@@ -197,4 +197,20 @@ Flip the input video vertically.

 ./ffmpeg -i in.avi -vfilters "vflip" out.avi

 @end example

+@chapter Available video sources

+

+Below is a description of the currently available video sources.

+

+@section nullsrc

+

+Null video source, never return images. It is mainly useful as a

+template and to be employed in analysis / debugging tools.

+

+It accepts as optional parameter a string of the form

+``width:height'', where ``width'' and ``height'' specify the size of

+the configured source.

+

+The default values of ``width'' and ``height'' are respectively 352

+and 288 (corresponding to the CIF size format).

+

 @bye

@@ -20,4 +20,6 @@ OBJS-$(CONFIG_SCALE_FILTER)                  += vf_scale.o

 OBJS-$(CONFIG_SLICIFY_FILTER)                += vf_slicify.o

 OBJS-$(CONFIG_VFLIP_FILTER)                  += vf_vflip.o

+OBJS-$(CONFIG_NULLSRC_FILTER)                += vsrc_nullsrc.o

+

 include $(SUBDIR)../subdir.mak

@@ -41,4 +41,6 @@ void avfilter_register_all(void)

     REGISTER_FILTER (SCALE, scale, vf);

     REGISTER_FILTER (SLICIFY, slicify, vf);

     REGISTER_FILTER (VFLIP, vflip, vf);

+

+    REGISTER_FILTER (NULLSRC, nullsrc, vsrc);

 }

@@ -25,7 +25,7 @@

 #include "libavutil/avutil.h"

 #define LIBAVFILTER_VERSION_MAJOR  1

-#define LIBAVFILTER_VERSION_MINOR 15

+#define LIBAVFILTER_VERSION_MINOR 16

 #define LIBAVFILTER_VERSION_MICRO  0

 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \

new file mode 100644

@@ -0,0 +1,83 @@

+/*

+ * 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 libavfilter/vsrc_nullsrc.c

+ * null video source

+ */

+

+#include "avfilter.h"

+

+typedef struct {

+    int w, h;

+} NullContext;

+

+static int init(AVFilterContext *ctx, const char *args, void *opaque)

+{

+    NullContext *priv = ctx->priv;

+

+    priv->w = 352;

+    priv->h = 288;

+

+    if (args)

+        sscanf(args, "%d:%d", &priv->w, &priv->h);

+

+    if (priv->w <= 0 || priv->h <= 0) {

+        av_log(ctx, AV_LOG_ERROR, "Non-positive size values are not acceptable.\n");

+        return -1;

+    }

+

+    return 0;

+}

+

+static int config_props(AVFilterLink *outlink)

+{

+    NullContext *priv = outlink->src->priv;

+

+    outlink->w = priv->w;

+    outlink->h = priv->h;

+

+    av_log(outlink->src, AV_LOG_INFO, "w:%d h:%d\n", priv->w, priv->h);

+

+    return 0;

+}

+

+static int request_frame(AVFilterLink *link)

+{

+    return -1;

+}

+

+AVFilter avfilter_vsrc_nullsrc = {

+    .name        = "nullsrc",

+    .description = "Null video source, never return images.",

+

+    .init       = init,

+    .priv_size = sizeof(NullContext),

+

+    .inputs    = (AVFilterPad[]) {{ .name = NULL}},

+

+    .outputs   = (AVFilterPad[]) {

+        {

+            .name            = "default",

+            .type            = CODEC_TYPE_VIDEO,

+            .config_props    = config_props,

+            .request_frame   = request_frame,

+        },

+        { .name = NULL}

+    },

+};