[Pkg-utopia-maintainers] Bug#1054019: broken sample rate passthrough

[Nicholas D Steeves]

Package: pipewire
Version: 0.3.65-3
Severity: normal

Hi,

Unfortunately using mpv's Pipewire driver results in audio being
resampled, which introduces resampling artifacts.  While I discovered
this bug in bookworm's mpv_0.31.1-4, I've confirmed that it is still
present in 0.36.0-1.  That said, as a result of the investigation when
filing this bug, I found what seems to be evidence that points to
Pipewire as the true cause of the bug.  Any software that uses Pipewire directly, or pipewire-jack appears to be affected.

Steps to reproduce:

1. Uninstall and disable pulseaudio (if it's installed).
2. Install pipewire-pulse.
3. Cp /usr/share/pipewire/pipewire.conf /etc/pipewire/pipewire.conf
4. Set "default.clock.allowed-rates = [ 44100 48000 88200 96000 ]"
5. Restart pipewire's --user session.
6. mpv --ao=pipewire 01.ripped.from-CD.flac
7. cat /proc/asound/card0/pcm0p/sub0/hw_params | grep rate

  rate: 48000 (48000/1)

When playing music with mpd (with Pulse audio backed) or with "mpv
--ao=pulse", the sample rate is correctly passed through to Pipewire, and thus to the hardware:

  rate: 44100 (44100/1)

Yes, I tested to see if the creation of a pipewire.conf with
"default.clock.allowed-rates", and it appears to be for bookworm's
Pipewire 0.3.65-3.

The people who would probably be bothered the most by this bug are
those who purchased "High-resolution audio" files (sample rates up to
192kHz, and usually 24bit), because playback will be limited to 48kHz
due to this bug, as well as people who can hear 44.1khz to 48khz
resampling artifacts.

With the hypothesis that it was a Pipewire bug, I tried running
Audacious with pipewire-jack (with JACK output configured), and a popup dialogue showed "Error"

  The JACK server requires a sample rate of 48000 Hz, but
  Audacious is playing at 44100 Hz. Please use the Sample rate
  Converter effect to correct the mismatch.

And testing with "pw-jack mpv --ao=jack 01.ripped.from-CD.flac" shows

  AO: [jack] 48000Hz stereo 2ch floatp

and of course cat /proc/asound/card0/pcm0p/sub0/hw_params | grep rate shows

  rate: 48000 (48000/1)

So yeah, it looks like Pipewire's default sample rate is always
applied when using pipewire or JACK sinks, despite
"default.clock.allowed-rates" being set, except with using pulseaudio.
I'm not sure why this is the case, but it seems wrong that everything
is buggy except Pipewire and Pulseaudio...and that's why I'm reporting
this bug against pipewire.  Please feel free to reassign if this is a
naive assessment.

I hope this is enough to identify which package[s] is[are] affected as
well as to forward the bug upstream.  Please let me know if any more
info is required.

Thanks,
Nicholas

-- System Information:
Debian Release: 12.2
  APT prefers stable-security
  APT policy: (500, 'stable-security'), (500, 'stable-debug'), (500, 'proposed-updates-debug'), (500, 'stable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 6.1.0-13-rt-amd64 (SMP w/4 CPU threads; PREEMPT)
Locale: LANG=en_CA.UTF-8, LC_CTYPE=en_CA.UTF-8 (charmap=UTF-8), LANGUAGE=en_CA:en
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages mpv depends on:
ii  libarchive13                       3.6.2-1
ii  libasound2                         1.2.8-1+b1
ii  libass9                            1:0.17.1-1
ii  libavcodec-extra59 [libavcodec59]  7:5.1.3-1
ii  libavdevice59                      7:5.1.3-1
ii  libavfilter8                       7:5.1.3-1
ii  libavformat59                      7:5.1.3-1
ii  libavutil57                        7:5.1.3-1
ii  libbluray2                         1:1.3.4-1
ii  libc6                              2.36-9+deb12u3
ii  libcaca0                           0.99.beta20-3
ii  libcdio-cdda2                      10.2+2.0.1-1
ii  libcdio-paranoia2                  10.2+2.0.1-1
ii  libcdio19                          2.1.0-4
ii  libdrm2                            2.4.114-1+b1
ii  libdvdnav4                         6.1.1-1
ii  libegl1                            1.6.0-1
ii  libgbm1                            22.3.6-1+deb12u1
ii  libjack-jackd2-0 [libjack-0.125]   1.9.21~dfsg-3
ii  libjpeg62-turbo                    1:2.1.5-2
ii  liblcms2-2                         2.14-2
ii  liblua5.2-0                        5.2.4-3
ii  libmujs2                           1.3.2-1
ii  libpipewire-0.3-0                  0.3.65-3
ii  libplacebo208                      4.208.0-3
ii  libpulse0                          16.1+dfsg1-2+b1
ii  librubberband2                     3.1.2+dfsg0-1
ii  libsdl2-2.0-0                      2.26.5+dfsg-1
ii  libsixel1                          1.10.3-3
ii  libswresample4                     7:5.1.3-1
ii  libswscale6                        7:5.1.3-1
ii  libuchardet0                       0.0.7-1
ii  libva-drm2                         2.17.0-1
ii  libva-wayland2                     2.17.0-1
ii  libva-x11-2                        2.17.0-1
ii  libva2                             2.17.0-1
ii  libvdpau1                          1.5-2
ii  libvulkan1                         1.3.239.0-1
ii  libwayland-client0                 1.21.0-1
ii  libwayland-cursor0                 1.21.0-1
ii  libwayland-egl1                    1.21.0-1
ii  libx11-6                           2:1.8.4-2+deb12u2
ii  libxext6                           2:1.3.4-1+b1
ii  libxinerama1                       2:1.1.4-3
ii  libxkbcommon0                      1.5.0-1
ii  libxpresent1                       1.0.0-2+b10
ii  libxrandr2                         2:1.5.2-2+b1
ii  libxss1                            1:1.2.3-1
ii  libxv1                             2:1.0.11-1.1
ii  libzimg2                           3.0.4+ds1-1
ii  zlib1g                             1:1.2.13.dfsg-1

Versions of packages mpv recommends:
ii  xdg-utils  1.1.3-4.1
ii  yt-dlp     2023.09.24-2~bpo12+1

Versions of packages mpv suggests:
pn  libcuda1  <none>

-- no debconf information