avfilter: add random video filter

Signed-off-by: Paul B Mahol <onemda@gmail.com>

Changelog

@@ -19,6 +19,7 @@ version <next>:
 - erosion, dilation, deflate and inflate video filters
 - Dynamic Audio Normalizer as dynaudnorm filter
 - Reverse filter
+- Random filter
 
 
 version 2.7:

doc/filters.texi

@@ -8279,6 +8279,24 @@ qp=2+2*sin(PI*qp)
 @end example
 @end itemize
 
+@section random
+
+Flush video frames from internal cache of frames into a random order.
+No frame is discarded.
+Inspired by @ref{frei0r} nervous filter.
+
+@table @option
+@item frames
+Set size in number of frames of internal cache, in range from @code{2} to
+@code{512}. Default is @code{30}.
+
+@item seed
+Set seed for random number generator, must be an integer included between
+@code{0} and @code{UINT32_MAX}. If not specified, or if explicitly set to
+less than @code{0}, the filter will try to use a good random seed on a
+best effort basis.
+@end table
+
 @section removegrain
 
 The removegrain filter is a spatial denoiser for progressive video.

libavfilter/Makefile

@@ -183,6 +183,7 @@ OBJS-$(CONFIG_PP7_FILTER)                    += vf_pp7.o
 OBJS-$(CONFIG_PSNR_FILTER)                   += vf_psnr.o dualinput.o framesync.o
 OBJS-$(CONFIG_PULLUP_FILTER)                 += vf_pullup.o
 OBJS-$(CONFIG_QP_FILTER)                     += vf_qp.o
+OBJS-$(CONFIG_RANDOM_FILTER)                 += vf_random.o
 OBJS-$(CONFIG_REMOVEGRAIN_FILTER)            += vf_removegrain.o
 OBJS-$(CONFIG_REMOVELOGO_FILTER)             += bbox.o lswsutils.o lavfutils.o vf_removelogo.o
 OBJS-$(CONFIG_REPEATFIELDS_FILTER)           += vf_repeatfields.o

libavfilter/allfilters.c

@@ -198,6 +198,7 @@ void avfilter_register_all(void)
     REGISTER_FILTER(PSNR,           psnr,           vf);
     REGISTER_FILTER(PULLUP,         pullup,         vf);
     REGISTER_FILTER(QP,             qp,             vf);
+    REGISTER_FILTER(RANDOM,         random,         vf);
     REGISTER_FILTER(REMOVEGRAIN,    removegrain,    vf);
     REGISTER_FILTER(REMOVELOGO,     removelogo,     vf);
     REGISTER_FILTER(REPEATFIELDS,   repeatfields,   vf);

libavfilter/version.h

@@ -30,7 +30,7 @@
 #include "libavutil/version.h"
 
 #define LIBAVFILTER_VERSION_MAJOR  5
-#define LIBAVFILTER_VERSION_MINOR  24
+#define LIBAVFILTER_VERSION_MINOR  25
 #define LIBAVFILTER_VERSION_MICRO 100
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \

libavfilter/vf_random.c

@@ -0,0 +1,144 @@
+/*
+ * Copyright (c) 2015 Paul B Mahol
+ *
+ * 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 "libavutil/lfg.h"
+#include "libavutil/opt.h"
+#include "libavutil/random_seed.h"
+#include "avfilter.h"
+#include "formats.h"
+#include "internal.h"
+#include "video.h"
+
+#define MAX_FRAMES 512
+
+typedef struct RandomContext {
+    const AVClass *class;
+
+    AVLFG lfg;
+    int nb_frames;
+    int64_t random_seed;
+    int nb_frames_filled;
+    AVFrame *frames[MAX_FRAMES];
+    int64_t pts[MAX_FRAMES];
+    int flush_idx;
+} RandomContext;
+
+#define OFFSET(x) offsetof(RandomContext, x)
+#define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
+
+static const AVOption random_options[] = {
+    { "frames", "set number of frames in cache", OFFSET(nb_frames),   AV_OPT_TYPE_INT,   {.i64=30},  2, MAX_FRAMES, FLAGS },
+    { "seed",   "set the seed",                  OFFSET(random_seed), AV_OPT_TYPE_INT64, {.i64=-1}, -1, UINT32_MAX, FLAGS },
+    { NULL }
+};
+
+AVFILTER_DEFINE_CLASS(random);
+
+static av_cold int init(AVFilterContext *ctx)
+{
+    RandomContext *s = ctx->priv;
+    uint32_t seed;
+
+    if (s->random_seed < 0)
+        s->random_seed = av_get_random_seed();
+    seed = s->random_seed;
+    av_lfg_init(&s->lfg, seed);
+
+    return 0;
+}
+
+static int config_output(AVFilterLink *outlink)
+{
+    outlink->flags |= FF_LINK_FLAG_REQUEST_LOOP;
+    return 0;
+}
+
+static int filter_frame(AVFilterLink *inlink, AVFrame *in)
+{
+    AVFilterContext *ctx = inlink->dst;
+    RandomContext *s = ctx->priv;
+    AVFilterLink *outlink = ctx->outputs[0];
+    AVFrame *out;
+    int idx;
+
+    if (s->nb_frames_filled < s->nb_frames) {
+        s->frames[s->nb_frames_filled] = in;
+        s->pts[s->nb_frames_filled++] = in->pts;
+        return 0;
+    }
+
+    idx = av_lfg_get(&s->lfg) % s->nb_frames;
+
+    out = s->frames[idx];
+    out->pts = s->pts[0];
+    memmove(&s->pts[0], &s->pts[1], (s->nb_frames - 1) * sizeof(s->pts[0]));
+    s->frames[idx] = in;
+    s->pts[s->nb_frames - 1] = in->pts;
+
+    return ff_filter_frame(outlink, out);
+}
+
+static int request_frame(AVFilterLink *outlink)
+{
+    AVFilterContext *ctx = outlink->src;
+    RandomContext *s = ctx->priv;
+    int ret;
+
+    ret = ff_request_frame(ctx->inputs[0]);
+
+    if (ret == AVERROR_EOF && !ctx->is_disabled && s->nb_frames > 0) {
+        AVFrame *out = s->frames[s->nb_frames - 1];
+        out->pts = s->pts[s->flush_idx++];
+        ret = ff_filter_frame(outlink, out);
+        s->frames[s->nb_frames - 1] = NULL;
+        s->nb_frames--;
+    }
+
+    return ret;
+}
+
+static const AVFilterPad random_inputs[] = {
+    {
+        .name         = "default",
+        .type         = AVMEDIA_TYPE_VIDEO,
+        .filter_frame = filter_frame,
+    },
+    { NULL }
+};
+
+static const AVFilterPad random_outputs[] = {
+    {
+        .name          = "default",
+        .type          = AVMEDIA_TYPE_VIDEO,
+        .request_frame = request_frame,
+        .config_props  = config_output,
+    },
+    { NULL }
+};
+
+AVFilter ff_vf_random = {
+    .name        = "random",
+    .description = NULL_IF_CONFIG_SMALL("Return random frames."),
+    .priv_size   = sizeof(RandomContext),
+    .priv_class  = &random_class,
+    .init        = init,
+    .inputs      = random_inputs,
+    .outputs     = random_outputs,
+};