As per discussions with FordPrefect. tanuk, theBear, ohsix, etc. on 
#pulseaudio. 

This is an initial, working version. Testing and review are most welcome, plus 
thoughts on a better lp filter.

-- 
#---------------------------------------------------------------------------#
Justin Chudgar | 530-921-0738 | 5040 Saddlehorn Rd, Weed, CA 96094
#---------------------------------------------------------------------------#
subject: patch to add module-lfe-lp for lowpass filtered lfe channel output
diff --git a/src/Makefile.am b/src/Makefile.am
index 8aacf92..3ceb236 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -1076,6 +1076,7 @@ modlibexec_LTLIBRARIES += \
 		module-remap-sink.la \
 		module-ladspa-sink.la \
 		module-tunnel-sink.la \
+		module-lfe-lp.la \
 		module-tunnel-source.la \
 		module-position-event-sounds.la \
 		module-augment-properties.la \
@@ -1088,7 +1089,7 @@ modlibexec_LTLIBRARIES += \
 		module-switch-on-port-available.la \
 		module-filter-apply.la \
 		module-filter-heuristics.la \
-		module-role-ducking.la
+		module-role-ducking.la 
 
 if HAVE_ESOUND
 modlibexec_LTLIBRARIES += \
@@ -1340,6 +1341,7 @@ SYMDEF_FILES = \
 		module-combine-sink-symdef.h \
 		module-remap-sink-symdef.h \
 		module-ladspa-sink-symdef.h \
+		module-lfe-lp-symdef.h \
 		module-equalizer-sink-symdef.h \
 		module-match-symdef.h \
 		module-tunnel-sink-symdef.h \
@@ -1599,6 +1601,10 @@ module_ladspa_sink_la_CFLAGS += $(DBUS_CFLAGS)
 module_ladspa_sink_la_LIBADD += $(DBUS_LIBS)
 endif
 
+module_lfe_lp_la_SOURCES = modules/module-lfe-lp.c
+module_lfe_lp_la_LDFLAGS = $(MODULE_LDFLAGS)
+module_lfe_lp_la_LIBADD = $(MODULE_LIBADD) $(LIBLTDL)
+
 module_equalizer_sink_la_SOURCES = modules/module-equalizer-sink.c
 module_equalizer_sink_la_CFLAGS = $(AM_CFLAGS) $(SERVER_CFLAGS) $(DBUS_CFLAGS) $(FFTW_CFLAGS)
 module_equalizer_sink_la_LDFLAGS = $(MODULE_LDFLAGS)
diff --git a/src/modules/module-lfe-lp.c b/src/modules/module-lfe-lp.c
new file mode 100644
index 0000000..2c2db73
--- /dev/null
+++ b/src/modules/module-lfe-lp.c
@@ -0,0 +1,768 @@
+/***
+    This file is part of PulseAudio.
+
+    Copyright 2013 Justin Chudgar <[email protected]>
+
+    PulseAudio is free software; you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published
+    by the Free Software Foundation; either version 2.1 of the License,
+    or (at your option) any later version.
+
+    PulseAudio is distributed in the hope that it will be useful, but
+    WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+    General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with PulseAudio; if not, write to the Free Software
+    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+    USA.
+***/
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <stdio.h>
+
+#include <pulse/gccmacro.h>
+#include <pulse/xmalloc.h>
+#include <pulse/def.h>
+
+#include <pulsecore/i18n.h>
+#include <pulsecore/namereg.h>
+#include <pulsecore/sink.h>
+#include <pulsecore/module.h>
+#include <pulsecore/core-util.h>
+#include <pulsecore/modargs.h>
+#include <pulsecore/log.h>
+#include <pulsecore/rtpoll.h>
+#include <pulsecore/sample-util.h>
+#include <pulsecore/ltdl-helper.h>
+
+#include "module-lfe-lp-symdef.h"
+
+PA_MODULE_AUTHOR("Justin Chudgar");
+PA_MODULE_DESCRIPTION(_("LFE LP Filter"));
+PA_MODULE_VERSION(PACKAGE_VERSION);
+PA_MODULE_LOAD_ONCE(FALSE);
+PA_MODULE_USAGE(
+        _("sink_name=<name for the sink> "
+          "sink_properties=<properties for the sink> "
+		  "lpfreq=low pass cutoff freq 50-500 Hz"
+          "master=<name of sink to filter> "
+          "rate=<sample rate> "
+          "channels=<number of channels> "
+          "channel_map=<channel map> "
+          "use_volume_sharing=<yes or no> "
+          "force_flat_volume=<yes or no> "
+        ));
+
+#define MEMBLOCKQ_MAXLENGTH (16*1024*1024)
+
+struct userdata {
+    pa_module *module;
+    pa_bool_t autoloaded;
+    pa_sink *sink;
+    pa_sink_input *sink_input;
+    pa_memblockq *memblockq;
+    pa_bool_t auto_desc;
+	pa_sample_spec sample_spec;
+	double lpfreq;
+	unsigned int lfe_index;
+	unsigned int center_index;
+	double hp_factor, lp_factor;
+	double prev_sample[PA_CHANNELS_MAX];
+    double filtered[PA_CHANNELS_MAX];
+	// TODO: debugging, remove me
+	FILE *lfe_lp_log;
+};
+
+static const char* const valid_modargs[] = {
+    "sink_name",
+    "sink_properties",
+	"lpfreq",
+    "master",
+    "rate",
+    "channels",
+    "channel_map",
+    "use_volume_sharing",
+    "force_flat_volume",
+    NULL
+};
+
+/* Called from I/O thread context */
+static int sink_process_msg_cb(pa_msgobject *o, int code, void *data, int64_t offset, pa_memchunk *chunk) {
+    struct userdata *u = PA_SINK(o)->userdata;
+
+    switch (code) {
+        case PA_SINK_MESSAGE_GET_LATENCY:
+            /* The sink is _put() before the sink input is, so let's make sure
+			 * we don't access it in that time. Also, the sink input is first
+			 * shut down, the sink second. */
+            if (!PA_SINK_IS_LINKED(u->sink->thread_info.state) ||
+                !PA_SINK_INPUT_IS_LINKED(u->sink_input->thread_info.state)) {
+                *((pa_usec_t*) data) = 0;
+                return 0;
+            }
+            /* Get the latency of the master sink and add the latency internal
+			   to our sink input on top */
+            *((pa_usec_t*) data) =
+				pa_sink_get_latency_within_thread(u->sink_input->sink) +
+				pa_bytes_to_usec(pa_memblockq_get_length(u->sink_input->thread_info.render_memblockq),
+								 &u->sink_input->sink->sample_spec);
+            return 0;
+    }
+    return pa_sink_process_msg(o, code, data, offset, chunk);
+}
+
+/* Called from main context */
+static int sink_set_state_cb(pa_sink *s, pa_sink_state_t state) {
+    struct userdata *u;
+
+    pa_sink_assert_ref(s);
+    pa_assert_se(u = s->userdata);
+
+    if (!PA_SINK_IS_LINKED(state) ||
+        !PA_SINK_INPUT_IS_LINKED(pa_sink_input_get_state(u->sink_input)))
+        return 0;
+
+    pa_sink_input_cork(u->sink_input, state == PA_SINK_SUSPENDED);
+    return 0;
+}
+
+/* Called from I/O thread context */
+static void sink_request_rewind_cb(pa_sink *s) {
+    struct userdata *u;
+
+    pa_sink_assert_ref(s);
+    pa_assert_se(u = s->userdata);
+
+    if (!PA_SINK_IS_LINKED(u->sink->thread_info.state) ||
+        !PA_SINK_INPUT_IS_LINKED(u->sink_input->thread_info.state))
+        return;
+
+    /* Just hand this one over to the master sink */
+    pa_sink_input_request_rewind(u->sink_input,
+                                 s->thread_info.rewind_nbytes +
+                                 pa_memblockq_get_length(u->memblockq), TRUE, FALSE, FALSE);
+}
+
+/* Called from I/O thread context */
+static void sink_update_requested_latency_cb(pa_sink *s) {
+    struct userdata *u;
+
+    pa_sink_assert_ref(s);
+    pa_assert_se(u = s->userdata);
+
+    if (!PA_SINK_IS_LINKED(u->sink->thread_info.state) ||
+        !PA_SINK_INPUT_IS_LINKED(u->sink_input->thread_info.state))
+        return;
+
+    /* Just hand this one over to the master sink */
+    pa_sink_input_set_requested_latency_within_thread(
+            u->sink_input,
+            pa_sink_get_requested_latency_within_thread(s));
+}
+
+/* Called from main context */
+static void sink_set_volume_cb(pa_sink *s) {
+    struct userdata *u;
+
+    pa_sink_assert_ref(s);
+    pa_assert_se(u = s->userdata);
+
+    if (!PA_SINK_IS_LINKED(pa_sink_get_state(s)) ||
+        !PA_SINK_INPUT_IS_LINKED(pa_sink_input_get_state(u->sink_input)))
+        return;
+
+    pa_sink_input_set_volume(u->sink_input, &s->real_volume, s->save_volume, TRUE);
+}
+
+/* Called from main context */
+static void sink_set_mute_cb(pa_sink *s) {
+    struct userdata *u;
+
+    pa_sink_assert_ref(s);
+    pa_assert_se(u = s->userdata);
+
+    if (!PA_SINK_IS_LINKED(pa_sink_get_state(s)) ||
+        !PA_SINK_INPUT_IS_LINKED(pa_sink_input_get_state(u->sink_input)))
+        return;
+
+    pa_sink_input_set_mute(u->sink_input, s->muted, s->save_muted);
+}
+
+/**
+ * \fn sink_input_pop_cb
+ * \return int: What is the significance of the return value?
+ * \param sink_input
+ * \param nbytes
+ * \param chunk
+ * Called from I/O thread context
+ * Low pass filters the LFE channel and high pass filters the remaining channels.
+ */
+static int sink_input_pop_cb(pa_sink_input *sink_input,
+							 size_t nbytes,
+							 pa_memchunk *chunk) {
+    struct userdata *u;
+    float *src, *dst, *cur_sample, *cur_frame, *dst_frame, *dst_sample;
+	size_t framesize;
+    unsigned num_frames, frame_index, channel_index;
+    pa_memchunk tchunk;
+    pa_usec_t current_latency PA_GCC_UNUSED;
+
+    pa_sink_input_assert_ref(sink_input);
+    pa_assert(chunk);
+    pa_assert_se(u = sink_input->userdata);
+
+    /* Hmm, process any rewind request that might be queued up */
+    pa_sink_process_rewind(u->sink, 0);
+
+    /* (1) IF YOU NEED A FIXED BLOCK SIZE USE
+     * pa_memblockq_peek_fixed_size() HERE INSTEAD. NOTE THAT FILTERS
+     * WHICH CAN DEAL WITH DYNAMIC BLOCK SIZES ARE HIGHLY
+     * PREFERRED. */
+    while (pa_memblockq_peek(u->memblockq, &tchunk) < 0) {
+		pa_memchunk nchunk;
+        pa_sink_render(u->sink, nbytes, &nchunk);
+        pa_memblockq_push(u->memblockq, &nchunk);
+        pa_memblock_unref(nchunk.memblock);
+    }
+
+    /* (2) IF YOU NEED A FIXED BLOCK SIZE, THIS NEXT LINE IS NOT NECESSARY */
+    tchunk.length = PA_MIN(nbytes, tchunk.length);
+    pa_assert(tchunk.length > 0);
+	//pa_log_debug ("JZ: %s[%d] tchunk.length=%d\n", __FILE__, __LINE__, tchunk.length);
+
+    framesize = pa_frame_size(&sink_input->sample_spec);
+	//pa_log_debug ("JZ: %s[%d] framesize=%d", __FILE__, __LINE__, framesize);
+	num_frames = (unsigned) (tchunk.length / framesize);
+	//pa_log_debug ("JZ: %s[%d] num_frames=%d", __FILE__, __LINE__, num_frames);
+
+    pa_assert(num_frames > 0);
+
+    chunk->index = 0;
+    chunk->length = num_frames*framesize;
+    chunk->memblock = pa_memblock_new(sink_input->sink->core->mempool, chunk->length);
+
+    pa_memblockq_drop(u->memblockq, chunk->length);
+
+    src = pa_memblock_acquire_chunk(&tchunk);
+    dst = pa_memblock_acquire(chunk->memblock);
+
+    /* (3) PUT YOUR CODE HERE TO DO SOMETHING WITH THE DATA */
+
+	for (frame_index = 0; frame_index < num_frames; frame_index++) {
+		cur_frame = src + frame_index * u->sample_spec.channels;
+		dst_frame = dst + frame_index * u->sample_spec.channels;
+		for (channel_index = 0; channel_index < u->sample_spec.channels; channel_index++) {
+			cur_sample = cur_frame + channel_index;
+			dst_sample = dst_frame + channel_index;
+			if (channel_index == u->lfe_index) {					// low pass
+				u->filtered[channel_index] += (u->lp_factor *
+											   ((double)*cur_sample -
+												u->filtered[channel_index]));
+			} else if (channel_index == u->center_index) {			// high pass
+				u->filtered[channel_index] = (u->hp_factor *
+											  (u->filtered[channel_index] +
+											   (double)*cur_sample -
+											   u->prev_sample[channel_index]));
+				u->prev_sample[channel_index] = (double)*cur_sample;
+			} else {
+				u->filtered[channel_index] = (double)*cur_sample;
+				u->prev_sample[channel_index] = (double)*cur_sample;
+			}
+			*dst_sample = (float)u->filtered[channel_index];
+			/* TODO: debugging, remove me
+			fprintf (u->lfe_lp_log,
+					 "%u,%+01.12f,%+01.12f\n",
+					 channel_index,
+					 u->filtered[channel_index],
+					 (double)*cur_sample);
+			*/
+		}
+    }
+
+    pa_memblock_release(tchunk.memblock);
+    pa_memblock_release(chunk->memblock);
+
+    pa_memblock_unref(tchunk.memblock);
+
+    /* (4) IF YOU NEED THE LATENCY FOR SOMETHING ACQUIRE IT LIKE THIS: */
+	/* Get the latency of master and add the latency internal to our sink input*/
+    current_latency = (pa_sink_get_latency_within_thread(sink_input->sink) +
+					   pa_bytes_to_usec(pa_memblockq_get_length(sink_input->thread_info.render_memblockq),
+										&sink_input->sink->sample_spec)
+					  );
+
+    return 0;
+}
+
+/* Called from I/O thread context */
+static void sink_input_process_rewind_cb(pa_sink_input *i, size_t nbytes) {
+    struct userdata *u;
+    size_t amount = 0;
+
+    pa_sink_input_assert_ref(i);
+    pa_assert_se(u = i->userdata);
+
+    if (u->sink->thread_info.rewind_nbytes > 0) {
+        size_t max_rewrite;
+
+        max_rewrite = nbytes + pa_memblockq_get_length(u->memblockq);
+        amount = PA_MIN(u->sink->thread_info.rewind_nbytes, max_rewrite);
+        u->sink->thread_info.rewind_nbytes = 0;
+
+        if (amount > 0) {
+            pa_memblockq_seek(u->memblockq, - (int64_t) amount, PA_SEEK_RELATIVE, TRUE);
+            /* (5) PUT YOUR CODE HERE TO RESET YOUR FILTER  */
+			// TODO: Determine how to reset.
+        }
+    }
+
+    pa_sink_process_rewind(u->sink, amount);
+    pa_memblockq_rewind(u->memblockq, nbytes);
+}
+
+/* Called from I/O thread context */
+static void sink_input_update_max_rewind_cb(pa_sink_input *i, size_t nbytes) {
+    struct userdata *u;
+    pa_sink_input_assert_ref(i);
+    pa_assert_se(u = i->userdata);
+    /* FIXME: Too small max_rewind:
+     * https://bugs.freedesktop.org/show_bug.cgi?id=53709 */
+    pa_memblockq_set_maxrewind(u->memblockq, nbytes);
+    pa_sink_set_max_rewind_within_thread(u->sink, nbytes);
+}
+
+/* Called from I/O thread context */
+static void sink_input_update_max_request_cb(pa_sink_input *i, size_t nbytes) {
+    struct userdata *u;
+    pa_sink_input_assert_ref(i);
+    pa_assert_se(u = i->userdata);
+    /* (6) IF YOU NEED A FIXED BLOCK SIZE ROUND nbytes UP TO MULTIPLES
+     * OF IT HERE. THE PA_ROUND_UP MACRO IS USEFUL FOR THAT. */
+    pa_sink_set_max_request_within_thread(u->sink, nbytes);
+}
+
+/* Called from I/O thread context */
+static void sink_input_update_sink_latency_range_cb(pa_sink_input *i) {
+    struct userdata *u;
+    pa_sink_input_assert_ref(i);
+    pa_assert_se(u = i->userdata);
+    pa_sink_set_latency_range_within_thread(u->sink,
+											i->sink->thread_info.min_latency,
+											i->sink->thread_info.max_latency);
+}
+
+/* Called from I/O thread context */
+static void sink_input_update_sink_fixed_latency_cb(pa_sink_input *i) {
+    struct userdata *u;
+    pa_sink_input_assert_ref(i);
+    pa_assert_se(u = i->userdata);
+    /* (7) IF YOU NEED A FIXED BLOCK SIZE ADD THE LATENCY FOR ONE BLOCK MINUS
+	 * ONE SAMPLE HERE. pa_usec_to_bytes_round_up() IS USEFUL FOR THAT. */
+    pa_sink_set_fixed_latency_within_thread(u->sink, i->sink->thread_info.fixed_latency);
+}
+
+/* Called from I/O thread context */
+static void sink_input_detach_cb(pa_sink_input *i) {
+    struct userdata *u;
+    pa_sink_input_assert_ref(i);
+    pa_assert_se(u = i->userdata);
+    pa_sink_detach_within_thread(u->sink);
+    pa_sink_set_rtpoll(u->sink, NULL);
+}
+
+/* Called from I/O thread context */
+static void sink_input_attach_cb(pa_sink_input *i) {
+    struct userdata *u;
+    pa_sink_input_assert_ref(i);
+    pa_assert_se(u = i->userdata);
+
+    pa_sink_set_rtpoll(u->sink, i->sink->thread_info.rtpoll);
+    pa_sink_set_latency_range_within_thread(u->sink,
+											i->sink->thread_info.min_latency,
+											i->sink->thread_info.max_latency);
+    /* (8.1) IF YOU NEED A FIXED BLOCK SIZE ADD THE LATENCY FOR ONE BLOCK MINUS
+	 * ONE SAMPLE HERE. SEE (7) */
+    pa_sink_set_fixed_latency_within_thread(u->sink, i->sink->thread_info.fixed_latency);
+    /* (8.2) IF YOU NEED A FIXED BLOCK SIZE ROUND pa_sink_input_get_max_request(i)
+	 * UP TO MULTIPLES OF IT HERE. SEE (6) */
+    pa_sink_set_max_request_within_thread(u->sink, pa_sink_input_get_max_request(i));
+    /* FIXME: Too small max_rewind:
+     * https://bugs.freedesktop.org/show_bug.cgi?id=53709 */
+    pa_sink_set_max_rewind_within_thread(u->sink, pa_sink_input_get_max_rewind(i));
+
+    pa_sink_attach_within_thread(u->sink);
+}
+
+/* Called from main context */
+static void sink_input_kill_cb(pa_sink_input *i) {
+    struct userdata *u;
+
+    pa_sink_input_assert_ref(i);
+    pa_assert_se(u = i->userdata);
+
+    /* The order here matters! We first kill the sink input, followed by the sink.
+	 * That means the sink callbacks must be protected against an unconnected sink input! */
+    pa_sink_input_unlink(u->sink_input);
+    pa_sink_unlink(u->sink);
+
+    pa_sink_input_unref(u->sink_input);
+    u->sink_input = NULL;
+
+    pa_sink_unref(u->sink);
+    u->sink = NULL;
+
+    pa_module_unload_request(u->module, TRUE);
+}
+
+/* Called from IO thread context */
+static void sink_input_state_change_cb(pa_sink_input *i, pa_sink_input_state_t state) {
+    struct userdata *u;
+    pa_sink_input_assert_ref(i);
+    pa_assert_se(u = i->userdata);
+    /* If we are added for the first time, ask for a rewinding so that we are heard right-away. */
+    if (PA_SINK_INPUT_IS_LINKED(state) &&
+        i->thread_info.state == PA_SINK_INPUT_INIT) {
+        pa_log_debug("Requesting rewind due to state change.");
+        pa_sink_input_request_rewind(i, 0, FALSE, TRUE, TRUE);
+    }
+}
+
+/* Called from main context */
+static pa_bool_t sink_input_may_move_to_cb(pa_sink_input *i, pa_sink *dest) {
+    struct userdata *u;
+    pa_sink_input_assert_ref(i);
+    pa_assert_se(u = i->userdata);
+    return u->sink != dest;
+}
+
+/* Called from main context */
+static void sink_input_moving_cb(pa_sink_input *i, pa_sink *dest) {
+    struct userdata *u;
+
+    pa_sink_input_assert_ref(i);
+    pa_assert_se(u = i->userdata);
+
+    if (dest) {
+        pa_sink_set_asyncmsgq(u->sink, dest->asyncmsgq);
+        pa_sink_update_flags(u->sink, PA_SINK_LATENCY|PA_SINK_DYNAMIC_LATENCY, dest->flags);
+    } else
+        pa_sink_set_asyncmsgq(u->sink, NULL);
+
+    if (u->auto_desc && dest) {
+        const char *z;
+        pa_proplist *pl;
+
+        pl = pa_proplist_new();
+        z = pa_proplist_gets(dest->proplist, PA_PROP_DEVICE_DESCRIPTION);
+        pa_proplist_setf(pl, PA_PROP_DEVICE_DESCRIPTION, "lfe-lp %s on %s",
+                         pa_proplist_gets(u->sink->proplist, "device.vsink.name"), z ? z : dest->name);
+
+        pa_sink_update_proplist(u->sink, PA_UPDATE_REPLACE, pl);
+        pa_proplist_free(pl);
+    }
+}
+
+/* Called from main context */
+static void sink_input_volume_changed_cb(pa_sink_input *i) {
+    struct userdata *u;
+    pa_sink_input_assert_ref(i);
+    pa_assert_se(u = i->userdata);
+    pa_sink_volume_changed(u->sink, &i->volume);
+}
+
+/* Called from main context */
+static void sink_input_mute_changed_cb(pa_sink_input *i) {
+    struct userdata *u;
+    pa_sink_input_assert_ref(i);
+    pa_assert_se(u = i->userdata);
+    pa_sink_mute_changed(u->sink, i->muted);
+}
+
+int pa__init(pa_module *m) {
+    struct userdata *u;
+    pa_channel_map map;
+    pa_modargs *ma;
+    pa_sink *master=NULL;
+    pa_sink_input_new_data sink_input_data;
+    pa_sink_new_data sink_data;
+    pa_bool_t use_volume_sharing = TRUE;
+    pa_bool_t force_flat_volume = FALSE;
+	float arg_lpfreq = 100.0;
+	double  rc_lp, rc_hp, dt;
+    pa_memchunk silence;
+
+    pa_assert(m);
+
+    if (!(ma = pa_modargs_new(m->argument, valid_modargs))) {
+        pa_log("Failed to parse module arguments.");
+        goto fail;
+    }
+
+    if (!(master = pa_namereg_get(m->core, pa_modargs_get_value(ma, "master", NULL), PA_NAMEREG_SINK))) {
+        pa_log("Master sink not found");
+        goto fail;
+    }
+    pa_assert(master);
+
+	u = pa_xnew0(struct userdata, 1);
+
+	/* TODO: debugging, remove me
+	u->lfe_lp_log = fopen("/tmp/lfe_lp_log","w"); */
+
+	// get, validate and assign lowpass cutoff freq
+	arg_lpfreq = atof(pa_modargs_get_value(ma, "lpfreq", "100.0"));
+	if ((arg_lpfreq < 20.0) || (arg_lpfreq > 500.0)) {
+		pa_log ("JZ: %s[%d] lpfreq must be between 20.0 and 500.0.", __FILE__, __LINE__);
+		goto fail;
+	}
+	u->lpfreq = arg_lpfreq;
+	pa_log_debug ("JZ: %s[%d] lpfreq=%f\n", __FILE__, __LINE__, u->lpfreq );
+
+	u->sample_spec = master->sample_spec;
+    u->sample_spec.format = PA_SAMPLE_FLOAT32;
+
+	// setup filter factors
+	rc_lp = ((double)1.0 /
+			 ((u->lpfreq * (double)0.8408964152537146) * 	// / sqrt(sqrt(2))
+			  (double)2.0 *
+			  (double)3.1415926535897932384626433
+			 )
+			);
+	rc_hp = ((double)1.0 /
+			 ((u->lpfreq * (double)1.189207115002721) * 	// * sqrt(sqrt(2))
+			  (double)2.0 *
+			  (double)3.1415926535897932384626433
+			 )
+			);
+	dt = ((double)1.0 / (double)u->sample_spec.rate);
+	u->lp_factor = dt / (dt + rc_lp);
+	u->hp_factor = rc_hp / (dt + rc_hp);
+	pa_log ("JZ: %s[%d]\n\tlp_factor=%f\n\thp_factor=%f\n",
+				  __FILE__, __LINE__, u->lp_factor, u->hp_factor );
+
+	// init filter data
+	for (unsigned int i=0; i<PA_CHANNELS_MAX; i++) {
+		u->filtered[i] = (double)0.0;
+		u->prev_sample[i] = (double)0.0;
+	}
+
+    map = master->channel_map;
+    if (pa_modargs_get_sample_spec_and_channel_map(ma, &u->sample_spec, &map, PA_CHANNEL_MAP_DEFAULT) < 0) {
+        pa_log("Invalid sample format specification or channel map");
+        goto fail;
+    }
+
+    // make sure we have and lfe channel
+    u->lfe_index = PA_CHANNELS_MAX + 1;
+    u->center_index = PA_CHANNELS_MAX + 2;
+    for (int i=0; i<u->sample_spec.channels; i++) {
+		if (map.map[i] == PA_CHANNEL_POSITION_LFE) {
+			u->lfe_index = i;
+			pa_log ("JZ: %s[%d] lfe_index=%u", __FILE__, __LINE__, u->lfe_index);
+		}
+		if (map.map[i] == PA_CHANNEL_POSITION_CENTER) {
+			u->center_index = i;
+			pa_log ("JZ: %s[%d] center_index=%u", __FILE__, __LINE__, u->center_index);
+		}
+    }
+    if (u->lfe_index > PA_CHANNELS_MAX) {
+		pa_log("JZ: %s[%d] no lfe channel found", __FILE__, __LINE__ );
+		// TODO: debugging, remove me and reenable fail
+		//u->lfe_index = 0;
+		//goto fail;
+	}
+
+    if (pa_modargs_get_value_boolean(ma, "use_volume_sharing", &use_volume_sharing) < 0) {
+        pa_log("use_volume_sharing= expects a boolean argument");
+        goto fail;
+    }
+
+    if (pa_modargs_get_value_boolean(ma, "force_flat_volume", &force_flat_volume) < 0) {
+        pa_log("force_flat_volume= expects a boolean argument");
+        goto fail;
+    }
+
+    if (use_volume_sharing && force_flat_volume) {
+        pa_log("Flat volume can't be forced when using volume sharing.");
+        goto fail;
+    }
+
+    u->module = m;
+    m->userdata = u;
+
+    /* Create sink */
+    pa_sink_new_data_init(&sink_data);
+    sink_data.driver = __FILE__;
+    sink_data.module = m;
+    if (!(sink_data.name =
+			pa_xstrdup(pa_modargs_get_value(ma, "sink_name", NULL)))) {
+        sink_data.name = pa_sprintf_malloc("%s.lfe_lp", master->name);
+	}
+    pa_sink_new_data_set_sample_spec(&sink_data, &u->sample_spec);
+    pa_sink_new_data_set_channel_map(&sink_data, &map);
+    pa_proplist_sets(sink_data.proplist,
+					 PA_PROP_DEVICE_MASTER_DEVICE,
+					 master->name);
+    pa_proplist_sets(sink_data.proplist,
+					 PA_PROP_DEVICE_CLASS,
+					 "filter");
+    pa_proplist_sets(sink_data.proplist,
+					 "device.lfe_lp.name",
+					 sink_data.name);
+
+    if (pa_modargs_get_proplist(ma,
+								"sink_properties",
+								sink_data.proplist,
+								PA_UPDATE_REPLACE) < 0) {
+        pa_log("Invalid properties");
+        pa_sink_new_data_done(&sink_data);
+        goto fail;
+    }
+
+    if ((u->auto_desc = !pa_proplist_contains(sink_data.proplist,
+											  PA_PROP_DEVICE_DESCRIPTION))) {
+        const char *z;
+        z = pa_proplist_gets(master->proplist, PA_PROP_DEVICE_DESCRIPTION);
+        pa_proplist_setf(sink_data.proplist,
+						 PA_PROP_DEVICE_DESCRIPTION,
+						 "lfe-lp %s on %s",
+						 sink_data.name,
+						 z ? z : master->name);
+    }
+
+    // FIXME: should be PA_SINK_SHARE_VOLUME_WITH_MASTER not 0x1000000U
+    u->sink = pa_sink_new(m->core, &sink_data, (master->flags & (PA_SINK_LATENCY|PA_SINK_DYNAMIC_LATENCY))
+    					  | (use_volume_sharing ? 0x1000000U : 0));
+    pa_sink_new_data_done(&sink_data);
+
+    if (!u->sink) {
+        pa_log("Failed to create sink.");
+        goto fail;
+    }
+
+    u->sink->parent.process_msg = sink_process_msg_cb;
+    u->sink->set_state = sink_set_state_cb;
+    u->sink->update_requested_latency = sink_update_requested_latency_cb;
+    u->sink->request_rewind = sink_request_rewind_cb;
+    pa_sink_set_set_mute_callback(u->sink, sink_set_mute_cb);
+    if (!use_volume_sharing) {
+        pa_sink_set_set_volume_callback(u->sink, sink_set_volume_cb);
+        pa_sink_enable_decibel_volume(u->sink, TRUE);
+    }
+    /* Normally this flag would be enabled automatically be we can force it. */
+    if (force_flat_volume)
+        u->sink->flags |= PA_SINK_FLAT_VOLUME;
+    u->sink->userdata = u;
+
+    pa_sink_set_asyncmsgq(u->sink, master->asyncmsgq);
+
+    /* Create sink input */
+    pa_sink_input_new_data_init(&sink_input_data);
+    sink_input_data.driver = __FILE__;
+    sink_input_data.module = m;
+    pa_sink_input_new_data_set_sink(&sink_input_data, master, FALSE);
+    sink_input_data.origin_sink = u->sink;
+    pa_proplist_setf(sink_input_data.proplist,
+					 PA_PROP_MEDIA_NAME,
+					 "lfe-lp Stream from %s",
+					 pa_proplist_gets(u->sink->proplist,
+									  PA_PROP_DEVICE_DESCRIPTION)
+					);
+    pa_proplist_sets(sink_input_data.proplist, PA_PROP_MEDIA_ROLE, "filter");
+    pa_sink_input_new_data_set_sample_spec(&sink_input_data, &u->sample_spec);
+    pa_sink_input_new_data_set_channel_map(&sink_input_data, &map);
+
+    pa_sink_input_new(&u->sink_input, m->core, &sink_input_data);
+    pa_sink_input_new_data_done(&sink_input_data);
+
+    if (!u->sink_input)
+        goto fail;
+
+    u->sink_input->pop = sink_input_pop_cb;
+    u->sink_input->process_rewind = sink_input_process_rewind_cb;
+    u->sink_input->update_max_rewind = sink_input_update_max_rewind_cb;
+    u->sink_input->update_max_request = sink_input_update_max_request_cb;
+    u->sink_input->update_sink_latency_range = sink_input_update_sink_latency_range_cb;
+    u->sink_input->update_sink_fixed_latency = sink_input_update_sink_fixed_latency_cb;
+    u->sink_input->kill = sink_input_kill_cb;
+    u->sink_input->attach = sink_input_attach_cb;
+    u->sink_input->detach = sink_input_detach_cb;
+    u->sink_input->state_change = sink_input_state_change_cb;
+    u->sink_input->may_move_to = sink_input_may_move_to_cb;
+    u->sink_input->moving = sink_input_moving_cb;
+    u->sink_input->volume_changed = use_volume_sharing ? NULL : sink_input_volume_changed_cb;
+    u->sink_input->mute_changed = sink_input_mute_changed_cb;
+    u->sink_input->userdata = u;
+
+    u->sink->input_to_master = u->sink_input;
+
+    pa_sink_input_get_silence(u->sink_input, &silence);
+    u->memblockq = pa_memblockq_new("module-lfe-lp memblockq", 	//name
+									0, 							//start index
+									MEMBLOCKQ_MAXLENGTH, 		//max length
+									0, 							//target length
+									&u->sample_spec, 			//sample_spec
+									1, 							//prebuf
+									1, 							//minreq
+									0, 							//maxrewind
+									&silence);					//silence
+    pa_memblock_unref(silence.memblock);
+
+    /* (9) INITIALIZE ANYTHING ELSE YOU NEED HERE */
+    pa_sink_put(u->sink);
+    pa_sink_input_put(u->sink_input);
+    pa_modargs_free(ma);
+	pa_log_debug ("JZ: %s[%d] finished lfe-lp.pa__init().", __FILE__, __LINE__ );
+    return 0;
+
+fail:
+    if (ma)
+        pa_modargs_free(ma);
+    pa__done(m);
+    return -1;
+}
+
+int pa__get_n_used(pa_module *m) {
+    struct userdata *u;
+    pa_assert(m);
+    pa_assert_se(u = m->userdata);
+    return pa_sink_linked_by(u->sink);
+}
+
+void pa__done(pa_module*m) {
+    struct userdata *u;
+	pa_log_debug ("JZ: %s[%d] ", __FILE__, __LINE__ );
+    pa_assert(m);
+
+    if (!(u = m->userdata))
+        return;
+
+	/* TODO: debugging, remove me
+	fflush(u->lfe_lp_log);
+	fclose(u->lfe_lp_log); */
+
+    /* See comments in sink_input_kill_cb() above regarding
+     * destruction order! */
+
+    if (u->sink_input)
+        pa_sink_input_unlink(u->sink_input);
+
+    if (u->sink)
+        pa_sink_unlink(u->sink);
+
+    if (u->sink_input)
+        pa_sink_input_unref(u->sink_input);
+
+    if (u->sink)
+        pa_sink_unref(u->sink);
+
+    if (u->memblockq)
+        pa_memblockq_free(u->memblockq);
+
+    pa_xfree(u);
+}
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