echo-cancel: Enable different sample specs for rec and out stream

Enable advanced AEC methods to use different specs (i.e., number of
channels) for rec and out stream. A typical application is beam forming
resp. multi-channel AEC, which takes multiple record channels to produce
an echo-canceled output stream.
This commit alters the EC API as follows: the EC's init() used to get
source and sink's sample spec/channel map. The new interface renamed
source to rec and sink to play and additionally passes sample spec and
channel map of the out stream. The new parameter names of init()
{rec,play,out}_{ss,map} are more intuitive and also resemble to the
parameter names known from run(). Both rec_{ss,map} and out_{ss,map} are
initialized as we knew it from source_{ss,map} before being passed to
init(). The previous EC implementations only require trivial changes,
i.e., setting rec_{ss,map} to out_{ss,map} at the end of init() in case
that out_{ss,map} is modified in init().

6 files changed, 133 insertions, 95 deletions

diff --git a/src/modules/echo-cancel/adrian.c b/src/modules/echo-cancel/adrian.c
index 40e9654d..ab828be8 100644
--- a/src/modules/echo-cancel/adrian.c
+++ b/src/modules/echo-cancel/adrian.c
@@ -43,21 +43,25 @@ static const char* const valid_modargs[] = {
     NULL
 };
 
-static void pa_adrian_ec_fixate_spec(pa_sample_spec *source_ss, pa_channel_map *source_map,
-                                    pa_sample_spec *sink_ss, pa_channel_map *sink_map)
+static void pa_adrian_ec_fixate_spec(pa_sample_spec *rec_ss, pa_channel_map *rec_map,
+                                     pa_sample_spec *play_ss, pa_channel_map *play_map,
+                                     pa_sample_spec *out_ss, pa_channel_map *out_map)
 {
-    source_ss->format = PA_SAMPLE_S16NE;
-    source_ss->channels = 1;
-    pa_channel_map_init_mono(source_map);
-
-    *sink_ss = *source_ss;
-    *sink_map = *source_map;
+    out_ss->format = PA_SAMPLE_S16NE;
+    out_ss->channels = 1;
+    pa_channel_map_init_mono(out_map);
+
+    *play_ss = *out_ss;
+    *play_map = *out_map;
+    *rec_ss = *out_ss;
+    *rec_map = *out_map;
 }
 
 pa_bool_t pa_adrian_ec_init(pa_core *c, pa_echo_canceller *ec,
-                           pa_sample_spec *source_ss, pa_channel_map *source_map,
-                           pa_sample_spec *sink_ss, pa_channel_map *sink_map,
-                           uint32_t *nframes, const char *args)
+                            pa_sample_spec *rec_ss, pa_channel_map *rec_map,
+                            pa_sample_spec *play_ss, pa_channel_map *play_map,
+                            pa_sample_spec *out_ss, pa_channel_map *out_map,
+                            uint32_t *nframes, const char *args)
 {
     int rate, have_vector = 0;
     uint32_t frame_size_ms;
@@ -74,13 +78,13 @@ pa_bool_t pa_adrian_ec_init(pa_core *c, pa_echo_canceller *ec,
         goto fail;
     }
 
-    pa_adrian_ec_fixate_spec(source_ss, source_map, sink_ss, sink_map);
+    pa_adrian_ec_fixate_spec(rec_ss, rec_map, play_ss, play_map, out_ss, out_map);
 
-    rate = source_ss->rate;
+    rate = out_ss->rate;
     *nframes = (rate * frame_size_ms) / 1000;
-    ec->params.priv.adrian.blocksize = (*nframes) * pa_frame_size(source_ss);
+    ec->params.priv.adrian.blocksize = (*nframes) * pa_frame_size(out_ss);
 
-    pa_log_debug ("Using nframes %d, blocksize %u, channels %d, rate %d", *nframes, ec->params.priv.adrian.blocksize, source_ss->channels, source_ss->rate);
+    pa_log_debug ("Using nframes %d, blocksize %u, channels %d, rate %d", *nframes, ec->params.priv.adrian.blocksize, out_ss->channels, out_ss->rate);
 
     /* For now we only support SSE */
     if (c->cpu_info.cpu_type == PA_CPU_X86 && (c->cpu_info.flags.x86 & PA_CPU_X86_SSE))
diff --git a/src/modules/echo-cancel/echo-cancel.h b/src/modules/echo-cancel/echo-cancel.h
index c33b1ef4..cdc509d0 100644
--- a/src/modules/echo-cancel/echo-cancel.h
+++ b/src/modules/echo-cancel/echo-cancel.h
@@ -47,7 +47,7 @@ typedef struct pa_echo_canceller_params pa_echo_canceller_params;
 struct pa_echo_canceller_params {
     union {
         struct {
-            pa_sample_spec source_ss;
+            pa_sample_spec out_ss;
         } null;
 #ifdef HAVE_SPEEX
         struct {
@@ -85,10 +85,12 @@ struct pa_echo_canceller {
     /* Initialise canceller engine. */
     pa_bool_t   (*init)                 (pa_core *c,
                                          pa_echo_canceller *ec,
-                                         pa_sample_spec *source_ss,
-                                         pa_channel_map *source_map,
-                                         pa_sample_spec *sink_ss,
-                                         pa_channel_map *sink_map,
+                                         pa_sample_spec *rec_ss,
+                                         pa_channel_map *rec_map,
+                                         pa_sample_spec *play_ss,
+                                         pa_channel_map *play_map,
+                                         pa_sample_spec *out_ss,
+                                         pa_channel_map *out_map,
                                          uint32_t *nframes,
                                          const char *args);
 
@@ -137,17 +139,19 @@ uint32_t pa_echo_canceller_blocksize_power2(unsigned rate, unsigned ms);
 
 /* Null canceller functions */
 pa_bool_t pa_null_ec_init(pa_core *c, pa_echo_canceller *ec,
-                           pa_sample_spec *source_ss, pa_channel_map *source_map,
-                           pa_sample_spec *sink_ss, pa_channel_map *sink_map,
-                           uint32_t *nframes, const char *args);
+                          pa_sample_spec *rec_ss, pa_channel_map *rec_map,
+                          pa_sample_spec *play_ss, pa_channel_map *play_map,
+                          pa_sample_spec *out_ss, pa_channel_map *out_map,
+                          uint32_t *nframes, const char *args);
 void pa_null_ec_run(pa_echo_canceller *ec, const uint8_t *rec, const uint8_t *play, uint8_t *out);
 void pa_null_ec_done(pa_echo_canceller *ec);
 
 #ifdef HAVE_SPEEX
 /* Speex canceller functions */
 pa_bool_t pa_speex_ec_init(pa_core *c, pa_echo_canceller *ec,
-                           pa_sample_spec *source_ss, pa_channel_map *source_map,
-                           pa_sample_spec *sink_ss, pa_channel_map *sink_map,
+                           pa_sample_spec *rec_ss, pa_channel_map *rec_map,
+                           pa_sample_spec *play_ss, pa_channel_map *play_map,
+                           pa_sample_spec *out_ss, pa_channel_map *out_map,
                            uint32_t *nframes, const char *args);
 void pa_speex_ec_run(pa_echo_canceller *ec, const uint8_t *rec, const uint8_t *play, uint8_t *out);
 void pa_speex_ec_done(pa_echo_canceller *ec);
@@ -156,9 +160,10 @@ void pa_speex_ec_done(pa_echo_canceller *ec);
 #ifdef HAVE_ADRIAN_EC
 /* Adrian Andre's echo canceller */
 pa_bool_t pa_adrian_ec_init(pa_core *c, pa_echo_canceller *ec,
-                           pa_sample_spec *source_ss, pa_channel_map *source_map,
-                           pa_sample_spec *sink_ss, pa_channel_map *sink_map,
-                           uint32_t *nframes, const char *args);
+                            pa_sample_spec *rec_ss, pa_channel_map *rec_map,
+                            pa_sample_spec *play_ss, pa_channel_map *play_map,
+                            pa_sample_spec *out_ss, pa_channel_map *out_map,
+                            uint32_t *nframes, const char *args);
 void pa_adrian_ec_run(pa_echo_canceller *ec, const uint8_t *rec, const uint8_t *play, uint8_t *out);
 void pa_adrian_ec_done(pa_echo_canceller *ec);
 #endif
@@ -167,8 +172,9 @@ void pa_adrian_ec_done(pa_echo_canceller *ec);
 /* WebRTC canceller functions */
 PA_C_DECL_BEGIN
 pa_bool_t pa_webrtc_ec_init(pa_core *c, pa_echo_canceller *ec,
-                            pa_sample_spec *source_ss, pa_channel_map *source_map,
-                            pa_sample_spec *sink_ss, pa_channel_map *sink_map,
+                            pa_sample_spec *rec_ss, pa_channel_map *rec_map,
+                            pa_sample_spec *play_ss, pa_channel_map *play_map,
+                            pa_sample_spec *out_ss, pa_channel_map *out_map,
                             uint32_t *nframes, const char *args);
 void pa_webrtc_ec_play(pa_echo_canceller *ec, const uint8_t *play);
 void pa_webrtc_ec_record(pa_echo_canceller *ec, const uint8_t *rec, uint8_t *out);
diff --git a/src/modules/echo-cancel/module-echo-cancel.c b/src/modules/echo-cancel/module-echo-cancel.c
index 1e9af37f..8bf24a60 100644
--- a/src/modules/echo-cancel/module-echo-cancel.c
+++ b/src/modules/echo-cancel/module-echo-cancel.c
@@ -211,6 +211,7 @@ struct userdata {
     pa_bool_t save_aec;
 
     pa_echo_canceller *ec;
+    uint32_t source_output_blocksize;
     uint32_t source_blocksize;
     uint32_t sink_blocksize;
 
@@ -418,7 +419,7 @@ static int source_process_msg_cb(pa_msgobject *o, int code, void *data, int64_t
                 /* 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->source_blocksize, &u->source_output->source->sample_spec);
+                pa_bytes_to_usec(u->source_output_blocksize, &u->source_output->source->sample_spec);
 
             return 0;
 
@@ -737,7 +738,7 @@ static void do_push_drift_comp(struct userdata *u) {
      */
     drift = ((float)(plen - u->sink_rem) - (rlen - u->source_rem)) / ((float)(rlen - u->source_rem));
     u->sink_rem = plen % u->sink_blocksize;
-    u->source_rem = rlen % u->source_blocksize;
+    u->source_rem = rlen % u->source_output_blocksize;
 
     /* Now let the canceller work its drift compensation magic */
     u->ec->set_drift(u->ec, drift);
@@ -770,14 +771,14 @@ static void do_push_drift_comp(struct userdata *u) {
     }
 
     /* And now the capture samples */
-    while (rlen >= u->source_blocksize) {
-        pa_memblockq_peek_fixed_size(u->source_memblockq, u->source_blocksize, &rchunk);
+    while (rlen >= u->source_output_blocksize) {
+        pa_memblockq_peek_fixed_size(u->source_memblockq, u->source_output_blocksize, &rchunk);
 
         rdata = pa_memblock_acquire(rchunk.memblock);
         rdata += rchunk.index;
 
         cchunk.index = 0;
-        cchunk.length = u->source_blocksize;
+        cchunk.length = u->source_output_blocksize;
         cchunk.memblock = pa_memblock_new(u->source->core->mempool, cchunk.length);
         cdata = pa_memblock_acquire(cchunk.memblock);
 
@@ -785,11 +786,11 @@ static void do_push_drift_comp(struct userdata *u) {
 
         if (u->save_aec) {
             if (u->drift_file)
-                fprintf(u->drift_file, "c %d\n", u->source_blocksize);
+                fprintf(u->drift_file, "c %d\n", u->source_output_blocksize);
             if (u->captured_file)
-                unused = fwrite(rdata, 1, u->source_blocksize, u->captured_file);
+                unused = fwrite(rdata, 1, u->source_output_blocksize, u->captured_file);
             if (u->canceled_file)
-                unused = fwrite(cdata, 1, u->source_blocksize, u->canceled_file);
+                unused = fwrite(cdata, 1, u->source_output_blocksize, u->canceled_file);
         }
 
         pa_memblock_release(cchunk.memblock);
@@ -800,8 +801,8 @@ static void do_push_drift_comp(struct userdata *u) {
         pa_source_post(u->source, &cchunk);
         pa_memblock_unref(cchunk.memblock);
 
-        pa_memblockq_drop(u->source_memblockq, u->source_blocksize);
-        rlen -= u->source_blocksize;
+        pa_memblockq_drop(u->source_memblockq, u->source_output_blocksize);
+        rlen -= u->source_output_blocksize;
     }
 }
 
@@ -819,10 +820,10 @@ static void do_push(struct userdata *u) {
     rlen = pa_memblockq_get_length(u->source_memblockq);
     plen = pa_memblockq_get_length(u->sink_memblockq);
 
-    while (rlen >= u->source_blocksize) {
+    while (rlen >= u->source_output_blocksize) {
 
         /* take fixed blocks from recorded and played samples */
-        pa_memblockq_peek_fixed_size(u->source_memblockq, u->source_blocksize, &rchunk);
+        pa_memblockq_peek_fixed_size(u->source_memblockq, u->source_output_blocksize, &rchunk);
         pa_memblockq_peek_fixed_size(u->sink_memblockq, u->sink_blocksize, &pchunk);
 
         /* we ran out of played data and pchunk has been filled with silence bytes */
@@ -841,7 +842,7 @@ static void do_push(struct userdata *u) {
 
         if (u->save_aec) {
             if (u->captured_file)
-                unused = fwrite(rdata, 1, u->source_blocksize, u->captured_file);
+                unused = fwrite(rdata, 1, u->source_output_blocksize, u->captured_file);
             if (u->played_file)
                 unused = fwrite(pdata, 1, u->sink_blocksize, u->played_file);
         }
@@ -859,9 +860,9 @@ static void do_push(struct userdata *u) {
         pa_memblock_release(rchunk.memblock);
 
         /* drop consumed source samples */
-        pa_memblockq_drop(u->source_memblockq, u->source_blocksize);
+        pa_memblockq_drop(u->source_memblockq, u->source_output_blocksize);
         pa_memblock_unref(rchunk.memblock);
-        rlen -= u->source_blocksize;
+        rlen -= u->source_output_blocksize;
 
         /* drop consumed sink samples */
         pa_memblockq_drop(u->sink_memblockq, u->sink_blocksize);
@@ -909,7 +910,7 @@ static void source_output_push_cb(pa_source_output *o, const pa_memchunk *chunk)
     plen = pa_memblockq_get_length(u->sink_memblockq);
 
     /* Let's not do anything else till we have enough data to process */
-    if (rlen < u->source_blocksize)
+    if (rlen < u->source_output_blocksize)
         return;
 
     /* See if we need to drop samples in order to sync */
@@ -925,7 +926,7 @@ static void source_output_push_cb(pa_source_output *o, const pa_memchunk *chunk)
          * means the only way to try to catch up is drop sink samples and let
          * the canceller cope up with this. */
         to_skip = rlen >= u->source_skip ? u->source_skip : rlen;
-        to_skip -= to_skip % u->source_blocksize;
+        to_skip -= to_skip % u->source_output_blocksize;
 
         if (to_skip) {
             pa_memblockq_peek_fixed_size(u->source_memblockq, to_skip, &rchunk);
@@ -938,9 +939,9 @@ static void source_output_push_cb(pa_source_output *o, const pa_memchunk *chunk)
             u->source_skip -= to_skip;
         }
 
-        if (rlen && u->source_skip % u->source_blocksize) {
-            u->sink_skip += (uint64_t) (u->source_blocksize - (u->source_skip % u->source_blocksize)) * u->sink_blocksize / u->source_blocksize;
-            u->source_skip -= (u->source_skip % u->source_blocksize);
+        if (rlen && u->source_skip % u->source_output_blocksize) {
+            u->sink_skip += (uint64_t) (u->source_output_blocksize - (u->source_skip % u->source_output_blocksize)) * u->sink_blocksize / u->source_output_blocksize;
+            u->source_skip -= (u->source_skip % u->source_output_blocksize);
         }
     }
 
@@ -1646,8 +1647,8 @@ fail:
 /* Called from main context. */
 int pa__init(pa_module*m) {
     struct userdata *u;
-    pa_sample_spec source_ss, sink_ss;
-    pa_channel_map source_map, sink_map;
+    pa_sample_spec source_output_ss, source_ss, sink_ss;
+    pa_channel_map source_output_map, source_map, sink_map;
     pa_modargs *ma;
     pa_source *source_master=NULL;
     pa_sink *sink_master=NULL;
@@ -1747,12 +1748,24 @@ int pa__init(pa_module*m) {
     u->asyncmsgq = pa_asyncmsgq_new(0);
     u->need_realign = TRUE;
 
+    source_output_ss = source_ss;
+    source_output_map = source_map;
+
+    if (sink_ss.rate != source_ss.rate) {
+        pa_log_info("Sample rates of play and out stream differ. Adjusting rate of play stream.");
+        sink_ss.rate = source_ss.rate;
+    }
+
     pa_assert(u->ec->init);
-    if (!u->ec->init(u->core, u->ec, &source_ss, &source_map, &sink_ss, &sink_map, &nframes, pa_modargs_get_value(ma, "aec_args", NULL))) {
+    if (!u->ec->init(u->core, u->ec, &source_output_ss, &source_output_map, &sink_ss, &sink_map, &source_ss, &source_map, &nframes, pa_modargs_get_value(ma, "aec_args", NULL))) {
         pa_log("Failed to init AEC engine");
         goto fail;
     }
 
+    pa_assert(source_output_ss.rate == source_ss.rate);
+    pa_assert(sink_ss.rate == source_ss.rate);
+
+    u->source_output_blocksize = nframes * pa_frame_size(&source_output_ss);
     u->source_blocksize = nframes * pa_frame_size(&source_ss);
     u->sink_blocksize = nframes * pa_frame_size(&sink_ss);
 
@@ -1871,8 +1884,8 @@ int pa__init(pa_module*m) {
 
     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, &source_ss);
-    pa_source_output_new_data_set_channel_map(&source_output_data, &source_map);
+    pa_source_output_new_data_set_sample_spec(&source_output_data, &source_output_ss);
+    pa_source_output_new_data_set_channel_map(&source_output_data, &source_output_map);
 
     pa_source_output_new(&u->source_output, m->core, &source_output_data);
     pa_source_output_new_data_done(&source_output_data);
@@ -1939,7 +1952,7 @@ int pa__init(pa_module*m) {
     pa_sink_input_get_silence(u->sink_input, &silence);
 
     u->source_memblockq = pa_memblockq_new("module-echo-cancel source_memblockq", 0, MEMBLOCKQ_MAXLENGTH, 0,
-        &source_ss, 1, 1, 0, &silence);
+        &source_output_ss, 1, 1, 0, &silence);
     u->sink_memblockq = pa_memblockq_new("module-echo-cancel sink_memblockq", 0, MEMBLOCKQ_MAXLENGTH, 0,
         &sink_ss, 0, 1, 0, &silence);
 
@@ -2083,8 +2096,8 @@ void pa__done(pa_module*m) {
  */
 int main(int argc, char* argv[]) {
     struct userdata u;
-    pa_sample_spec source_ss, sink_ss;
-    pa_channel_map source_map, sink_map;
+    pa_sample_spec source_output_ss, source_ss, sink_ss;
+    pa_channel_map source_output_map, source_map, sink_map;
     pa_modargs *ma = NULL;
     uint8_t *rdata = NULL, *pdata = NULL, *cdata = NULL;
     int unused PA_GCC_UNUSED;
@@ -2140,11 +2153,15 @@ int main(int argc, char* argv[]) {
     if (init_common(ma, &u, &source_ss, &source_map) < 0)
         goto fail;
 
-    if (!u.ec->init(u.core, u.ec, &source_ss, &source_map, &sink_ss, &sink_map, &nframes,
+    source_output_ss = source_ss;
+    source_output_map = source_map;
+
+    if (!u.ec->init(u.core, u.ec, &source_output_ss, &source_output_map, &sink_ss, &sink_map, &source_ss, &source_map, &nframes,
                      pa_modargs_get_value(ma, "aec_args", NULL))) {
         pa_log("Failed to init AEC engine");
         goto fail;
     }
+    u.source_output_blocksize = nframes * pa_frame_size(&source_output_ss);
     u.source_blocksize = nframes * pa_frame_size(&source_ss);
     u.sink_blocksize = nframes * pa_frame_size(&sink_ss);
 
@@ -2162,12 +2179,12 @@ int main(int argc, char* argv[]) {
         }
     }
 
-    rdata = pa_xmalloc(u.source_blocksize);
+    rdata = pa_xmalloc(u.source_output_blocksize);
     pdata = pa_xmalloc(u.sink_blocksize);
     cdata = pa_xmalloc(u.source_blocksize);
 
     if (!u.ec->params.drift_compensation) {
-        while (fread(rdata, u.source_blocksize, 1, u.captured_file) > 0) {
+        while (fread(rdata, u.source_output_blocksize, 1, u.captured_file) > 0) {
             if (fread(pdata, u.sink_blocksize, 1, u.played_file) == 0) {
                 perror("Played file ended before captured file");
                 goto fail;
diff --git a/src/modules/echo-cancel/null.c b/src/modules/echo-cancel/null.c
index 6d9531a1..e89a4f4e 100644
--- a/src/modules/echo-cancel/null.c
+++ b/src/modules/echo-cancel/null.c
@@ -26,18 +26,22 @@ PA_C_DECL_BEGIN
 PA_C_DECL_END
 
 pa_bool_t pa_null_ec_init(pa_core *c, pa_echo_canceller *ec,
-                           pa_sample_spec *source_ss, pa_channel_map *source_map,
-                           pa_sample_spec *sink_ss, pa_channel_map *sink_map,
-                           uint32_t *nframes, const char *args) {
+                          pa_sample_spec *rec_ss, pa_channel_map *rec_map,
+                          pa_sample_spec *play_ss, pa_channel_map *play_map,
+                          pa_sample_spec *out_ss, pa_channel_map *out_map,
+                          uint32_t *nframes, const char *args) {
     char strss_source[PA_SAMPLE_SPEC_SNPRINT_MAX];
     char strss_sink[PA_SAMPLE_SPEC_SNPRINT_MAX];
 
     *nframes = 256;
-    ec->params.priv.null.source_ss = *source_ss;
+    ec->params.priv.null.out_ss = *out_ss;
+
+    *rec_ss = *out_ss;
+    *rec_map = *out_map;
 
     pa_log_debug("null AEC: nframes=%u, sample spec source=%s, sample spec sink=%s", *nframes,
-            pa_sample_spec_snprint(strss_source, sizeof(strss_source), source_ss),
-            pa_sample_spec_snprint(strss_sink, sizeof(strss_sink), sink_ss));
+                 pa_sample_spec_snprint(strss_source, sizeof(strss_source), out_ss),
+                 pa_sample_spec_snprint(strss_sink, sizeof(strss_sink), play_ss));
 
     return TRUE;
 }
@@ -45,7 +49,7 @@ pa_bool_t pa_null_ec_init(pa_core *c, pa_echo_canceller *ec,
 void pa_null_ec_run(pa_echo_canceller *ec, const uint8_t *rec, const uint8_t *play, uint8_t *out) {
     /* The null implementation simply copies the recorded buffer to the output
        buffer and ignores the play buffer. */
-    memcpy(out, rec, 256 * pa_frame_size(&ec->params.priv.null.source_ss));
+    memcpy(out, rec, 256 * pa_frame_size(&ec->params.priv.null.out_ss));
 }
 
 void pa_null_ec_done(pa_echo_canceller *ec) {
diff --git a/src/modules/echo-cancel/speex.c b/src/modules/echo-cancel/speex.c
index 9469092d..ddb09b54 100644
--- a/src/modules/echo-cancel/speex.c
+++ b/src/modules/echo-cancel/speex.c
@@ -49,16 +49,19 @@ static const char* const valid_modargs[] = {
     NULL
 };
 
-static void pa_speex_ec_fixate_spec(pa_sample_spec *source_ss, pa_channel_map *source_map,
-                                    pa_sample_spec *sink_ss, pa_channel_map *sink_map)
+static void pa_speex_ec_fixate_spec(pa_sample_spec *rec_ss, pa_channel_map *rec_map,
+                                    pa_sample_spec *play_ss, pa_channel_map *play_map,
+                                    pa_sample_spec *out_ss, pa_channel_map *out_map)
 {
-    source_ss->format = PA_SAMPLE_S16NE;
+    out_ss->format = PA_SAMPLE_S16NE;
 
-    *sink_ss = *source_ss;
-    *sink_map = *source_map;
+    *play_ss = *out_ss;
+    *play_map = *out_map;
+    *rec_ss = *out_ss;
+    *rec_map = *out_map;
 }
 
-static pa_bool_t pa_speex_ec_preprocessor_init(pa_echo_canceller *ec, pa_sample_spec *source_ss, uint32_t nframes, pa_modargs *ma) {
+static pa_bool_t pa_speex_ec_preprocessor_init(pa_echo_canceller *ec, pa_sample_spec *out_ss, uint32_t nframes, pa_modargs *ma) {
     pa_bool_t agc;
     pa_bool_t denoise;
     pa_bool_t echo_suppress;
@@ -106,12 +109,12 @@ static pa_bool_t pa_speex_ec_preprocessor_init(pa_echo_canceller *ec, pa_sample_
     if (agc || denoise || echo_suppress) {
         spx_int32_t tmp;
 
-        if (source_ss->channels != 1) {
+        if (out_ss->channels != 1) {
             pa_log("AGC, denoising and echo suppression only work with channels=1");
             goto fail;
         }
 
-        ec->params.priv.speex.pp_state = speex_preprocess_state_init(nframes, source_ss->rate);
+        ec->params.priv.speex.pp_state = speex_preprocess_state_init(nframes, out_ss->rate);
 
         tmp = agc;
         speex_preprocess_ctl(ec->params.priv.speex.pp_state, SPEEX_PREPROCESS_SET_AGC, &tmp);
@@ -146,8 +149,9 @@ fail:
 
 
 pa_bool_t pa_speex_ec_init(pa_core *c, pa_echo_canceller *ec,
-                           pa_sample_spec *source_ss, pa_channel_map *source_map,
-                           pa_sample_spec *sink_ss, pa_channel_map *sink_map,
+                           pa_sample_spec *rec_ss, pa_channel_map *rec_map,
+                           pa_sample_spec *play_ss, pa_channel_map *play_map,
+                           pa_sample_spec *out_ss, pa_channel_map *out_map,
                            uint32_t *nframes, const char *args)
 {
     int rate;
@@ -171,20 +175,20 @@ pa_bool_t pa_speex_ec_init(pa_core *c, pa_echo_canceller *ec,
         goto fail;
     }
 
-    pa_speex_ec_fixate_spec(source_ss, source_map, sink_ss, sink_map);
+    pa_speex_ec_fixate_spec(rec_ss, rec_map, play_ss, play_map, out_ss, out_map);
 
-    rate = source_ss->rate;
+    rate = out_ss->rate;
     *nframes = pa_echo_canceller_blocksize_power2(rate, frame_size_ms);
 
-    pa_log_debug ("Using nframes %d, channels %d, rate %d", *nframes, source_ss->channels, source_ss->rate);
-    ec->params.priv.speex.state = speex_echo_state_init_mc(*nframes, (rate * filter_size_ms) / 1000, source_ss->channels, source_ss->channels);
+    pa_log_debug ("Using nframes %d, channels %d, rate %d", *nframes, out_ss->channels, out_ss->rate);
+    ec->params.priv.speex.state = speex_echo_state_init_mc(*nframes, (rate * filter_size_ms) / 1000, out_ss->channels, out_ss->channels);
 
     if (!ec->params.priv.speex.state)
         goto fail;
 
     speex_echo_ctl(ec->params.priv.speex.state, SPEEX_ECHO_SET_SAMPLING_RATE, &rate);
 
-    if (!pa_speex_ec_preprocessor_init(ec, source_ss, *nframes, ma))
+    if (!pa_speex_ec_preprocessor_init(ec, out_ss, *nframes, ma))
         goto fail;
 
     pa_modargs_free(ma);
diff --git a/src/modules/echo-cancel/webrtc.cc b/src/modules/echo-cancel/webrtc.cc
index 6ced28ce..71f6ebb8 100644
--- a/src/modules/echo-cancel/webrtc.cc
+++ b/src/modules/echo-cancel/webrtc.cc
@@ -77,8 +77,9 @@ static int routing_mode_from_string(const char *rmode) {
 }
 
 pa_bool_t pa_webrtc_ec_init(pa_core *c, pa_echo_canceller *ec,
-                            pa_sample_spec *source_ss, pa_channel_map *source_map,
-                            pa_sample_spec *sink_ss, pa_channel_map *sink_map,
+                            pa_sample_spec *rec_ss, pa_channel_map *rec_map,
+                            pa_sample_spec *play_ss, pa_channel_map *play_map,
+                            pa_sample_spec *out_ss, pa_channel_map *out_map,
                             uint32_t *nframes, const char *args)
 {
     webrtc::AudioProcessing *apm = NULL;
@@ -158,23 +159,25 @@ pa_bool_t pa_webrtc_ec_init(pa_core *c, pa_echo_canceller *ec,
 
     apm = webrtc::AudioProcessing::Create(0);
 
-    source_ss->format = PA_SAMPLE_S16NE;
-    *sink_ss = *source_ss;
+    out_ss->format = PA_SAMPLE_S16NE;
+    *play_ss = *out_ss;
     /* FIXME: the implementation actually allows a different number of
      * source/sink channels. Do we want to support that? */
-    *sink_map = *source_map;
+    *play_map = *out_map;
+    *rec_ss = *out_ss;
+    *rec_map = *out_map;
 
-    apm->set_sample_rate_hz(source_ss->rate);
+    apm->set_sample_rate_hz(out_ss->rate);
 
-    apm->set_num_channels(source_ss->channels, source_ss->channels);
-    apm->set_num_reverse_channels(sink_ss->channels);
+    apm->set_num_channels(out_ss->channels, out_ss->channels);
+    apm->set_num_reverse_channels(play_ss->channels);
 
     if (hpf)
         apm->high_pass_filter()->Enable(true);
 
     if (!mobile) {
         if (ec->params.drift_compensation) {
-            apm->echo_cancellation()->set_device_sample_rate_hz(source_ss->rate);
+            apm->echo_cancellation()->set_device_sample_rate_hz(out_ss->rate);
             apm->echo_cancellation()->enable_drift_compensation(true);
         } else {
             apm->echo_cancellation()->enable_drift_compensation(false);
@@ -215,9 +218,9 @@ pa_bool_t pa_webrtc_ec_init(pa_core *c, pa_echo_canceller *ec,
     apm->voice_detection()->Enable(true);
 
     ec->params.priv.webrtc.apm = apm;
-    ec->params.priv.webrtc.sample_spec = *source_ss;
-    ec->params.priv.webrtc.blocksize = (uint64_t)pa_bytes_per_second(source_ss) * BLOCK_SIZE_US / PA_USEC_PER_SEC;
-    *nframes = ec->params.priv.webrtc.blocksize / pa_frame_size(source_ss);
+    ec->params.priv.webrtc.sample_spec = *out_ss;
+    ec->params.priv.webrtc.blocksize = (uint64_t)pa_bytes_per_second(out_ss) * BLOCK_SIZE_US / PA_USEC_PER_SEC;
+    *nframes = ec->params.priv.webrtc.blocksize / pa_frame_size(out_ss);
 
     pa_modargs_free(ma);
     return TRUE;