I want to record (line in) from an audio device and separate the left and right channel each to a different process, or record them separately of course. What I want is something like that (play command just as example): either:

arecord (left channel only) -q -D plughw:1,0 -f S16_LE -r 22050 | play -t raw -r 22050 -b 16 -e signed -q - 
arecord (right channel only) -q -D plughw:1,0 -f S16_LE -r 22050 | play -t raw -r 22050 -b 16 -e signed -q -

(may also result in device or resource busy?) or something like "arecord | splitchannels (leftchannel | process 1) (rightchannel | process 2)" or possibly more like that "arecord | tee >(getleftchannel | process1) >(getrightchannel | process2) > /dev/null" as intensive web searches didn't give any usable results. Any idea how I can accomplish that?

I am wondering why, when using vaapi with ffmpeg, if I use x11grab I must use -vf format=nv12,hwupload but with kmsgrab I must use -vf scale_vaapi=format=nv12 instead. In particular I want to know 2 things. - Why is it this way? - Is there any way to use normal filters (like eq=brightness=50 or zscale) with vaapi when using kmsgrab? Because the dilemma that's causing me to ask these questions is that I need to do some color corrections and filters seem like the best way to do that, but I'm unable to use filters when I'm using kmsgrab because scale_vaapi breaks other filters, and I even tried using some obscure filters like procamp_vaapi which shuold allow me to do the same things as eq, but I couldn't get it to work. my kmsgrab command: ffmpeg -y -device /dev/dri/card1 -f kmsgrab -i - -vf 'hwmap=derive_device=vaapi,scale_vaapi=format=nv12' -c:v h264_vaapi -qp 24 output.mkv

Is it possible to record the screen with ffmpeg on wayland using the Hyprland compositor? I've read some posts that imply people managed to do it with kmsgrab, but cannot figure out how to do it myself (I tried the common examples with kmsgrab and it didn't work, possibly because I'm on wayland) Is there a way to do it? I've tried: ffmpeg -device /dev/dri/card1 -f kmsgrab -i - -vf 'format=nv12,hwupload' -c:v h264_vaapi output.mkv But get the following error: [kmsgrab @ 0x556c9ae1fec0] Using plane 58 to locate framebuffers. [kmsgrab @ 0x556c9ae1fec0] Template framebuffer is 142: 2560x1600 format 34325258 modifier 200000000401b03 flags 2. [kmsgrab @ 0x556c9ae1fec0] No handle set on framebuffer: maybe you need some additional capabilities? [in#0 @ 0x556c9ae1fc00] Error opening input: Invalid argument Error opening input file -. Error opening input files: Invalid argument Recording with vaapi with wf-recorder or wl-screenrec works fine btw, but I would prefer to directly use ffmpeg. I'm also curious if it can be used with nvenc (which would be on card0 for me), but if I try to use it with my nvidia gpu I get: [kmsgrab @ 0x558916595e80] No usable planes found. [in#0 @ 0x558916595bc0] Error opening input: Invalid argument Error opening input file -. Error opening input files: Invalid argument

In kde wayland when you choose the pipewire source in obs, you get the Desktop Portal dialog that allows you to choose one of your screens or a "Full Workspace". But also there is an option "New Virtual Output". When I choose it, in system settings in Monitors I see another screen appeared with no name. What is a purpose of it? How it is intended to be used?

I want to do this from commandline: What I've done so far is to create a ~/.asoundrc file with the following contents:

pcm.pulse_monitor {
  type pulse
  device alsa_output.pci-0000_00_1b.0.analog-stereo.monitor
}

ctl.pulse_monitor {
  type pulse
  device alsa_output.pci-0000_00_1b.0.analog-stereo.monitor
}

With alsa_output.pci-0000_00_1b.0.analog-stereo.monitor as the desired monitor source.But it doesn't work because if I launch **Audacity** and set the source to Built-in ... via **pavucontrol** and then relaunch the Audacity the default source would be still Builtin ... not Monitor of builtin ... Is there any way to make it work in command-line ? Note that restarting the pulse-audio server is not preferred because it would cut the sound of all the current clients of the PA server. Thanks in advance.

Is there a simple, application-independent way to record audio on given sound card? Lets say I plug in USB headset, which appears as /dev/snd/foo. I then use zoom or skype or any other application to make a call. If the application does not allow recording natively, can I record the audio independently on the sound card level? I am using alsa, and I imagine (naively) that there might be some infrastructure to attach to, or "mirror" the sound card and dump audio to file? I need to record both channels (microphone, speaker), so there might be some mixing necesary? My OS is Debian 10, and I am using alsa (not pulseaudio)

When I was using DOS and Windows I've seen quite a selection of tools to check optical disks for readability and benchmark an optical drive itself. Most of them were even visualising the results in form of a pretty chart. Are there any such for GNU/Linux OSes? I'd prefer to have a full-featured visual GUI tool, but for the particular case I've got now, I just need to check if my CD drive can read every byte of a particular heavily-scratched CD-RW disk.

I'm trying to record my screen losslessly (or at near lossless quality) with hardware acceleration on a 6700 XT with ffmpeg. I'm running Linux Mint with the 5.14.14-051414-generic kernel. I've tried: ffmpeg -vaapi_device /dev/dri/renderD128 -f x11grab -video_size 2560x1440 -i :0 -r 60 -vf 'hwupload,scale_vaapi=format=nv12' -c:v h264_vaapi -qp 0 output.mp4 ffmpeg says it's recording at 60 fps, but the recording is choppy and slightly miscolored. I'm assuming the color issue is from the color format nv12, but rgb or rgb8 gives an error. I've also tried using kmsgrab: ffmpeg -device /dev/dri/card0 -f kmsgrab -i - -vf 'hwmap=derive_device=vaapi,scale_vaapi=w=2560:h=1440:format=nv12' -c:v h264_vaapi -qp 0 output.mp4 But it gives the error:

[kmsgrab @ 0x558f001c8d80] Using plane 65 to locate framebuffers.
[kmsgrab @ 0x558f001c8d80] Failed to get framebuffer 127: Invalid argument.
pipe:: Invalid argument

The number after Failed to get framebuffer is usually 127 or somewhere from 134 to 136. I got these commands [here](https://trac.ffmpeg.org/wiki/Hardware/VAAPI) .

As mentioned in the title, I'm unable to simultaneously record my headset microphone *and* my desktop audio when using SimpleScreenRecorder in KDE Neon 5.24. In the "Audio Input" section of the recording settings, I selected "PulseAudio" as **Backend**, whereas for **Source** I've tried both "Built-in Audio Analog Stereo" as well as "Monitor of Built-in Audio Analog Stereo" (see below): When selecting "Built-in Audio Analog Stereo", the microphone gets recorded but the desktop audio does not, while the situation is exactly the opposite when I select "Monitor of Built-in Audio Analog Stereo" (can record desktop audio but not headset microphone). Does anybody have an idea of how to solve this issue?

What is the ffmpeg command to record screen and internal audio (on Ubuntu 18.04)? I'll omit the many things I tried that did not work and skip to the something close to what I am looking for; V="$(xdpyinfo | grep dimensions | perl -pe 's/.* ([0-9]+x[0-9]+) .*/$1/g')" A="$(pacmd list-sources | grep -PB 1 "analog.*monitor>" | head -n 1 | perl -pe 's/.* //g')" F="$(date --iso-8601=minutes).mkv" ffmpeg -video_size "$V" -framerate 10 -f x11grab -i :0.0 -f pulse -ac 2 -i "$A" "$F" I can get video but no audio. parecord -d alsa_output.pci-0000_00_1b.0.analog-stereo.monitor example.wav # index: 1 will get audio.

I'm trying to record audio that is being played on separate channels using arecord. I do this by executing the following command in separate threads in a python script: arecord -D plug:"+str(in_id)+" -c 1 -d "+str(duration)+" -f S16_LE -r "+str(rate)+" "+rec_filename where in_id is the input channel variable that I pass to each of the threads. But then, the following error is thrown: ALSA lib pcm_dsnoop.c:606:(snd_pcm_dsnoop_open) unable to open slave arecord: main:722: audio open error: Device or resource busy When I run lsof /dev/snd/pcm* right before I start recording using arecord in my record function in the program, I see the following: COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME aplay 12236 user4 mem CHR 116,3 493 /dev/snd/pcmC1D0p aplay 12236 user4 4u CHR 116,3 0t0 493 /dev/snd/pcmC1D0p My device definition for input channels in .asoundrc is as follows: pcm.!default { type plug slave { pcm "hw:1,0" } } ctl.!default { type hw card 1 } pcm_slave.usb_audio_1 { pcm "hw:1,0" channels 8 rate 44100 buffer_size 4096 period_size 1024 } pcm.outch { type dshare ipc_key slave usb_audio_1 bindings [ ] hint.description "USB output/playback channel (from output port )" } pcm.inch { type dsnoop ipc_key slave usb_audio_1 bindings [ ] hint.description "USB input/capture channel (from input port )" } where ` takes all values between 1 and 8 and ` takes all values between 0 and 7. Since, the error clearly says there is a definite problem with dsnoop, does that mean that it is not meant for simultaneous/multi-channel recording? I mean is there a conflict between dsnoop and dshare or if dsnoop can record/capture from only one channel at a time? Is there another way I can achieve this?

I have found a ffmpeg command to record area of my screen: ffmpeg -video_size 2000x1600 -framerate 25 -f x11grab -i :0.0+2140,280 output.mp4 But to find the correct area, I had to do multiple trial/error runs and it was tedious. Is there some possibility to select area by mouse, and have it recorded by ffmpeg ? If there is no ready made solution, how would I hack together something that works in this way? in another post , somebody mentioned xrectsel , which prints coordinates of a rectangle selected by mouse. Is there some easier way to do this?

I am currently using Pop!_OS version 22.04 LTS. I was trying to get on a Discord call with a friend, but he couldn't hear me. I later discovered that it would detect audio out as the input. I went to settings to find out that it was not detecting my headphone mic for the input, even though it said it was. I tried everything online from using

,

,

, and resetting the audio manager, following instructions on the Pop!_OS audio page. After doing this, it doesn't detect audio at all, and there is no system audio either. Under

it shows that it is plugged in (which it is), but no audio from the mic. Nothing seems to work, and the only way to use a mic is to plug in a USB-C headset with a built in mic. Is there any way to resolve this?

I have installed [SimpleScreenRecorder](https://www.maartenbaert.be/simplescreenrecorder/) On My Linux Machine but I recorded and Edited Some Videos With it Like This [Example](https://youtu.be/p970tQJnoME) But the Recorded Quality is Not Good Enough, Please Tell me Some Settings Which I Can use For Recording Quality My PC Details: 2 GB Ram, 2.2GHz Intel Dual Core Processor & 500GB HDD & Linux Mint XFCE4

I searched for video recording equipment to use with Linux. Upon searching I find some products that state that they do not come with drivers because it is a UVC device. Assuming that other products that do come with a driver are for Windows only, I purchased one labeled no driver and it worked just fine without any tinkering. How do these so called UVC devices work without drivers?

I am using gtk-recordmydesktop to record the video output to my desktop. However, the videos have no sound. All the tutorials I found regarding this involved getting sound recorded from a microphone, while I am interested in getting the sound output recorded. How can I do this? The official FAQ says "The solution is in your mixer's settings. Keep playing with it ;)." which doesn't clarify anything. How can I get the sound output recorded, while being able to hear it myself also?

I'm having psychoterapy through Google Meet and would like to record the sessions for studying them later. But Google does not allows recording natively except if you are the inviter and pay for a premium account. This is not the case. How can, then, I record both the microphone and the speaker audio of my PC on the same file, without needing to downgrade the audio quality by using a second microphone to record the speakers, like I'm doing by placing a cellphone on the room and recording through it?

I'm using the following command to record the screen with ffmpeg.

ffmpeg -nostdin -video_size 720x878 -framerate 24 -f x11grab -i :0.0+720,0 -vf setpts=N/FR/TB -vcodec libx264 -y -loglevel quiet output.mkv &

Also I'm using the following commands to pause, resume and stop the recording:

bash
# to pause
pkill -STOP ffmpeg 

#to resume
pkill -CONT ffmpeg

# to stop
pkill -INT ffmpeg

I noticed that the total time of the recording is longer than the actual time that it took to record the video. Simply put, the output is longer than expected to be. To test my understanding, I ran the following loop that prints elapsed time every second and then I recorded it for about one minute.

i=1 && while true; do echo $((i++)) && sleep 1; done

# example output
1
2
3
...

Whenever I resume the recording, new echos come slightly slower than a second and it lasts for about 4 to 5 seconds, then everything goes back to normal. Actually each echo then corresponds to one second. So I thought that maybe its encoding/decoding that takes time. Any idea how can I fix this?

I know there it is possible to record sound from the speaker of the computer using command such as:

ffmpeg -f avfoundation -i ":0" -t 10 audiocapture.aiff

But as the recorded sound is far from perfect (due to the imperfection of the microphone), is there a way to record the audio directly from the soundcard (e.g. using ffmpeg)?

Audios recorded from the microphone start with a pop and a fade in. I tried 2 mics from two hardware inputs. I found this solution that describes my problem but Fedora 35 has no default.pa file:

In the /etc/pulse/default.pa file, comment out this line:
load-module module-suspend-on-idle

>It seems this is just default Pulse Audio behavior and essentially tries to save resources by “dimming” sources of audio that become idle for “too long.” I haven’t really timed it to figure out how long “too long” is, but with the change above, it doesn’t matter anyway What would be the Fedora 35 equivalent? Indeed if I start recording immediately after another recording there is no fade in but the pop persists. I found the pipewire-pulse systemd user unit but no obvious setting:

[Unit]
Description=PipeWire PulseAudio

# We require pipewire-pulse.socket to be active before starting the daemon, because
# while it is possible to use the service without the socket, it is not clear
# why it would be desirable.
#
# A user installing pipewire and doing systemctl --user start pipewire-pulse
# will not get the socket started, which might be confusing and problematic if
# the server is to be restarted later on, as the client autospawn feature
# might kick in. Also, a start of the socket unit will fail, adding to the
# confusion.
#
# After=pipewire-pulse.socket is not needed, as it is already implicit in the
# socket-service relationship, see systemd.socket(5).
Requires=pipewire-pulse.socket
ConditionUser=!root
Wants=pipewire.service pipewire-session-manager.service
After=pipewire.service pipewire-session-manager.service
Conflicts=pulseaudio.service

[Service]
LockPersonality=yes
MemoryDenyWriteExecute=yes
NoNewPrivileges=yes
RestrictNamespaces=yes
SystemCallArchitectures=native
SystemCallFilter=@system-service
Type=simple
ExecStart=/usr/bin/pipewire-pulse
Restart=on-failure
Slice=session.slice

[Install]
Also=pipewire-pulse.socket
WantedBy=default.target

journalctl shows this:

dez 31 15:21:15 d3.localdomain plasmashell: 15:21:15: Debug: AudioIO::GetBestRate() for playback
dez 31 15:21:15 d3.localdomain plasmashell: 15:21:15: Debug: GetBestRate() suggested rate 44100 Hz
dez 31 15:21:15 d3.localdomain plasmashell: 15:21:15: Debug: GetBestRate() Returning 44100 Hz

Would it be Plasma adding the delay?

$ systemctl --user status session.slice
● session.slice - User Core Session Slice
     Loaded: loaded (/usr/lib/systemd/user/session.slice; static)
     Active: active since Sat 2022-01-01 10:14:18 -03; 29min ago
       Docs: man:systemd.special(7)
      Tasks: 95
     Memory: 638.7M
        CPU: 38.748s
     CGroup: /user.slice/user-1000.slice/user@1000.service/session.slice
             ├─at-spi-dbus-bus.service
             │ ├─2403 /usr/libexec/at-spi-bus-launcher
             │ ├─2409 /usr/bin/dbus-broker-launch --config-file=/usr/share/defaults/at-spi2/accessibility.conf --scope user
             │ └─2410 dbus-broker --log 4 --controller 9 --machine-id 938e97f50c4f42609f51bf4ed43fe113 --max-bytes 100000000>
             ├─dbus-broker.service
             │ ├─1818 /usr/bin/dbus-broker-launch --scope user
             │ └─1821 dbus-broker --log 4 --controller 11 --machine-id 938e97f50c4f42609f51bf4ed43fe113 --max-bytes 10000000>
             ├─gvfs-daemon.service
             │ └─1862 /usr/libexec/gvfsd
             ├─gvfs-metadata.service
             │ └─4700 /usr/libexec/gvfsd-metadata
             ├─pipewire-pulse.service
             │ └─1804 /usr/bin/pipewire-pulse
             ├─pipewire.service
             │ └─1802 /usr/bin/pipewire
             ├─plasma-kded.service
             │ ├─2030 /usr/bin/kded5
             │ ├─4242 /usr/libexec/kf5/kioslave5 /usr/lib64/qt5/plugins/kf5/kio/kio_file.so file "" local:/run/user/1000/kde>
             │ └─4244 /usr/libexec/kf5/kioslave5 /usr/lib64/qt5/plugins/kf5/kio/kio_file.so file "" local:/run/user/1000/kde>
             ├─plasma-ksmserver.service
             │ └─2028 /usr/bin/ksmserver
             ├─plasma-kwin_x11.service
             │ └─2033 /usr/bin/kwin_x11 --replace
             ├─plasma-plasmashell.service
             │ ├─2071 /usr/bin/plasmashell --no-respawn
             │ ├─2678 /usr/bin/ksysguardd
             │ └─2843 /usr/libexec/kf5/kio_http_cache_cleaner
             ├─wireplumber.service
             │ └─1803 /usr/bin/wireplumber
             ├─xdg-desktop-portal.service
             │ └─2441 /usr/libexec/xdg-desktop-portal
             └─xdg-document-portal.service
               ├─2445 /usr/libexec/xdg-document-portal
               └─2453 fusermount -o rw,nosuid,nodev,fsname=portal,auto_unmount,subtype=portal -- /run/user/1000/doc