From bb9915658d1089e36f5b3131ec5851a058a57c62 Mon Sep 17 00:00:00 2001
From: Sanchit Sinha <sanchit15083@iiitd.ac.in>
Date: Sat, 11 Mar 2017 17:04:47 +0530
Subject: [PATCH] avfiler/af_ambisonic.c: file added avfilter/allfilters.c and
 Makefile: entry added Changelog: entry mentioned

---
 Changelog                  |   1 +
 libavfilter/Makefile       |   1 +
 libavfilter/af_ambisonic.c | 137 +++++++++++++++++++++++++++++++++++++++++++++
 libavfilter/allfilters.c   |   1 +
 4 files changed, 140 insertions(+)
 create mode 100644 libavfilter/af_ambisonic.c

diff --git a/Changelog b/Changelog
index 13628ca..b917ac2 100644
--- a/Changelog
+++ b/Changelog
@@ -26,6 +26,7 @@ version <next>:
 - native Opus encoder
 - ScreenPressor decoder
 - incomplete ClearVideo decoder
+- Ambisonic Decoder
 
 version 3.2:
 - libopenmpt demuxer
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index 0ba1c74..16fd612 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -47,6 +47,7 @@ OBJS-$(CONFIG_ALOOP_FILTER)                  += f_loop.o
 OBJS-$(CONFIG_AMERGE_FILTER)                 += af_amerge.o
 OBJS-$(CONFIG_AMETADATA_FILTER)              += f_metadata.o
 OBJS-$(CONFIG_AMIX_FILTER)                   += af_amix.o
+OBJS-$(CONFIG_AMBISONIC_FILTER)              += af_ambisonic.o
 OBJS-$(CONFIG_ANEQUALIZER_FILTER)            += af_anequalizer.o
 OBJS-$(CONFIG_ANULL_FILTER)                  += af_anull.o
 OBJS-$(CONFIG_APAD_FILTER)                   += af_apad.o
diff --git a/libavfilter/af_ambisonic.c b/libavfilter/af_ambisonic.c
new file mode 100644
index 0000000..32f3c0c
--- /dev/null
+++ b/libavfilter/af_ambisonic.c
@@ -0,0 +1,137 @@
+/*
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg 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.
+ *
+ * FFmpeg 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 FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <stdio.h>
+#include "libavutil/avstring.h"
+#include "libavutil/channel_layout.h"
+#include "libavutil/opt.h"
+#include "audio.h"
+#include "avfilter.h"
+#include "formats.h"
+#include <math.h>
+
+typedef struct AmbisonicContext {
+	const AVClass *class;
+	/*Not needed, if any new variables are to be used, this struct can be populated(f)*/
+
+} AmbisonicContext;
+
+#define OFFSET(x) offsetof(AmbisonicContext, x)
+
+static const AVOption ambisonic_options[] = {  //square will be an option
+{NULL}
+};
+
+AVFILTER_DEFINE_CLASS(ambisonic);
+static int query_formats(AVFilterContext *ctx)
+{
+	AVFilterFormats *formats = NULL;
+	AVFilterChannelLayouts *layout = NULL;
+	int ret;
+	if ((ret = ff_add_format     (&formats, AV_SAMPLE_FMT_FLTP   )) < 0 ||
+	(ret = ff_set_common_formats     (ctx    , formats )) < 0 ||
+	(ret = ff_add_channel_layout     (&layout , AV_CH_LAYOUT_4POINT0)) < 0 ||
+	(ret = ff_set_common_channel_layouts (ctx    , layout   )) < 0)
+	return ret;
+	formats = ff_all_samplerates();
+	return ff_set_common_samplerates(ctx, formats);
+}
+static int filter_frame(AVFilterLink *inlink, AVFrame *in)
+{
+	AVFilterContext *ctx = inlink->dst;
+	AVFilterLink *outlink = ctx->outputs[0];
+	/*If variables used, this has to be created*/
+	// AmbisonicContext *s = ctx->priv;
+	// const float *src = (const float *)in->data[0];
+	// float *dst;
+	AVFrame *out;
+	int itr;
+	float *w,*x,*y;
+	float root8= sqrt(8);
+	float lf=0,lb=0,rb=0,rf=0;
+
+	if (av_frame_is_writable(in))
+	{
+		out = in;
+	}
+	else
+	{
+		out = ff_get_audio_buffer(inlink, in->nb_samples);
+		if (!out)
+		{
+			av_frame_free(&in);
+			return AVERROR(ENOMEM);
+		}
+		av_frame_copy_props(out, in);
+	}
+
+	/*If planar samples are used, output must be put in dst*/
+	//dst = (float *)out->data[0];
+
+	w=(float *)in->extended_data[0];
+	x=(float *)in->extended_data[1];
+	y=(float *)in->extended_data[2];
+
+	for(itr=0;itr<in->nb_samples;itr++)
+	{
+		/*Float pointers to the samples*/
+
+		lf = root8 * (2*(w[itr])+x[itr]+y[itr]);
+		lb = root8 * (2*(w[itr])-x[itr]+y[itr]);
+		rb = root8 * (2*(w[itr])-x[itr]-y[itr]);
+		rf = root8 * (2*(w[itr])+x[itr]-y[itr]);
+
+		out->extended_data[0][itr]= lf;
+		out->extended_data[1][itr]= lb;
+		out->extended_data[2][itr]= rb;
+		out->extended_data[3][itr]= rf;
+	}
+
+	if (out != in)
+	av_frame_free(&in);
+	return ff_filter_frame(outlink, out);
+}
+
+static const AVFilterPad inputs[] = {
+	{
+	.name    = "default",
+	.type    = AVMEDIA_TYPE_AUDIO,
+	.filter_frame = filter_frame,
+	// .config_props = config_input,
+	},
+	{ NULL }
+};
+
+static const AVFilterPad outputs[] = {
+	{
+	.name = "default",
+	.type = AVMEDIA_TYPE_AUDIO,
+	},
+	{ NULL }
+};
+
+AVFilter ff_af_ambisonic = {
+	.name      = "ambisonic",
+	.description    = NULL_IF_CONFIG_SMALL("An ambisonic filter"),
+	.query_formats  = query_formats,
+	.priv_size    = sizeof(AmbisonicContext),
+	.priv_class  = &ambisonic_class,
+	// .uninit   = uninit,
+	.inputs  = inputs,
+	.outputs    = outputs,
+};
\ No newline at end of file
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index df1af8d..59aeb6d 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -56,6 +56,7 @@ static void register_all(void)
     REGISTER_FILTER(ALIMITER,       alimiter,       af);
     REGISTER_FILTER(ALLPASS,        allpass,        af);
     REGISTER_FILTER(ALOOP,          aloop,          af);
+    REGISTER_FILTER(AMBISONIC,      ambisonic,      af);
     REGISTER_FILTER(AMERGE,         amerge,         af);
     REGISTER_FILTER(AMETADATA,      ametadata,      af);
     REGISTER_FILTER(AMIX,           amix,           af);
-- 
2.7.4

