vf_dlopen examples: add framestep filter

Usage: -vf dlopen=./framestep.so:5

TOOLS/vf_dlopen/Makefile

@@ -19,7 +19,7 @@
 # 02110-1301 USA
 #
 
-FILTERS = showqscale telecine tile rectangle
+FILTERS = showqscale telecine tile rectangle framestep
 COMMON = filterutils.o
 
 OBJECTS = $(patsubst %,%.o,$(FILTERS)) $(COMMON)
@@ -28,7 +28,7 @@ OUT = $(patsubst %,%.so,$(FILTERS))
 
 CFLAGS ?= -Wall -Wextra -O3 -march=native -mtune=native -ffast-math
 
-CPPFLAGS += -I../../libmpcodecs
+CPPFLAGS += -I../../video/filter
 CFLAGS += -fPIC
 LDFLAGS += -shared -fPIC
 

TOOLS/vf_dlopen/framestep.c

@@ -0,0 +1,104 @@
+/*
+ * Copyright (c) 2012 Rudolf Polzer <divVerent@xonotic.org>
+ *
+ * This file is part of mpv's vf_dlopen examples.
+ *
+ * mpv's vf_dlopen examples are free software; you can redistribute them and/or
+ * modify them 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.
+ *
+ * mpv's vf_dlopen examples are distributed in the hope that they 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 mpv's vf_dlopen examples; if not, write to the Free
+ * Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ */
+
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "vf_dlopen.h"
+#include "filterutils.h"
+
+#define MIN(a,b) ((a)<(b)?(a):(b))
+
+/*
+ * frame stepping filter
+ *
+ * usage: -vf dlopen=./framestep.so:5
+ *
+ * outputs every 5th frame
+ */
+
+typedef struct {
+    int step, pos;
+} framestep_data_t;
+
+static int framestep_config(struct vf_dlopen_context *ctx)
+{
+    (void) ctx;
+    return 1;
+}
+
+static int framestep_put_image(struct vf_dlopen_context *ctx)
+{
+    framestep_data_t *framestep = ctx->priv;
+
+    // stepping
+    ++framestep->pos;
+    if (framestep->pos < framestep->step)
+        return 0;
+    framestep->pos = 0;
+
+    // copying
+    assert(ctx->inpic.planes == ctx->outpic[0].planes);
+    int np = ctx->inpic.planes;
+    int p;
+    for (p = 0; p < np; ++p) {
+        assert(ctx->inpic.planewidth[p] == ctx->outpic->planewidth[p]);
+        assert(ctx->inpic.planeheight[p] == ctx->outpic->planeheight[p]);
+        copy_plane(
+            ctx->outpic->plane[p],
+            ctx->outpic->planestride[p],
+            ctx->inpic.plane[p],
+            ctx->inpic.planestride[p],
+            MIN(ctx->inpic.planestride[p], ctx->outpic->planestride[p]),
+            ctx->inpic.planeheight[p]
+            );
+    }
+    ctx->outpic->pts = ctx->inpic.pts;
+
+    return 1;
+}
+
+void framestep_uninit(struct vf_dlopen_context *ctx)
+{
+    (void) ctx;
+}
+
+int vf_dlopen_getcontext(struct vf_dlopen_context *ctx, int argc, const char **argv)
+{
+    VF_DLOPEN_CHECK_VERSION(ctx);
+
+    if (argc != 1)
+        return -1;
+
+    framestep_data_t *framestep = malloc(sizeof(framestep_data_t));
+    memset(framestep, 0, sizeof(*framestep));
+
+    framestep->step = atoi(argv[0]);
+
+    ctx->priv = framestep;
+    ctx->config = framestep_config;
+    ctx->put_image = framestep_put_image;
+    ctx->uninit = framestep_uninit;
+
+    return 1;
+}