Multichannel audio on a Pi will get a whole lot easier and cheaper!

[voodooless]

The release date of the Raspberry Pi 5 is growing ever closer, although it’s still not clear when exactly it’s going to be released. So actually, it will be available Oktober 23rd Even so, more I formation has surfaced lately, and it may be really interesting for those who are after affordable multichannel DSP monsters

First of, the new Pi will be about 2x faster, meaning about a gazillion multichannel FIR taps . But the bigger thing is we finally have an PCI-e interface exposed! And this means we can cram in some relatively cheap soundcard.

So for below €$£ 200 you can have a monster DSP with better than 100 SINAD 8-channel sound

Now I only hope this model doesn’t fry as fast as my Pi 4 did

 

[Multicore]

Is a Pi better at running these algorithms than other €$£ 200 computers?

 

[voodooless]

Is a Pi better at running these algorithms than other €$£ 200 computers?

The pi is about 60, a soundcard about 75 to 100, the rest is for power supply, cables and some other random stuff. Since your PC will need the same soundcard as well, your down to 100 to 125 for a PC. Sure, you’ll find some second hand PC for that kind of money… I don’t think it will be faster than a new pi though, and probably way bigger and bulkier. Not that you would really need it be be much faster. Even a Pi 3 can handle a lot of multichannel FIR taps.

 

[mitchco]

Raspberry Pi 5 Review: A New Standard for Makers (Updated)

The first new flagship Pi in four years was worth the wait.

www.tomshardware.com

 

[phofman]

We will see parameters of the new Pi. No specs of their RP1 southbridge have been released, we do not know if only 2ch I2S or 8ch like basically all other arm SBCs. My guess is 2ch as so far.

I am afraid the 16nm process will not allow full long-run power without active cooling.

What multichannel PCI-e -> I2S controllers are on the market, apart of proprietary unavailable XFi? Maybe some Asus Oxygens, but I am not sure they are freely available and IIRC they even lack public datasheets. In fact one of the few "third-party" PCI-e "high-end" soundcards was USB internally. But maybe the availability of the PCI-e for the widely used RPi will result in some FPGA PCIe I2S project... On the other hand the inexpensive RPi CM4 has had PCI-e for many years and no such project has appeared. A clone of ICE1724/Envy24 with the same registers to allow using the existing driver...

 

[voodooless]

What multichannel PCI-e -> I2S controllers are on the market, apart of proprietary unavailable XFi?

What for? For a few dB more of inaudible SINAD, you’ll pay a huge premium.

Maybe some Asus Oxygens, but I am not sure they are freely available and IIRC they even lack public datasheets. In fact one of the few "third-party" PCI-e "high-end" soundcards was USB internally. But maybe the availability of the PCI-e for the widely used RPi will result in some FPGA PCIe I2S project... On the other hand the inexpensive RPi CM4 has had PCI-e for many years and no such project has appeared. A clone of ICE1724/Envy24 with the same registers to allow using the existing driver...

Something like SoundblasterX AE-5 Plus will deliver 8 channel audio with 100+ SINAD, works with Linux, is native PCI-e.

 

[chnan]

If 8 ch I2S is built-in Pi5, I guess I might be able to send the 8ch signals into a AV receiver via HDMI and do the simple DSP Cross-over. No additional devices needed.

 

[abdo123]

There is nothing easy or cheap about this.

 

[voodooless]

There is nothing easy or cheap about this.

So what alternative do you have for around €$£ 200 that gives 8 channeles of 100+ SINAD DSP goodness?

And “simple” is obviously relative

 

[abdo123]

This is an incomplete impractical dare I say deluded option for a multichannel experience.

It might be fun, it might be very slightly more flexible than what else is out there but it’s just not in anyway worth it imo.

 

[popej]

I guess I might be able to send the 8ch signals into a AV receiver via HDMI

I was never able to get multichannel audio over HDMI with Raspios. Probably possible, but not trivial.

 

[voodooless]

This is an incomplete impractical dare I say deluded option for a multichannel experience.

I think your definition of multichannel might be limited to home theater. For that purpose, I would agree that this is utterly impractical.

For an active stereo speaker system however, this could really be quite interesting.

 

[ernestcarl]

I was never able to get multichannel audio over HDMI with Raspios. Probably possible, but not trivial.

I wonder if anyone has actually done this successfully...

A miniDSP Flex 8 or HT might be the "simplest" options for who don't want to go through the DIY route -- still, FIR is very limited and accessible to Dirac only for the latter -- so uploading user created FIRs is not possible like with their non-MCH versions. I also don't really care about Wisa and would rather have Bluetooth as another source input.

 

[MCH]

I was never able to get multichannel audio over HDMI with Raspios. Probably possible, but not trivial.

I use a 8 channel HDMI extractor to output 8 channels out of a RPI. Has some little issues though.

Looking forward to a raspberry pi with multichannel tdm. Would open many possibilities for my projects.

 

[phofman]

If 8 ch I2S is built-in Pi5, I guess I might be able to send the 8ch signals into a AV receiver via HDMI and do the simple DSP Cross-over. No additional devices needed.

The HDMI block of RPi is in the proprietary VideoCore block of the Broadcom SoC, unrelated to I2S.

8ch 24bit HDMI on RPi4 should work, the HW supports it, the drivers do support it as well, e.g. https://github.com/raspberrypi/linux/issues/4204 . I have never tested as I have no 8ch HDMI receiver.

 

[phofman]

Looking forward to a raspberry pi with multichannel tdm. Would open many possibilities for my projects.

Recently I played with Radxa Rock 3 with RK3568, both 8ch TDM (48kHz) and 8ch 4x I2S_DO (up to 384kHz) work fine. If you are not dependent on some RPi-only project like moode (which hard-codes configuration hacks specifically for RPi) and debian 12 with the latest kernel would suffice, it's viable.

 

[phofman]

Something like SoundblasterX AE-5 Plus will deliver 8 channel audio with 100+ SINAD, works with Linux, is native PCI-e.

I was thinking about PCI-e controllers which would allow building PCI-e soundcard hats, to integrate with the RPi format. For standard PCIe cards the x86 world offers countless options, with decent price comparable to RPi (refurbished thin clients), reasonable consumption, original quality power supply adapter, fanless, nice cases, lots of USBs, and very decent CPU performance.

If RPi5 has only 2 channels I2S, IMO it will not be a major improvement for embedded DSP devices as the extra computing capability (compared to RPi4) will not be useful for 2ch, for multichannel the USB will be the only option like so far (unless using OTC PCI-e soundcards with RPi in some unwieldy combo). Plus I am afraid loading all 4 cores at max will require active cooling, 16nm is an older technology.

 

[voodooless]

I was thinking about PCI-e controllers which would allow building PCI-e soundcard hats, to integrate with the RPi format. For standard PCIe cards the x86 world offers countless options, with decent price comparable to RPi (refurbished thin clients), reasonable consumption, original quality power supply adapter, fanless, nice cases, lots of USBs, and very decent CPU performance.

So, what can you get for ~ €$£ 100?

If RPi5 has only 2 channels I2S,

Can anyone confirm or deny this? We’ve heard conflicting things now.

Plus I am afraid loading all 4 cores at max will require active cooling, 16nm is an older technology.

Or a much higher heatsink. My previous pi4 died a heat death. DSP-hat and case were clearly a fatal combination, even with almost no CPU utilization.

 

[phofman]

So, what can you get for ~ €$£ 100?

E.g. https://www.parkytowers.me.uk/thin/hp/t630/ refurbished costs about 50EUR + shipping on ebay e.g. https://www.ebay.com/itm/185756340161 . The wifi M.2 PCI-e slot can be used for other PCI-e boards, like http://www.miccet.se/2023/01/11/extra-nic-on-the-hp-thin-client-t630/ . I believe (not having tested) an adapter to standard PCI-e would work OK https://www.ebay.at/itm/275817131171

Can anyone confirm or deny this? We’ve heard conflicting things now.

AFAIK the I2S specs have not been detailed in any way yet in https://forums.raspberrypi.com/viewtopic.php?t=356922

Or a much higher heatsink. My previous pi4 died a heat death. DSP-hat and case were clearly a fatal combination, even with almost no CPU utilization.

Passive heatsinks are where good-brand x86 thin clients shine - just look at how they are made inside https://www.parkytowers.me.uk/thin/hware/hardware.shtml . RPi4 (and I believe RPI5 too due to no major technology improvement 22nm -> 16nm) are not designed for full performance without major sinking (small active or quite large passive).

 

[MCH]

Recently I played with Radxa Rock 3 with RK3568, both 8ch TDM (48kHz) and 8ch 4x I2S_DO (up to 384kHz) work fine. If you are not dependent on some RPi-only project like moode (which hard-codes configuration hacks specifically for RPi) and debian 12 with the latest kernel would suffice, it's viable.

Thanks Pavel. No, i don't have a reason to stick to the raspberry. Will wait for the specs of the new raspberry 5 anyways, but with a rock pi S in the basket at aliexpress