audio_filter: add RNNoise denoiser filter

NEWS

@@ -81,6 +81,9 @@ Video output:
  * Remove Real demuxer plugin
  * Fix washed out black on NVIDIA cards with Direct3D9
 
+Audio filter:
+ * Add RNNoise recurrent neural network denoiser
+
 Video filter:
  * Update yadif
  * Remove remote OSD plugin

configure.ac

@@ -3011,6 +3011,11 @@ AS_IF([test "${enable_speex}" != "no"], [
 ])
 AM_CONDITIONAL([HAVE_SPEEXDSP], [test "$have_speexdsp" = "yes"])
 
+dnl
+dnl  RNNoise plugin - Recurrent neural network for audio noise reduction
+dnl
+PKG_ENABLE_MODULES_VLC([RNNOISE], [], [rnnoise], [Rnnoise denoiser], [auto])
+
 dnl
 dnl  Opus plugin
 dnl

modules/audio_filter/Makefile.am

@@ -147,3 +147,11 @@ libspeex_resampler_plugin_la_LIBADD = $(SPEEXDSP_LIBS)
 if HAVE_SPEEXDSP
 audio_filter_LTLIBRARIES += libspeex_resampler_plugin.la
 endif
+
+librnnoise_plugin_la_SOURCES = audio_filter/rnnoise.c
+librnnoise_plugin_la_CFLAGS = $(AM_CFLAGS) $(RNNOISE_CFLAGS)
+librnnoise_plugin_la_LIBADD = $(RNNOISE_LIBS) $(LIBM)
+librnnoise_plugin_la_LDFLAGS = $(AM_LDFLAGS) -rpath '$(audio_filterdir)'
+
+audio_filter_LTLIBRARIES += $(LTLIBrnnoise)
+EXTRA_LTLIBRARIES += librnnoise_plugin.la

modules/audio_filter/rnnoise.c

@@ -0,0 +1,182 @@
+/*****************************************************************************
+ * rnnoise.c : Recurrent neural network for audio noise reduction
+ *****************************************************************************
+ * Copyright © 2019 Tristan Matthews
+ *
+ * This program 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.
+ *
+ * This program 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 Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
+ *****************************************************************************/
+
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include <vlc_common.h>
+#include <vlc_aout.h>
+#include <vlc_filter.h>
+#include <vlc_plugin.h>
+
+#include <rnnoise.h>
+
+typedef struct
+{
+    DenoiseState **p_sts;
+    float *p_scratch_buffer;
+    bool b_first;
+} filter_sys_t;
+
+static void
+Flush(filter_t *p_filter)
+{
+    filter_sys_t *p_sys = p_filter->p_sys;
+
+    if (p_sys->p_sts) {
+        int i_channels = p_filter->fmt_in.audio.i_channels;
+        for (int i = 0; i < i_channels; i++) {
+            rnnoise_destroy( p_sys->p_sts[i] );
+        }
+        free(p_sys->p_sts);
+        p_sys->p_sts = NULL;
+        p_sys->b_first = true;
+    }
+}
+
+static DenoiseState **init_denoise_state(unsigned i_channels)
+{
+    DenoiseState **p_sts = malloc(i_channels * sizeof(DenoiseState *));
+    if (unlikely(!p_sts))
+        return NULL;
+
+    for (unsigned i = 0; i < i_channels; i++)
+    {
+        p_sts[i] = rnnoise_create(NULL);
+        if (unlikely(!p_sts[i]))
+        {
+            for (unsigned j = 0; j < i; j++)
+                rnnoise_destroy( p_sts[j] );
+
+            return NULL;
+        }
+    }
+
+    return p_sts;
+}
+
+
+#define FRAME_SIZE 480
+
+static block_t *Process(filter_t *p_filter, block_t *p_block)
+{
+    filter_sys_t *p_sys = p_filter->p_sys;
+    float *p_buffer = (float *)p_block->p_buffer;
+    const int i_channels = p_filter->fmt_in.audio.i_channels;
+
+    float *tmp = p_sys->p_scratch_buffer;
+
+    if (unlikely(p_sys->p_sts == NULL))
+    {
+        /* Can happen after a flush */
+        p_sys->p_sts = init_denoise_state(i_channels);
+        if (p_sys->p_sts == NULL)
+            return p_block;
+    }
+
+    for (int i_nb_samples = p_block->i_nb_samples; i_nb_samples > 0; i_nb_samples -= FRAME_SIZE)
+    {
+        /* handle case where we have fewer than FRAME_SIZE samples left to process */
+        const unsigned frame_size = __MIN(FRAME_SIZE, i_nb_samples);
+
+        /* rnnoise processes blocks of 480 samples, and expects input to be in the 32768 scale. */
+        for (unsigned i = 0; i < frame_size; i++) {
+            for (int j = 0; j < i_channels; j++) {
+                tmp[i + j * frame_size] = p_buffer[i * i_channels + j] * 32768.f;
+            }
+        }
+
+        for (int i = 0; i < i_channels; i++) {
+            rnnoise_process_frame(p_sys->p_sts[i], tmp + i * frame_size , tmp + i * frame_size);
+        }
+
+        /* Skip writing first frame to output (as per the examples) I guess to prime rnnoise? */
+        if(!p_sys->b_first)
+        {
+            for (unsigned i = 0; i < frame_size; i++) {
+                for (int j = 0; j < i_channels; j++) {
+                    p_buffer[i * i_channels + j] = tmp[i + j * frame_size] / 32768.f;
+                }
+            }
+        }
+        else
+        {
+            p_sys->b_first = false;
+        }
+        p_buffer += frame_size * i_channels;
+    }
+
+    return p_block;
+}
+
+static void Close( filter_t *obj )
+{
+    filter_t *p_filter = (filter_t *)obj;
+    filter_sys_t *p_sys = p_filter->p_sys;
+    Flush(p_filter);
+    free(p_sys->p_scratch_buffer);
+}
+
+static int Open (vlc_object_t *obj)
+{
+    filter_t *p_filter = (filter_t *)obj;
+
+    filter_sys_t *p_sys = p_filter->p_sys = vlc_obj_malloc(VLC_OBJECT(p_filter), sizeof(*p_sys));
+    if(unlikely(!p_sys))
+        return VLC_ENOMEM;
+
+    p_sys->b_first = true;
+
+    int i_channels = p_filter->fmt_in.audio.i_channels;
+    p_sys->p_sts = init_denoise_state(i_channels);
+    if (unlikely(!p_sys->p_sts)) {
+        vlc_obj_free(VLC_OBJECT(p_filter), p_sys);
+        return VLC_ENOMEM;
+    }
+
+    p_sys->p_scratch_buffer = malloc(FRAME_SIZE * i_channels * sizeof(*p_sys->p_scratch_buffer));
+    if (unlikely(!p_sys->p_scratch_buffer)) {
+        Flush(p_filter);
+        vlc_obj_free(VLC_OBJECT(p_filter), p_sys);
+        return VLC_ENOMEM;
+    }
+
+    p_filter->fmt_in.audio.i_format = VLC_CODEC_FL32;
+    aout_FormatPrepare(&p_filter->fmt_in.audio);
+    p_filter->fmt_out.audio = p_filter->fmt_in.audio;
+
+    static const struct vlc_filter_operations filter_ops =
+    {
+        .filter_audio = Process, .flush = Flush, .close = Close,
+    };
+    p_filter->ops = &filter_ops;
+
+    return VLC_SUCCESS;
+}
+
+vlc_module_begin ()
+    set_shortname (N_("RNNoise"))
+    set_description (N_("RNNoise filter"))
+    set_category (CAT_AUDIO)
+    set_subcategory (SUBCAT_AUDIO_AFILTER)
+    set_capability ("audio filter", 0)
+    set_callback( Open )
+vlc_module_end ()

po/POTFILES.in

@@ -247,6 +247,7 @@ modules/audio_filter/resampler/soxr.c
 modules/audio_filter/resampler/speex.c
 modules/audio_filter/resampler/src.c
 modules/audio_filter/resampler/ugly.c
+modules/audio_filter/rnnoise.c
 modules/audio_filter/scaletempo.c
 modules/audio_filter/spatializer/spatializer.cpp
 modules/audio_filter/stereo_widen.c