modules: Add null/dummy echo canceller

I find a dummy/passthrough implementation useful for AEC debugging

Signed-off-by: Peter Meerwald <p.meerwald@bct-electronic.com>

src/Makefile.am

@@ -1815,7 +1815,9 @@ module_suspend_on_idle_la_CFLAGS = $(AM_CFLAGS)
 
 # echo-cancel module
 module_echo_cancel_la_SOURCES = \
-		modules/echo-cancel/module-echo-cancel.c modules/echo-cancel/echo-cancel.h
+		modules/echo-cancel/module-echo-cancel.c \
+		modules/echo-cancel/null.c \
+		modules/echo-cancel/echo-cancel.h
 module_echo_cancel_la_LDFLAGS = $(MODULE_LDFLAGS)
 module_echo_cancel_la_LIBADD = $(MODULE_LIBADD) $(LIBSPEEX_LIBS)
 module_echo_cancel_la_CFLAGS = $(AM_CFLAGS) $(SERVER_CFLAGS) $(LIBSPEEX_CFLAGS)

src/modules/echo-cancel/echo-cancel.h

@@ -128,6 +128,14 @@ struct pa_echo_canceller {
 void pa_echo_canceller_get_capture_volume(pa_echo_canceller *ec, pa_cvolume *v);
 void pa_echo_canceller_set_capture_volume(pa_echo_canceller *ec, pa_cvolume *v);
 
+/* 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 *blocksize, 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,

src/modules/echo-cancel/module-echo-cancel.c

@@ -82,6 +82,7 @@ PA_MODULE_USAGE(
 /* NOTE: Make sure the enum and ec_table are maintained in the correct order */
 typedef enum {
     PA_ECHO_CANCELLER_INVALID = -1,
+    PA_ECHO_CANCELLER_NULL,
 #ifdef HAVE_SPEEX
     PA_ECHO_CANCELLER_SPEEX,
 #endif
@@ -100,6 +101,12 @@ typedef enum {
 #endif
 
 static const pa_echo_canceller ec_table[] = {
+    {
+        /* Null, Dummy echo canceller (just copies data) */
+        .init                   = pa_null_ec_init,
+        .run                    = pa_null_ec_run,
+        .done                   = pa_null_ec_done,
+    },
 #ifdef HAVE_SPEEX
     {
         /* Speex */
@@ -1553,6 +1560,8 @@ void pa_echo_canceller_set_capture_volume(pa_echo_canceller *ec, pa_cvolume *v)
 }
 
 static pa_echo_canceller_method_t get_ec_method_from_string(const char *method) {
+    if (pa_streq(method, "null"))
+        return PA_ECHO_CANCELLER_NULL;
 #ifdef HAVE_SPEEX
     if (pa_streq(method, "speex"))
         return PA_ECHO_CANCELLER_SPEEX;

src/modules/echo-cancel/null.c

@@ -0,0 +1,50 @@
+/***
+    Copyright 2012 Peter Meerwald <p.meerwald@bct-electronic.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.
+
+***/
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <pulse/cdecl.h>
+
+PA_C_DECL_BEGIN
+#include <pulsecore/core-util.h>
+#include <pulsecore/modargs.h>
+#include "echo-cancel.h"
+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 *blocksize, const char *args) {
+    unsigned framelen = 256;
+
+    source_ss->format = PA_SAMPLE_S16NE;
+    *sink_ss = *source_ss;
+    *sink_map = *source_map;
+
+    *blocksize = framelen * pa_frame_size(source_ss);
+
+    pa_log_debug("null AEC: framelen %u, blocksize %u, channels %d, rate %d", framelen, *blocksize, source_ss->channels, source_ss->rate);
+
+    return TRUE;
+}
+
+void pa_null_ec_run(pa_echo_canceller *ec, const uint8_t *rec, const uint8_t *play, uint8_t *out) {
+    memcpy(out, rec, 256 * 2);
+}
+
+void pa_null_ec_done(pa_echo_canceller *ec) {
+}