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Pi 4 Compute Module released, expansion board looks interesting

somebodyelse

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The Pi 4 compute module has been released and could be interesting for DIY stuff. The IO board has all the connectors on one edge, as well as exposing the edge of a hat to the same side, so for many hat DACs the connectors will be on that edge. The compute module has options for wifi/bluetooth with a connector for an external antenna if the on-board one isn't good enouth, and finally also for eMMC. The USB situation is changed from the usual Pi 4. The PCI-e lane has been exposed to a standard connector instead of being used for the USB2 and USB3 interfaces. The onboard OTG interface goes via a switch to a micro-b socket and to a USB2 hub with 2 type A sockets and another 2 ports on headers. This is either/or - if the micro-B is used then the hub is disabled. It will be interesting if this reintroduces the pop issue from the earlier Pi models, but you could always add a PCI-e USB adapter.

The PCI-e socket introduces some other interesting options though - like a PCI-e to PCI bridge for older audio interfaces, or a firewire interface. That's assuming no x86-isms lurking in the drivers of course - they're unlikely to have been used much if at all on arm.
 
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somebodyelse

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I assumed Foobar2000 would be a total non-starter as it says quite prominently it's for Windows, but perhaps not. I was surprised to see an active thread on linux/wine compatibility so it might be worth a try on a linux PC, especially as there's a plugin to let it use PulseAudio natively rather than going through Wine. That doesn't help with the pi, but the Android version might. There are multiple android ports to different Pi models, with or without GApps support depending on preference, so it might just work. There are a bunch of howtos out there - this one is fairly recent using LineageOS, while GloDroid sticks close to AOSP. I've no idea what features the Android version sacrifices - perhaps it's no use to you. And I've not tried any of the android ports myself - it would be good to hear anyone else's experience with it.

I'm not sure which previous form factor you meant, but it's a departure from all of them. I don't know how quickly the various audio distros will adapt to the hardware changes either - it might be a case of rolling your own for a while.
 
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somebodyelse

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Assuming you use the IO board the hats should just work as the interface is unchanged. The eMMC just takes the place of the uSD card, and the real time clock is an I2C device that was on some hats anyway. The different memory options already exist on the Pi 4, as does with/without wireless. The bit I expect to need some work is support for the PCI-e slot - and that's mostly enabling kernel config options and packages that already exist but weren't previously useful in Raspbian etc.

We'll have to wait for some hands on reports to see whether my guesses are right though...
 

L5730

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@somebodyelse
Re: Foobar2000.
On Linux x86 one can install WINE and Foobar2000 runs pretty much fine, with only a few small things that's aren't 100%. Bit perfect playback is possible, but DSD might have to go DoP.
We have Linux Mint 20 XFCE running Fb2k under Wine, and it's happily reading the media library from an NTF partition. foo_jesus component backs up fb2k portable install to the NTFS partition, so that rebooting to Win10 can then update it's own fb2k with the playlists etc. from the one in Linux/WINE.
Install WINE on Linux Mint 20.
https://www.linuxmadesimple.info/2020/06/how-to-install-wine-501-on-linux-mint-20.html

Now a Raspberry Pi is ARM, not x86. Different instruction set. So would not only need a WINE, but also an environment emulator like ExaGear or QEMU.
It gets complicated and starts to strain resources, having to translate everything at the low level. I ended up not even bothering with FB2K on RPi.
https://thepi.io/how-to-run-x86-programs-on-the-raspberry-pi/

There is another way, whereby you control FB2K running on a Windows machine (physically or remotely with VNC), and have it serve audio to a RPi connected to your audio equipment.
I have tested a RPi 3B running Volumio and uPnP output from Fb2k to Volumio does work.
https://pinkfishmedia.net/forum/thr...spberry-pi-and-foobar2000-integration.236746/
 

Feanor

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Thanks to somebodyelse and L5730 for mentioning Foobar2000. I'll admit I was being facetious asking about Foobar on a Raspberry. I run Foobar on a mini PC win Win 10 and despite the Raspberry as media server hoopla I fully intent to stick with Windows 10.
 
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somebodyelse

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I guessed as much, but but it looked like it might lead somewhere interesting so I followed :)
 

BabbRust

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Hi....the CM with if and how they manage that PCI-e path is genuine intriguing.

Pi4a they may very well overlook a hdmi, eth and usb3 and for make it's anything but a Pi4b-2b with more modest organization and connectors missing.

Perhaps give bind cushions and potential hacks or just thoroughly preclude so its lower cost doesn't struggle with the register.

Pi3 after this period of time I would think will stay with no guarantees, actually got a piece before EoL however not too long.

Figure model will be pro likely a serious fascinating auto suggestion and some more.
 

Madjalapeno

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Apparently it can be done, just not sure I would want to.

 
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