Add null audio filter.

Patch by S.N. Hemanth Meenakshisundaram -af smeenaks,ucsd,edu.

Originally committed as revision 24856 to svn://svn.ffmpeg.org/ffmpeg/trunk

doc/filters.texi

@@ -8,6 +8,10 @@ build.
 
 Below is a description of the currently available audio filters.
 
+@section anull
+
+Pass the audio source unchanged to the output.
+
 @c man end AUDIO FILTERS
 
 @chapter Video Filters
@@ -97,7 +101,7 @@ input to the vflip filter.
 
 @section null
 
-Pass the source unchanged to the output.
+Pass the video source unchanged to the output.
 
 @section pad
 

libavfilter/Makefile

@@ -14,6 +14,8 @@ OBJS = allfilters.o                                                     \
        graphparser.o                                                    \
        parseutils.o                                                     \
 
+OBJS-$(CONFIG_ANULL_FILTER)                  += af_anull.o
+
 OBJS-$(CONFIG_ASPECT_FILTER)                 += vf_aspect.o
 OBJS-$(CONFIG_CROP_FILTER)                   += vf_crop.o
 OBJS-$(CONFIG_FORMAT_FILTER)                 += vf_format.o

libavfilter/af_anull.c

@@ -0,0 +1,41 @@
+/*
+ * 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
+ */
+
+/**
+ * @file
+ * null audio filter
+ */
+
+#include "avfilter.h"
+
+AVFilter avfilter_af_anull = {
+    .name      = "anull",
+    .description = NULL_IF_CONFIG_SMALL("Pass the source unchanged to the output."),
+
+    .priv_size = 0,
+
+    .inputs    = (AVFilterPad[]) {{ .name             = "default",
+                                    .type             = AVMEDIA_TYPE_AUDIO,
+                                    .get_audio_buffer = avfilter_null_get_audio_buffer,
+                                    .filter_samples   = avfilter_null_filter_samples },
+                                  { .name = NULL}},
+
+    .outputs   = (AVFilterPad[]) {{ .name             = "default",
+                                    .type             = AVMEDIA_TYPE_AUDIO, },
+                                  { .name = NULL}},
+};

libavfilter/allfilters.c

@@ -34,6 +34,8 @@ void avfilter_register_all(void)
         return;
     initialized = 1;
 
+    REGISTER_FILTER (ANULL,       anull,       af);
+
     REGISTER_FILTER (ASPECT,      aspect,      vf);
     REGISTER_FILTER (CROP,        crop,        vf);
     REGISTER_FILTER (FORMAT,      format,      vf);

libavfilter/avfilter.h

@@ -25,8 +25,8 @@
 #include "libavutil/avutil.h"
 
 #define LIBAVFILTER_VERSION_MAJOR  1
-#define LIBAVFILTER_VERSION_MINOR 36
-#define LIBAVFILTER_VERSION_MICRO  1
+#define LIBAVFILTER_VERSION_MINOR 37
+#define LIBAVFILTER_VERSION_MICRO  0
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \
                                                LIBAVFILTER_VERSION_MINOR, \