Disable LFE remixing by default

The current LFE crossover filter removes low frequencies from the main
channels and puts them into the LFE channel with the wrong amplitude.
It is not known for sure what is the correct relative amplitude (acoustic
measurements are required with real hardware), and changing that might
introduce a new bug, "it clips the LFE channel".

So just disable the feature by default until a better understanding
emerges how it should work. This, essentially, returns the defaults
to their state as of PulseAudio 6.0.

Some more observations:

- Most of available active analog speakers on the market do the
necessary crossover filtering already, and HDMI receivers can be
configured to do that, too, so a crossover filter in PulseAudio is
harmful in these use cases.

- The "laptop with a builtin subwoofer" use case requires manual
configuration anyway because the default crossover frequency (120 Hz) is
wrong for laptop speakers.

- Finally, Windows 10 with a built-in USB audio driver does not synthesize
the LFE channel given a 5.1 card and a stereo audio stream by default.

Hides: https://bugs.freedesktop.org/show_bug.cgi?id=95021
Signed-off-by: Alexander E. Patrakov <patrakov@gmail.com>

3 files changed, 6 insertions, 6 deletions

diff --git a/src/daemon/daemon-conf.c b/src/daemon/daemon-conf.c
index 965a5c802..427730139 100644
--- a/src/daemon/daemon-conf.c
+++ b/src/daemon/daemon-conf.c
@@ -82,8 +82,8 @@ static const pa_daemon_conf default_conf = {
     .log_time = false,
     .resample_method = PA_RESAMPLER_AUTO,
     .disable_remixing = false,
-    .disable_lfe_remixing = false,
-    .lfe_crossover_freq = 120,
+    .disable_lfe_remixing = true,
+    .lfe_crossover_freq = 0,
     .config_file = NULL,
     .use_pid_file = true,
     .system_instance = false,
diff --git a/src/daemon/daemon.conf.in b/src/daemon/daemon.conf.in
index b48afa23f..fcc9cb963 100644
--- a/src/daemon/daemon.conf.in
+++ b/src/daemon/daemon.conf.in
@@ -54,8 +54,8 @@ ifelse(@HAVE_DBUS@, 1, [dnl
 
 ; resample-method = speex-float-1
 ; enable-remixing = yes
-; enable-lfe-remixing = yes
-; lfe-crossover-freq = 120
+; enable-lfe-remixing = no
+; lfe-crossover-freq = 0
 
 ; flat-volumes = yes
 
diff --git a/src/pulsecore/core.c b/src/pulsecore/core.c
index 6d102f58a..2a96dfa5e 100644
--- a/src/pulsecore/core.c
+++ b/src/pulsecore/core.c
@@ -142,8 +142,8 @@ pa_core* pa_core_new(pa_mainloop_api *m, bool shared, bool enable_memfd, size_t
     c->realtime_scheduling = false;
     c->realtime_priority = 5;
     c->disable_remixing = false;
-    c->disable_lfe_remixing = false;
-    c->lfe_crossover_freq = 120;
+    c->disable_lfe_remixing = true;
+    c->lfe_crossover_freq = 0;
     c->deferred_volume = true;
     c->resample_method = PA_RESAMPLER_SPEEX_FLOAT_BASE + 1;