echo-cancel: Add alternative echo-cancellation implementation

This adds Andre Adrian's AEC implementation from his intercom project
(http://andreadrian.de/intercom/) as an alternative to the speex echo
cancellation routines. Since the implementation was in C++ and not in
the form of a library, I have converted the code to C and made a local
copy of the implementation.

The implementation actually works on floating point data, so we can
tweak it to work with both integer and floating point samples (currently
we just use S16LE).

1 files changed, 121 insertions, 0 deletions

diff --git a/src/modules/echo-cancel/adrian.c b/src/modules/echo-cancel/adrian.c
new file mode 100644
index 00000000..86c22cb3
--- /dev/null
+++ b/src/modules/echo-cancel/adrian.c
@@ -0,0 +1,121 @@
+/***
+    This file is part of PulseAudio.
+
+    Copyright 2010 Arun Raghavan <arun.raghavan@collabora.co.uk>
+
+    Contributor: Wim Taymans <wim.taymans@gmail.com>
+
+    The actual implementation is taken from the sources at
+    http://andreadrian.de/intercom/ - for the license, look for
+    adrian-license.txt in the same directory as this file.
+
+    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 <pulsecore/modargs.h>
+#include "echo-cancel.h"
+
+/* should be between 10-20 ms */
+#define DEFAULT_FRAME_SIZE_MS 20
+
+static const char* const valid_modargs[] = {
+    "frame_size_ms",
+    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)
+{
+    source_ss->format = PA_SAMPLE_S16LE;
+    source_ss->channels = 1;
+    pa_channel_map_init_mono(source_map);
+
+    *sink_ss = *source_ss;
+    *sink_map = *source_map;
+}
+
+pa_bool_t pa_adrian_ec_init(pa_echo_canceller *ec,
+                           pa_sample_spec *source_ss, pa_channel_map *source_map,
+                           pa_sample_spec *sink_ss, pa_channel_map *sink_map,
+                           const char *args)
+{
+    int framelen, rate;
+    uint32_t frame_size_ms;
+    pa_modargs *ma;
+
+    if (!(ma = pa_modargs_new(args, valid_modargs))) {
+        pa_log("Failed to parse submodule arguments.");
+        goto fail;
+    }
+
+    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;
+    }
+
+    pa_adrian_ec_fixate_spec(source_ss, source_map, sink_ss, sink_map);
+
+    rate = source_ss->rate;
+    framelen = (rate * frame_size_ms) / 1000;
+
+    ec->params.priv.adrian.blocksize = framelen * pa_frame_size (source_ss);
+
+    pa_log_debug ("Using framelen %d, blocksize %lld, channels %d, rate %d", framelen, (long long) ec->params.priv.adrian.blocksize, source_ss->channels, source_ss->rate);
+
+    ec->params.priv.adrian.aec = AEC_init(rate);
+    if (!ec->params.priv.adrian.aec)
+	goto fail;
+
+    pa_modargs_free(ma);
+    return TRUE;
+
+fail:
+    if (ma)
+	pa_modargs_free(ma);
+    return FALSE;
+}
+
+void pa_adrian_ec_run(pa_echo_canceller *ec, uint8_t *rec, uint8_t *play, uint8_t *out)
+{
+    unsigned int i;
+
+    for (i = 0; i < ec->params.priv.adrian.blocksize; i += 2) {
+        /* We know it's S16LE mono data */
+        int r = (((int8_t) rec[i + 1]) << 8) | rec[i];
+        int p = (((int8_t) play[i + 1]) << 8) | play[i];
+        int res;
+
+        res = AEC_doAEC(ec->params.priv.adrian.aec, r, p);
+        out[i] = (uint8_t) (res & 0xff);
+        out[i + 1] = (uint8_t) ((res >> 8) & 0xff);
+    }
+}
+
+void pa_adrian_ec_done(pa_echo_canceller *ec)
+{
+    pa_xfree(ec->params.priv.adrian.aec);
+    ec->params.priv.adrian.aec = NULL;
+}
+
+uint32_t pa_adrian_ec_get_block_size(pa_echo_canceller *ec)
+{
+    return ec->params.priv.adrian.blocksize;
+}