Crossfeed playback for more realistic headphone audio

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Crossfeed playback for more realistic headphone audio

Postby Tobbes » 04 Oct 2015, 19:51

Hello,
I started a thread in the feature request list but maybe some experts could help me.
I want to use runeaudio on a Raspberry Pi B and hifiberry with headphone.

Is there an easy way to get crossfeed Out of the pi?
There are some things mentioned in the net but I do not understand how it works.
One project is named bs2b http://bs2b.sourceforge.net/ and other sides speak about ecasound http://ecasound.seul.org/ecasound/.

Could anybody help me to find a way to play crossfeed audio with runeaudio?

Regards Tobbes
Tobbes
 
Posts: 3
Joined: 01 Oct 2015, 19:30

Re: Crossfeed playback for more realistic headphone audio

Postby hondagx35 » 04 Oct 2015, 21:26

Hi Tobbes,

Is there an easy way to get crossfeed Out of the pi?

What is easy for you?

Rune Audio is based on Arch Linux and ecasound is available as a package.
You can install it by:
Code: Select all
pacman -S ecasound


Ecasound can use mpd as input, so it fits nicely into the concept of Rune Audio.
The only problem is, that Rune has its hands on the mpd.conf file.
You can not modify this file without modifying Rune Audio.

You also have to recompile mpd with "pipe" as output option.

So please tell us a bit more about your linux skills.

Frank
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Joined: 11 Sep 2014, 22:06
Location: Germany

Re: Crossfeed playback for more realistic headphone audio

Postby Tobbes » 12 Oct 2015, 11:45

Hello,
I found a solution with LADSPA and bs2b for ALSA.
I did it on a moode Image because it is based on raspian (hope it is no problem to post my solution here).
That is what I did:
Code: Select all
apt-get install bs2b-ladspa

This is what I add to /etc/mpd.conf
Code: Select all
audio_output {
   type "alsa"
   name "ALSA default"
   device "hw:0,0"
   dsd_usb "yes"
}
#
audio_output {
   type "alsa"
   name "ALSA crossfeed"
   device "crossfeed"
   dsd_usb "yes"   
}



And this is the /etc/asound.conf
Code: Select all
pcm.!default "crossfeed"
ctl.!default "crossfeed"

pcm.soundcard { type hw; card 0; device 0; }
pcm.plugSoundcard { type plug; slave.pcm "soundcard"; }

pcm.bs2b {
    type ladspa
    slave.pcm "plugSoundcard"
    path "/usr/lib/ladspa" #path under arch linux will be an other ?
    playback_plugins [ {
        label bs2b
   input {
   controls [650 9.5]
}   
} ]
}

pcm.crossfeed { type plug; slave.pcm "bs2b"; }
ctl.crossfeed { type hw; card 0; }



parameters in "controls [x x]" can be changed.
Here are some configurations of HZ and dB for Crossfeed:
source: http://bs2b.sourceforge.net/
These results shows a three versions with different sets of cut-off frequency and crossfeed level:
1) 700 Hz, 4.5 dB - default.
This setting is closest to the virtual speaker placement with azimuth 30 degrees and the removal of about 3 meters, while listening by headphones.
2) 700 Hz, 6 dB - most popular.
This setting is close to the parameters of a Chu Moy's [3] crossfeeder.
3) 650 Hz, 9.5 dB - making the smallest changes in the original signal only for relaxing listening by headphones.
This setting is close to the parameters of a crossfeeder implemented in Jan Meier's [4] CORDA amplifiers.

Change of output is possible with:
mpc disable 1
mpc enable 2

output of "aplay -L"
Code: Select all
null
    Discard all samples (playback) or generate zero samples (capture)
plugSoundcard
bs2b
crossfeed
sysdefault:CARD=sndrpihifiberry
    snd_rpi_hifiberry_dac,
    Default Audio Device
dmix:CARD=sndrpihifiberry,DEV=0
    snd_rpi_hifiberry_dac,
    Direct sample mixing device
dsnoop:CARD=sndrpihifiberry,DEV=0
    snd_rpi_hifiberry_dac,
    Direct sample snooping device
hw:CARD=sndrpihifiberry,DEV=0
    snd_rpi_hifiberry_dac,
    Direct hardware device without any conversions
plughw:CARD=sndrpihifiberry,DEV=0
    snd_rpi_hifiberry_dac,
    Hardware device with all software conversions


Interesting is "top":
crossfeed disabled 12%
crossfeed enabled 19%

tobbes
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Posts: 3
Joined: 01 Oct 2015, 19:30

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