc.) They still include S/PDIF inputs but S/PDIF is limited to 5.1 audio only due to bandwidth constraints.

I'd like to be able to use 7.1 audio, or even higher channel counts, with modern AVRs. Hence, I'm wondering if there is an ADC which will take multi-channel analogue input and spit out an HDMI stream to feed into an AVR?

For similar reasons, is anyone aware of a means of converting multi-channel digital audio to HDMI? For example, a USB sound card that will take 11.2 PCM or a Dolby TrueHD bitstream and spit out an HDMI stream? The closest I've been able to find are USB graphics adapters (example) but they seem to universally use DisplayLink chipsets for which there are no open source drivers on GNU/Linux and that makes them a no-go for me.

Thanks,

rah

May I ask what the application is and where your analog 7.1 signal (or more) comes from?

 

[voodooless]

I'm happy to use an adapter whose internals can't be accessed.

I don't think there is something in the consumer market that does what you want. Any pro-audio stuff will be way above your budget. Maybe just get an old AVR?

 

[phofman]

Would an old AVR convert multichannel analog input to HDMI output? IMHO the AVR is the end device/renderer for audio and HDMI outputs are mostly only for video.

 

[rah]

why would you need non-PCM bitstream support for outputting 8ch PCM over HDMI?

I don't need to convert bitstream to PCM. I don't really understand what you're asking.

 

[rah]

Any pro-audio stuff will be way above your budget.

LOL that's very presumptuous. If there's pro-audio stuff that will do what I need then please tell me what it is.

 

[phofman]

I don't need to convert bitstream to PCM. I don't really understand what you're asking.

Well, you would have PCM from the ADCs (as mentioned in your thread title), but you say that RK3399 supports only PCM over HDMI, no bitstream. That's why I ask about the need for the non-PCM bitstream capability.

 

[rah]

Would an old AVR convert multichannel analog input to HDMI output?

Sure I suppose a whole AVR could be used as a multi-channel ADC with HDMI output but that's a bit excessive and not really what I'm after. I don't want an additional 20kg lump in my lounge, drinking electricity, just to act as an ADC. I'm looking for some specific (reasonably sized) gadget to do just the ADC and HDMI output.

 

[rah]

May I ask what the application is and where your analog 7.1 signal (or more) comes from?

I don't have a specific application in mind. I'm more concerned with having the ability to input multi-channel audio into an AVR whose only multi-channel inputs are HDMI, regardless of the source of the multi-channel audio.

 

[phofman]

Sure I suppose a whole AVR could be used as a multi-channel ADC with HDMI output

Just wondering whether AVRs can actually do that... even if you would not want to use it which would really be very awkward to do.

I just doubt a dedicated device like that exists. 8ch analog input is more pro level, while HDMI is consumer level. That RK3399 should handle it ok (I2S or USB input) -> HDMI, with appropriate linux configuration (assuming its HDMI driver is working, the audio part is I2S2 IIUC the datasheet).

 

[rah]

Well, you would have PCM from the ADCs (as mentioned in your thread title), but you say that RK3399 supports only PCM over HDMI, no bitstream. That's why I ask about the need for the non-PCM bitstream capability.

I still don't really understand what you're asking. The desire for bitstream support is nothing to do with the desire for an ADC. If you look back at my post, you'll see I'm asking about two different things: (1) multi-channel analogue sources and (2) multi-channel digital sources, including both PCM and bitstreams.

 

[voodooless]

LOL that's very presumptuous.

Let's call it a preminition

If there's pro-audio stuff that will do what I need then please tell me what it is.

You'll probably end up with some pro-audio digital mixer and something that converts the Dante output of the mixer to HDMI. Such a mixer alone, like from Yamaha (QL1) is already $€ 11k. Such a Dante to HDMI is probably another $€ 2.5K. Is that within budget? Maybe you can make it work with multiple Dante stereo ADCs? Also not budge friendly.

Better just buy a PC with multichannel HDMI output and a USB audio interface and have some software put the two together.

 

[phofman]

including both PCM and bitstreams

OK, I missed that Dolby HD part.

IMHO a method for transferring Dolby TrueHD bitstream to a potential USB soundcard would require a specific driver, I am not sure these new high-bandwith non-PCM formats are part of UAC2 specs.

 

[rah]

Let's call it a preminition

I've reported your post.

You'll probably end up with some pro-audio digital mixer and something that converts the Dante output of the mixer to HDMI.

That's not pro-audio stuff that will do what I need, that's pro-audio stuff which one could use to DIY a solution. As I already said, I'd prefer to buy a converter off the shelf if it's available, rather than DIYing something, with a computer or anything else.

 

[phofman]

I've reported your post.

Why should people try to help you here?