** Summary changed: - Truncated audio frequency response on monitor device + Truncated audio frequency response on snd-aloop device
-- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to pulseaudio in Ubuntu. https://bugs.launchpad.net/bugs/1882587 Title: Truncated audio frequency response on snd-aloop device Status in pulseaudio package in Ubuntu: New Bug description: Hi. I've found something strange happening when I record the output of a sound card through loopback device audio monitor. If I load the snd-aloop module, then setup a player to play a chirp sound that spans a sine wave between 10Hz and 22kHz through it, and then record the virtual monitor device through Audacity it drops the frequencies something over 16kHz like it have a low pass filter on it. The sampling rate is 44100 or 48000, it doesn't matters, the result is the same. Also in some cases I found that the signal path between channels doesn't have correct syncing. A chirp sound is ideal for testing, because if there is some delay between channels, it would produce a comb filter like frequency response on the mono mix. It also happens with real sound cards, not virtual ones. The question is about how to narrow down the issue. I think it's not ALSA related, because it happens both on the hardware device and the virtual loop one. Attached I put my chirp test sound. I played it on the command line with: $ ffplay -loop 1000 chirp_test.flac Then I setup the recording path with pavucontrol, to target the Audacity input My versions: pulseaudio 12.2-2 linux kernel 5.6.13 $ lsb_release -rd Description: Ubuntu 18.04.4 LTS Release: 18.04 pulseaudio: Installed: 1:12.2-9~bionic1 Candidate: 1:12.2-9~bionic1 Version table: *** 1:12.2-9~bionic1 500 500 http://ppa.launchpad.net/mikhailnov/pulseeffects/ubuntu bionic/main amd64 Packages 100 /var/lib/dpkg/status 1:11.1-1ubuntu7.8 500 500 http://ar.archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages 1:11.1-1ubuntu7.7 500 500 http://security.ubuntu.com/ubuntu bionic-security/main amd64 Packages 1:11.1-1ubuntu7 500 500 http://ar.archive.ubuntu.com/ubuntu bionic/main amd64 Packages Attached on this there is a .tar.gz containing both .flac files chirp_test.flac is the original file. chirp_loopback_recorded.flac is the recorded file from the loopback device. Thank You. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/pulseaudio/+bug/1882587/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
