virtual-source: boilerplate virtual source for PCM processing on inputs

1 files changed, 771 insertions, 0 deletions

diff --git a/src/modules/module-virtual-source.c b/src/modules/module-virtual-source.c
new file mode 100644
index 00000000..fdf89b02
--- /dev/null
+++ b/src/modules/module-virtual-source.c
@@ -0,0 +1,771 @@
+/***
+    This file is part of PulseAudio.
+
+    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 <pulse/xmalloc.h>
+#include <pulse/i18n.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-virtual-source-symdef.h"
+
+PA_MODULE_AUTHOR("Pierre-Louis Bossart");
+PA_MODULE_DESCRIPTION("Virtual source");
+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> "
+          "master=<name of source to filter> "
+          "uplink_sink=<name> (optional)"
+          "format=<sample format> "
+          "rate=<sample rate> "
+          "channels=<number of channels> "
+          "channel_map=<channel map> "
+        ));
+
+#define MEMBLOCKQ_MAXLENGTH (16*1024*1024)
+#define BLOCK_USEC 1000 /* FIXME */
+
+struct userdata {
+    pa_module *module;
+
+    pa_source *source;
+    pa_source_output *source_output;
+
+    pa_memblockq *memblockq;
+
+    pa_bool_t auto_desc;
+    unsigned channels;
+
+    /* optional fields for uplink sink */
+    pa_sink *sink;
+    pa_usec_t block_usec;
+    pa_memblockq *sink_memblockq;
+
+};
+
+static const char* const valid_modargs[] = {
+    "source_name",
+    "source_properties",
+    "master",
+    "uplink_sink",
+    "format",
+    "rate",
+    "channels",
+    "channel_map",
+    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) {
+
+    switch (code) {
+
+        case PA_SINK_MESSAGE_GET_LATENCY:
+
+            /* there's no real latency here */
+            *((pa_usec_t*) data) = 0;
+
+            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)) {
+        return 0;
+    }
+
+    if (state == PA_SINK_RUNNING) {
+        /* need to wake-up source if it was suspended */
+        pa_source_suspend(u->source, FALSE, PA_SUSPEND_ALL);
+
+        /* FIXME: if there's no client connected, the source will suspend
+           and playback will be stuck. You'd want to prevent the source from
+           sleeping when the uplink sink is active; even if the audio is
+           discarded at least the app isn't stuck */
+
+    } else {
+        /* nothing to do, if the sink becomes idle or suspended let
+           module-suspend-idle handle the sources later */
+    }
+
+    return 0;
+}
+
+static void sink_update_requested_latency_cb(pa_sink *s) {
+    struct userdata *u;
+
+    pa_sink_assert_ref(s);
+    pa_assert_se(u = s->userdata);
+
+    /* FIXME: there's no latency support */
+
+}
+
+
+/* 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);
+
+    /* Do nothing */
+    pa_sink_process_rewind(u->sink, 0);
+
+}
+
+/* Called from 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 */
+                /* FIXME, no idea what I am doing here */
+                pa_bytes_to_usec(pa_memblockq_get_length(u->source_output->thread_info.delay_memblockq), &u->source_output->source->sample_spec);
+
+            return 0;
+    }
+
+    return pa_source_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_source_output_cork(u->source_output, state == PA_SOURCE_SUSPENDED);
+    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;
+
+    /* 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 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);
+}
+
+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 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);
+}
+
+/* Called from input thread context */
+static void source_output_push_cb(pa_source_output *o, const pa_memchunk *chunk) {
+    struct userdata *u;
+
+    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;
+    }
+
+    /* PUT YOUR CODE HERE TO DO SOMETHING WITH THE SOURCE DATA */
+
+    /* if uplink sink exists, pull data from there; simplify by using
+       same length as chunk provided by source */
+    if(u->sink && (pa_sink_get_state(u->sink) == PA_SINK_RUNNING)) {
+        pa_memchunk tchunk;
+        size_t nbytes = chunk->length;
+        pa_mix_info streams[2];
+        pa_memchunk target_chunk;
+        void *target;
+        int ch;
+
+        /* Hmm, process any rewind request that might be queued up */
+        pa_sink_process_rewind(u->sink, 0);
+
+        /* get data from the sink */
+        while (pa_memblockq_peek(u->sink_memblockq, &tchunk) < 0) {
+            pa_memchunk nchunk;
+
+            /* make sure we get nbytes from the sink with render_full,
+               otherwise we cannot mix with the uplink */
+            pa_sink_render_full(u->sink, nbytes, &nchunk);
+            pa_memblockq_push(u->sink_memblockq, &nchunk);
+            pa_memblock_unref(nchunk.memblock);
+        }
+        pa_assert(tchunk.length == chunk->length);
+
+        /* move the read pointer for sink memblockq */
+        pa_memblockq_drop(u->sink_memblockq, tchunk.length);
+
+        /* allocate target chunk */
+        /* this could probably be done in-place, but having chunk as both
+           the input and output creates issues with reference counts */
+        target_chunk.index = 0;
+        target_chunk.length = chunk->length;
+        pa_assert(target_chunk.length == chunk->length);
+
+        target_chunk.memblock = pa_memblock_new(o->source->core->mempool,
+                                                target_chunk.length);
+        pa_assert( target_chunk.memblock );
+
+        /* get target pointer */
+        target = (void*)((uint8_t*)pa_memblock_acquire(target_chunk.memblock)
+                         + target_chunk.index);
+
+        /* set-up mixing structure
+           volume was taken care of in sink and source already */
+        streams[0].chunk = *chunk;
+        for(ch=0;ch<o->sample_spec.channels;ch++)
+            streams[0].volume.values[ch] = PA_VOLUME_NORM; /* FIXME */
+        streams[0].volume.channels = o->sample_spec.channels;
+
+        streams[1].chunk = tchunk;
+        for(ch=0;ch<o->sample_spec.channels;ch++)
+            streams[1].volume.values[ch] = PA_VOLUME_NORM; /* FIXME */
+        streams[1].volume.channels = o->sample_spec.channels;
+
+        /* do mixing */
+        pa_mix(streams,                /* 2 streams to be mixed */
+               2,
+               target,                 /* put result in target chunk */
+               chunk->length,          /* same length as input */
+               (const pa_sample_spec *)&o->sample_spec, /* same sample spec for input and output */
+               NULL,                   /* no volume information */
+               FALSE);                 /* no mute */
+
+        pa_memblock_release(target_chunk.memblock);
+        pa_memblock_unref(tchunk.memblock); /* clean-up */
+
+        /* forward the data to the virtual source */
+        pa_source_post(u->source, &target_chunk);
+
+        pa_memblock_unref(target_chunk.memblock); /* clean-up */
+
+    } else {
+        /* forward the data to the virtual source */
+        pa_source_post(u->source, chunk);
+    }
+
+
+}
+
+/* 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);
+
+    /* FIXME, no idea what I am doing here */
+#if 0
+    pa_asyncmsgq_post(u->asyncmsgq, PA_MSGOBJECT(u->sink_input), SINK_INPUT_MESSAGE_REWIND, NULL, (int64_t) nbytes, NULL, NULL);
+    u->send_counter -= (int64_t) nbytes;
+#endif
+}
+
+/* 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) {
+
+    /* FIXME, nothing to do here ? */
+
+    return pa_source_output_process_msg(obj, code, data, offset, chunk);
+}
+
+/* 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_source_attach_within_thread(u->source);
+}
+
+/* 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);
+}
+
+/* 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);
+
+    /* FIXME */
+#if 0
+    if (PA_SOURCE_OUTPUT_IS_LINKED(state) && o->thread_info.state == PA_SOURCE_OUTPUT_INIT) {
+
+        u->skip = pa_usec_to_bytes(PA_CLIP_SUB(pa_source_get_latency_within_thread(o->source),
+                                               u->latency),
+                                   &o->sample_spec);
+
+        pa_log_info("Skipping %lu bytes", (unsigned long) u->skip);
+    }
+#endif
+}
+
+/* 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_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);
+
+    /* FIXME */
+    //return dest != u->source_input->source->monitor_source;
+
+    return TRUE;
+}
+
+/* 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->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, "Virtual Source %s on %s",
+                         pa_proplist_gets(u->source->proplist, "device.vsource.name"), z ? z : dest->name);
+
+        pa_source_update_proplist(u->source, PA_UPDATE_REPLACE, pl);
+        pa_proplist_free(pl);
+    }
+}
+
+
+int pa__init(pa_module*m) {
+    struct userdata *u;
+    pa_sample_spec ss;
+    pa_channel_map map;
+    pa_modargs *ma;
+    pa_source *master=NULL;
+    pa_source_output_new_data source_output_data;
+    pa_source_new_data source_data;
+    pa_bool_t *use_default = NULL;
+
+    /* optional for uplink_sink */
+    pa_sink_new_data sink_data;
+    size_t nbytes;
+
+    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_SOURCE))) {
+        pa_log("Master source not found");
+        goto fail;
+    }
+
+    pa_assert(master);
+
+    ss = master->sample_spec;
+    ss.format = PA_SAMPLE_FLOAT32;
+    map = 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->module = m;
+    m->userdata = u;
+    u->memblockq = pa_memblockq_new(0, MEMBLOCKQ_MAXLENGTH, 0, pa_frame_size(&ss), 1, 1, 0, NULL);
+    if (!u->memblockq) {
+        pa_log("Failed to create source memblockq.");
+        goto fail;
+    }
+    u->channels = ss.channels;
+
+    /* 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.vsource", 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, master->name);
+    pa_proplist_sets(source_data.proplist, PA_PROP_DEVICE_CLASS, "filter");
+    pa_proplist_sets(source_data.proplist, "device.vsource.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->auto_desc = !pa_proplist_contains(source_data.proplist, PA_PROP_DEVICE_DESCRIPTION))) {
+        const char *z;
+
+        z = pa_proplist_gets(master->proplist, PA_PROP_DEVICE_DESCRIPTION);
+        pa_proplist_setf(source_data.proplist, PA_PROP_DEVICE_DESCRIPTION, "Virtual Source %s on %s", source_data.name, z ? z : 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|
+                          (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, 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 = master;
+    /* FIXME
+       source_output_data.flags = PA_SOURCE_OUTPUT_DONT_INHIBIT_AUTO_SUSPEND; */
+
+    pa_proplist_sets(source_output_data.proplist, PA_PROP_MEDIA_NAME, "Virtual 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->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;
+
+    pa_source_put(u->source);
+    pa_source_output_put(u->source_output);
+
+    /* Create optional uplink 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, "uplink_sink", NULL)))) {
+        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, master->name);
+        pa_proplist_sets(sink_data.proplist, PA_PROP_DEVICE_CLASS, "uplink sink");
+        pa_proplist_sets(sink_data.proplist, "device.uplink_sink.name", sink_data.name);
+
+        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, "Uplink Sink %s on %s", sink_data.name, z ? z : master->name);
+        }
+
+        u->sink_memblockq = pa_memblockq_new(0, MEMBLOCKQ_MAXLENGTH, 0, pa_frame_size(&ss), 1, 1, 0, NULL);
+        if (!u->sink_memblockq) {
+            pa_log("Failed to create sink memblockq.");
+            goto fail;
+        }
+
+        u->sink = pa_sink_new(m->core, &sink_data, 0);  /* FIXME, sink has no capabilities */
+        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->update_requested_latency = sink_update_requested_latency_cb;
+        u->sink->request_rewind = sink_request_rewind_cb;
+        u->sink->set_state = sink_set_state_cb;
+        u->sink->userdata = u;
+
+        pa_sink_set_asyncmsgq(u->sink, master->asyncmsgq);
+
+        /* FIXME: no idea what I am doing here */
+        u->block_usec = BLOCK_USEC;
+        nbytes = pa_usec_to_bytes(u->block_usec, &u->sink->sample_spec);
+        pa_sink_set_max_rewind(u->sink, nbytes);
+        pa_sink_set_max_request(u->sink, nbytes);
+
+        pa_sink_put(u->sink);
+    } else {
+        /* optional uplink sink not enabled */
+        u->sink = NULL;
+    }
+
+    pa_modargs_free(ma);
+
+    pa_xfree(use_default);
+
+    return 0;
+
+ fail:
+    if (ma)
+        pa_modargs_free(ma);
+
+    pa_xfree(use_default);
+
+    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_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->source)
+        pa_source_unlink(u->source);
+
+    if (u->source_output)
+        pa_source_output_unref(u->source_output);
+
+    if (u->source)
+        pa_source_unref(u->source);
+
+    if (u->sink)
+        pa_sink_unref(u->sink);
+
+    if (u->memblockq)
+        pa_memblockq_free(u->memblockq);
+
+    if (u->sink_memblockq)
+         pa_memblockq_free(u->sink_memblockq);
+
+    pa_xfree(u);
+}