avfilter: add acopy filter

Signed-off-by: Paul B Mahol <onemda@gmail.com>

doc/filters.texi

@@ -395,6 +395,11 @@ How much to use compressed signal in output. Default is 1.
 Range is between 0 and 1.
 @end table
 
+@section acopy
+
+Copy the input audio source unchanged to the output. This is mainly useful for
+testing purposes.
+
 @section acrossfade
 
 Apply cross fade from one input audio stream to another input audio stream.
@@ -5665,7 +5670,7 @@ convolution="-2 -1 0 -1 1 1 0 1 2:-2 -1 0 -1 1 1 0 1 2:-2 -1 0 -1 1 1 0 1 2:-2 -
 
 @section copy
 
-Copy the input source unchanged to the output. This is mainly useful for
+Copy the input video source unchanged to the output. This is mainly useful for
 testing purposes.
 
 @anchor{coreimage}

libavfilter/Makefile

@@ -29,6 +29,7 @@ OBJS-$(HAVE_THREADS)                         += pthread.o
 # audio filters
 OBJS-$(CONFIG_ABENCH_FILTER)                 += f_bench.o
 OBJS-$(CONFIG_ACOMPRESSOR_FILTER)            += af_sidechaincompress.o
+OBJS-$(CONFIG_ACOPY_FILTER)                  += af_acopy.o
 OBJS-$(CONFIG_ACROSSFADE_FILTER)             += af_afade.o
 OBJS-$(CONFIG_ACRUSHER_FILTER)               += af_acrusher.o
 OBJS-$(CONFIG_ADELAY_FILTER)                 += af_adelay.o

libavfilter/af_acopy.c

@@ -0,0 +1,60 @@
+/*
+ * 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 "audio.h"
+#include "avfilter.h"
+#include "internal.h"
+
+static int filter_frame(AVFilterLink *inlink, AVFrame *in)
+{
+    AVFilterLink *outlink = inlink->dst->outputs[0];
+    AVFrame *out = ff_get_audio_buffer(outlink, in->nb_samples);
+
+    if (!out) {
+        av_frame_free(&in);
+        return AVERROR(ENOMEM);
+    }
+    av_frame_copy_props(out, in);
+    av_frame_copy(out, in);
+    av_frame_free(&in);
+    return ff_filter_frame(outlink, out);
+}
+
+static const AVFilterPad acopy_inputs[] = {
+    {
+        .name         = "default",
+        .type         = AVMEDIA_TYPE_AUDIO,
+        .filter_frame = filter_frame,
+    },
+    { NULL }
+};
+
+static const AVFilterPad acopy_outputs[] = {
+    {
+        .name = "default",
+        .type = AVMEDIA_TYPE_AUDIO,
+    },
+    { NULL }
+};
+
+AVFilter ff_af_acopy = {
+    .name          = "acopy",
+    .description   = NULL_IF_CONFIG_SMALL("Copy the input audio unchanged to the output."),
+    .inputs        = acopy_inputs,
+    .outputs       = acopy_outputs,
+};

libavfilter/allfilters.c

@@ -42,6 +42,7 @@ static void register_all(void)
 {
     REGISTER_FILTER(ABENCH,         abench,         af);
     REGISTER_FILTER(ACOMPRESSOR,    acompressor,    af);
+    REGISTER_FILTER(ACOPY,          acopy,          af);
     REGISTER_FILTER(ACROSSFADE,     acrossfade,     af);
     REGISTER_FILTER(ACRUSHER,       acrusher,       af);
     REGISTER_FILTER(ADELAY,         adelay,         af);