[FFmpeg-devel] [PATCH] avfilter: add vfrdet filter

[Paul B Mahol]

Signed-off-by: Paul B Mahol <onemda at gmail.com>
---
 doc/filters.texi         |  11 +++++
 libavfilter/Makefile     |   1 +
 libavfilter/allfilters.c |   1 +
 libavfilter/vf_vfrdet.c  | 111 +++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 124 insertions(+)
 create mode 100644 libavfilter/vf_vfrdet.c

diff --git a/doc/filters.texi b/doc/filters.texi
index fc912b6716..f439edc0df 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -15892,6 +15892,17 @@ For example, to vertically flip a video with @command{ffmpeg}:
 ffmpeg -i in.avi -vf "vflip" out.avi
 @end example
 
+ at section vfrdet
+
+Detect variable frame rate video.
+
+This filter tries to detect if the input is variable or constant frame rate.
+
+At end it will output number of frames detected as having variable delta pts,
+and ones with constant delta pts.
+If there was frames with variable delta, than it will also show min and max delta
+encountered.
+
 @anchor{vignette}
 @section vignette
 
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index 6b06d57234..e75fc09e30 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -340,6 +340,7 @@ OBJS-$(CONFIG_USPP_FILTER)                   += vf_uspp.o
 OBJS-$(CONFIG_VAGUEDENOISER_FILTER)          += vf_vaguedenoiser.o
 OBJS-$(CONFIG_VECTORSCOPE_FILTER)            += vf_vectorscope.o
 OBJS-$(CONFIG_VFLIP_FILTER)                  += vf_vflip.o
+OBJS-$(CONFIG_VFRDET_FILTER)                 += vf_vfrdet.o
 OBJS-$(CONFIG_VIDSTABDETECT_FILTER)          += vidstabutils.o vf_vidstabdetect.o
 OBJS-$(CONFIG_VIDSTABTRANSFORM_FILTER)       += vidstabutils.o vf_vidstabtransform.o
 OBJS-$(CONFIG_VIGNETTE_FILTER)               += vf_vignette.o
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index 707faad777..3023fac4c3 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -348,6 +348,7 @@ static void register_all(void)
     REGISTER_FILTER(VAGUEDENOISER,  vaguedenoiser,  vf);
     REGISTER_FILTER(VECTORSCOPE,    vectorscope,    vf);
     REGISTER_FILTER(VFLIP,          vflip,          vf);
+    REGISTER_FILTER(VFRDET,         vfrdet,         vf);
     REGISTER_FILTER(VIDSTABDETECT,  vidstabdetect,  vf);
     REGISTER_FILTER(VIDSTABTRANSFORM, vidstabtransform, vf);
     REGISTER_FILTER(VIGNETTE,       vignette,       vf);
diff --git a/libavfilter/vf_vfrdet.c b/libavfilter/vf_vfrdet.c
new file mode 100644
index 0000000000..617efeda92
--- /dev/null
+++ b/libavfilter/vf_vfrdet.c
@@ -0,0 +1,111 @@
+/*
+ * Copyright (C) 2017 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/common.h"
+#include "libavutil/opt.h"
+#include "internal.h"
+
+typedef struct VFRDETContext {
+    const AVClass *class;
+
+    int64_t prev_pts;
+    int64_t delta;
+    int64_t min_delta;
+    int64_t max_delta;
+
+    int64_t vfr;
+    int64_t cfr;
+} VFRDETContext;
+
+static int filter_frame(AVFilterLink *inlink, AVFrame *in)
+{
+    AVFilterContext *ctx = inlink->dst;
+    VFRDETContext *s = ctx->priv;
+
+    if (s->prev_pts != AV_NOPTS_VALUE) {
+        int64_t delta = in->pts - s->prev_pts;
+
+        if (s->delta == AV_NOPTS_VALUE) {
+            s->delta = delta;
+        }
+
+        if (s->delta != delta) {
+            s->vfr++;
+            s->delta = delta;
+            s->min_delta = FFMIN(delta, s->min_delta);
+            s->max_delta = FFMAX(delta, s->max_delta);
+        } else {
+            s->cfr++;
+        }
+    }
+
+    s->prev_pts = in->pts;
+
+    return ff_filter_frame(ctx->outputs[0], in);
+}
+
+static av_cold int init(AVFilterContext *ctx)
+{
+    VFRDETContext *s = ctx->priv;
+
+    s->prev_pts = AV_NOPTS_VALUE;
+    s->delta    = AV_NOPTS_VALUE;
+    s->min_delta = INT64_MAX;
+    s->max_delta = INT64_MIN;
+
+    return 0;
+}
+
+static av_cold void uninit(AVFilterContext *ctx)
+{
+    VFRDETContext *s = ctx->priv;
+
+    av_log(ctx, AV_LOG_INFO, "VFR:%f (%ld/%ld)", s->vfr / (float)(s->vfr + s->cfr), s->vfr, s->cfr);
+    if (s->vfr)
+        av_log(ctx, AV_LOG_INFO, " min: %ld max: %ld)", s->min_delta, s->max_delta);
+    av_log(ctx, AV_LOG_INFO, "\n");
+}
+
+static const AVFilterPad vfrdet_inputs[] = {
+    {
+        .name         = "default",
+        .type         = AVMEDIA_TYPE_VIDEO,
+        .filter_frame = filter_frame,
+    },
+    { NULL }
+};
+
+static const AVFilterPad vfrdet_outputs[] = {
+    {
+        .name = "default",
+        .type = AVMEDIA_TYPE_VIDEO,
+    },
+    { NULL }
+};
+
+AVFilter ff_vf_vfrdet = {
+    .name        = "vfrdet",
+    .description = NULL_IF_CONFIG_SMALL("Variable frame rate detect filter."),
+    .priv_size   = sizeof(VFRDETContext),
+    .init        = init,
+    .uninit      = uninit,
+    .inputs      = vfrdet_inputs,
+    .outputs     = vfrdet_outputs,
+};
-- 
2.11.0