Would it be possible to use a multichannel USB audio device to get four or more channels into a Handheld Device to output HDMI?

[atrocity]

With the writing being not just on the wall but having worked its way into the studs regarding multichannel analog inputs on current hardware, I suddenly had what passes for a thought: Would it be possible to use a multichannel USB audio device to get four or more channels into a Raspberry Pi which it could then output via HDMI?

The Pi itself would be cheap, but I have no idea if an appropriate input device exists nor whether output redirection to HDMI is possible.

My main Onkyo receiver went into the shop on Monday (a shop with a FOUR MONTH backlog!) and I'm a pessimist by nature, so I'm worried that I will have to replace it with something that will render my Surround Master useless. We already know there aren't off-the-shelf gadgets to convert multichannel analog to HDMI PCM, but it seems like building something like this just might be doable. Unfortunately, I'm not smart enough myself.

Maybe this is even something Involve could engineer? They wouldn't have to pay the Hate Defecation Murder Interface Mafia any royalties as they'd just be selling a (modified?) Raspberry Pi. And if they came up with an input device that only worked for this particular purpose, maybe it would be cheaper than what's out there now since versatility wouldn't be any concern.

In a perfect world:

1. Small device with four RCA inputs that digitizes the signal and sends it to the Pi over USB.

2. Software on the Pi to send the input straight to HDMI with no other conversion.

3. Software could even run entirely in RAM (as piCorePlayer currently does), which would mean no wear on the MicroSD boot card and no concerns about corruption if it's struck by a sudden power loss.

Have I lost what's left of my mind or am I onto something here or am I just on something?

 

[Kal Rubinson]

With the writing being not just on the wall but having worked its way into the studs regarding multichannel analog inputs on current hardware, I suddenly had what passes for a thought: Would it be possible to use a multichannel USB audio device to get four or more channels into a Raspberry Pi which it could then output via HDMI?

MacOS will permit you to output many channels over multiple USB ports. What you attach to each is up to you. I've done it with DACs. Using multiple RPs might work but I'd be concerned about maintaining synch across the processors/processing.

 

[atrocity]

Using multiple RPs might work but I'd be concerned about maintaining synch across the processors/processing.

I know that an RP can output multichannel PCM via HDMI. Are you hinting that it's not possible to input more than two channels into a single USB port?

 

[Kal Rubinson]

I know that an RP can output multichannel PCM via HDMI. Are you hinting that it's not possible to input more than two channels into a single USB port?

Of course not. I run 8 all the time and I am now undertaking an expansion. How many channels are you talking about?
Are talking about multichannel analog sources?

 

[atrocity]

Of course not. I run 8 all the time and I am now undertaking an expansion. How many channels are you talking about?
Are talking about multichannel analog sources?

Ah, OK! I got confused when you mentioned syncing multiple RPs.

I'm thinking about only four channels. In my head, this might be a relatively low-cost way for Involve to provide HDMI to those who need it without having to pay the horrific HDMI royalties.

Thinking further, they wouldn't even need to sell the Pi...they'd only (!) need to engineer a device to shoot the analog output of the Surround Master into the USB device, which in turn would shoot it into the USB port of the Pi, which would then shoot it out HDMI (preferably as 5.1 for maximum compatibility). Charge ~$100 for that, make the software downloadable, and everyone wins.

Of course, I'm making multiple assumptions here. I'm assuming it would be worth Involve's time, that the device I envision can be made for a reasonable price (or indeed at all), that the USB->HDMI conversion is possible and that someone can write what I think should be relatively simple software...though you'll notice I'm not volunteering!

In my head, it could be an EXTREMELY stripped-down Linux that literally does nothing other than convert USB input to HDMI output. And if it's that stripped down, I'm also assuming that it could run entirely in RAM (there's precedent for that in Pi-land), which would have some major reliability and longevity advantages.

Thank you to whichever moderator changed my not-thought-through subject line, too. I have a bad habit of thinking everyone is able to read my "mind" which often leads to something coming out of my mouth and/or keyboard that I think makes sense but to normal people is gibberish.

 

[atrocity]

I should also add for those who don't know that a Raspberry Pi is a very small computer that comes in multiple versions, all relatively inexpensive, runs on 5 volts, is extremely popular, which in turn makes it extremely well-supported.

The current top of the line is the Model 4, which can include up to 8 gigs of RAM. I assume that's total overkill for what we're talking about here, but they have other lower-powered models that cost less. In fact, the "Zero" model costs a mere $15 and includes a USB port as well as two HDMI outputs. It would be great if that little thing had enough horsepower to do the conversion...maybe it does, I have no clue.

 

[barfle]

As a retired electronics engineer, I’ve given the idea of a quad (or more) to HDMI some thought, aand even done a bit of research on the topic. At this point, it seems pretty doable with off-the-shelf components.

Like most of us, I’m frustrated by the lack of MCH audio inputs on modern AVRs and pre-pros. I kicked around a reed relay matrix, but integrating that into the remote control seemed beyond my talents at the moment. Analog video and stereo to HDMI adapters are cheap and plentiful, so reverse-engineering one of those doesn’t seem like rocket science, although it is science.

So it’s on my bucket list to design one of those things, just for my own use. I. don’t intend to go into business making and selling hardware (been there, done that, got the t-shirt), but if a prototype run has leftovers, I’d be willing to share. But in the meantime, I have other big fish frying in the pan.

If there are others with the same idea, at this point I have a suggestion regarding the spec. Put the back channels in both the back and surround ports of the encoder. I see a handful of complaints about how those channels do or don’t get decoded properly on quad media.

 

[Kal Rubinson]

I am baffled by this whole thing.

 

[chucky3042]

I am thinking......................................................................

 

[quadsearcher]

I am baffled by this whole thing.

I gather it's to convert 4 analog channels to HDMI on the fly, to add analog in to equipment that was made with only HDMI inputs, without spending as much as a new receiver/prepro/etc.
I'd add to the wishlist to have 6 channels converted,

 

[atrocity]

I am thinking......................................................................

It's all I can ask...and more than I can do!

I have no idea if it's practical or not...doesn't help that a Raspberry Pi is hard to come by these days, though my understanding is that they're trying to prioritize industrial customers, so you may be able to cut in line!

 

[atrocity]

I gather it's to convert 4 analog channels to HDMI on the fly, to add analog in to equipment that was made with only HDMI inputs, without spending as much as a new receiver/prepro/etc.
I'd add to the wishlist to have 6 channels converted,

Yes, that was what I was getting at. And might as well go for 8 channels, unless that would be difficult and/or expensive.

My Onkyo is in a shop with a four-month backlog (and I suspect the issue is an HDMI board that needs to be replaced but can't be sourced), so I managed to score an older Marantz with multichannel analog in, but I know one day those of us who can't afford expensive separates are really going to be in trouble.

 

[DudeRocks]

As a retired electronics engineer, I’ve given the idea of a quad (or more) to HDMI some thought, aand even done a bit of research on the topic. At this point, it seems pretty doable with off-the-shelf components.

Like most of us, I’m frustrated by the lack of MCH audio inputs on modern AVRs and pre-pros. I kicked around a reed relay matrix, but integrating that into the remote control seemed beyond my talents at the moment. Analog video and stereo to HDMI adapters are cheap and plentiful, so reverse-engineering one of those doesn’t seem like rocket science, although it is science.

So it’s on my bucket list to design one of those things, just for my own use. I. don’t intend to go into business making and selling hardware (been there, done that, got the t-shirt), but if a prototype run has leftovers, I’d be willing to share. But in the meantime, I have other big fish frying in the pan.

If there are others with the same idea, at this point I have a suggestion regarding the spec. Put the back channels in both the back and surround ports of the encoder. I see a handful of complaints about how those channels do or don’t get decoded properly on quad media.

Any luck on hooking your quad anything to your HDMI system? I'm looking into this as well. I'm about to pick up my first quadraphonic record player. I already have a great Dolby atmos 5.1.4 surround sound system the Onkyo TX-NR7100 installed with many stereo RCA inputs but no 5.1 RCA. Recently seen the 5.1 inputs called AC3. I have seen other receivers (like a Pyle branded karaoke pre-amp) which include AC3 inputs but they also have RCA outputs and there's rarely any documentation whether or not it will move the signal through an HDMI out. Looks like I get to buy a whole bunch of different amplifiers on Amazon just to find out if they "might" work for this. Was hoping someone here would have made an attempt at this already, but reading these forums it seems either I have bad luck on my search criteria or there's no such item out there to be bought. Curious on where to even start to go about making one, I'm not an engineer, but annoyed enough at the fact my entire installed system is a paperweight when introducing a quad RCA component. I really am not a fan of putting together an entire second system just to find out what a quad record sounds like.

 

[barfle]

Any luck on hooking your quad anything to your HDMI system? I'm looking into this as well. I'm about to pick up my first quadraphonic record player. I already have a great Dolby atmos 5.1.4 surround sound system the Onkyo TX-NR7100 installed with many stereo RCA inputs but no 5.1 RCA. Recently seen the 5.1 inputs called AC3. I have seen other receivers (like a Pyle branded karaoke pre-amp) which include AC3 inputs but they also have RCA outputs and there's rarely any documentation whether or not it will move the signal through an HDMI out. Looks like I get to buy a whole bunch of different amplifiers on Amazon just to find out if they "might" work for this. Was hoping someone here would have made an attempt at this already, but reading these forums it seems either I have bad luck on my search criteria or there's no such item out there to be bought. Curious on where to even start to go about making one, I'm not an engineer, but annoyed enough at the fact my entire installed system is a paperweight when introducing a quad RCA component. I really am not a fan of putting together an entire second system just to find out what a quad record sounds like.

I see @chucky3042 liked your post. He’s with Involve Audio, an Australian manufacturer who has hinted that he’s working on a MCH audio to HDMI box. Since he’s in the business and I’ve degenerated into a hobbyist, he’s far more likely to produce some hardware than I am.

My Marantz pre-pro has one set of MCH audio inputs that are presently occupied by my OPPO 105’s audio outputs. I prefer the OPPO’s DAC sound to that of the Marantz, although it’s not by a lot. I intend to upgrade to an Atmos-capable pre-pro, and Marantz has one with a single set of MCH inputs, although it’s price is a pretty deep bite into my wallet.

As I noted in my post, I’m also considering a relay array, but integrating that into the Logitech remote is a task that might require a different set of research. Some members of the forum have successfully used component video switches in their systems, and that is also an option worth looking into.

If you’re using a receiver without analog audio inputs, it’s going to be quite the challenge to get the output from a legacy quad decoder connected. Separate amps has always been my go-to, primarily because it allows for more versatility. Line-level, passive, manually operated switches aren’t complicated to build, but they do require you to keep your head about you when you’re using the system. Most of my family would be totally befuddled by the addition of such a device to my setup.

Nobody said this hobby (integrating antique electronics and modern gear) was simple. But, to me, it’s one of the facets that keeps me interested. Solving technical problems is what I do, and just because I’m not getting paid for it doesn’t mean I’ve stopped.

 

[DudeRocks]

I see @chucky3042 liked your post. He’s with Involve Audio, an Australian manufacturer who has hinted that he’s working on a MCH audio to HDMI box. Since he’s in the business and I’ve degenerated into a hobbyist, he’s far more likely to produce some hardware than I am.

My Marantz pre-pro has one set of MCH audio inputs that are presently occupied by my OPPO 105’s audio outputs. I prefer the OPPO’s DAC sound to that of the Marantz, although it’s not by a lot. I intend to upgrade to an Atmos-capable pre-pro, and Marantz has one with a single set of MCH inputs, although it’s price is a pretty deep bite into my wallet.

As I noted in my post, I’m also considering a relay array, but integrating that into the Logitech remote is a task that might require a different set of research. Some members of the forum have successfully used component video switches in their systems, and that is also an option worth looking into.

If you’re using a receiver without analog audio inputs, it’s going to be quite the challenge to get the output from a legacy quad decoder connected. Separate amps has always been my go-to, primarily because it allows for more versatility. Line-level, passive, manually operated switches aren’t complicated to build, but they do require you to keep your head about you when you’re using the system. Most of my family would be totally befuddled by the addition of such a device to my setup.

Nobody said this hobby (integrating antique electronics and modern gear) was simple. But, to me, it’s one of the facets that keeps me interested. Solving technical problems is what I do, and just because I’m not getting paid for it doesn’t mean I’ve stopped.

I'm leaning towards picking up either 2x computer speaker 2.1 systems or one of the Logitach 5.1 systems with RCA inputs. I have no idea if the output from the demodulator will be best for phono or if it requires a pre-amp. I will be testing by plugging it right up and crossing my fingers.

 

[SeeMoreDigital]

@atrocity

I'm a bit lost... If your Onkyo receiver is out of action what amplification device is the multi-channel PCM HDMI audio output going to be connected to?

What's your proposed device connection chain?

 

[DudeRocks]

@atrocity

I'm a bit lost... If your Onkyo receiver is out of action what amplification device is the multi-channel PCM HDMI audio output going to be connected to?

What's your proposed device connection chain?

Onkyo is not out of action at all, if there is an HDMI device out there it certainly can and will connect to it. The issue is where to find a 5.1 RCA surround to HDMI converter. The comment is stating when you attempt to connect quad channels of RCA into a modern audio system you might as well chuck it all in the trash and start over for a quad setup. Have you tried and successfully connected a quad channel device into your HDMI based system?

 

[atrocity]

@atrocity

I'm a bit lost... If your Onkyo receiver is out of action what amplification device is the multi-channel PCM HDMI audio output going to be connected to?

What's your proposed device connection chain?

The Onkyo did wind up getting recycled because--of course!--the HDMI board died and there are no available parts. Though given that my HDMI luck with Onkyo has been entirely awful, it's probably for the best.

I had assumed I'd be forced to buy a new receiver that would not have multichannel analog in, which is why I raised this topic, but I wound up spending $260 for an older used Marantz with multichannel input.

But at some point, probably in the VERY near future, our options will either be the hassle of multiple amplifiers or something that can convert analog with more than two channels to HDMI.

 

[DudeRocks]

The Onkyo did wind up getting recycled because--of course!--the HDMI board died and there are no available parts. Though given that my HDMI luck with Onkyo has been entirely awful, it's probably for the best.

I had assumed I'd be forced to buy a new receiver that would not have multichannel analog in, which is why I raised this topic, but I wound up spending $260 for an older used Marantz with multichannel input.

But at some point, probably in the VERY near future, our options will either be the hassle of multiple amplifiers or something that can convert analog with more than two channels to HDMI.

What model Marantz are you using? I'm definitely on the market for a receiver with RCA input that might possibly output to optical or HDMI.

 

[atrocity]

What model Marantz are you using? I'm definitely on the market for a receiver with RCA input that might possibly output to optical or HDMI.

It's an SR5008. It's...OK. Seems like having the rears properly adjusted for movies makes them WAY too loud for music, which I don't understand. I'm also not crazy about how difficult it is to find out which surround mode it's currently using.

It outputs HDMI to a monitor but I don't think there are any audio-only digital outputs, optical or coaxial.