@@ -1000,33 +1000,37 @@ For more information about libfreetype, check:

 Apply fade-in/out effect to input video.

-It accepts the parameters:

-@var{type}:@var{start_frame}:@var{nb_frames}

+This filter accepts the following options:

+

+@table @option

-@var{type} specifies if the effect type, can be either "in" for

-fade-in, or "out" for a fade-out effect.

+@item type

+The effect type -- can be either "in" for fade-in, or "out" for a fade-out

+effect.

+

+@item start_frame

+The number of the start frame for starting to apply the fade effect.

-@var{start_frame} specifies the number of the start frame for starting

-to apply the fade effect.

+@item nb_frames

+The number of frames for which the fade effect has to last. At the end of the

+fade-in effect the output video will have the same intensity as the input video,

+at the end of the fade-out transition the output video will be completely black.

-@var{nb_frames} specifies the number of frames for which the fade

-effect has to last. At the end of the fade-in effect the output video

-will have the same intensity as the input video, at the end of the

-fade-out transition the output video will be completely black.

+@end table

 A few usage examples follow, usable too as test scenarios.

 @example

 # fade in first 30 frames of video

-fade=in:0:30

+fade=type=in:nb_frames=30

 # fade out last 45 frames of a 200-frame video

-fade=out:155:45

+fade=type=out:start_frame=155:nb_frames=45

 # fade in first 25 frames and fade out last 25 frames of a 1000-frame video

-fade=in:0:25, fade=out:975:25

+fade=type=in:start_frame=0:nb_frames=25, fade=type=out:start_frame=975:nb_frames=25

 # make first 5 frames black, then fade in from frame 5-24

-fade=in:5:20

+fade=type=in:start_frame=5:nb_frames=20

 @end example

 @section fieldorder

@@ -26,48 +26,42 @@

  */

 #include "libavutil/common.h"

+#include "libavutil/opt.h"

 #include "libavutil/pixdesc.h"

 #include "avfilter.h"

 #include "formats.h"

 #include "internal.h"

 #include "video.h"

+#define FADE_IN  0

+#define FADE_OUT 1

+

 typedef struct {

+    const AVClass *class;

+    int type;

     int factor, fade_per_frame;

-    unsigned int frame_index, start_frame, stop_frame;

+    int start_frame, nb_frames;

+    unsigned int frame_index, stop_frame;

     int hsub, vsub, bpp;

 } FadeContext;

 static av_cold int init(AVFilterContext *ctx, const char *args)

 {

     FadeContext *fade = ctx->priv;

-    unsigned int nb_frames;

-    char in_out[4];

-

-    if (!args ||

-        sscanf(args, " %3[^:]:%u:%u", in_out, &fade->start_frame, &nb_frames) != 3) {

-        av_log(ctx, AV_LOG_ERROR,

-               "Expected 3 arguments '(in|out):#:#':'%s'\n", args);

-        return AVERROR(EINVAL);

-    }

-    nb_frames = nb_frames ? nb_frames : 1;

-    fade->fade_per_frame = (1 << 16) / nb_frames;

-    if (!strcmp(in_out, "in"))

+    fade->fade_per_frame = (1 << 16) / fade->nb_frames;

+    if (fade->type == FADE_IN) {

         fade->factor = 0;

-    else if (!strcmp(in_out, "out")) {

+    } else if (fade->type == FADE_OUT) {

         fade->fade_per_frame = -fade->fade_per_frame;

         fade->factor = (1 << 16);

-    } else {

-        av_log(ctx, AV_LOG_ERROR,

-               "first argument must be 'in' or 'out':'%s'\n", in_out);

-        return AVERROR(EINVAL);

     }

-    fade->stop_frame = fade->start_frame + nb_frames;

+    fade->stop_frame = fade->start_frame + fade->nb_frames;

     av_log(ctx, AV_LOG_VERBOSE,

            "type:%s start_frame:%d nb_frames:%d\n",

-           in_out, fade->start_frame, nb_frames);

+           fade->type == FADE_IN ? "in" : "out", fade->start_frame,

+           fade->nb_frames);

     return 0;

 }

@@ -143,6 +137,26 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *frame)

     return ff_filter_frame(inlink->dst->outputs[0], frame);

 }

+#define OFFSET(x) offsetof(FadeContext, x)

+#define FLAGS AV_OPT_FLAG_VIDEO_PARAM

+static const AVOption options[] = {

+    { "type", "'in' or 'out' for fade-in/fade-out", OFFSET(type), AV_OPT_TYPE_INT, { .i64 = FADE_IN }, FADE_IN, FADE_OUT, FLAGS, "type" },

+        { "in",  "fade-in",  0, AV_OPT_TYPE_CONST, { .i64 = FADE_IN },  .unit = "type" },

+        { "out", "fade-out", 0, AV_OPT_TYPE_CONST, { .i64 = FADE_OUT }, .unit = "type" },

+    { "start_frame", "Number of the first frame to which to apply the effect.",

+                                                    OFFSET(start_frame), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, FLAGS },

+    { "nb_frames",   "Number of frames to which the effect should be applied.",

+                                                    OFFSET(nb_frames),   AV_OPT_TYPE_INT, { .i64 = 1 }, 0, INT_MAX, FLAGS },

+    { NULL },

+};

+

+static const AVClass fade_class = {

+    .class_name = "fade",

+    .item_name  = av_default_item_name,

+    .option     = options,

+    .version    = LIBAVUTIL_VERSION_INT,

+};

+

 static const AVFilterPad avfilter_vf_fade_inputs[] = {

     {

         .name             = "default",

@@ -168,6 +182,7 @@ AVFilter avfilter_vf_fade = {

     .description   = NULL_IF_CONFIG_SMALL("Fade in/out input video"),

     .init          = init,

     .priv_size     = sizeof(FadeContext),

+    .priv_class    = &fade_class,

     .query_formats = query_formats,

     .inputs    = avfilter_vf_fade_inputs,