avfilter: add framerate video filter

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

6 files changed, 641 insertions, 1 deletions

diff --git a/Changelog b/Changelog
index 99aae00275..5911761b08 100644
--- a/Changelog
+++ b/Changelog
@@ -37,6 +37,7 @@ version <next>:
 - hstack and vstack filter
 - Support DNx100 (1440x1080@8)
 - VAAPI hevc hwaccel
+- framerate filter
 
 
 version 2.7:
diff --git a/doc/filters.texi b/doc/filters.texi
index 178252f12d..5bef4b119c 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -6015,6 +6015,51 @@ ffmpeg -i LEFT -i RIGHT -filter_complex framepack=frameseq OUTPUT
 ffmpeg -i LEFT -i RIGHT -filter_complex [0:v]scale=w=iw/2[left],[1:v]scale=w=iw/2[right],[left][right]framepack=sbs OUTPUT
 @end example
 
+@section framerate
+
+Change the frame rate by interpolating new video output frames from the source
+frames.
+
+This filter is not designed to function correctly with interlaced media. If
+you wish to change the frame rate of interlaced media then you are required
+to deinterlace before this filter and re-interlace after this filter.
+
+A description of the accepted options follows.
+
+@table @option
+@item fps
+Specify the output frames per second. This option can also be specified
+as a value alone. The default is @code{50}.
+
+@item interp_start
+Specify the start of a range where the output frame will be created as a
+linear interpolation of two frames. The range is [@code{0}-@code{255}],
+the default is @code{15}.
+
+@item interp_end
+Specify the end of a range where the output frame will be created as a
+linear interpolation of two frames. The range is [@code{0}-@code{255}],
+the default is @code{240}.
+
+@item scene
+Specify the level at which a scene change is detected as a value between
+0 and 100 to indicate a new scene; a low value reflects a low
+probability for the current frame to introduce a new scene, while a higher
+value means the current frame is more likely to be one.
+The default is @code{7}.
+
+@item flags
+Specify flags influencing the filter process.
+
+Available value for @var{flags} is:
+
+@table @option
+@item scene_change_detect, scd
+Enable scene change detection using the value of the option @var{scene}.
+This flag is enabled by default.
+@end table
+@end table
+
 @section framestep
 
 Select one frame every N-th frame.
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index 58f990a925..ac7412d41b 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -142,6 +142,7 @@ OBJS-$(CONFIG_FIND_RECT_FILTER)              += vf_find_rect.o lavfutils.o
 OBJS-$(CONFIG_FORMAT_FILTER)                 += vf_format.o
 OBJS-$(CONFIG_FPS_FILTER)                    += vf_fps.o
 OBJS-$(CONFIG_FRAMEPACK_FILTER)              += vf_framepack.o
+OBJS-$(CONFIG_FRAMERATE_FILTER)              += vf_framerate.o
 OBJS-$(CONFIG_FRAMESTEP_FILTER)              += vf_framestep.o
 OBJS-$(CONFIG_FREI0R_FILTER)                 += vf_frei0r.o
 OBJS-$(CONFIG_FSPP_FILTER)                   += vf_fspp.o
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index 0a1bdfdf46..9068e833ff 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -158,6 +158,7 @@ void avfilter_register_all(void)
     REGISTER_FILTER(FORMAT,         format,         vf);
     REGISTER_FILTER(FPS,            fps,            vf);
     REGISTER_FILTER(FRAMEPACK,      framepack,      vf);
+    REGISTER_FILTER(FRAMERATE,      framerate,      vf);
     REGISTER_FILTER(FRAMESTEP,      framestep,      vf);
     REGISTER_FILTER(FREI0R,         frei0r,         vf);
     REGISTER_FILTER(FSPP,           fspp,           vf);
diff --git a/libavfilter/version.h b/libavfilter/version.h
index 6b836d394d..15eb5407be 100644
--- a/libavfilter/version.h
+++ b/libavfilter/version.h
@@ -30,7 +30,7 @@
 #include "libavutil/version.h"
 
 #define LIBAVFILTER_VERSION_MAJOR  5
-#define LIBAVFILTER_VERSION_MINOR  38
+#define LIBAVFILTER_VERSION_MINOR  39
 #define LIBAVFILTER_VERSION_MICRO 100
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \
diff --git a/libavfilter/vf_framerate.c b/libavfilter/vf_framerate.c
new file mode 100644
index 0000000000..5c9da1921d
--- /dev/null
+++ b/libavfilter/vf_framerate.c
@@ -0,0 +1,592 @@
+/*
+ * Copyright (C) 2012 Mark Himsley
+ *
+ * get_scene_score() Copyright (c) 2011 Stefano Sabatini
+ * taken from libavfilter/vf_select.c
+ *
+ * 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
+ */
+
+/**
+ * @file
+ * filter for upsampling or downsampling a progressive source
+ */
+
+#define DEBUG
+
+#include "libavutil/avassert.h"
+#include "libavutil/imgutils.h"
+#include "libavutil/internal.h"
+#include "libavutil/opt.h"
+#include "libavutil/pixdesc.h"
+#include "libavutil/pixelutils.h"
+
+#include "avfilter.h"
+#include "internal.h"
+#include "video.h"
+
+#define N_SRCE 3
+
+typedef struct FrameRateContext {
+    const AVClass *class;
+    // parameters
+    AVRational dest_frame_rate;         ///< output frames per second
+    int flags;                          ///< flags affecting frame rate conversion algorithm
+    double scene_score;                 ///< score that denotes a scene change has happened
+    int interp_start;                   ///< start of range to apply linear interpolation
+    int interp_end;                     ///< end of range to apply linear interpolation
+
+    int line_size[4];                   ///< bytes of pixel data per line for each plane
+    int vsub;
+
+    int frst, next, prev, crnt, last;
+    int pending_srce_frames;            ///< how many input frames are still waiting to be processed
+    int flush;                          ///< are we flushing final frames
+    int pending_end_frame;              ///< flag indicating we are waiting to call filter_frame()
+
+    AVRational srce_time_base;          ///< timebase of source
+
+    AVRational dest_time_base;          ///< timebase of destination
+    int32_t dest_frame_num;
+    int64_t last_dest_frame_pts;        ///< pts of the last frame output
+    int64_t average_srce_pts_dest_delta;///< average input pts delta converted from input rate to output rate
+    int64_t average_dest_pts_delta;     ///< calculated average output pts delta
+
+    av_pixelutils_sad_fn sad;           ///< Sum of the absolute difference function (scene detect only)
+    double prev_mafd;                   ///< previous MAFD                           (scene detect only)
+
+    AVFrame *srce[N_SRCE];              ///< buffered source frames
+    int64_t srce_pts_dest[N_SRCE];      ///< pts for source frames scaled to output timebase
+    int64_t pts;                        ///< pts of frame we are working on
+} FrameRateContext;
+
+#define OFFSET(x) offsetof(FrameRateContext, x)
+#define V AV_OPT_FLAG_VIDEO_PARAM
+#define F AV_OPT_FLAG_FILTERING_PARAM
+#define FRAMERATE_FLAG_SCD 01
+
+static const AVOption framerate_options[] = {
+    {"fps",                 "required output frames per second rate", OFFSET(dest_frame_rate), AV_OPT_TYPE_VIDEO_RATE, {.str="50"},             0,       INT_MAX, V|F },
+
+    {"interp_start",        "point to start linear interpolation",    OFFSET(interp_start),    AV_OPT_TYPE_INT,      {.i64=15},                 0,       255,     V|F },
+    {"interp_end",          "point to end linear interpolation",      OFFSET(interp_end),      AV_OPT_TYPE_INT,      {.i64=240},                0,       255,     V|F },
+    {"scene",               "scene change level",                     OFFSET(scene_score),     AV_OPT_TYPE_DOUBLE,   {.dbl=7.0},                0,       INT_MAX, V|F },
+
+    {"flags",               "set flags",                              OFFSET(flags),           AV_OPT_TYPE_FLAGS,    {.i64=1},                  0,       INT_MAX, V|F, "flags" },
+    {"scene_change_detect", "enable scene change detection",          0,                       AV_OPT_TYPE_CONST,    {.i64=FRAMERATE_FLAG_SCD}, INT_MIN, INT_MAX, V|F, "flags" },
+    {"scd",                 "enable scene change detection",          0,                       AV_OPT_TYPE_CONST,    {.i64=FRAMERATE_FLAG_SCD}, INT_MIN, INT_MAX, V|F, "flags" },
+
+    {NULL}
+};
+
+AVFILTER_DEFINE_CLASS(framerate);
+
+static void next_source(AVFilterContext *ctx)
+{
+    FrameRateContext *s = ctx->priv;
+    int i;
+
+    ff_dlog(ctx,  "next_source()\n");
+
+    if (s->srce[s->last] && s->srce[s->last] != s->srce[s->last-1]) {
+        ff_dlog(ctx, "next_source() unlink %d\n", s->last);
+        av_frame_free(&s->srce[s->last]);
+    }
+    for (i = s->last; i > s->frst; i--) {
+        ff_dlog(ctx, "next_source() copy %d to %d\n", i - 1, i);
+        s->srce[i] = s->srce[i - 1];
+    }
+    ff_dlog(ctx, "next_source() make %d null\n", s->frst);
+    s->srce[s->frst] = NULL;
+}
+
+static double get_scene_score(AVFilterContext *ctx, AVFrame *crnt, AVFrame *next)
+{
+    FrameRateContext *s = ctx->priv;
+    double ret = 0;
+
+    ff_dlog(ctx, "get_scene_score()\n");
+
+    if (crnt &&
+        crnt->height == next->height &&
+        crnt->width  == next->width) {
+        int x, y;
+        int64_t sad;
+        double mafd, diff;
+        uint8_t *p1 = crnt->data[0];
+        uint8_t *p2 = next->data[0];
+        const int p1_linesize = crnt->linesize[0];
+        const int p2_linesize = next->linesize[0];
+
+        ff_dlog(ctx, "get_scene_score() process\n");
+
+        for (sad = y = 0; y < crnt->height; y += 8) {
+            for (x = 0; x < p1_linesize; x += 8) {
+                sad += s->sad(p1 + y * p1_linesize + x,
+                              p1_linesize,
+                              p2 + y * p2_linesize + x,
+                              p2_linesize);
+            }
+        }
+        emms_c();
+        mafd = sad / (crnt->height * crnt->width * 3);
+        diff = fabs(mafd - s->prev_mafd);
+        ret  = av_clipf(FFMIN(mafd, diff), 0, 100.0);
+        s->prev_mafd = mafd;
+    }
+        ff_dlog(ctx, "get_scene_score() result is:%f\n", ret);
+    return ret;
+}
+
+static int process_work_frame(AVFilterContext *ctx, int stop)
+{
+    FrameRateContext *s = ctx->priv;
+    AVFilterLink *outlink = ctx->outputs[0];
+    int64_t work_next_pts;
+    AVFrame *copy_src1, *copy_src2, *work;
+    int interpolate;
+
+    ff_dlog(ctx, "process_work_frame()\n");
+
+    ff_dlog(ctx, "process_work_frame() pending_input_frames %d\n", s->pending_srce_frames);
+
+    if (s->srce[s->prev]) ff_dlog(ctx, "process_work_frame() srce prev pts:%"PRId64"\n", s->srce[s->prev]->pts);
+    if (s->srce[s->crnt]) ff_dlog(ctx, "process_work_frame() srce crnt pts:%"PRId64"\n", s->srce[s->crnt]->pts);
+    if (s->srce[s->next]) ff_dlog(ctx, "process_work_frame() srce next pts:%"PRId64"\n", s->srce[s->next]->pts);
+
+    if (!s->srce[s->crnt]) {
+        // the filter cannot do anything
+        ff_dlog(ctx, "process_work_frame() no current frame cached: move on to next frame, do not output a frame\n");
+        next_source(ctx);
+        return 0;
+    }
+
+    work_next_pts = s->pts + s->average_dest_pts_delta;
+
+    ff_dlog(ctx, "process_work_frame() work crnt pts:%"PRId64"\n", s->pts);
+    ff_dlog(ctx, "process_work_frame() work next pts:%"PRId64"\n", work_next_pts);
+    if (s->srce[s->prev])
+        ff_dlog(ctx, "process_work_frame() srce prev pts:%"PRId64" at dest time base:%u/%u\n",
+            s->srce_pts_dest[s->prev], s->dest_time_base.num, s->dest_time_base.den);
+    if (s->srce[s->crnt])
+        ff_dlog(ctx, "process_work_frame() srce crnt pts:%"PRId64" at dest time base:%u/%u\n",
+            s->srce_pts_dest[s->crnt], s->dest_time_base.num, s->dest_time_base.den);
+    if (s->srce[s->next])
+        ff_dlog(ctx, "process_work_frame() srce next pts:%"PRId64" at dest time base:%u/%u\n",
+            s->srce_pts_dest[s->next], s->dest_time_base.num, s->dest_time_base.den);
+
+    av_assert0(s->srce[s->next]);
+
+    // should filter be skipping input frame (output frame rate is lower than input frame rate)
+    if (!s->flush && s->pts >= s->srce_pts_dest[s->next]) {
+        ff_dlog(ctx, "process_work_frame() work crnt pts >= srce next pts: SKIP FRAME, move on to next frame, do not output a frame\n");
+        next_source(ctx);
+        s->pending_srce_frames--;
+        return 0;
+    }
+
+    // calculate interpolation
+    interpolate = (int) ((s->pts - s->srce_pts_dest[s->crnt]) * 256.0 / s->average_srce_pts_dest_delta);
+    ff_dlog(ctx, "process_work_frame() interpolate:%d/256\n", interpolate);
+    copy_src1 = s->srce[s->crnt];
+    if (interpolate > s->interp_end) {
+        ff_dlog(ctx, "process_work_frame() source is:NEXT\n");
+        copy_src1 = s->srce[s->next];
+    }
+    if (s->srce[s->prev] && interpolate < -s->interp_end) {
+        ff_dlog(ctx, "process_work_frame() source is:PREV\n");
+        copy_src1 = s->srce[s->prev];
+    }
+
+    // decide whether to blend two frames
+    if ((interpolate >= s->interp_start && interpolate <= s->interp_end) || (interpolate <= -s->interp_start && interpolate >= -s->interp_end)) {
+        double interpolate_scene_score = 0;
+
+        if (interpolate > 0) {
+            ff_dlog(ctx, "process_work_frame() interpolate source is:NEXT\n");
+            copy_src2 = s->srce[s->next];
+        } else {
+            ff_dlog(ctx, "process_work_frame() interpolate source is:PREV\n");
+            copy_src2 = s->srce[s->prev];
+        }
+        if ((s->flags & FRAMERATE_FLAG_SCD) && copy_src2) {
+            interpolate_scene_score = get_scene_score(ctx, copy_src1, copy_src2);
+            ff_dlog(ctx, "process_work_frame() interpolate scene score:%f\n", interpolate_scene_score);
+        }
+        // decide if the shot-change detection allows us to blend two frames
+        if (interpolate_scene_score < s->scene_score && copy_src2) {
+            uint16_t src2_factor = abs(interpolate);
+            uint16_t src1_factor = 256 - src2_factor;
+            int plane, line, pixel;
+
+            // get work-space for output frame
+            work = ff_get_video_buffer(outlink, outlink->w, outlink->h);
+            if (!work)
+                return AVERROR(ENOMEM);
+
+            av_frame_copy_props(work, s->srce[s->crnt]);
+
+            ff_dlog(ctx, "process_work_frame() INTERPOLATE to create work frame\n");
+            for (plane = 0; plane < 4 && copy_src1->data[plane] && copy_src2->data[plane]; plane++) {
+                int cpy_line_width = s->line_size[plane];
+                uint8_t *cpy_src1_data = copy_src1->data[plane];
+                int cpy_src1_line_size = copy_src1->linesize[plane];
+                uint8_t *cpy_src2_data = copy_src2->data[plane];
+                int cpy_src2_line_size = copy_src2->linesize[plane];
+                int cpy_src_h = (plane > 0 && plane < 3) ? (copy_src1->height >> s->vsub) : (copy_src1->height);
+                uint8_t *cpy_dst_data = work->data[plane];
+                int cpy_dst_line_size = work->linesize[plane];
+                if (plane <1 || plane >2) {
+                    // luma or alpha
+                    for (line = 0; line < cpy_src_h; line++) {
+                        for (pixel = 0; pixel < cpy_line_width; pixel++) {
+                            // integer version of (src1 * src1_factor) + (src2 + src2_factor) + 0.5
+                            // 0.5 is for rounding
+                            // 128 is the integer representation of 0.5 << 8
+                            cpy_dst_data[pixel] = ((cpy_src1_data[pixel] * src1_factor) + (cpy_src2_data[pixel] * src2_factor) + 128) >> 8;
+                        }
+                        cpy_src1_data += cpy_src1_line_size;
+                        cpy_src2_data += cpy_src2_line_size;
+                        cpy_dst_data += cpy_dst_line_size;
+                    }
+                } else {
+                    // chroma
+                    for (line = 0; line < cpy_src_h; line++) {
+                        for (pixel = 0; pixel < cpy_line_width; pixel++) {
+                            // as above
+                            // because U and V are based around 128 we have to subtract 128 from the components.
+                            // 32896 is the integer representation of 128.5 << 8
+                            cpy_dst_data[pixel] = (((cpy_src1_data[pixel] - 128) * src1_factor) + ((cpy_src2_data[pixel] - 128) * src2_factor) + 32896) >> 8;
+                        }
+                        cpy_src1_data += cpy_src1_line_size;
+                        cpy_src2_data += cpy_src2_line_size;
+                        cpy_dst_data += cpy_dst_line_size;
+                    }
+                }
+            }
+            goto copy_done;
+        }
+        else {
+            ff_dlog(ctx, "process_work_frame() CUT - DON'T INTERPOLATE\n");
+        }
+    }
+
+    ff_dlog(ctx, "process_work_frame() COPY to the work frame\n");
+    // copy the frame we decided is our base source
+    work = av_frame_clone(copy_src1);
+    if (!work)
+        return AVERROR(ENOMEM);
+
+copy_done:
+    work->pts = s->pts;
+
+    // should filter be re-using input frame (output frame rate is higher than input frame rate)
+    if (!s->flush && (work_next_pts + s->average_dest_pts_delta) < (s->srce_pts_dest[s->crnt] + s->average_srce_pts_dest_delta)) {
+        ff_dlog(ctx, "process_work_frame() REPEAT FRAME\n");
+    } else {
+        ff_dlog(ctx, "process_work_frame() CONSUME FRAME, move to next frame\n");
+        s->pending_srce_frames--;
+        next_source(ctx);
+    }
+    ff_dlog(ctx, "process_work_frame() output a frame\n");
+    s->dest_frame_num++;
+    if (stop)
+        s->pending_end_frame = 0;
+    s->last_dest_frame_pts = work->pts;
+
+    return ff_filter_frame(ctx->outputs[0], work);
+}
+
+static void set_srce_frame_dest_pts(AVFilterContext *ctx)
+{
+    FrameRateContext *s = ctx->priv;
+
+    ff_dlog(ctx, "set_srce_frame_output_pts()\n");
+
+    // scale the input pts from the timebase difference between input and output
+    if (s->srce[s->prev])
+        s->srce_pts_dest[s->prev] = av_rescale_q(s->srce[s->prev]->pts, s->srce_time_base, s->dest_time_base);
+    if (s->srce[s->crnt])
+        s->srce_pts_dest[s->crnt] = av_rescale_q(s->srce[s->crnt]->pts, s->srce_time_base, s->dest_time_base);
+    if (s->srce[s->next])
+        s->srce_pts_dest[s->next] = av_rescale_q(s->srce[s->next]->pts, s->srce_time_base, s->dest_time_base);
+}
+
+static void set_work_frame_pts(AVFilterContext *ctx)
+{
+    FrameRateContext *s = ctx->priv;
+    int64_t pts, average_srce_pts_delta = 0;
+
+    ff_dlog(ctx, "set_work_frame_pts()\n");
+
+    av_assert0(s->srce[s->next]);
+    av_assert0(s->srce[s->crnt]);
+
+    ff_dlog(ctx, "set_work_frame_pts() srce crnt pts:%"PRId64"\n", s->srce[s->crnt]->pts);
+    ff_dlog(ctx, "set_work_frame_pts() srce next pts:%"PRId64"\n", s->srce[s->next]->pts);
+    if (s->srce[s->prev])
+        ff_dlog(ctx, "set_work_frame_pts() srce prev pts:%"PRId64"\n", s->srce[s->prev]->pts);
+
+    average_srce_pts_delta = s->average_srce_pts_dest_delta;
+    ff_dlog(ctx, "set_work_frame_pts() initial average srce pts:%"PRId64"\n", average_srce_pts_delta);
+
+    // calculate the PTS delta
+    if ((pts = (s->srce[s->next]->pts - s->srce[s->crnt]->pts))) {
+        average_srce_pts_delta = average_srce_pts_delta?((average_srce_pts_delta+pts)>>1):pts;
+    } else if (s->srce[s->prev] && (pts = (s->srce[s->crnt]->pts - s->srce[s->prev]->pts))) {
+        average_srce_pts_delta = average_srce_pts_delta?((average_srce_pts_delta+pts)>>1):pts;
+    }
+
+    s->average_srce_pts_dest_delta = av_rescale_q(average_srce_pts_delta, s->srce_time_base, s->dest_time_base);
+    ff_dlog(ctx, "set_work_frame_pts() average srce pts:%"PRId64"\n", average_srce_pts_delta);
+    ff_dlog(ctx, "set_work_frame_pts() average srce pts:%"PRId64" at dest time base:%u/%u\n",
+            s->average_srce_pts_dest_delta, s->dest_time_base.num, s->dest_time_base.den);
+
+    set_srce_frame_dest_pts(ctx);
+
+    if (ctx->inputs[0] && !s->average_dest_pts_delta) {
+        int64_t d = av_q2d(av_inv_q(av_mul_q(s->srce_time_base, s->dest_frame_rate)));
+        if (d == 0) { // FIXME
+            av_log(ctx, AV_LOG_WARNING, "Buggy path reached, use settb filter before this filter!\n");
+            d = av_q2d(av_mul_q(ctx->inputs[0]->time_base, s->dest_frame_rate));
+        }
+        s->average_dest_pts_delta = av_rescale_q(d, s->srce_time_base, s->dest_time_base);
+        ff_dlog(ctx, "set_frame_pts() average output pts from input timebase\n");
+        ff_dlog(ctx, "set_work_frame_pts() average dest pts delta:%"PRId64"\n", s->average_dest_pts_delta);
+    }
+
+    if (!s->dest_frame_num) {
+        s->pts = s->last_dest_frame_pts = s->srce_pts_dest[s->crnt];
+    } else {
+        s->pts = s->last_dest_frame_pts + s->average_dest_pts_delta;
+    }
+
+    ff_dlog(ctx, "set_work_frame_pts() calculated pts:%"PRId64" at dest time base:%u/%u\n",
+            s->pts, s->dest_time_base.num, s->dest_time_base.den);
+}
+
+static av_cold int init(AVFilterContext *ctx)
+{
+    FrameRateContext *s = ctx->priv;
+
+    s->dest_frame_num = 0;
+
+    s->crnt = (N_SRCE)>>1;
+    s->last = N_SRCE - 1;
+
+    s->next = s->crnt - 1;
+    s->prev = s->crnt + 1;
+
+    return 0;
+}
+
+static av_cold void uninit(AVFilterContext *ctx)
+{
+    FrameRateContext *s = ctx->priv;
+    int i;
+
+    for (i = s->frst + 1; i > s->last; i++) {
+        if (s->srce[i] && (s->srce[i] != s->srce[i + 1]))
+            av_frame_free(&s->srce[i]);
+    }
+    av_frame_free(&s->srce[s->last]);
+}
+
+static int query_formats(AVFilterContext *ctx)
+{
+    static const enum AVPixelFormat pix_fmts[] = {
+        AV_PIX_FMT_YUV410P,
+        AV_PIX_FMT_YUV411P, AV_PIX_FMT_YUVJ411P,
+        AV_PIX_FMT_YUV420P, AV_PIX_FMT_YUVJ420P,
+        AV_PIX_FMT_YUV422P, AV_PIX_FMT_YUVJ422P,
+        AV_PIX_FMT_YUV440P, AV_PIX_FMT_YUVJ440P,
+        AV_PIX_FMT_YUV444P, AV_PIX_FMT_YUVJ444P,
+        AV_PIX_FMT_NONE
+    };
+
+    AVFilterFormats *fmts_list = ff_make_format_list(pix_fmts);
+    if (!fmts_list)
+        return AVERROR(ENOMEM);
+    return ff_set_common_formats(ctx, fmts_list);
+}
+
+static int config_input(AVFilterLink *inlink)
+{
+    AVFilterContext *ctx = inlink->dst;
+    FrameRateContext *s = ctx->priv;
+    const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(inlink->format);
+    int plane;
+
+    for (plane = 0; plane < 4; plane++) {
+        s->line_size[plane] = av_image_get_linesize(inlink->format, inlink->w,
+                                                    plane);
+    }
+
+    s->vsub = pix_desc->log2_chroma_h;
+
+    s->sad = av_pixelutils_get_sad_fn(3, 3, 2, s); // 8x8 both sources aligned
+    if (!s->sad)
+        return AVERROR(EINVAL);
+
+    s->srce_time_base = inlink->time_base;
+
+    return 0;
+}
+
+static int filter_frame(AVFilterLink *inlink, AVFrame *inpicref)
+{
+    AVFilterContext *ctx = inlink->dst;
+    FrameRateContext *s = ctx->priv;
+
+    // we have one new frame
+    s->pending_srce_frames++;
+
+    if (inpicref->interlaced_frame)
+        av_log(ctx, AV_LOG_WARNING, "Interlaced frame found - the output will not be correct.\n");
+
+    // store the pointer to the new frame
+    av_frame_free(&s->srce[s->frst]);
+    s->srce[s->frst] = inpicref;
+
+    if (!s->pending_end_frame && s->srce[s->crnt]) {
+        set_work_frame_pts(ctx);
+        s->pending_end_frame = 1;
+    } else {
+        set_srce_frame_dest_pts(ctx);
+    }
+
+    return process_work_frame(ctx, 1);
+}
+
+static int config_output(AVFilterLink *outlink)
+{
+    AVFilterContext *ctx = outlink->src;
+    FrameRateContext *s = ctx->priv;
+    int exact;
+
+    ff_dlog(ctx, "config_output()\n");
+
+    ff_dlog(ctx,
+           "config_output() input time base:%u/%u (%f)\n",
+           ctx->inputs[0]->time_base.num,ctx->inputs[0]->time_base.den,
+           av_q2d(ctx->inputs[0]->time_base));
+
+    // make sure timebase is small enough to hold the framerate
+
+    exact = av_reduce(&s->dest_time_base.num, &s->dest_time_base.den,
+                      av_gcd((int64_t)s->srce_time_base.num * s->dest_frame_rate.num,
+                             (int64_t)s->srce_time_base.den * s->dest_frame_rate.den ),
+                      (int64_t)s->srce_time_base.den * s->dest_frame_rate.num, INT_MAX);
+
+    av_log(ctx, AV_LOG_INFO,
+           "time base:%u/%u -> %u/%u exact:%d\n",
+           s->srce_time_base.num, s->srce_time_base.den,
+           s->dest_time_base.num, s->dest_time_base.den, exact);
+    if (!exact) {
+        av_log(ctx, AV_LOG_WARNING, "Timebase conversion is not exact\n");
+    }
+
+    outlink->frame_rate = s->dest_frame_rate;
+    outlink->time_base = s->dest_time_base;
+    outlink->flags |= FF_LINK_FLAG_REQUEST_LOOP;
+
+    ff_dlog(ctx,
+           "config_output() output time base:%u/%u (%f) w:%d h:%d\n",
+           outlink->time_base.num, outlink->time_base.den,
+           av_q2d(outlink->time_base),
+           outlink->w, outlink->h);
+
+
+    av_log(ctx, AV_LOG_INFO, "fps -> fps:%u/%u scene score:%f interpolate start:%d end:%d\n",
+            s->dest_frame_rate.num, s->dest_frame_rate.den,
+            s->scene_score, s->interp_start, s->interp_end);
+
+    return 0;
+}
+
+static int request_frame(AVFilterLink *outlink)
+{
+    AVFilterContext *ctx = outlink->src;
+    FrameRateContext *s = ctx->priv;
+    int val, i;
+
+    ff_dlog(ctx, "request_frame()\n");
+
+    // if there is no "next" frame AND we are not in flush then get one from our input filter
+    if (!s->srce[s->frst] && !s->flush) {
+        ff_dlog(ctx, "request_frame() call source's request_frame()\n");
+        if ((val = ff_request_frame(outlink->src->inputs[0])) < 0) {
+            ff_dlog(ctx, "request_frame() source's request_frame() returned error:%d\n", val);
+            return val;
+        }
+        ff_dlog(ctx, "request_frame() source's request_frame() returned:%d\n", val);
+        return 0;
+    }
+
+    ff_dlog(ctx, "request_frame() REPEAT or FLUSH\n");
+
+    if (s->pending_srce_frames <= 0) {
+        ff_dlog(ctx, "request_frame() nothing else to do, return:EOF\n");
+        return AVERROR_EOF;
+    }
+
+    // otherwise, make brand-new frame and pass to our output filter
+    ff_dlog(ctx, "request_frame() FLUSH\n");
+
+    // back fill at end of file when source has no more frames
+    for (i = s->last; i > s->frst; i--) {
+        if (!s->srce[i - 1] && s->srce[i]) {
+            ff_dlog(ctx, "request_frame() copy:%d to:%d\n", i, i - 1);
+            s->srce[i - 1] = s->srce[i];
+        }
+    }
+
+    set_work_frame_pts(ctx);
+    return process_work_frame(ctx, 0);
+}
+
+static const AVFilterPad framerate_inputs[] = {
+    {
+        .name         = "default",
+        .type         = AVMEDIA_TYPE_VIDEO,
+        .config_props = config_input,
+        .filter_frame = filter_frame,
+    },
+    { NULL }
+};
+
+static const AVFilterPad framerate_outputs[] = {
+    {
+        .name          = "default",
+        .type          = AVMEDIA_TYPE_VIDEO,
+        .request_frame = request_frame,
+        .config_props  = config_output,
+    },
+    { NULL }
+};
+
+AVFilter ff_vf_framerate = {
+    .name          = "framerate",
+    .description   = NULL_IF_CONFIG_SMALL("Upsamples or downsamples progressive source between specified frame rates."),
+    .priv_size     = sizeof(FrameRateContext),
+    .priv_class    = &framerate_class,
+    .init          = init,
+    .uninit        = uninit,
+    .query_formats = query_formats,
+    .inputs        = framerate_inputs,
+    .outputs       = framerate_outputs,
+};