ALSA: Setting FIFO type as the slave for dsnoop

[cnkoder]

Problem

I am facing problems in using "dsnoop" to share/divide the audio stream into two. When dsnoop plugins' slave is set to be a FIFO it throws an error.

executed:

sudo arecord -D default -f cd defRecording.wav -c 1 -r 32000

error:

ALSA lib pcm_direct.c:1809:(_snd_pcm_direct_get_slave_ipc_offset) Invalid type 'fifo' for slave PCM

arecord: main:828: audio open error: Invalid argument

This is the current asound.conf settings

asound.conf

pcm.!default {
    type asym
    playback.pcm "playback"
    capture.pcm "capture1 "
}

pcm.playback {
    type plug
    slave.pcm "eci"
}

# Stream Output 1: Final
pcm.capture1 {
    type plug
    slave.pcm "array"
}

# Stream Output 2: Final
pcm.capture2 {
    type plug
    slave.pcm "array"
}

# Used to share the record device
pcm.array {
    type dsnoop
    slave {
        pcm "eco"
        channels 1
    }
    ipc_key 666666
}

# Writes audio coming from any sort of player to ec.input, this is read by the echo
# cancellation software.
pcm.eci {
    type plug
    slave {
        format S16_LE
        rate 32000
        channels 1
        pcm {
            type file
            slave.pcm null
            file "/tmp/ec.input"
            format "raw"
        }
    }
}

# Read FIFO output which contains echo cancelled audio
pcm.eco {
    type plug
    slave.pcm {
        type fifo
        infile "/tmp/ec.output"
        rate 32000
        format S16_LE
        channels 1
    }
    #ipc_key 666666
}

Note:
eco is used to read the FIFO file which contains the echo canceled audio coming in from cancellation software. This software's input is hw:0 and records audio directly from the microphone, and then processes and passes this over to ec.output

Dsnoop works well when the slave.pcm is a hardware device but as soon as I point to something else it fails.
Is there a workaround or any other solution to tackle this problem?

[perexg]

Dsnoop works well when the slave.pcm is a hardware device but as soon as I point to something else it fails.
Is there a workaround or any other solution to tackle this problem?

dsnoop, dshare, dmix plugins works only with hw: plugins (direct ALSA devices). Why you cannot use the eco pcm device two times directly ?

[perexg]

Replying to myself - pipe right...

[perexg]

Pehaps, the used software may write output to two pipes, if possible. Or you may use the ALSA loopback soundcard (snd-aloop kernel module) and dsnoop on top of it.

[cnkoder]

Pehaps, the used software may write output to two pipes, if possible. Or you may use the ALSA loopback soundcard (snd-aloop kernel module) and dsnoop on top of it.

Thank you, will search on the compatibility of dsnoop with snd-aloop and try this out first and then maybe move the first option.
Will update as soon as I get some results

[cnkoder]

Replying to inform on what was done.
Searched on snd-aloop but I could not achieve what was required, therefore edited the software to write data to two pipes and managed to solve the problem.
Thanks again