make echo-cancel module that exposes a new sink and source

Make a new echo-cancel module that exposes a new sink and source. All data sent
to the sink is matched against the data captured from the source and
echo-canceled using the speex echo canceler.

2 files changed, 1617 insertions, 0 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index ec301dad..4345e024 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -1017,6 +1017,7 @@ modlibexec_LTLIBRARIES += \
 		module-rescue-streams.la \
 		module-intended-roles.la \
 		module-suspend-on-idle.la \
+		module-echo-cancel.la \
 		module-http-protocol-tcp.la \
 		module-sine.la \
 		module-native-protocol-tcp.la \
@@ -1248,6 +1249,7 @@ SYMDEF_FILES = \
 		modules/module-rescue-streams-symdef.h \
 		modules/module-intended-roles-symdef.h \
 		modules/module-suspend-on-idle-symdef.h \
+		modules/module-echo-cancel-symdef.h \
 		modules/module-hal-detect-symdef.h \
 		modules/module-udev-detect-symdef.h \
 		modules/bluetooth/module-bluetooth-proximity-symdef.h \
@@ -1602,6 +1604,12 @@ module_suspend_on_idle_la_LDFLAGS = $(MODULE_LDFLAGS)
 module_suspend_on_idle_la_LIBADD = $(AM_LIBADD) libpulsecore-@PA_MAJORMINORMICRO@.la libpulsecommon-@PA_MAJORMINORMICRO@.la libpulse.la
 module_suspend_on_idle_la_CFLAGS = $(AM_CFLAGS)
 
+# echo-cancel module
+module_echo_cancel_la_SOURCES = modules/module-echo-cancel.c
+module_echo_cancel_la_LDFLAGS = $(MODULE_LDFLAGS)
+module_echo_cancel_la_LIBADD = $(AM_LIBADD) libpulsecore-@PA_MAJORMINORMICRO@.la libpulsecommon-@PA_MAJORMINORMICRO@.la libpulse.la $(LIBSPEEX_LIBS)
+module_echo_cancel_la_CFLAGS = $(AM_CFLAGS) $(LIBSPEEX_CFLAGS)
+
 # RTP modules
 module_rtp_send_la_SOURCES = modules/rtp/module-rtp-send.c
 module_rtp_send_la_LDFLAGS = $(MODULE_LDFLAGS)
diff --git a/src/modules/module-echo-cancel.c b/src/modules/module-echo-cancel.c
new file mode 100644
index 00000000..3d7a6efb
--- /dev/null
+++ b/src/modules/module-echo-cancel.c
@@ -0,0 +1,1609 @@
+/***
+    This file is part of PulseAudio.
+
+    Copyright 2010 Wim Taymans <wim.taymans@gmail.com>
+
+    Based on module-virtual-sink.c
+             module-virtual-source.c
+             module-loopback.c
+
+        Copyright 2010 Intel Corporation
+        Contributor: Pierre-Louis Bossart <pierre-louis.bossart@intel.com>
+
+    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 <math.h>
+
+#include <speex/speex_echo.h>
+
+#include <pulse/xmalloc.h>
+#include <pulse/i18n.h>
+#include <pulse/timeval.h>
+#include <pulse/rtclock.h>
+
+#include <pulsecore/atomic.h>
+#include <pulsecore/macro.h>
+#include <pulsecore/core-error.h>
+#include <pulsecore/namereg.h>
+#include <pulsecore/sink.h>
+#include <pulsecore/module.h>
+#include <pulsecore/core-rtclock.h>
+#include <pulsecore/core-util.h>
+#include <pulsecore/core-error.h>
+#include <pulsecore/modargs.h>
+#include <pulsecore/log.h>
+#include <pulsecore/thread.h>
+#include <pulsecore/thread-mq.h>
+#include <pulsecore/rtpoll.h>
+#include <pulsecore/sample-util.h>
+#include <pulsecore/ltdl-helper.h>
+
+#include "module-echo-cancel-symdef.h"
+
+PA_MODULE_AUTHOR("Wim Taymans");
+PA_MODULE_DESCRIPTION("Echo Cancelation");
+PA_MODULE_VERSION(PACKAGE_VERSION);
+PA_MODULE_LOAD_ONCE(FALSE);
+PA_MODULE_USAGE(
+        _("source_name=<name for the source> "
+          "source_properties=<properties for the source> "
+          "source_master=<name of source to filter> "
+          "sink_name=<name for the sink> "
+          "sink_properties=<properties for the sink> "
+          "sink_master=<name of sink to filter> "
+          "frame_size_ms=<amount of data to process at one time> "
+          "filter_size_ms=<amount of echo to cancel> "
+          "adjust_time=<how often to readjust rates in s> "
+          "format=<sample format> "
+          "rate=<sample rate> "
+          "channels=<number of channels> "
+          "channel_map=<channel map> "
+          "save_aec=<save AEC data in /tmp> "
+        ));
+
+/* should be between 10-20 ms */
+#define DEFAULT_FRAME_SIZE_MS 20
+/* should be between 100-500 ms */
+#define DEFAULT_FILTER_SIZE_MS 200
+
+#define DEFAULT_ADJUST_TIME_USEC (1*PA_USEC_PER_SEC)
+#define DEFAULT_SAVE_AEC 0
+
+#define MEMBLOCKQ_MAXLENGTH (16*1024*1024)
+
+/* This module creates a new (virtual) source and sink.
+ *
+ * The data sent to the new sink is kept in a memblockq before being
+ * forwarded to the real sink_master.
+ *
+ * Data read from source_master is matched against the saved sink data and
+ * echo canceled data is then pushed onto the new source.
+ *
+ * Both source and sink masters have their own threads to push/pull data
+ * respectively. We however perform all our actions in the source IO thread.
+ * To do this we send all played samples to the source IO thread where they
+ * are then pushed into the memblockq.
+ *
+ * Alignment is performed in two steps:
+ *
+ * 1) when something happens that requires quick adjustement of the alignment of
+ *    capture and playback samples, we perform a resync. This adjusts the
+ *    position in the playback memblock to the requested sample. Quick
+ *    adjustements include moving the playback samples before the capture
+ *    samples (because else the echo canceler does not work) or when the
+ *    playback pointer drifts too far away.
+ *
+ * 2) periodically check the difference between capture and playback. we use a
+ *    low and high watermark for adjusting the alignment. playback should always
+ *    be before capture and the difference should not be bigger than one frame
+ *    size. We would ideally like to resample the sink_input but most driver
+ *    don't give enough accuracy to be able to do that right now.
+ */
+
+struct snapshot {
+    pa_usec_t sink_latency;
+    size_t sink_delay;
+    int64_t send_counter;
+
+    pa_usec_t source_latency;
+    size_t source_delay;
+    int64_t recv_counter;
+    size_t rlen;
+    size_t plen;
+};
+
+struct userdata {
+    pa_core *core;
+    pa_module *module;
+
+    uint32_t frame_size_ms;
+    uint32_t save_aec;
+
+    SpeexEchoState *echo_state;
+
+    size_t blocksize;
+    pa_bool_t need_realign;
+
+    /* to wakeup the source I/O thread */
+    pa_bool_t in_push;
+    pa_asyncmsgq *asyncmsgq;
+    pa_rtpoll_item *rtpoll_item_read, *rtpoll_item_write;
+
+    pa_source *source;
+    pa_bool_t source_auto_desc;
+    pa_source_output *source_output;
+    pa_memblockq *source_memblockq; /* echo canceler needs fixed sized chunks */
+    pa_atomic_t source_active;
+
+    pa_sink *sink;
+    pa_bool_t sink_auto_desc;
+    pa_sink_input *sink_input;
+    pa_memblockq *sink_memblockq;
+    int64_t send_counter;          /* updated in sink IO thread */
+    int64_t recv_counter;
+    pa_atomic_t sink_active;
+
+    pa_atomic_t request_resync;
+
+    pa_time_event *time_event;
+    pa_usec_t adjust_time;
+
+    FILE *captured_file;
+    FILE *played_file;
+    FILE *canceled_file;
+};
+
+static void source_output_snapshot_within_thread(struct userdata *u, struct snapshot *snapshot);
+
+static const char* const valid_modargs[] = {
+    "source_name",
+    "source_properties",
+    "source_master",
+    "sink_name",
+    "sink_properties",
+    "sink_master",
+    "frame_size_ms",
+    "filter_size_ms",
+    "adjust_time",
+    "format",
+    "rate",
+    "channels",
+    "channel_map",
+    "save_aec",
+    NULL
+};
+
+enum {
+    SOURCE_OUTPUT_MESSAGE_POST = PA_SOURCE_OUTPUT_MESSAGE_MAX,
+    SOURCE_OUTPUT_MESSAGE_REWIND,
+    SOURCE_OUTPUT_MESSAGE_LATENCY_SNAPSHOT,
+    SOURCE_OUTPUT_MESSAGE_APPLY_DIFF_TIME
+};
+
+enum {
+    SINK_INPUT_MESSAGE_LATENCY_SNAPSHOT
+};
+
+static int64_t calc_diff(struct userdata *u, struct snapshot *snapshot) {
+    int64_t buffer, diff_time, buffer_latency;
+
+    /* get the number of samples between capture and playback */
+    if (snapshot->plen > snapshot->rlen)
+        buffer = snapshot->plen - snapshot->rlen;
+    else
+        buffer = 0;
+
+    buffer += snapshot->source_delay + snapshot->sink_delay;
+
+    /* add the amount of samples not yet transfered to the source context */
+    if (snapshot->recv_counter <= snapshot->send_counter)
+        buffer += (int64_t) (snapshot->send_counter - snapshot->recv_counter);
+    else
+        buffer += PA_CLIP_SUB(buffer, (int64_t) (snapshot->recv_counter - snapshot->send_counter));
+
+    /* convert to time */
+    buffer_latency = pa_bytes_to_usec(buffer, &u->source_output->sample_spec);
+
+    /* capture and playback samples are perfectly aligned when diff_time is 0 */
+    diff_time = (snapshot->sink_latency - buffer_latency) + snapshot->source_latency;
+
+    pa_log_debug("diff %lld (%lld - %lld + %lld) %lld %lld %lld", (long long) diff_time,
+        (long long) snapshot->sink_latency,
+        (long long) buffer_latency, (long long) snapshot->source_latency,
+        (long long) snapshot->source_delay, (long long) snapshot->sink_delay,
+        (long long) (snapshot->send_counter - snapshot->recv_counter));
+
+    return diff_time;
+}
+
+/* Called from main context */
+static void time_callback(pa_mainloop_api *a, pa_time_event *e, const struct timeval *t, void *userdata) {
+    struct userdata *u = userdata;
+    uint32_t old_rate, base_rate, new_rate;
+    int64_t diff_time;
+    size_t fs;
+    struct snapshot latency_snapshot;
+
+    pa_assert(u);
+    pa_assert(a);
+    pa_assert(u->time_event == e);
+    pa_assert_ctl_context();
+
+    if (pa_atomic_load (&u->sink_active) == 0 || pa_atomic_load (&u->source_active) == 0)
+        goto done;
+
+    /* update our snapshots */
+    pa_asyncmsgq_send(u->source_output->source->asyncmsgq, PA_MSGOBJECT(u->source_output), SOURCE_OUTPUT_MESSAGE_LATENCY_SNAPSHOT, &latency_snapshot, 0, NULL);
+    pa_asyncmsgq_send(u->sink_input->sink->asyncmsgq, PA_MSGOBJECT(u->sink_input), SINK_INPUT_MESSAGE_LATENCY_SNAPSHOT, &latency_snapshot, 0, NULL);
+
+    /* calculate drift between capture and playback */
+    diff_time = calc_diff(u, &latency_snapshot);
+
+    fs = pa_frame_size(&u->source_output->sample_spec);
+    old_rate = u->sink_input->sample_spec.rate;
+    base_rate = u->source_output->sample_spec.rate;
+
+    if (diff_time < 0) {
+        pa_log_info("Playback after capture (%lld), realign", (long long) diff_time);
+        pa_asyncmsgq_post(u->asyncmsgq, PA_MSGOBJECT(u->source_output), SOURCE_OUTPUT_MESSAGE_APPLY_DIFF_TIME,
+            NULL, diff_time, NULL, NULL);
+        /* recording before playback, we need to adjust quickly. The echo
+         * canceler does not work in this case. */
+        //new_rate = base_rate - ((pa_usec_to_bytes (-diff_time, &u->source_output->sample_spec) / fs) * PA_USEC_PER_SEC) / u->adjust_time;
+        new_rate = base_rate;
+    }
+    else {
+        if (diff_time > (u->frame_size_ms / 2) * 1000) {
+            pa_log_info("playback too far ahead (%lld), realign", (long long) diff_time);
+            /* diff too big, quickly adjust */
+            pa_asyncmsgq_post(u->asyncmsgq, PA_MSGOBJECT(u->source_output), SOURCE_OUTPUT_MESSAGE_APPLY_DIFF_TIME,
+                NULL, diff_time, NULL, NULL);
+        }
+
+        /* recording behind playback, we need to slowly adjust the rate to match */
+        //new_rate = base_rate + ((pa_usec_to_bytes (diff_time, &u->source_output->sample_spec) / fs) * PA_USEC_PER_SEC) / u->adjust_time;
+
+        /* assume equal samplerates for now */
+        new_rate = base_rate;
+    }
+
+    /* make sure we don't make too big adjustements because that sounds horrible */
+    if (new_rate > base_rate * 1.1 || new_rate < base_rate * 0.9)
+        new_rate = base_rate;
+
+    if (new_rate != old_rate) {
+        pa_log_info("Old rate %lu Hz, new rate %lu Hz", (unsigned long) old_rate, (unsigned long) new_rate);
+
+        pa_sink_input_set_rate(u->sink_input, new_rate);
+    }
+
+done:
+    pa_core_rttime_restart(u->core, u->time_event, pa_rtclock_now() + u->adjust_time);
+}
+
+/* Called from source I/O thread context */
+static int source_process_msg_cb(pa_msgobject *o, int code, void *data, int64_t offset, pa_memchunk *chunk) {
+    struct userdata *u = PA_SOURCE(o)->userdata;
+
+    switch (code) {
+
+        case PA_SOURCE_MESSAGE_GET_LATENCY:
+
+            /* The source is _put() before the source output is, so let's
+             * make sure we don't access it in that time. Also, the
+             * source output is first shut down, the source second. */
+            if (!PA_SOURCE_IS_LINKED(u->source->thread_info.state) ||
+                !PA_SOURCE_OUTPUT_IS_LINKED(u->source_output->thread_info.state)) {
+                *((pa_usec_t*) data) = 0;
+                return 0;
+            }
+
+            *((pa_usec_t*) data) =
+
+                /* Get the latency of the master source */
+                pa_source_get_latency_within_thread(u->source_output->source) +
+                /* Add the latency internal to our source output on top */
+                pa_bytes_to_usec(pa_memblockq_get_length(u->source_output->thread_info.delay_memblockq), &u->source_output->source->sample_spec) +
+                /* and the buffering we do on the source */
+                pa_bytes_to_usec(u->blocksize, &u->source_output->source->sample_spec);
+
+            return 0;
+
+    }
+
+    return pa_source_process_msg(o, code, data, offset, chunk);
+}
+
+/* Called from sink 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;
+            }
+
+            *((pa_usec_t*) data) =
+
+                /* Get the latency of the master sink */
+                pa_sink_get_latency_within_thread(u->sink_input->sink) +
+
+                /* Add the latency internal to our sink input on top */
+                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 source_set_state_cb(pa_source *s, pa_source_state_t state) {
+    struct userdata *u;
+
+    pa_source_assert_ref(s);
+    pa_assert_se(u = s->userdata);
+
+    if (!PA_SOURCE_IS_LINKED(state) ||
+        !PA_SOURCE_OUTPUT_IS_LINKED(pa_source_output_get_state(u->source_output)))
+        return 0;
+
+    pa_log_debug("Source state %d", state);
+
+    if (state == PA_SOURCE_RUNNING) {
+        pa_atomic_store (&u->source_active, 1);
+        pa_atomic_store (&u->request_resync, 1);
+        pa_source_output_cork(u->source_output, FALSE);
+    } else if (state == PA_SOURCE_SUSPENDED) {
+        pa_atomic_store (&u->source_active, 0);
+        pa_source_output_cork(u->source_output, TRUE);
+    }
+    return 0;
+}
+
+/* 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_log_debug("Sink state %d", state);
+
+    if (state == PA_SINK_RUNNING) {
+        pa_atomic_store (&u->sink_active, 1);
+        pa_atomic_store (&u->request_resync, 1);
+        pa_sink_input_cork(u->sink_input, FALSE);
+    } else if (state == PA_SINK_SUSPENDED) {
+        pa_atomic_store (&u->sink_active, 0);
+        pa_sink_input_cork(u->sink_input, TRUE);
+    }
+    return 0;
+}
+
+/* Called from I/O thread context */
+static void source_update_requested_latency_cb(pa_source *s) {
+    struct userdata *u;
+
+    pa_source_assert_ref(s);
+    pa_assert_se(u = s->userdata);
+
+    if (!PA_SOURCE_IS_LINKED(u->source->thread_info.state) ||
+        !PA_SOURCE_OUTPUT_IS_LINKED(u->source_output->thread_info.state))
+        return;
+
+    pa_log_debug("Source update requested latency");
+
+    /* Just hand this one over to the master source */
+    pa_source_output_set_requested_latency_within_thread(
+            u->source_output,
+            pa_source_get_requested_latency_within_thread(s));
+}
+
+/* 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;
+
+    pa_log_debug("Sink update requested latency");
+
+    /* 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 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;
+
+    pa_log_debug("Sink request rewind %lld", (long long) s->thread_info.rewind_nbytes);
+
+    /* Just hand this one over to the master sink */
+    pa_sink_input_request_rewind(u->sink_input,
+                                 s->thread_info.rewind_nbytes, TRUE, FALSE, FALSE);
+}
+
+/* Called from main context */
+static void source_set_volume_cb(pa_source *s) {
+    struct userdata *u;
+
+    pa_source_assert_ref(s);
+    pa_assert_se(u = s->userdata);
+
+    if (!PA_SOURCE_IS_LINKED(pa_source_get_state(s)) ||
+        !PA_SOURCE_OUTPUT_IS_LINKED(pa_source_output_get_state(u->source_output)))
+        return;
+
+    /* FIXME, no volume control in source_output, set volume at the master */
+    pa_source_set_volume(u->source_output->source, &s->volume, TRUE);
+}
+
+/* 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);
+}
+
+static void source_get_volume_cb(pa_source *s) {
+    struct userdata *u;
+
+    pa_source_assert_ref(s);
+    pa_assert_se(u = s->userdata);
+
+    if (!PA_SOURCE_IS_LINKED(pa_source_get_state(s)) ||
+        !PA_SOURCE_OUTPUT_IS_LINKED(pa_source_output_get_state(u->source_output)))
+        return;
+
+    /* FIXME, no volume control in source_output, get the info from the master */
+    pa_source_get_volume(u->source_output->source, TRUE);
+
+    if (pa_cvolume_equal(&s->volume,&u->source_output->source->volume))
+        /* no change */
+        return;
+
+    s->volume = u->source_output->source->volume;
+    pa_source_set_soft_volume(s, NULL);
+}
+
+
+/* Called from main context */
+static void source_set_mute_cb(pa_source *s) {
+    struct userdata *u;
+
+    pa_source_assert_ref(s);
+    pa_assert_se(u = s->userdata);
+
+    if (!PA_SOURCE_IS_LINKED(pa_source_get_state(s)) ||
+        !PA_SOURCE_OUTPUT_IS_LINKED(pa_source_output_get_state(u->source_output)))
+        return;
+
+    /* FIXME, no volume control in source_output, set mute at the master */
+    pa_source_set_mute(u->source_output->source, TRUE, 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);
+}
+
+/* Called from main context */
+static void source_get_mute_cb(pa_source *s) {
+    struct userdata *u;
+
+    pa_source_assert_ref(s);
+    pa_assert_se(u = s->userdata);
+
+    if (!PA_SOURCE_IS_LINKED(pa_source_get_state(s)) ||
+        !PA_SOURCE_OUTPUT_IS_LINKED(pa_source_output_get_state(u->source_output)))
+        return;
+
+    /* FIXME, no volume control in source_output, get the info from the master */
+    pa_source_get_mute(u->source_output->source, TRUE);
+}
+
+/* must be called from the input thread context */
+static void apply_diff_time(struct userdata *u, int64_t diff_time) {
+    int64_t diff;
+
+    if (diff_time < 0) {
+        diff = pa_usec_to_bytes (-diff_time, &u->source_output->sample_spec);
+
+        pa_log_debug("drop sink (%lld)", (long long) diff);
+
+        /* go forwards on the read side */
+        pa_memblockq_drop(u->sink_memblockq, diff);
+    } else {
+        diff = pa_usec_to_bytes (diff_time, &u->source_output->sample_spec);
+
+        pa_log_debug("drop source (%lld)", (long long) diff);
+
+        /* go back on the read side */
+        pa_memblockq_rewind(u->sink_memblockq, diff);
+    }
+}
+
+/* must be called from the input thread */
+static void do_resync(struct userdata *u) {
+    int64_t diff_time;
+    struct snapshot latency_snapshot;
+
+    pa_log("Doing resync");
+
+    /* update our snapshot */
+    source_output_snapshot_within_thread(u, &latency_snapshot);
+    pa_asyncmsgq_send(u->sink_input->sink->asyncmsgq, PA_MSGOBJECT(u->sink_input), SINK_INPUT_MESSAGE_LATENCY_SNAPSHOT, &latency_snapshot, 0, NULL);
+
+    /* calculate drift between capture and playback */
+    diff_time = calc_diff(u, &latency_snapshot);
+
+    /* and adjust for the drift */
+    apply_diff_time(u, diff_time);
+}
+
+/* Called from input thread context */
+static void source_output_push_cb(pa_source_output *o, const pa_memchunk *chunk) {
+    struct userdata *u;
+    size_t rlen, plen;
+
+    pa_source_output_assert_ref(o);
+    pa_source_output_assert_io_context(o);
+    pa_assert_se(u = o->userdata);
+
+    if (!PA_SOURCE_OUTPUT_IS_LINKED(pa_source_output_get_state(u->source_output))) {
+        pa_log("push when no link?");
+        return;
+    }
+
+    /* handle queued messages */
+    u->in_push = TRUE;
+    while (pa_asyncmsgq_process_one(u->asyncmsgq) > 0)
+        ;
+    u->in_push = FALSE;
+
+    if (pa_atomic_load (&u->request_resync) == 1) {
+        do_resync (u);
+        pa_atomic_store (&u->request_resync, 0);
+    }
+
+    pa_memblockq_push_align(u->source_memblockq, chunk);
+
+    rlen = pa_memblockq_get_length(u->source_memblockq);
+    plen = pa_memblockq_get_length(u->sink_memblockq);
+
+    while (rlen >= u->blocksize) {
+        pa_memchunk rchunk, pchunk;
+
+        /* take fixed block from recorded samples */
+        pa_memblockq_peek_fixed_size(u->source_memblockq, u->blocksize, &rchunk);
+
+        if (plen > u->blocksize) {
+            uint8_t *rdata, *pdata, *cdata;
+            pa_memchunk cchunk;
+
+            /* take fixed block from played samples */
+            pa_memblockq_peek_fixed_size(u->sink_memblockq, u->blocksize, &pchunk);
+
+            rdata = pa_memblock_acquire(rchunk.memblock);
+            rdata += rchunk.index;
+            pdata = pa_memblock_acquire(pchunk.memblock);
+            pdata += pchunk.index;
+
+            cchunk.index = 0;
+            cchunk.length = u->blocksize;
+            cchunk.memblock = pa_memblock_new(u->source->core->mempool, cchunk.length);
+            cdata = pa_memblock_acquire(cchunk.memblock);
+
+            /* perform echo cancelation */
+            speex_echo_cancellation(u->echo_state, (const spx_int16_t *) rdata,
+                (const spx_int16_t *) pdata, (spx_int16_t *) cdata);
+
+            if (u->save_aec) {
+                if (u->captured_file)
+                    fwrite(rdata, 1, u->blocksize, u->captured_file);
+                if (u->played_file)
+                    fwrite(pdata, 1, u->blocksize, u->played_file);
+                if (u->canceled_file)
+                    fwrite(cdata, 1, u->blocksize, u->canceled_file);
+                pa_log_debug("AEC frame saved.");
+            }
+
+            pa_memblock_release(cchunk.memblock);
+            pa_memblock_release(pchunk.memblock);
+            pa_memblock_release(rchunk.memblock);
+
+            /* drop consumed sink samples */
+            pa_memblockq_drop(u->sink_memblockq, u->blocksize);
+            pa_memblock_unref(pchunk.memblock);
+
+            pa_memblock_unref(rchunk.memblock);
+            /* the filtered samples now become the samples from our
+             * source */
+            rchunk = cchunk;
+
+            plen -= u->blocksize;
+        } else {
+            /* not enough played samples to perform echo cancelation,
+             * drop what we have */
+            pa_memblockq_drop(u->sink_memblockq, u->blocksize - plen);
+            plen = 0;
+        }
+
+        /* forward the (echo-canceled) data to the virtual source */
+        pa_source_post(u->source, &rchunk);
+        pa_memblock_unref(rchunk.memblock);
+
+        pa_memblockq_drop(u->source_memblockq, u->blocksize);
+
+        rlen -= u->blocksize;
+    }
+}
+
+/* Called from I/O thread context */
+static int sink_input_pop_cb(pa_sink_input *i, size_t nbytes, pa_memchunk *chunk) {
+    struct userdata *u;
+
+    pa_sink_input_assert_ref(i);
+    pa_assert(chunk);
+    pa_assert_se(u = i->userdata);
+
+    if (u->sink->thread_info.rewind_requested)
+        pa_sink_process_rewind(u->sink, 0);
+
+    pa_sink_render_full(u->sink, nbytes, chunk);
+
+    if (i->thread_info.underrun_for > 0) {
+        pa_log_debug("Handling end of underrun.");
+        pa_atomic_store (&u->request_resync, 1);
+    }
+
+    /* let source thread handle the chunk. pass the sample count as well so that
+     * the source IO thread can update the right variables. */
+    pa_asyncmsgq_post(u->asyncmsgq, PA_MSGOBJECT(u->source_output), SOURCE_OUTPUT_MESSAGE_POST,
+        NULL, 0, chunk, NULL);
+    u->send_counter += chunk->length;
+
+    return 0;
+}
+
+/* Called from input thread context */
+static void source_output_process_rewind_cb(pa_source_output *o, size_t nbytes) {
+    struct userdata *u;
+
+    pa_source_output_assert_ref(o);
+    pa_source_output_assert_io_context(o);
+    pa_assert_se(u = o->userdata);
+
+    pa_source_process_rewind(u->source, nbytes);
+
+    /* go back on read side, we need to use older sink data for this */
+    pa_memblockq_rewind(u->sink_memblockq, nbytes);
+
+    /* manipulate write index */
+    pa_memblockq_seek(u->source_memblockq, -nbytes, PA_SEEK_RELATIVE, TRUE);
+
+    pa_log_debug("Source rewind (%lld) %lld", (long long) nbytes,
+        (long long) pa_memblockq_get_length (u->source_memblockq));
+}
+
+/* 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);
+
+    pa_log_debug("Sink process rewind %lld", (long long) nbytes);
+
+    if (u->sink->thread_info.rewind_nbytes > 0) {
+        amount = PA_MIN(u->sink->thread_info.rewind_nbytes, nbytes);
+        u->sink->thread_info.rewind_nbytes = 0;
+    }
+
+    pa_sink_process_rewind(u->sink, amount);
+
+    pa_asyncmsgq_post(u->asyncmsgq, PA_MSGOBJECT(u->source_output), SOURCE_OUTPUT_MESSAGE_REWIND, NULL, (int64_t) nbytes, NULL, NULL);
+    u->send_counter -= nbytes;
+}
+
+static void source_output_snapshot_within_thread(struct userdata *u, struct snapshot *snapshot) {
+    size_t delay, rlen, plen;
+    pa_usec_t latency;
+
+    latency = pa_source_get_latency_within_thread(u->source_output->source);
+    delay = pa_memblockq_get_length(u->source_output->thread_info.delay_memblockq);
+
+    delay = (u->source_output->thread_info.resampler ? pa_resampler_request(u->source_output->thread_info.resampler, delay) : delay);
+    rlen = pa_memblockq_get_length(u->source_memblockq);
+    plen = pa_memblockq_get_length(u->sink_memblockq);
+
+    snapshot->source_latency = latency;
+    snapshot->source_delay = delay;
+    snapshot->recv_counter = u->recv_counter;
+    snapshot->rlen = rlen;
+    snapshot->plen = plen;
+}
+
+
+/* Called from output thread context */
+static int source_output_process_msg_cb(pa_msgobject *obj, int code, void *data, int64_t offset, pa_memchunk *chunk) {
+    struct userdata *u = PA_SOURCE_OUTPUT(obj)->userdata;
+
+    switch (code) {
+
+        case SOURCE_OUTPUT_MESSAGE_POST:
+
+            pa_source_output_assert_io_context(u->source_output);
+
+            if (PA_SOURCE_IS_OPENED(u->source_output->source->thread_info.state))
+                pa_memblockq_push_align(u->sink_memblockq, chunk);
+            else
+                pa_memblockq_flush_write(u->sink_memblockq, TRUE);
+
+            u->recv_counter += (int64_t) chunk->length;
+
+            return 0;
+
+        case SOURCE_OUTPUT_MESSAGE_REWIND:
+            pa_source_output_assert_io_context(u->source_output);
+
+            /* manipulate write index, never go past what we have */
+            if (PA_SOURCE_IS_OPENED(u->source_output->source->thread_info.state))
+                pa_memblockq_seek(u->sink_memblockq, -offset, PA_SEEK_RELATIVE, TRUE);
+            else
+                pa_memblockq_flush_write(u->sink_memblockq, TRUE);
+
+            pa_log_debug("Sink rewind (%lld)", (long long) offset);
+
+            u->recv_counter -= offset;
+
+            return 0;
+
+        case SOURCE_OUTPUT_MESSAGE_LATENCY_SNAPSHOT: {
+            struct snapshot *snapshot = (struct snapshot *) data;
+
+            source_output_snapshot_within_thread(u, snapshot);
+            return 0;
+        }
+
+        case SOURCE_OUTPUT_MESSAGE_APPLY_DIFF_TIME:
+            apply_diff_time(u, offset);
+            return 0;
+
+    }
+
+    return pa_source_output_process_msg(obj, code, data, offset, chunk);
+}
+
+static int sink_input_process_msg_cb(pa_msgobject *obj, int code, void *data, int64_t offset, pa_memchunk *chunk) {
+    struct userdata *u = PA_SINK_INPUT(obj)->userdata;
+
+    switch (code) {
+
+        case SINK_INPUT_MESSAGE_LATENCY_SNAPSHOT: {
+            size_t delay;
+            pa_usec_t latency;
+            struct snapshot *snapshot = (struct snapshot *) data;
+
+            pa_sink_input_assert_io_context(u->sink_input);
+
+            latency = pa_sink_get_latency_within_thread(u->sink_input->sink);
+            delay = pa_memblockq_get_length(u->sink_input->thread_info.render_memblockq);
+
+            delay = (u->sink_input->thread_info.resampler ? pa_resampler_request(u->sink_input->thread_info.resampler, delay) : delay);
+
+            snapshot->sink_latency = latency;
+            snapshot->sink_delay = delay;
+            snapshot->send_counter = u->send_counter;
+            return 0;
+        }
+    }
+
+    return pa_sink_input_process_msg(obj, code, data, offset, chunk);
+}
+
+/* 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);
+
+    pa_log_debug("Sink input update max rewind %lld", (long long) nbytes);
+
+    pa_sink_set_max_rewind_within_thread(u->sink, nbytes);
+}
+
+/* Called from I/O thread context */
+static void source_output_update_max_rewind_cb(pa_source_output *o, size_t nbytes) {
+    struct userdata *u;
+
+    pa_source_output_assert_ref(o);
+    pa_assert_se(u = o->userdata);
+
+    pa_log_debug("Source output update max rewind %lld", (long long) nbytes);
+
+    pa_source_set_max_rewind_within_thread(u->source, 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);
+
+    pa_log_debug("Sink input update max rewind %lld", (long long) nbytes);
+
+    pa_sink_set_max_request_within_thread(u->sink, nbytes);
+}
+
+/* Called from I/O thread context */
+static void sink_input_update_sink_requested_latency_cb(pa_sink_input *i) {
+    struct userdata *u;
+    pa_usec_t latency;
+
+    pa_sink_input_assert_ref(i);
+    pa_assert_se(u = i->userdata);
+
+    latency = pa_sink_get_requested_latency_within_thread(i->sink);
+
+    pa_log_debug("Sink input update requested latency %lld", (long long) latency);
+    pa_atomic_store (&u->request_resync, 1);
+}
+
+/* Called from I/O thread context */
+static void source_output_update_source_requested_latency_cb(pa_source_output *o) {
+    struct userdata *u;
+    pa_usec_t latency;
+
+    pa_source_output_assert_ref(o);
+    pa_assert_se(u = o->userdata);
+
+    latency = pa_source_get_requested_latency_within_thread(o->source);
+
+    pa_log_debug("source output update requested latency %lld", (long long) latency);
+    pa_atomic_store (&u->request_resync, 1);
+}
+
+/* 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_log_debug("Sink input update latency range %lld %lld",
+        (long long) i->sink->thread_info.min_latency,
+        (long long) i->sink->thread_info.max_latency);
+
+    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 source_output_update_source_latency_range_cb(pa_source_output *o) {
+    struct userdata *u;
+
+    pa_source_output_assert_ref(o);
+    pa_assert_se(u = o->userdata);
+
+    pa_log_debug("Source output update latency range %lld %lld",
+        (long long) o->source->thread_info.min_latency,
+        (long long) o->source->thread_info.max_latency);
+
+    pa_source_set_latency_range_within_thread(u->source, o->source->thread_info.min_latency, o->source->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);
+
+    pa_log_debug("Sink input update fixed latency %lld",
+        (long long) i->sink->thread_info.fixed_latency);
+
+    pa_sink_set_fixed_latency_within_thread(u->sink, i->sink->thread_info.fixed_latency);
+}
+
+/* Called from I/O thread context */
+static void source_output_update_source_fixed_latency_cb(pa_source_output *o) {
+    struct userdata *u;
+
+    pa_source_output_assert_ref(o);
+    pa_assert_se(u = o->userdata);
+
+    pa_log_debug("Source output update fixed latency %lld",
+        (long long) o->source->thread_info.fixed_latency);
+
+    pa_source_set_fixed_latency_within_thread(u->source, o->source->thread_info.fixed_latency);
+}
+
+/* Called from output thread context */
+static void source_output_attach_cb(pa_source_output *o) {
+    struct userdata *u;
+
+    pa_source_output_assert_ref(o);
+    pa_source_output_assert_io_context(o);
+    pa_assert_se(u = o->userdata);
+
+    pa_source_set_rtpoll(u->source, o->source->thread_info.rtpoll);
+    pa_source_set_latency_range_within_thread(u->source, o->source->thread_info.min_latency, o->source->thread_info.max_latency);
+    pa_source_set_fixed_latency_within_thread(u->source, o->source->thread_info.fixed_latency);
+    pa_source_set_max_rewind_within_thread(u->source, pa_source_output_get_max_rewind(o));
+
+    pa_log_debug("Source output %p attach", o);
+
+    pa_source_attach_within_thread(u->source);
+
+    u->rtpoll_item_read = pa_rtpoll_item_new_asyncmsgq_read(
+            o->source->thread_info.rtpoll,
+            PA_RTPOLL_LATE,
+            u->asyncmsgq);
+}
+
+/* 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));
+    pa_sink_set_max_rewind_within_thread(u->sink, pa_sink_input_get_max_rewind(i));
+
+    pa_log_debug("Sink input %p attach", i);
+
+    u->rtpoll_item_write = pa_rtpoll_item_new_asyncmsgq_write(
+            i->sink->thread_info.rtpoll,
+            PA_RTPOLL_LATE,
+            u->asyncmsgq);
+
+    pa_sink_attach_within_thread(u->sink);
+}
+
+
+/* Called from output thread context */
+static void source_output_detach_cb(pa_source_output *o) {
+    struct userdata *u;
+
+    pa_source_output_assert_ref(o);
+    pa_source_output_assert_io_context(o);
+    pa_assert_se(u = o->userdata);
+
+    pa_source_detach_within_thread(u->source);
+    pa_source_set_rtpoll(u->source, NULL);
+
+    pa_log_debug("Source output %p detach", o);
+
+    if (u->rtpoll_item_read) {
+        pa_rtpoll_item_free(u->rtpoll_item_read);
+        u->rtpoll_item_read = NULL;
+    }
+}
+
+/* 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);
+
+    pa_log_debug("Sink input %p detach", i);
+
+    if (u->rtpoll_item_write) {
+        pa_rtpoll_item_free(u->rtpoll_item_write);
+        u->rtpoll_item_write = NULL;
+    }
+}
+
+/* Called from output thread context */
+static void source_output_state_change_cb(pa_source_output *o, pa_source_output_state_t state) {
+    struct userdata *u;
+
+    pa_source_output_assert_ref(o);
+    pa_source_output_assert_io_context(o);
+    pa_assert_se(u = o->userdata);
+
+    pa_log_debug("Source output %p state %d", o, state);
+}
+
+/* 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);
+
+    pa_log_debug("Sink input %p state %d", i, state);
+
+    /* 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 thread */
+static void source_output_kill_cb(pa_source_output *o) {
+    struct userdata *u;
+
+    pa_source_output_assert_ref(o);
+    pa_assert_ctl_context();
+    pa_assert_se(u = o->userdata);
+
+    /* The order here matters! We first kill the source output, followed
+     * by the source. That means the source callbacks must be protected
+     * against an unconnected source output! */
+    pa_source_output_unlink(u->source_output);
+    pa_source_unlink(u->source);
+
+    pa_source_output_unref(u->source_output);
+    u->source_output = NULL;
+
+    pa_source_unref(u->source);
+    u->source = NULL;
+
+    pa_log_debug("Source output kill %p", o);
+
+    pa_module_unload_request(u->module, TRUE);
+}
+
+/* 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_log_debug("Sink input kill %p", i);
+
+    pa_module_unload_request(u->module, TRUE);
+}
+
+/* Called from main thread */
+static pa_bool_t source_output_may_move_to_cb(pa_source_output *o, pa_source *dest) {
+    struct userdata *u;
+
+    pa_source_output_assert_ref(o);
+    pa_assert_ctl_context();
+    pa_assert_se(u = o->userdata);
+
+    return 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 thread */
+static void source_output_moving_cb(pa_source_output *o, pa_source *dest) {
+    struct userdata *u;
+
+    pa_source_output_assert_ref(o);
+    pa_assert_ctl_context();
+    pa_assert_se(u = o->userdata);
+
+    if (dest) {
+        pa_source_set_asyncmsgq(u->source, dest->asyncmsgq);
+        pa_source_update_flags(u->source, PA_SOURCE_LATENCY|PA_SOURCE_DYNAMIC_LATENCY, dest->flags);
+    } else
+        pa_source_set_asyncmsgq(u->source, NULL);
+
+    if (u->source_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, "Echo-Cancel Source %s on %s",
+                         pa_proplist_gets(u->source->proplist, "device.echo-cancel.name"), z ? z : dest->name);
+
+        pa_source_update_proplist(u->source, PA_UPDATE_REPLACE, pl);
+        pa_proplist_free(pl);
+    }
+}
+
+/* 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->sink_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, "Echo-Cancel Sink %s on %s",
+                         pa_proplist_gets(u->sink->proplist, "device.echo-cancel.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_sample_spec ss;
+    pa_channel_map map;
+    pa_modargs *ma;
+    pa_source *source_master=NULL;
+    pa_sink *sink_master=NULL;
+    pa_source_output_new_data source_output_data;
+    pa_sink_input_new_data sink_input_data;
+    pa_source_new_data source_data;
+    pa_sink_new_data sink_data;
+    pa_memchunk silence;
+    int framelen, rate;
+    uint32_t frame_size_ms, filter_size_ms;
+    uint32_t adjust_time_sec;
+
+    pa_assert(m);
+
+    if (!(ma = pa_modargs_new(m->argument, valid_modargs))) {
+        pa_log("Failed to parse module arguments.");
+        goto fail;
+    }
+
+    if (!(source_master = pa_namereg_get(m->core, pa_modargs_get_value(ma, "source_master", NULL), PA_NAMEREG_SOURCE))) {
+        pa_log("Master source not found");
+        goto fail;
+    }
+    pa_assert(source_master);
+
+    if (!(sink_master = pa_namereg_get(m->core, pa_modargs_get_value(ma, "sink_master", NULL), PA_NAMEREG_SINK))) {
+        pa_log("Master sink not found");
+        goto fail;
+    }
+    pa_assert(sink_master);
+
+    frame_size_ms = DEFAULT_FRAME_SIZE_MS;
+    if (pa_modargs_get_value_u32(ma, "frame_size_ms", &frame_size_ms) < 0 || frame_size_ms < 1 || frame_size_ms > 200) {
+        pa_log("Invalid frame_size_ms specification");
+        goto fail;
+    }
+
+    filter_size_ms = DEFAULT_FILTER_SIZE_MS;
+    if (pa_modargs_get_value_u32(ma, "filter_size_ms", &filter_size_ms) < 0 || filter_size_ms < 1 || filter_size_ms > 2000) {
+        pa_log("Invalid filter_size_ms specification");
+        goto fail;
+    }
+
+    ss = source_master->sample_spec;
+    ss.format = PA_SAMPLE_S16LE;
+    map = source_master->channel_map;
+    if (pa_modargs_get_sample_spec_and_channel_map(ma, &ss, &map, PA_CHANNEL_MAP_DEFAULT) < 0) {
+        pa_log("Invalid sample format specification or channel map");
+        goto fail;
+    }
+
+    u = pa_xnew0(struct userdata, 1);
+    if (!u) {
+        pa_log("Failed to alloc userdata");
+        goto fail;
+    }
+    u->core = m->core;
+    u->module = m;
+    m->userdata = u;
+    u->frame_size_ms = frame_size_ms;
+    rate = ss.rate;
+    framelen = (rate * frame_size_ms) / 1000;
+    u->blocksize = framelen * pa_frame_size (&ss);
+    pa_log_debug ("Using framelen %d, blocksize %lld, channels %d, rate %d", framelen, (long long) u->blocksize,
+        ss.channels, ss.rate);
+
+    adjust_time_sec = DEFAULT_ADJUST_TIME_USEC / PA_USEC_PER_SEC;
+    if (pa_modargs_get_value_u32(ma, "adjust_time", &adjust_time_sec) < 0) {
+        pa_log("Failed to parse adjust_time value");
+        goto fail;
+    }
+
+    if (adjust_time_sec != DEFAULT_ADJUST_TIME_USEC / PA_USEC_PER_SEC)
+        u->adjust_time = adjust_time_sec * PA_USEC_PER_SEC;
+    else
+        u->adjust_time = DEFAULT_ADJUST_TIME_USEC;
+
+    u->save_aec = DEFAULT_SAVE_AEC;
+    if (pa_modargs_get_value_u32(ma, "save_aec", &u->save_aec) < 0) {
+        pa_log("Failed to parse save_aec value");
+        goto fail;
+    }
+
+    u->asyncmsgq = pa_asyncmsgq_new(0);
+    u->need_realign = TRUE;
+    u->echo_state = speex_echo_state_init_mc (framelen, (rate * filter_size_ms) / 1000, ss.channels, ss.channels);
+    speex_echo_ctl(u->echo_state, SPEEX_ECHO_SET_SAMPLING_RATE, &rate);
+
+    /* Create source */
+    pa_source_new_data_init(&source_data);
+    source_data.driver = __FILE__;
+    source_data.module = m;
+    if (!(source_data.name = pa_xstrdup(pa_modargs_get_value(ma, "source_name", NULL))))
+        source_data.name = pa_sprintf_malloc("%s.echo-cancel", source_master->name);
+    pa_source_new_data_set_sample_spec(&source_data, &ss);
+    pa_source_new_data_set_channel_map(&source_data, &map);
+    pa_proplist_sets(source_data.proplist, PA_PROP_DEVICE_MASTER_DEVICE, source_master->name);
+    pa_proplist_sets(source_data.proplist, PA_PROP_DEVICE_CLASS, "filter");
+    pa_proplist_sets(source_data.proplist, "device.echo-cancel.name", source_data.name);
+
+    if (pa_modargs_get_proplist(ma, "source_properties", source_data.proplist, PA_UPDATE_REPLACE) < 0) {
+        pa_log("Invalid properties");
+        pa_source_new_data_done(&source_data);
+        goto fail;
+    }
+
+    if ((u->source_auto_desc = !pa_proplist_contains(source_data.proplist, PA_PROP_DEVICE_DESCRIPTION))) {
+        const char *z;
+
+        z = pa_proplist_gets(source_master->proplist, PA_PROP_DEVICE_DESCRIPTION);
+        pa_proplist_setf(source_data.proplist, PA_PROP_DEVICE_DESCRIPTION, "Echo-Cancel Source %s on %s", source_data.name, z ? z : source_master->name);
+    }
+
+    u->source = pa_source_new(m->core, &source_data,
+                          PA_SOURCE_HW_MUTE_CTRL|PA_SOURCE_HW_VOLUME_CTRL|PA_SOURCE_DECIBEL_VOLUME|
+                          (source_master->flags & (PA_SOURCE_LATENCY|PA_SOURCE_DYNAMIC_LATENCY)));
+    pa_source_new_data_done(&source_data);
+
+    if (!u->source) {
+        pa_log("Failed to create source.");
+        goto fail;
+    }
+
+    u->source->parent.process_msg = source_process_msg_cb;
+    u->source->set_state = source_set_state_cb;
+    u->source->update_requested_latency = source_update_requested_latency_cb;
+    u->source->set_volume = source_set_volume_cb;
+    u->source->set_mute = source_set_mute_cb;
+    u->source->get_volume = source_get_volume_cb;
+    u->source->get_mute = source_get_mute_cb;
+    u->source->userdata = u;
+
+    pa_source_set_asyncmsgq(u->source, source_master->asyncmsgq);
+
+    /* 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.echo-cancel", sink_master->name);
+    pa_sink_new_data_set_sample_spec(&sink_data, &ss);
+    pa_sink_new_data_set_channel_map(&sink_data, &map);
+    pa_proplist_sets(sink_data.proplist, PA_PROP_DEVICE_MASTER_DEVICE, sink_master->name);
+    pa_proplist_sets(sink_data.proplist, PA_PROP_DEVICE_CLASS, "filter");
+    pa_proplist_sets(sink_data.proplist, "device.echo-cancel.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->sink_auto_desc = !pa_proplist_contains(sink_data.proplist, PA_PROP_DEVICE_DESCRIPTION))) {
+        const char *z;
+
+        z = pa_proplist_gets(sink_master->proplist, PA_PROP_DEVICE_DESCRIPTION);
+        pa_proplist_setf(sink_data.proplist, PA_PROP_DEVICE_DESCRIPTION, "Echo-Cancel Sink %s on %s", sink_data.name, z ? z : sink_master->name);
+    }
+
+    u->sink = pa_sink_new(m->core, &sink_data,
+                          PA_SINK_HW_MUTE_CTRL|PA_SINK_HW_VOLUME_CTRL|PA_SINK_DECIBEL_VOLUME|
+                          (sink_master->flags & (PA_SINK_LATENCY|PA_SINK_DYNAMIC_LATENCY)));
+    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;
+    u->sink->set_volume = sink_set_volume_cb;
+    u->sink->set_mute = sink_set_mute_cb;
+    u->sink->userdata = u;
+
+    pa_sink_set_asyncmsgq(u->sink, sink_master->asyncmsgq);
+
+    /* Create source output */
+    pa_source_output_new_data_init(&source_output_data);
+    source_output_data.driver = __FILE__;
+    source_output_data.module = m;
+    source_output_data.source = source_master;
+    /* FIXME
+       source_output_data.flags = PA_SOURCE_OUTPUT_DONT_INHIBIT_AUTO_SUSPEND; */
+
+    pa_proplist_sets(source_output_data.proplist, PA_PROP_MEDIA_NAME, "Echo-Cancel Source Stream");
+    pa_proplist_sets(source_output_data.proplist, PA_PROP_MEDIA_ROLE, "filter");
+    pa_source_output_new_data_set_sample_spec(&source_output_data, &ss);
+    pa_source_output_new_data_set_channel_map(&source_output_data, &map);
+
+    pa_source_output_new(&u->source_output, m->core, &source_output_data);
+    pa_source_output_new_data_done(&source_output_data);
+
+    if (!u->source_output)
+        goto fail;
+
+    u->source_output->parent.process_msg = source_output_process_msg_cb;
+    u->source_output->push = source_output_push_cb;
+    u->source_output->process_rewind = source_output_process_rewind_cb;
+    u->source_output->update_max_rewind = source_output_update_max_rewind_cb;
+    u->source_output->update_source_requested_latency = source_output_update_source_requested_latency_cb;
+    u->source_output->update_source_latency_range = source_output_update_source_latency_range_cb;
+    u->source_output->update_source_fixed_latency = source_output_update_source_fixed_latency_cb;
+    u->source_output->kill = source_output_kill_cb;
+    u->source_output->attach = source_output_attach_cb;
+    u->source_output->detach = source_output_detach_cb;
+    u->source_output->state_change = source_output_state_change_cb;
+    u->source_output->may_move_to = source_output_may_move_to_cb;
+    u->source_output->moving = source_output_moving_cb;
+    u->source_output->userdata = u;
+
+    /* Create sink input */
+    pa_sink_input_new_data_init(&sink_input_data);
+    sink_input_data.driver = __FILE__;
+    sink_input_data.module = m;
+    sink_input_data.sink = sink_master;
+    pa_proplist_sets(sink_input_data.proplist, PA_PROP_MEDIA_NAME, "Echo-Cancel Sink Stream");
+    pa_proplist_sets(sink_input_data.proplist, PA_PROP_MEDIA_ROLE, "filter");
+    pa_sink_input_new_data_set_sample_spec(&sink_input_data, &ss);
+    pa_sink_input_new_data_set_channel_map(&sink_input_data, &map);
+    sink_input_data.flags = PA_SINK_INPUT_VARIABLE_RATE;
+
+    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->parent.process_msg = sink_input_process_msg_cb;
+    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_requested_latency = sink_input_update_sink_requested_latency_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 = sink_input_volume_changed_cb;
+    u->sink_input->mute_changed = sink_input_mute_changed_cb;
+    u->sink_input->userdata = u;
+
+    pa_sink_input_get_silence(u->sink_input, &silence);
+
+    u->source_memblockq = pa_memblockq_new(0, MEMBLOCKQ_MAXLENGTH, 0,
+        pa_frame_size(&ss), 1, 1, 0, &silence);
+    u->sink_memblockq = pa_memblockq_new(0, MEMBLOCKQ_MAXLENGTH, 0,
+        pa_frame_size(&ss), 1, 1, 0, &silence);
+
+    pa_memblock_unref(silence.memblock);
+
+    if (!u->source_memblockq || !u->sink_memblockq) {
+        pa_log("Failed to create memblockq.");
+        goto fail;
+    }
+
+    if (u->adjust_time > 0)
+        u->time_event = pa_core_rttime_new(m->core, pa_rtclock_now() + u->adjust_time, time_callback, u);
+
+    if (u->save_aec) {
+        pa_log("Creating AEC files in /tmp");
+        u->captured_file = fopen("/tmp/aec_rec.sw", "wb");
+        if (u->captured_file == NULL)
+            perror ("fopen failed");
+        u->played_file = fopen("/tmp/aec_play.sw", "wb");
+        if (u->played_file == NULL)
+            perror ("fopen failed");
+        u->canceled_file = fopen("/tmp/aec_out.sw", "wb");
+        if (u->canceled_file == NULL)
+            perror ("fopen failed");
+    }
+
+    pa_sink_put(u->sink);
+    pa_source_put(u->source);
+
+    pa_sink_input_put(u->sink_input);
+    pa_source_output_put(u->source_output);
+
+    pa_modargs_free(ma);
+
+    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) +  pa_source_linked_by(u->source);
+}
+
+void pa__done(pa_module*m) {
+    struct userdata *u;
+
+    pa_assert(m);
+
+    if (!(u = m->userdata))
+        return;
+
+    /* See comments in source_output_kill_cb() above regarding
+     * destruction order! */
+
+    if (u->source_output)
+        pa_source_output_unlink(u->source_output);
+    if (u->sink_input)
+        pa_sink_input_unlink(u->sink_input);
+
+    if (u->source)
+        pa_source_unlink(u->source);
+    if (u->sink)
+        pa_sink_unlink(u->sink);
+
+    if (u->source_output)
+        pa_source_output_unref(u->source_output);
+    if (u->sink_input)
+        pa_sink_input_unref(u->sink_input);
+
+    if (u->source)
+        pa_source_unref(u->source);
+    if (u->sink)
+        pa_sink_unref(u->sink);
+
+    if (u->time_event)
+        u->core->mainloop->time_free(u->time_event);
+
+    if (u->source_memblockq)
+        pa_memblockq_free(u->source_memblockq);
+    if (u->sink_memblockq)
+        pa_memblockq_free(u->sink_memblockq);
+
+    if (u->echo_state)
+        speex_echo_state_destroy (u->echo_state);
+
+    if (u->asyncmsgq)
+        pa_asyncmsgq_unref(u->asyncmsgq);
+
+    pa_xfree(u);
+}