ALSA Loopback not recording system audio on Xubuntu 18.04 in ffmpeg command

I have an ffmpeg script to do my screencasts. I have Debian 9 at the office and Xubuntu 18.04 at home. On those two operating systems, the following works to record system audio and from my microphone. pacmd set-default-source alsa_output.pci-0000_00_14.2.analog-stereo.monitor ffmpeg \ -thread_queue_size 4096 -f alsa -ac 1 -ar 48000 -i default \ -thread_queue_size 4096 -f alsa -ac 1 -ar 48000 -i plughw:CARD=Device,DEV=0 \ -filter_complex amix=inputs=2 \ -thread_queue_size 4096 -f x11grab -r 30 -s 1920x1080 -i $DISPLAY+1920,0 \ -c:v libx264 -crf 20 -preset veryfast \ -c:a aac -ac 2 -b:a 192k \ -pix_fmt yuv420p -movflags faststart \ ~/Desktop/out.mp4 This uses the pulse 'Monitor of Built-in Audio' to capture desktop audio. Unfortunately, on Debian 10, Xubuntu 19.04 & 19.10, and on Fedora 30, when I want to end my screen recording and press q it does not stop properly. It hangs. Then I have to use ctrl+c multiple times to get back to the prompt. It kills my script and does not run the needed following commands. I will report this bug as soon as I get a chance. I am not sure if it is an ALSA or Pulse bug. I do not think it is an ffmpeg bug because I had the same ffmpeg version on both Debian 9 and Debian 10, and it only occured on Debian 10 and not Debian 9. I have a Lenovo ThinkCentre. There is a front and back audio out and microphone 3.5mm jack. I used a 3.5mm cable to route audio out back in to the microphone jack. It worked, but the audio was poor quality. To do this I used -f alsa -i plughw:CARD=Generic,DEV=0 in my ffmpeg command. By using the ALSA device name, it did not hang on Xubuntu 19.10, etc. I have therefore been trying to get the ALSA Loopback device to work to record the system audio. I have not been able to get it to record at all. I am loading the snd-aloop kernel module at boot. I have tried various configuration options in my ~/.asoundrc including at the bottom of the page here and also here . Here is the output of arecord -L on my system. default Playback/recording through the PulseAudio sound server null Discard all samples (playback) or generate zero samples (capture) pulse PulseAudio Sound Server sysdefault:CARD=Loopback Loopback, Loopback PCM Default Audio Device front:CARD=Loopback,DEV=0 Loopback, Loopback PCM Front speakers surround21:CARD=Loopback,DEV=0 Loopback, Loopback PCM 2.1 Surround output to Front and Subwoofer speakers surround40:CARD=Loopback,DEV=0 Loopback, Loopback PCM 4.0 Surround output to Front and Rear speakers surround41:CARD=Loopback,DEV=0 Loopback, Loopback PCM 4.1 Surround output to Front, Rear and Subwoofer speakers surround50:CARD=Loopback,DEV=0 Loopback, Loopback PCM 5.0 Surround output to Front, Center and Rear speakers surround51:CARD=Loopback,DEV=0 Loopback, Loopback PCM 5.1 Surround output to Front, Center, Rear and Subwoofer speakers surround71:CARD=Loopback,DEV=0 Loopback, Loopback PCM 7.1 Surround output to Front, Center, Side, Rear and Woofer speakers dmix:CARD=Loopback,DEV=0 Loopback, Loopback PCM Direct sample mixing device dmix:CARD=Loopback,DEV=1 Loopback, Loopback PCM Direct sample mixing device dsnoop:CARD=Loopback,DEV=0 Loopback, Loopback PCM Direct sample snooping device dsnoop:CARD=Loopback,DEV=1 Loopback, Loopback PCM Direct sample snooping device hw:CARD=Loopback,DEV=0 Loopback, Loopback PCM Direct hardware device without any conversions hw:CARD=Loopback,DEV=1 Loopback, Loopback PCM Direct hardware device without any conversions plughw:CARD=Loopback,DEV=0 Loopback, Loopback PCM Hardware device with all software conversions plughw:CARD=Loopback,DEV=1 Loopback, Loopback PCM Hardware device with all software conversions sysdefault:CARD=Generic HD-Audio Generic, ALC662 rev3 Analog Default Audio Device front:CARD=Generic,DEV=0 HD-Audio Generic, ALC662 rev3 Analog Front speakers dmix:CARD=Generic,DEV=0 HD-Audio Generic, ALC662 rev3 Analog Direct sample mixing device dmix:CARD=Generic,DEV=2 HD-Audio Generic, ALC662 rev3 Alt Analog Direct sample mixing device dsnoop:CARD=Generic,DEV=0 HD-Audio Generic, ALC662 rev3 Analog Direct sample snooping device dsnoop:CARD=Generic,DEV=2 HD-Audio Generic, ALC662 rev3 Alt Analog Direct sample snooping device hw:CARD=Generic,DEV=0 HD-Audio Generic, ALC662 rev3 Analog Direct hardware device without any conversions hw:CARD=Generic,DEV=2 HD-Audio Generic, ALC662 rev3 Alt Analog Direct hardware device without any conversions plughw:CARD=Generic,DEV=0 HD-Audio Generic, ALC662 rev3 Analog Hardware device with all software conversions plughw:CARD=Generic,DEV=2 HD-Audio Generic, ALC662 rev3 Alt Analog Hardware device with all software conversions sysdefault:CARD=Device USB PnP Audio Device, USB Audio Default Audio Device front:CARD=Device,DEV=0 USB PnP Audio Device, USB Audio Front speakers surround21:CARD=Device,DEV=0 USB PnP Audio Device, USB Audio 2.1 Surround output to Front and Subwoofer speakers surround40:CARD=Device,DEV=0 USB PnP Audio Device, USB Audio 4.0 Surround output to Front and Rear speakers surround41:CARD=Device,DEV=0 USB PnP Audio Device, USB Audio 4.1 Surround output to Front, Rear and Subwoofer speakers surround50:CARD=Device,DEV=0 USB PnP Audio Device, USB Audio 5.0 Surround output to Front, Center and Rear speakers surround51:CARD=Device,DEV=0 USB PnP Audio Device, USB Audio 5.1 Surround output to Front, Center, Rear and Subwoofer speakers surround71:CARD=Device,DEV=0 USB PnP Audio Device, USB Audio 7.1 Surround output to Front, Center, Side, Rear and Woofer speakers iec958:CARD=Device,DEV=0 USB PnP Audio Device, USB Audio IEC958 (S/PDIF) Digital Audio Output dmix:CARD=Device,DEV=0 USB PnP Audio Device, USB Audio Direct sample mixing device dsnoop:CARD=Device,DEV=0 USB PnP Audio Device, USB Audio Direct sample snooping device hw:CARD=Device,DEV=0 USB PnP Audio Device, USB Audio Direct hardware device without any conversions plughw:CARD=Device,DEV=0 USB PnP Audio Device, USB Audio Hardware device with all software conversions sysdefault:CARD=U0x46d0x825 USB Device 0x46d:0x825, USB Audio Default Audio Device front:CARD=U0x46d0x825,DEV=0 USB Device 0x46d:0x825, USB Audio Front speakers surround21:CARD=U0x46d0x825,DEV=0 USB Device 0x46d:0x825, USB Audio 2.1 Surround output to Front and Subwoofer speakers surround40:CARD=U0x46d0x825,DEV=0 USB Device 0x46d:0x825, USB Audio 4.0 Surround output to Front and Rear speakers surround41:CARD=U0x46d0x825,DEV=0 USB Device 0x46d:0x825, USB Audio 4.1 Surround output to Front, Rear and Subwoofer speakers surround50:CARD=U0x46d0x825,DEV=0 USB Device 0x46d:0x825, USB Audio 5.0 Surround output to Front, Center and Rear speakers surround51:CARD=U0x46d0x825,DEV=0 USB Device 0x46d:0x825, USB Audio 5.1 Surround output to Front, Center, Rear and Subwoofer speakers surround71:CARD=U0x46d0x825,DEV=0 USB Device 0x46d:0x825, USB Audio 7.1 Surround output to Front, Center, Side, Rear and Woofer speakers iec958:CARD=U0x46d0x825,DEV=0 USB Device 0x46d:0x825, USB Audio IEC958 (S/PDIF) Digital Audio Output dmix:CARD=U0x46d0x825,DEV=0 USB Device 0x46d:0x825, USB Audio Direct sample mixing device dsnoop:CARD=U0x46d0x825,DEV=0 USB Device 0x46d:0x825, USB Audio Direct sample snooping device hw:CARD=U0x46d0x825,DEV=0 USB Device 0x46d:0x825, USB Audio Direct hardware device without any conversions plughw:CARD=U0x46d0x825,DEV=0 USB Device 0x46d:0x825, USB Audio Hardware device with all software conversions I did the following test run with the loopback devices listed. None of the following recorded the audio I was playing. ffmpeg -f alsa -i loopin -t 10 1.wav ffmpeg -f alsa -i loopout -t 10 2.wav ffmpeg -f alsa -i sysdefault:CARD=Loopback -t 10 3.wav ffmpeg -f alsa -i front:CARD=Loopback,DEV=0 -t 10 4.wav ffmpeg -f alsa -i surround21:CARD=Loopback,DEV=0 -t 10 5.wav ffmpeg -f alsa -i surround40:CARD=Loopback,DEV=0 -t 10 6.wav ffmpeg -f alsa -i surround41:CARD=Loopback,DEV=0 -t 10 7.wav ffmpeg -f alsa -i surround50:CARD=Loopback,DEV=0 -t 10 8.wav ffmpeg -f alsa -i surround51:CARD=Loopback,DEV=0 -t 10 9.wav ffmpeg -f alsa -i surround71:CARD=Loopback,DEV=0 -t 10 10.wav ffmpeg -f alsa -i dmix:CARD=Loopback,DEV=0 -t 10 11.wav ffmpeg -f alsa -i dmix:CARD=Loopback,DEV=1 -t 10 12.wav ffmpeg -f alsa -i dsnoop:CARD=Loopback,DEV=0 -t 10 13.wav ffmpeg -f alsa -i dsnoop:CARD=Loopback,DEV=1 -t 10 14.wav ffmpeg -f alsa -i hw:CARD=Loopback,DEV=0 -t 10 15.wav ffmpeg -f alsa -i hw:CARD=Loopback,DEV=1 -t 10 16.wav ffmpeg -f alsa -i plughw:CARD=Loopback,DEV=0 -t 10 17.wav ffmpeg -f alsa -i plughw:CARD=Loopback,DEV=1 -t 10 18.wav I noticed that pavucontrol did not have any loopback devices listed. So, I ran the following pactl load-module module-loopback. Now it is only listed under the Playback tab and none of the other ones. I have been testing all of this on Xubuntu 18.04, but I also have a Xubuntu 19.10 install. In the past I have tried using ffmpeg with the pulse device, i.e. from pacmd list-sources. This created a 1-2 second delay on the system audio being recorded.