Raspberry Pi 4 (Page 2 of 2)

Hello,

I've acquired a Raspberry Pi 4 for a headless pianoteq standalone controlled via a USB midi controller. I have two questions before I jump into the setup process:

1. I'm considering buying a DAC to offload the sound generation part off of the pi and get other connectors (RCA or 1/4" jack, 5-pin midi would be nice too), but there are so many options.
   I'd like the best and most stable realtime performance but fanless if possible. I've read that USB DACs tend to be surprinsingly good, but the use cases mentioned there are very different. Do you guys have any recommandations as to what to prioritise, promising options etc. ?

2. In the spirit of headlessness, I'd like to use my controller's midi buttons and faders to change the sound. I couldn't find a midi control change to cycle between presets however. Is this currently not possible?

Thanks a lot for reading me!

Thank you hesitz for your input on both these devices!

Most of the discussion I've linked is for home cinema hi-fi use. I'd argue that there's a major difference with my/our use case because we're dealing with an audio stream that can't be pre-buffered as it gets fed midi notes in real time. And the lower the latency, the better for me (although anything under 15ms should be fine).

For stage use, I think the DAC will never be the bottleneck in terms of sound quality (rather the PA and the room acoustics), but I also intend to use the little devil in my studio so it would be nice to push it to the limits. Hence why I haven't purchased a DAC yet and I'm probing around.

(Also I'd love that 5-pin midi so I can plug any hardware without pesky adapters )

Thanks again, hope you manage to get the hifiberry working again!

Hi everyone,

I'm writing here to share my Raspberry Pi 4 touchscreen project and how I managed to achieve:

Maximum polyphony of 96
64 sample buffer
24000Hz internal sample rate

I'm using:

Raspberry Pi 4 Model B w/ 2GB RAM (£34)
HiFiBerry DAC2 Pro (£45)
Official 7" Touchscreen display (£60)
SmartiPi Touch 2 Case (£24)
SmartiPi Touch 2 Back Cover 35mm (£7)
USB-C Cable with On/Off Switch (£3)
Pianoteq 6 Stage

(all prices rounded up, and from The Pi Hut)

I followed Edgar's brilliant guide (https://forum.modartt.com/viewtopic.php?id=5351) for the Raspberry Pi 3, but seemingly had to spoof the Pianoteq software to run at a 24000Hz internal sample size, whilst the hardware was running at 48000Hz.  Pianoteq doesn't like it and complains of the wrong buffer size, and I get consistent spikes on the CPU graph, but the performance is flawless with no audio hitches whatsoever.

To do this I had to switch around the device sample rate, internal sample rate and buffer size - setting the buffer size I wanted first, with a setting that Pianoteq didn't complain about, then changing the sample size to one with which it thinks the buffer size is suboptimal.  The buffer size stays, but if I go to change it the 64 sample buffer size isn't one of the options from the drop down menu.

I'm sorry I can't be more specific - I've set the settings and don't want to go through the rigmarole of fiddling around, but if anyone has any questions please let me know.

A question for the forum - does this sound like a bug?  I don't want them to fix it in case I can't get these results again!

I was sceptical about the project, but I'm really happy with results.  I've wired the output from the Pi through a small amplifier (Lepy LP-2020A) and into the built in speakers on my Yamaha P-45.  The speakers aren't great, but the treble and bass settings on the little amp make it sound more alive.

I've set up the OS to start Pianoteq fullscreen when I turn on the Pi, and have a shutdown shortcut on the desktop, so I can turn it all off quite easily.  I don't have links to the guides, but searches relating to Linux brought be to results quickly.

To address something I read in my travels through the forums; in my experience RAM has little to no effect on the performance - 2GB is enough to run both the OS and Pianoteq with plenty of room to spare (current usage with Pianoteq open is consistently c.237MB).  CPU effects performance, and using a DAC hat offloads the processing of audio, increasing performance, and allowing for more connectivity.

Thanks to everyone for your posts and to Edgar, and Niclas for his help in posting Edgar's guide!

Tom

In my opinion the minimum internal sample rate should be 32000 Hz (~16000 Hz frequency spectrum incl. roll-off). Even with 32000 Hz sample rate especially the reverb and "naturalness" degrades significantly compared to 44100 and 48000 Hz in my experience. But that does not mean, one can't be perfectly happy with a less "natural" timbre. There might be cases, where a well balanced velocity and latency is more important, than the sound quality.

96 Samples...