can't get ./fplay to work

[UW5EHX]

i followed the instructions to install the loop http://www.sdrutah.org/info/rx_equipment.html I did everything but launching ./fplay does not work. Here's a mistake. Debian 11.1

root@websdr:/home/raketa/websdr/dist11# ./sdrplayalsa -r 768000 -f 3750000 | ./fplay -D plug:f_loop0_in -r 768000 -c 2 -f s16_le --disable-softvol -B 30000
ALSA lib pcm.c:2660:(snd_pcm_open_noupdate) Unknown PCM f_loop0_in
./fplay: main:765: audio open error: No such file or directory
   BWType value:  1536
   WBS value:  0 (0=off, 1=0n)
   AGC gain reduction step size:  1 dB (0=off, 1=0n)
   AGC gain increase step size:  1 dB (0=off, 1=0n)

aplay -l

root@websdr:/home/raketa/websdr/dist11# aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: Intel [HDA Intel], device 0: ALC888 Analog [ALC888 Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: Intel [HDA Intel], device 1: ALC888 Digital [ALC888 Digital]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 8: fl0 [Loopback], device 0: Loopback PCM [Loopback PCM]
  Subdevices: 8/8
  Subdevice #0: subdevice #0
  Subdevice #1: subdevice #1
  Subdevice #2: subdevice #2
  Subdevice #3: subdevice #3
  Subdevice #4: subdevice #4
  Subdevice #5: subdevice #5
  Subdevice #6: subdevice #6
  Subdevice #7: subdevice #7
card 8: fl0 [Loopback], device 1: Loopback PCM [Loopback PCM]
  Subdevices: 8/8
  Subdevice #0: subdevice #0
  Subdevice #1: subdevice #1
  Subdevice #2: subdevice #2
  Subdevice #3: subdevice #3
  Subdevice #4: subdevice #4
  Subdevice #5: subdevice #5
  Subdevice #6: subdevice #6
  Subdevice #7: subdevice #7
card 16: lp0 [Loopback], device 0: Loopback PCM [Loopback PCM]
  Subdevices: 8/8
  Subdevice #0: subdevice #0
  Subdevice #1: subdevice #1
  Subdevice #2: subdevice #2
  Subdevice #3: subdevice #3
  Subdevice #4: subdevice #4
  Subdevice #5: subdevice #5
  Subdevice #6: subdevice #6
  Subdevice #7: subdevice #7
card 16: lp0 [Loopback], device 1: Loopback PCM [Loopback PCM]
  Subdevices: 8/8
  Subdevice #0: subdevice #0
  Subdevice #1: subdevice #1
  Subdevice #2: subdevice #2
  Subdevice #3: subdevice #3
  Subdevice #4: subdevice #4
  Subdevice #5: subdevice #5
  Subdevice #6: subdevice #6
  Subdevice #7: subdevice #7

I will try again and again until I succeed.

[UW5EHX]

huh it works! i replaced "plug: f_loop0_in" with "hw: 8,0,0" for my sound card configuration

./sdrplayalsa -r 768000 -f 3750000 | ./fplay -D hw:8,0,0 -r 768000 -c 2 -f s16_le --disable-softvol -B 30000

in the file "websdr.cfg" the interface "hw: 8,1,0" was specified I conclude that I have not figured out the ".asoundrc" file

I'm new to Linux, installing the "sdrplayalsa" driver seemed easy for me if you follow the instructions http://www.sdrutah.org/info/rx_equipment.html but at the same time I had problems with the lack of basic knowledge of Linux.

[UW5EHX]

I have mastered on Linux Debian11.1 Perhaps the only caveat when installing "fastloop" in Debian11.1

make -C /lib/modules/5.10.0-9-amd64/build M=$PWD modules
make[1]: *** /lib/modules/5.10.0-9-amd64/build: There is no such file or directory. Stop.
make: *** [Makefile:12: modules] Error 2

to solve the problem with the "/ build" directory the following helped me

 sudo apt-get install linux-headers-`uname -r` 

this will provide a link /lib/modules/5.10.0-9-amd64/build https://askubuntu.com/questions/554624/how-to-resolve-the-lib-modules-3-13-0-27-generic-build-no-such-file-or-direct

[UW5EHX]

my "websdr.cfg" contains strings. i had to apply "swapiq" to do LSB demodulation on 80M band

############################################################################
#ALSA loop0 80M
############################################################################
band 80m
device $hw:8,1,0
samplerate 768000
centerfreq 3750
antenna funny dipole
gain -35
swapiq

This assembly can be heard here ( http://62.64.80.171:5557/

[CrumResearch]

Great job, glad you were able to figure out your issue! 73