Digital Room Correction with the HiFiBerry DSP card

[cliveb]

I've long been vaguely interested in experimenting with DRC, but whenever I read about Inguz it looked a bit daunting. Added to that, my LMS runs on a Raspberry Pi 3, so there's no chance of doing the necessary processing at the server end.

I seem to recall some discussions here about whether the HiFiBerry DSP cards could be used for this purpose. (Sorry, but I've done some forum searches and couldn't find the thread, but am pretty sure I'm not imagining it).

So I've been experimenting with HiFiBerry's Raspberry Pi DIGI2 Pro SPDIF card and DSP add-on board. I can confirm that it's fairly straightforward to load the necessary filters into the DSP card, and when you reboot the Pi using another operating system (eg. piCorePlayer), the filters are still active. I would assume that the same would be true if you use the HiFiBerry DAC+DSP or Beocreate card instead. (I use the SPDIF card because I have Meridian active speakers with digital inputs, so didn't need a DAC).

What I did find is that some of the facilities provided by the HiFiBerryOS seem a bit unreliable. In particular, they use an old version of Squeezelite that has problems with delays and failure to pause/seek, so my initial plan to run HiFiBerryOS as my Squeezelite player didn't work out. Also, their (experimental) room correction feature didn't work for me. I ended up using Room EQ Wizard to calculate the required filters, then added those filters manually using HiFiBerryOS's parametric EQ page. After adding the filters, you need to go to the DSP Programs page and instruct it to store the settings in the DSP card. Once that is done, you can shut down HiFiBerryOS and reboot into piCorePlayer.

This is just a heads-up that it does all work rather well, but if anyone wants some more details, let me know.

[Daverz]

I would suggest CamillaDSP since it supports both IIR and FIR filters and has a pretty straightforward configuration. You can find binaries for use on RPi on the CamillaDSP website

https://github.com/HEnquist/camilladsp/releases

and detailed setup instructions:

https://github.com/HEnquist/camilladsp-config

Note, you don't need the /etc/asound.conf there.

A further note on subtleties of resampling with CamillaDSP: if you don't care about "hi res", just set the CamillaDSP samplerate as 44100. Any downsampling that needs to be done will be done by LMS (using sox). If you use a higher processing samplerate for CamillaDSP, ALSA will do the upsampling (poorly). So in that case it's better to use squeezelite's -R flag to do the upsampling (which uses sox again). Or... you can use the cdsp plugin, which sets the CamillaDSP samplerate on the fly and let's CamillaDSP handle the resampling with its own algorithms.

https://github.com/scripple/alsa_cdsp

(I use squeezelite's -R flag to upsample everything to 96k. Any files with a sample rate above that are downsampled by the server.)

[schoeppi]

Just for those who are looking for a non DIY solution and want to use LMS
with players that can do room correction the easy way...

1. Get a MiniDSP device and activate the squeezelite client plugin. The
plugin does not work out of the box but with a little linux knowletge it is
possible to copy a actual squeezelite binary to the MiniDSP. I can write
a howto or help if someone wants to setup MiniDSP with squeezelite and
has no idea whow to do this... Room correction is done with DIRAC Lite, the
licence is included if you buy a MiniDSP. Using DIRAc seems to be easy and
no deep knowletge of filters e.g. is needed. Because I am blind I was not
able to do the measurements myself but my girlfriend helped and we went
through the procedure in just two hours.

2. Get a device called CleanVolver which is offered by AudioVero:

http://www.audiovero.de

the CleanVolver is a Raspberry 4 with a linux running on it. Room correction
is done by brutefir. The device can be connected e.g. via USB to your DAC.
The software to produce the filters is called Acourate and can be also buyed
via AudioVero. It is also possible to book online sessions to do the
measurements with Mr. Brueggemann, the head of AudioVero and Acourate.

I am no specialist regarding DSP and I don't know if REV is better then
Acourate or what are the differences between the filter types or if brutefir
is still state of the art, but both solutions, the MiniDSP and CleanVolver
setup, are doing a very good job for me and the service ans support of Mr.
Brueggemann is great.

For me, in my special situation as a blind user who can not use measuring
tools like Acourate, REV or DIRAC, those solutions are also great, because I
would not have been able to get a DSP setup installed and configured myself.
So for those who want to have a easy DSP solution both setups might also be
interesting...

BTW.: Are there any good sources where to get a better understanding of the
different filter types? And do you know any tools to build or rebuild such
filters without a grafical software which is unfortunatly unuseable for me
in most cases? I would be so happy to experiment with my two DSP setup and
changing filters, play aournd with different setting, e.g., but I am not
aware of any program or tool, e.g. for the linux command line, that I could
use :-(.

Cheers,

Schoepp

[adamdea]

Just for those who are looking for a non DIY solution and want to use LMS
with players that can do room correction the easy way...

1. Get a MiniDSP device and activate the squeezelite client plugin. The
plugin does not work out of the box but with a little linux knowletge it is
possible to copy a actual squeezelite binary to the MiniDSP. I can write
a howto or help if someone wants to setup MiniDSP with squeezelite and
has no idea whow to do this... Room correction is done with DIRAC Lite, the
licence is included if you buy a MiniDSP. Using DIRAc seems to be easy and
no deep knowletge of filters e.g. is needed. Because I am blind I was not
able to do the measurements myself but my girlfriend helped and we went
through the procedure in just two hours.

2. Get a device called CleanVolver which is offered by AudioVero:

http://www.audiovero.de
Schoepp

Thanks Schoepp
I have recently purchased a mini- dsp SHD snd will have a go at installing squeezelite
I was proposing to follow these instructions-
https://www.minidsp.com/forum/shd-se...a-server#47632
Are they correct or is these a better way?

[tw99]

Thanks Schoepp
I have recently purchased a mini- dsp SHD snd will have a go at installing squeezelite
I was proposing to follow these instructions-
https://www.minidsp.com/forum/shd-se...a-server#47632
Are they correct or is these a better way?

Those instructions work, first you will need to get the ssh credentials from MiniDSP support.

[schoeppi]

Am 06.07.2021 um 23:52 schrieb tw99:
>
> adamdea wrote:
>> Thanks Schoepp
>> I have recently purchased a mini- dsp SHD snd will have a go at
>> installing squeezelite
>> I was proposing to follow these instructions-
>> https://www.minidsp.com/forum/shd-se...a-server#47632
>> Are they correct or is these a better way?
>
> Those instructions work, first you will need to get the ssh credentials
> from MiniDSP support.

I am not sure if all necessary steps are included in the description but
in general the most important things are included.

In my case the newest version of squeezelite is working in the MiniDSP,
so no older version has to be downloaded.

I also had to edit the start script but because this only is described
via picture in the description I can not say if all needed changes are
included.

Also I had to make sure that squeezelite is started by systemd when the
device is powered on.

Write to MiniDSP to get the ssh credentials and try to get squeezelite
running following the description you posted and if there are problems
just let us know. I am sure we can help then.

Cheers,

Schöpp

[adamdea]

Thanks both
I have asked for credentials, been asked to acknowledge the "health warning" and now waiting for details. Not sure when I will get the chance to set up but will have a go.

I'm intrigued that you got latest version of squeezelite to work @schoeppi and wonderign whether to try. But nervous about trying anything too adventurous


The suggested parameters in the picture are

Output device: [(hw)] sun8i
Close soundcard after X seconds: 9
ALSA parameters : 80:4::1:
extra parameters : -R vE:::24 -r 44100-196000 -s ip_of_your_lms_server

to be honest I was struggling to read the ALSA settings as the picture was a bit pixelated when I zoomed in.

[adamdea]

So I have managed to get squeezelite running on the mini dsp and all seems to be well. Well almost. The audio device settings only allow either shd external outputs like s/pdif or a general alsa.
Is there a way of getting squeezelite to control volume via the shd volume control rather than the LMS/squeezelite control? This would really make it worthwhile using the internal squeezelite; otherwise one might as well use an external SBT.

[paul-]

Only if there is a real alsa mixer. The the name of the mixer in the volume control line of the squeezelite settings.

[adamdea]

Only if there is a real alsa mixer. The the name of the mixer in the volume control line of the squeezelite settings.

How would i find out if there is? Any if there isn't could one be installed by fiddlling with the volumio distro under which squeezelite runs

Or to put it another way... I seem to remember that when playing through volumio proper it does control the SHD's volume control. Will check when I get home.

EDIT- is it as simple as adding -V digital ? or would that be another software vc rather than the dac itself.