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Raspberry pi streamer

MCH

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Or a cheap usb card with spdif out, there are plenty of them. The ultra cheap from amazon that i know can go 96khz but only 16 bit, but a used sound blaster x-fi hd or xonar u7 can probably do 24 bit 192khz (cannot remember now, but 24/96 almost sure, just check it out)
 

somebodyelse

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One other thing I would like to do -- use the Rpi as a USB OTG audio receiver, so that I can connect a computer or mobile device via USB, pass the bit-perfect PCM audio stream through the wizz-bang room correction filters, and then forward to the receiver in pure digital form -- has anyone done that? Ditto for an SPDIF input, so that I can room correct my CD/SACD player if feel like spinning a disk.
For OTG you need a Pi model that exposes the OTG port, like the Zeros or 4, and the gadget audio driver. Gadget audio is waiting for some significant improvements to land in the 5.17 kernel I think - @phofman will know the details. There will be some lag before this hits the mainstream pi distros, but if you don't want to wait for all that you can compile your own kernel and put the other bits together.

For SPDIF there are hats like the HifiBerry Digi+ I/O, and various USB devices.
 

phofman

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My issue is that I cannot get higher than 48KHz/16bit output out of the HDMI output going into my AVR. Moode reports that has been supported since 2017, yet my Rpi 4B is not happy to go any higher. Reading up on the various forums did not help much... :(
Even the latest RPi kernel still supports only 16bit on HDMI https://github.com/raspberrypi/linu...vc04_services/bcm2835-audio/bcm2835-pcm.c#L16

IMO moode has no patches to this driver in its updated-kernel build https://github.com/moode-player/mos...7636b9946b6331ae34f54/mosbuild_worker.sh#L829
 

Ralph_Cramden

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I’ve been using a JustBoom Digi Zero Hat for a while now. Both coax and optical outputs. Currently evaluating the new WiiM Mini, which was recently updated to support up to 24/192 on its optical output. Appears to work nicely, though previous devices based on Linkplay modules have measured poorly. Maybe @amirm will measure one of these.


5CD4F5FB-A59E-4B36-98BC-95AF874F3216.jpeg
 
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phofman

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IMO adding a patch and recompiling mosbuild should not be that difficult.
 

Ata

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For OTG you need a Pi model that exposes the OTG port, like the Zeros or 4, and the gadget audio driver. Gadget audio is waiting for some significant improvements to land in the 5.17 kernel I think - @phofman will know the details. There will be some lag before this hits the mainstream pi distros, but if you don't want to wait for all that you can compile your own kernel and put the other bits together.

For SPDIF there are hats like the HifiBerry Digi+ I/O, and various USB devices.

Thanks for the info. Reliable digital-in means for Rpi is kind of a holy grail IMO, as that would enable accessible multichannel all of system DRC (room correction), which for me and many others is the largest sound quality improvement factor to be had.
 

Ata

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Even the latest RPi kernel still supports only 16bit on HDMI https://github.com/raspberrypi/linu...vc04_services/bcm2835-audio/bcm2835-pcm.c#L16

IMO moode has no patches to this driver in its updated-kernel build https://github.com/moode-player/mos...7636b9946b6331ae34f54/mosbuild_worker.sh#L829

Thanks, I have come around your work on other forums (only dabbed into Rpi this week!).

The question I have is, is this a HW limitation, or a kernel limitation? I have not been able to find a definitive answer to that. If it is a SW limitation, is there a known solution that just waits for someone to implement and upstream?
 

Ata

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Thanks again! For the moment, I will focus on the other aspects of my setup, in particular figuring how to integrate with the rest of my home setup -- music sources, etc., and setting up the DRC. Getting to 24-bit audio is a bit down the track, but I can easily try the kernel hacking necessary to when the time comes.

It is interesting that the linked post is 3 years old, did the solution not make it into the kernel mainline yet? Perhaps it is not yet considered stable?
 

phofman

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IMO that particular driver should be modified to separate hw_params for HDMI and the PWM audio output as they offer a different set of parameters. I tried to convince the RPi devs about such change but to no avail https://github.com/raspberrypi/linux/pull/3933 .

Still the easiest way is to change the value in the code and rebuild the kernel, either directly on the RPi (slow), or crosscompiling on any amd64 linux (the description at https://www.raspberrypi.com/documentation/computers/linux_kernel.html#cross-compiling-the-kernel works very good).
 
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Ata

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Thanks, luckily I am quite familiar with software and Linux from work, will definitely experiment.
 

Elfsberg

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Yes, that is a solution but requires a bit extra time and expense, will not fit physically in the case I have, and I will have to let go of multichannel (uncompressed) music. I think I will stick with 16-bit music for now, that should objectively be sufficient, and keep looking out for a solution down the track.

One other thing I would like to do -- use the Rpi as a USB OTG audio receiver, so that I can connect a computer or mobile device via USB, pass the bit-perfect PCM audio stream through the wizz-bang room correction filters, and then forward to the receiver in pure digital form -- has anyone done that? Ditto for an SPDIF input, so that I can room correct my CD/SACD player if feel like spinning a disk.
+1
This is what brought me to this thread.
As of now membership registration on their forum is suspended so I can't ask about this particular use. :(
 
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