[FFmpeg-soc] Help needed with new concatenate filter

[Brandon Mintern]

I'm trying to add a filter to concatenate multiple inputs together.
The idea is that the inputs should already be the same size and frame
rate, but I don't actually enforce that, I just ensure that the output
buffer is big enough to hold the biggest height/width. Here is a
sample usage:

./ffmpeg_g -y -i input1.wmv -vfilters "movie=0:wmv3:input2.wmv [in2];
[in][in2] concatenate" -r 15 out.wmv

Where input1.wmv and input2.wmv are both 15 fps and 800x600. As
written now, out.wmv seems to only be input1.wmv. I would appreciate
any insight into what I'm doing wrong. The patch is located at
http://bmintern.homeunix.com/~brandon/vf_concatenate.patch and is
included below.

Thanks,
Brandon

Index: allfilters.c
===================================================================
--- allfilters.c	(revision 5726)
+++ allfilters.c	(working copy)
@@ -35,6 +35,7 @@
     initialized = 1;

     REGISTER_FILTER (ASPECT,      aspect,      vf);
+    REGISTER_FILTER (CONCATENATE, concatenate, vf);
     REGISTER_FILTER (CROP,        crop,        vf);
     REGISTER_FILTER (DRAWBOX,     drawbox,     vf);
     REGISTER_FILTER (FIFO,        fifo,        vf);
Index: vf_concatenate.c
===================================================================
--- vf_concatenate.c	(revision 0)
+++ vf_concatenate.c	(revision 0)
@@ -0,0 +1,109 @@
+/*
+ * video concatenate filter
+ * copyright (c) 2007 Bobby Bingham
+ *
+ * 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 "avfilter.h"
+
+typedef struct {
+    int first_input_consumed;
+    AVFilterPicRef *pic;
+} ConcatenateContext;
+
+static av_cold void uninit(AVFilterContext *ctx)
+{
+    ConcatenateContext *con = ctx->priv;
+    if (con->pic)
+        avfilter_unref_pic(con->pic);
+}
+
+static int config_props(AVFilterLink *link)
+{
+    if (link->src->inputs[0]->w > link->src->inputs[1]->w)
+        link->w = link->src->inputs[0]->w;
+    else
+        link->w = link->src->inputs[1]->w;
+    if (link->src->inputs[1]->h > link->src->inputs[1]->h)
+        link->h = link->src->inputs[0]->h;
+    else
+        link->h = link->src->inputs[1]->h;
+    return 0;
+}
+
+static void start_frame(AVFilterLink *link, AVFilterPicRef *picref)
+{
+    ConcatenateContext *con = link->dst->priv;
+    con->pic = picref;
+}
+
+static void end_frame(AVFilterLink *link)
+{
+}
+
+static int poll_frame(AVFilterLink *link)
+{
+    ConcatenateContext *con = link->src->priv;
+    if (con->first_input_consumed)
+        return avfilter_poll_frame(link->src->inputs[1]);
+    return avfilter_poll_frame(link->src->inputs[0]);
+}
+
+static int request_frame(AVFilterLink *link)
+{
+    ConcatenateContext *con = link->src->priv;
+    if(!con->first_input_consumed &&
+       avfilter_request_frame(link->src->inputs[0]))
+        con->first_input_consumed = 1;
+    if(con->first_input_consumed &&
+       avfilter_request_frame(link->src->inputs[1]))
+        return AVERROR_EOF;
+    avfilter_start_frame(link, con->pic);
+    avfilter_draw_slice(link, 0, con->pic->h, 1);
+    avfilter_end_frame(link);
+    con->pic = NULL;
+    return 0;
+}
+
+AVFilter avfilter_vf_concatenate =
+{
+    .name      = "concatenate",
+
+    .uninit    = uninit,
+
+    .priv_size = sizeof(ConcatenateContext),
+
+    .inputs    = (AVFilterPad[]) {{ .name            = "default",
+                                    .type            = CODEC_TYPE_VIDEO,
+                                    .start_frame     = start_frame,
+                                    .end_frame       = end_frame,
+                                    .get_video_buffer=
avfilter_null_get_video_buffer, },
+                                  { .name            = "default2",
+                                    .type            = CODEC_TYPE_VIDEO,
+                                    .start_frame     = start_frame,
+                                    .end_frame       = end_frame,
+                                    .get_video_buffer=
avfilter_null_get_video_buffer, },
+                                  { .name = NULL}},
+    .outputs   = (AVFilterPad[]) {{ .name            = "default",
+                                    .type            = CODEC_TYPE_VIDEO,
+                                    .config_props    = config_props,
+                                    .poll_frame      = poll_frame,
+                                    .request_frame   = request_frame, },
+                                  { .name = NULL}},
+};
+
Index: Makefile
===================================================================
--- Makefile	(revision 5726)
+++ Makefile	(working copy)
@@ -16,6 +16,7 @@
        parseutils.o                                                     \

 OBJS-$(CONFIG_ASPECT_FILTER)                 += vf_aspect.o
+OBJS-$(CONFIG_CONCATENATE_FILTER)            += vf_concatenate.o
 OBJS-$(CONFIG_CROP_FILTER)                   += vf_crop.o
 OBJS-$(CONFIG_DRAWBOX_FILTER)                += vf_drawbox.o
 OBJS-$(CONFIG_FIFO_FILTER)                   += vf_fifo.o