Questions[audio-recording](ubuntu)

I have a big mp3 file including more songs. Is there any way to split the file by detecting silent parts? I would prefer a command line tool (e.g. ffmpeg).

Tried:

youtube-dl --ignore-errors --format bestaudio --extract-audio --audio-format mp3 --audio-quality 160K --output "%(title)s.%(ext)s" --yes-playlist

Two days back I upgraded ubuntu 19.04 into 20.04 lts. However, I noticed that the update got stuck at a particular stage saying 'Removing gnome-logs snap'. This window stays forever

Screenshot of the error while updating:

And the screen recording application Kazam is not recording audio. I tried with different screen recorders but of no use. No application detects the microphone. I looked for any changes in settings but everything was fine. I could see microphone detecting the sound from the dynamic bars. While trying to open it in terminal it shows this error

$ kazam
WARNING Kazam - Failed to correctly detect operating system

It was showing kazam failed to detect audio recording device few hours back. I uninstalled and reinstalled the application but nothing worked. I even installed PulseAudio volume controller but it neither detects any application that uses audio recording option.

Screenshot of PulseAudio volume controller detecting no recording device:

However, the Telegram desktop client is perfectly recording audio. I don't know what exactly happened with these applications.

This is the screenshot of Kazam not detecting the recording device:

I want to make a lecture video for my students but I'm stuck with these issues for hours. I would have changed the OS altogether. But since I don't have a USB I can't try that option. Somebody please answer.

I have some issues when recording/videocalling with Logitech C270 USB webcam: my voice is high-pitched, accelerated, squeaky. The odd thing is that this happens sometimes, not always, and independently from software used (Teams, Skype, Meet, Audacity, arecord, audio-recorder, Telegram); every time it happens, I get a

usb 1-2: reset high-speed USB device number 3 using ehci-pci

in dmesg output. More information:

• Using audio-recorder I can distinguish when my recording is going to be "bad" because time flows more slowly (a 3 s recording lasts 5-6 s);
• I have the same problem on Kubuntu 18.04 and MX 19.1;

• Restarting pulseaudio by

  pulseaudio -k
  pulseaudio --start
  

  sometimes fixes, sometimes not;

• Setting -r 16000 when invoking arecord doesn't fix (I tried this since many people solved similar issues by changing default sample rate in pulseaudio settings, which I have not tried since my issue is not exactly the same);

• The only application I had no issues with (if I remember correctly) is guvcview: when recording, anyway, dmesg complains

  uvcvideo: Failed to query (SET_CUR) UVC control 4 on unit 1: -32 (exp. 4).
  

Please ask for every piece of information you need.

How to convert .m4a audio files to .mp3 command line? (with no deterioration in quality, if possible). Ubuntu 16.04LTS media info:

General
Complete name                            : show.m4a
Format                                   : MPEG-4
Format profile                           : Apple audio with iTunes info
Codec ID                                 : M4A  (M4A /mp42/isom)
File size                                : 55.5 MiB
Duration                                 : 1h 48mn
Overall bit rate mode                    : Variable
Overall bit rate                         : 71.7 Kbps

Audio
ID                                       : 1
Format                                   : AAC
Format/Info                              : Advanced Audio Codec
Format profile                           : HE-AAC / LC
Codec ID                                 : 40
Duration                                 : 1h 48mn
Bit rate mode                            : Variable
Bit rate                                 : 72.0 Kbps
Maximum bit rate                         : 93.8 Kbps
Channel(s)                               : 2 channels
Channel positions                        : Front: L R
Sampling rate                            : 44.1 KHz / 22.05 KHz
Frame rate                               : 21.533 fps (1024 spf)
Compression mode                         : Lossy
Stream size                              : 54.9 MiB (99%)
Writing library                          : Nero AAC codec 1.5.4.0
Encoding settings                        : -q 0.25

I'm trying to record the output of my speakers, but when I do this, it also records from the microphone. I'd like to only record the non-microphone devices.

Trying:

$ (AUDIODEV=hw:0,0; rec test.mp3)    
$ rec -d hw:0,0 test.mp3

I've also tried ffmpeg:

$ ffmpeg -f alsa -i hw:CARD=PCH,DEV=0 test.mp3
$ ffmpeg -f alsa -i front:CARD=PCH,DEV=0 test.mp3
$ ffmpeg -f alsa -i surround40:CARD=PCH,DEV=0 test.mp3

I've seen elaborate things such as:

$ parec -v -d analog-output-speaker | sox -t raw -e signed-integer b 16 -r 44100 -c 2 test.mp3

Proposed online, but this still records the mic, and comes with obsolete sox options.

How can I record only non-mic input in ubuntu 14.04+ ?