Room correction?

jonas18z

Is it possible to add some Room correction like miniDSP or is the Raspberry pi to slow?

dwijtsma

Sorry for responding on an old post, but room correction would really be a nice feature. My brother uses room correction and this really improves the sound.

Would it be possible to measure the impulse response of a room with the pi using a microphone? Or measure the impulse response with a PC and import the data into the pi? Importing should be possible I guess but I don't know how much computing power is needed to add FIR filtering to the raspberry pi.

skrodahl

HifiBerry supports both FIR and IIR:
http://www.crazy-audio.com/2013/10/changing-the-output-filter-characteristics-of-the-hifiberry-mini-dac/

There's been talks about bruteFIR, don't know how far it's gotten. Seems to be pretty CPU intensive though:
http://www.crazy-audio.com/2014/01/fir-filtering-on-the-raspberry-pi/

koslowj

Hello,

On the German board "Aktives Hoeren" a contributer named "frankl" describes software experiments with Linux (Arch Linux) concerning high quality audio, using somewhat more powerful hardware than a Raspberry Pi:

http://www.aktives-hoeren.de/viewtopic.php?f=30&t=4532

On his home-page, in English, he even offers his programs for downloading, including a version for the Raspberry Pi

http://frank_l.bitbucket.org/stereoutils/index.html
http://frank_l.bitbucket.org/stereoutils/player.html

Hope this is useful for somebody here!

Tinitus

Hi,

digging up this feature request. integration of bruteFIR would reall be nice. Daphile has it integrated now. My dream would be RuneAudio to sox up/downsample all files to 24/96 ( inorder to be able to use USB 1.0 spec), room correction through bruteFIR and then go through a USB 1.0 Adum chip (http://hackaday.com/2014/04/27/galvanic-isolated-ftdi-saves-your-computer/ for instance) for galvanic isolation into the DAC. My bet is that would beat or be equal to euipment at least 50x more expensive. The advantage of using only 24/96 would be that only one filter for the room correction would be needed.

For those who read German:

http://www.aktives-hoeren.de/viewtopic.php?f=6&t=4604&start=60

Greetings

Uwe

Computing power of my C1 should be enough to implement bruteFIR (the same should be true for Pi) if not daisy chain 'em

maxonline

Hey, If you like, you can already get it ... RuneAudio & RPI 2 are able to do it as you like

My setup in short :

mpd with pipe-out and brutefir package from #862152

in mpd.conf :
resampling up/down to 96/24 ( samplerate "sox very high" )
audio output ( type "pipe" ) to bruteFIR

in brutefir conf file :
needed coeff&filter
output via device "alsa" { device: "hw:sndrpihifiberry"; ignore_xrun: true; } ( miniTOSLINK optical out in this case )

USB link to a CA DACMagic will do the job as well, but you have to (down)sample to 44/16 due to the DACMagic USB limit.

Ciao

max

Tinitus

Hi Max,

thanks for your answer. I only saw it a fourtnight ago. I have a Odroid C1 and somewhere I have the version with pipeout to brutefir on my PC. I have several questions, Where can I alter mpd.conf over the WebGUI or do I need to SSH into the Odroid C1? How does the commandline "pipe to brutefir" look like? I would have to find out what the hardwarename four the sound of the C1 for the alsa out of brutefir is. Is the setting for using usb instead of TOSLink the same? My DAC handles everything up to 32/192 over usb. If I find time I will have to tinker around with my spare C1. Given the fact that I do not yet have a correction file I would start with a 0 filter in brutefir.

Thanks again for the reply

Best Regards

Uwe

maxonline

Hi Uwe,

Where can I alter mpd.conf over the WebGUI or do I need to SSH into the Odroid C1?

As you touch(edit) it by ssh/cmd line, Rune (Web)Gui will start to give you the option to "Manual Edit" (MPD web page) it.

How does the commandline "pipe to brutefir" look like?

Here my (mpd.conf) brutefir output example

audio_output {
	type 	"pipe"
	name "brutefir 24-96k"
	command "brutefir -nodefault /home/brutefir/config/mpd_pipe_96k 2>/dev/null"
	enabled		"yes"
	format "96000:32:2"
}

Is the setting for using usb instead of TOSLink the same? My DAC handles everything up to 32/192 over usb.

Yes. Of course you have to use the right "physical" device in brutefir output setup.

Ciao

°pdi°

Hi,

i need a brutefir-package for armv6 (Raspberry Pi B+). I tried to install base-devel on the raspberry and get this error-message: " libtool and libltdl are in conflict"
Btw., i'm not familiar with crosscompiling and the arch-build-system. Maybe it 's better this way: Please, can someone build brutefir for armv6?

Regards

Klaus

°pdi°

°pdi° wrote Please, can someone build brutefir for armv6?

it has resolved itself...