Ubuntu 20.04 / Pulseaudio RTP receive broken sound

[Lionel Jeanson]

just upgraded some of my computers to Ubuntu 20.04, also tried with fresh install, in all case the pulseaudio rtp receive module is giving me very poor sound.

Easily reproducible on a single machine :

pacmd load-module module-null-sink sink_name=MyNullSink
pacmd load-module module-rtp-send source=MyNullSink.monitor loop=true
pacmd load-module module-rtp-recv

And then play something in the null sink, loopback sound will be bad (lags).

What I noticed : if I open the rtp stream with vlc, it's ok, sound is good.

Ubuntu 20 uses PulseAudio 13.99, aka (I guess) PulseAudio 14 which implements RTP through gstreamer, which is new.

So I tested my rtp stream with gstreamer:

gst-launch-1.0 udpsrc address=224.0.0.56 port=46586 caps="application/x-rtp, media=audio, payload=10, clock-rate=44100" ! .recv_rtp_sink_0 rtpbin ! rtpL16depay ! audioconvert ! audioresample ! pulsesink

And it works fine, so I definitively believe there is an issue in the new module-rtp-recv.so bundled with PulseAudio and that is now based on gstreamer.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: pulseaudio 1:13.99.1-1ubuntu3
ProcVersionSignature: Ubuntu 5.4.0-29.33-generic 5.4.30
Uname: Linux 5.4.0-29-generic x86_64
ApportVersion: 2.20.11-0ubuntu27
Architecture: amd64
AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/controlC0', '/dev/snd/hwC0D2', '/dev/snd/hwC0D0', '/dev/snd/pcmC0D9p', '/dev/snd/pcmC0D8p', '/dev/snd/pcmC0D7p', '/dev/snd/pcmC0D3p', '/dev/snd/pcmC0D2c', '/dev/snd/pcmC0D1p', '/dev/snd/pcmC0D0c', '/dev/snd/pcmC0D0p', '/dev/snd/by-id', '/dev/snd/by-path', '/dev/snd/controlC2', '/dev/snd/pcmC2D0c', '/dev/snd/controlC1', '/dev/snd/pcmC1D0p', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1:
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Mon May 11 22:22:55 2020
InstallationDate: Installed on 2019-03-31 (407 days ago)
InstallationMedia: Ubuntu 18.04.2 LTS "Bionic Beaver" - Release amd64 (20190210)
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=fr_FR.UTF-8
 SHELL=/bin/bash
PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No PulseAudio daemon running, or not running as session daemon.
SourcePackage: pulseaudio
UpgradeStatus: Upgraded to focal on 2020-05-09 (2 days ago)
dmi.bios.date: 09/13/2018
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 1404
dmi.board.asset.tag: Default string
dmi.board.name: ROG STRIX H370-I GAMING
dmi.board.vendor: ASUSTeK COMPUTER INC.
dmi.board.version: Rev X.0x
dmi.chassis.asset.tag: Default string
dmi.chassis.type: 3
dmi.chassis.vendor: Default string
dmi.chassis.version: Default string
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr1404:bd09/13/2018:svnSystemmanufacturer:pnSystemProductName:pvrSystemVersion:rvnASUSTeKCOMPUTERINC.:rnROGSTRIXH370-IGAMING:rvrRevX.0x:cvnDefaultstring:ct3:cvrDefaultstring:
dmi.product.family: To be filled by O.E.M.
dmi.product.name: System Product Name
dmi.product.sku: ASUS_MB_CNL
dmi.product.version: System Version
dmi.sys.vendor: System manufacturer
modified.conffile..etc.pulse.daemon.conf: [modified]
modified.conffile..etc.pulse.default.pa: [modified]
modified.conffile..etc.pulse.system.pa: [modified]
modified.conffile..etc.xdg.autostart.pulseaudio.desktop: [deleted]
mtime.conffile..etc.pulse.daemon.conf: 2020-05-10T12:17:27.278185
mtime.conffile..etc.pulse.default.pa: 2020-05-10T12:13:15.278817
mtime.conffile..etc.pulse.system.pa: 2020-05-11T16:24:47.654012

[Sebastien Bacher (seb128)]

Thank you for your bug report, that's likely an upstream issue, could you report it there?

https://gitlab.freedesktop.org/pulseaudio/pulseaudio/issues/

[Lionel Jeanson (hebbos)]

Ok bug created : https://gitlab.freedesktop.org/pulseaudio/pulseaudio/-/issues/889

[Lucas (meltingberg)]

This bug has now been fixed upstream. Can we pull this?

[Daniel van Vugt (vanvugt)]

pulseaudio (1:13.99.2-1ubuntu1) groovy; urgency=medium

[Guest (disposable-s)]

The bug was submitted for Ubuntu 20.04, which is an LTS release.
The comment changing the status to "Fix Released" mentions a fix is available for Ubuntu 20.10 (groovy), which is the next, non-LTS release.

I'm not familiar with the procedure of back-porting code to LTS releases, but since upstream did not release a new mayor/minor version but a small bug fix, the bug fix should not be that problematic to be included in Ubuntu 20.04.

Are there any chances for this bug to be fixed in the reported version Ubuntu 20.04, too?

[Daniel van Vugt (vanvugt)]

Now requested a fix for 20.04.

[Dmitry Mikhailov (roentgen256)]

You can rebuild 13.99-1 RTP modules without GStreamer support as per https://gitlab.freedesktop.org/pulseaudio/pulseaudio/-/issues/889

If you can't wait for fix you can grab prebuilt library binaries from there although I'm against using unsigned untested 3rd-party binaries in production. Works for me.