From f77db72965f834141a5c7cc405ff4b15b70eeacb Mon Sep 17 00:00:00 2001
From: Paul B Mahol <onemda@gmail.com>
Date: Thu, 11 Apr 2013 00:03:23 +0000
Subject: [PATCH 1/2] lavfi/framestep: switch to an AVOptions-based system

Signed-off-by: Paul B Mahol <onemda@gmail.com>
---
 doc/filters.texi           | 10 +++++++---
 libavfilter/avfilter.c     |  1 +
 libavfilter/vf_framestep.c | 27 ++++++++++-----------------
 3 files changed, 18 insertions(+), 20 deletions(-)

diff --git a/doc/filters.texi b/doc/filters.texi
index 5f85ac006a..c37529c6bc 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -3216,10 +3216,14 @@ See also the @ref{setpts} filter.
 
 @section framestep
 
-Select one frame every N.
+Select one frame every N-th frame.
 
-This filter accepts in input a string representing a positive
-integer. Default argument is @code{1}.
+This filter accepts the following option:
+@table @option
+@item step
+Select frame after every @code{step} frames.
+Allowed values are positive integers higher than 0. Default value is @code{1}.
+@end table
 
 @anchor{frei0r}
 @section frei0r
diff --git a/libavfilter/avfilter.c b/libavfilter/avfilter.c
index abf8cd6e41..9159b9e927 100644
--- a/libavfilter/avfilter.c
+++ b/libavfilter/avfilter.c
@@ -677,6 +677,7 @@ int avfilter_init_filter(AVFilterContext *filter, const char *args, void *opaque
         !strcmp(filter->filter->name,  "field"     ) ||
         !strcmp(filter->filter->name,  "fieldorder") ||
         !strcmp(filter->filter->name,  "fps"       ) ||
+        !strcmp(filter->filter->name,  "framestep" ) ||
         !strcmp(filter->filter->name,  "frei0r"    ) ||
         !strcmp(filter->filter->name,  "frei0r_src") ||
         !strcmp(filter->filter->name,  "geq"       ) ||
diff --git a/libavfilter/vf_framestep.c b/libavfilter/vf_framestep.c
index ca68df66dc..50a0f509ca 100644
--- a/libavfilter/vf_framestep.c
+++ b/libavfilter/vf_framestep.c
@@ -23,32 +23,25 @@
  * Daniele Fornighieri <guru AT digitalfantasy it>.
  */
 
+#include "libavutil/opt.h"
 #include "avfilter.h"
 #include "internal.h"
 #include "video.h"
 
 typedef struct {
+    const AVClass *class;
     int frame_step, frame_count, frame_selected;
 } FrameStepContext;
 
-static av_cold int init(AVFilterContext *ctx, const char *args)
-{
-    FrameStepContext *framestep = ctx->priv;
-    char *tailptr;
-    long int n = 1;
+#define OFFSET(x) offsetof(FrameStepContext, x)
+#define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
 
-    if (args) {
-        n = strtol(args, &tailptr, 10);
-        if (*tailptr || n <= 0 || n >= INT_MAX) {
-            av_log(ctx, AV_LOG_ERROR,
-                   "Invalid argument '%s', must be a positive integer <= INT_MAX\n", args);
-            return AVERROR(EINVAL);
-        }
-    }
+static const AVOption framestep_options[] = {
+    { "step", "set frame step",  OFFSET(frame_step), AV_OPT_TYPE_INT, {.i64=1}, 1, INT_MAX, FLAGS},
+    {NULL},
+};
 
-    framestep->frame_step = n;
-    return 0;
-}
+AVFILTER_DEFINE_CLASS(framestep);
 
 static int config_output_props(AVFilterLink *outlink)
 {
@@ -117,8 +110,8 @@ static const AVFilterPad framestep_outputs[] = {
 AVFilter avfilter_vf_framestep = {
     .name      = "framestep",
     .description = NULL_IF_CONFIG_SMALL("Select one frame every N frames."),
-    .init      = init,
     .priv_size = sizeof(FrameStepContext),
+    .priv_class = &framestep_class,
     .inputs    = framestep_inputs,
     .outputs   = framestep_outputs,
 };

From 7c79ec66b6cc25a150d33d7397c8f4310b77e70f Mon Sep 17 00:00:00 2001
From: Paul B Mahol <onemda@gmail.com>
Date: Thu, 11 Apr 2013 00:09:47 +0000
Subject: [PATCH 2/2] lavfi/framestep: remove request_frame hack

Signed-off-by: Paul B Mahol <onemda@gmail.com>
---
 libavfilter/vf_framestep.c | 21 ++-------------------
 1 file changed, 2 insertions(+), 19 deletions(-)

diff --git a/libavfilter/vf_framestep.c b/libavfilter/vf_framestep.c
index 50a0f509ca..bd079cc32c 100644
--- a/libavfilter/vf_framestep.c
+++ b/libavfilter/vf_framestep.c
@@ -30,7 +30,7 @@
 
 typedef struct {
     const AVClass *class;
-    int frame_step, frame_count, frame_selected;
+    int frame_step, frame_count;
 } FrameStepContext;
 
 #define OFFSET(x) offsetof(FrameStepContext, x)
@@ -49,6 +49,7 @@ static int config_output_props(AVFilterLink *outlink)
     FrameStepContext *framestep = ctx->priv;
     AVFilterLink *inlink = ctx->inputs[0];
 
+    outlink->flags |= FF_LINK_FLAG_REQUEST_LOOP;
     outlink->frame_rate =
         av_div_q(inlink->frame_rate, (AVRational){framestep->frame_step, 1});
 
@@ -64,34 +65,17 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *ref)
     FrameStepContext *framestep = inlink->dst->priv;
 
     if (!(framestep->frame_count++ % framestep->frame_step)) {
-        framestep->frame_selected = 1;
         return ff_filter_frame(inlink->dst->outputs[0], ref);
     } else {
-        framestep->frame_selected = 0;
         av_frame_free(&ref);
         return 0;
     }
 }
 
-static int request_frame(AVFilterLink *outlink)
-{
-    FrameStepContext *framestep = outlink->src->priv;
-    AVFilterLink *inlink = outlink->src->inputs[0];
-    int ret;
-
-    framestep->frame_selected = 0;
-    do {
-        ret = ff_request_frame(inlink);
-    } while (!framestep->frame_selected && ret >= 0);
-
-    return ret;
-}
-
 static const AVFilterPad framestep_inputs[] = {
     {
         .name             = "default",
         .type             = AVMEDIA_TYPE_VIDEO,
-        .get_video_buffer = ff_null_get_video_buffer,
         .filter_frame     = filter_frame,
     },
     { NULL }
@@ -102,7 +86,6 @@ static const AVFilterPad framestep_outputs[] = {
         .name          = "default",
         .type          = AVMEDIA_TYPE_VIDEO,
         .config_props  = config_output_props,
-        .request_frame = request_frame,
     },
     { NULL }
 };