[FFmpeg-devel] [PATCH] avfilter: add feedback video filter

[Paul B Mahol <onemda@gmail.com>]

Signed-off-by: Paul B Mahol <onemda@gmail.com>
---
 doc/filters.texi          |  38 +++++
 libavfilter/Makefile      |   1 +
 libavfilter/allfilters.c  |   1 +
 libavfilter/vf_feedback.c | 312 ++++++++++++++++++++++++++++++++++++++
 4 files changed, 352 insertions(+)
 create mode 100644 libavfilter/vf_feedback.c

diff --git a/doc/filters.texi b/doc/filters.texi
index 0300a4e2e3..de2b674ba2 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -12214,6 +12214,44 @@ fade=t=in:st=5.5:d=0.5
 
 @end itemize
 
+@section feedback
+Apply feedback video filter.
+
+This filter pass cropped input frames to 2nd output.
+From there it can be filtered with other video filters.
+After filter receives frame from 2nd input, that frame
+is combined on top of original frame from 1st input and passed
+to 1st output.
+
+The typical usage is filter only part of frame.
+
+The filter accepts the following options:
+@table @option
+@item x
+@item y
+Set the top left crop position.
+
+@item w
+@item h
+Set the crop size.
+@end table
+
+@subsection Examples
+
+@itemize
+@item
+Blur only top left rectangular part of video frame size 100x100 with gblur filter.
+@example
+[in][blurin]feedback=x=0:y=0:w=100:h=100[out][blurout];[blurout]gblur=8[blurin]
+@end example
+
+@item
+Draw black box on top left part of video frame of size 100x100 with drawbox filter.
+@example
+[in][blurin]feedback=x=0:y=0:w=100:h=100[out][blurout];[blurout]drawbox=x=0:y=0:w=100:h=100:t=100[blurin]
+@end example
+@end itemize
+
 @section fftdnoiz
 Denoise frames using 3D FFT (frequency domain filtering).
 
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index d69bd59bb6..bdfdfdc04a 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -279,6 +279,7 @@ OBJS-$(CONFIG_ESTDIF_FILTER)                 += vf_estdif.o
 OBJS-$(CONFIG_EXPOSURE_FILTER)               += vf_exposure.o
 OBJS-$(CONFIG_EXTRACTPLANES_FILTER)          += vf_extractplanes.o
 OBJS-$(CONFIG_FADE_FILTER)                   += vf_fade.o
+OBJS-$(CONFIG_FEEDBACK_FILTER)               += vf_feedback.o
 OBJS-$(CONFIG_FFTDNOIZ_FILTER)               += vf_fftdnoiz.o
 OBJS-$(CONFIG_FFTFILT_FILTER)                += vf_fftfilt.o
 OBJS-$(CONFIG_FIELD_FILTER)                  += vf_field.o
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index abd1fe2367..44fac46521 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -261,6 +261,7 @@ extern const AVFilter ff_vf_estdif;
 extern const AVFilter ff_vf_exposure;
 extern const AVFilter ff_vf_extractplanes;
 extern const AVFilter ff_vf_fade;
+extern const AVFilter ff_vf_feedback;
 extern const AVFilter ff_vf_fftdnoiz;
 extern const AVFilter ff_vf_fftfilt;
 extern const AVFilter ff_vf_field;
diff --git a/libavfilter/vf_feedback.c b/libavfilter/vf_feedback.c
new file mode 100644
index 0000000000..268aff0ebd
--- /dev/null
+++ b/libavfilter/vf_feedback.c
@@ -0,0 +1,312 @@
+/*
+ * 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
+ * feedback video filter
+ */
+
+#include "libavutil/fifo.h"
+#include "libavutil/imgutils.h"
+#include "libavutil/opt.h"
+#include "libavutil/internal.h"
+#include "avfilter.h"
+#include "filters.h"
+#include "internal.h"
+#include "video.h"
+
+typedef struct FeedbackContext {
+    const AVClass *class;
+
+    int x, y;
+    int w, h;
+
+    int max_step[4];
+    int hsub, vsub;
+
+    AVFrame *feed;
+
+    AVFifo *fifo;
+} FeedbackContext;
+
+static void adjust_pos(AVFilterContext *ctx, FeedbackContext *s)
+{
+    if (s->x + s->w > ctx->inputs[0]->w)
+        s->x = ctx->inputs[0]->w - s->w;
+    if (s->y + s->h > ctx->inputs[0]->h)
+        s->y = ctx->inputs[0]->h - s->h;
+}
+
+static void adjust_parameters(AVFilterContext *ctx, FeedbackContext *s)
+{
+    if (s->x >= ctx->inputs[0]->w)
+        s->x = 0;
+    if (s->y >= ctx->inputs[0]->h)
+        s->y = 0;
+
+    if (s->w <= 0)
+        s->w = ctx->inputs[0]->w - s->x;
+    if (s->h <= 0)
+        s->h = ctx->inputs[0]->h - s->y;
+
+    if (s->w > ctx->inputs[0]->w)
+        s->w = ctx->inputs[0]->w;
+    if (s->h > ctx->inputs[0]->h)
+        s->h = ctx->inputs[0]->h;
+
+    adjust_pos(ctx, s);
+}
+
+static int config_input(AVFilterLink *inlink)
+{
+    AVFilterContext *ctx = inlink->dst;
+    const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(inlink->format);
+    FeedbackContext *s = ctx->priv;
+
+    s->hsub = pix_desc->log2_chroma_w;
+    s->vsub = pix_desc->log2_chroma_h;
+
+    av_image_fill_max_pixsteps(s->max_step, NULL, pix_desc);
+
+    adjust_parameters(ctx, s);
+
+    ctx->inputs[1]->w = s->w;
+    ctx->inputs[1]->h = s->h;
+
+    return 0;
+}
+
+static int config_output(AVFilterLink *outlink)
+{
+    AVFilterContext *ctx = outlink->src;
+    FeedbackContext *s = ctx->priv;
+
+    adjust_parameters(ctx, s);
+
+    ctx->outputs[0]->w = ctx->inputs[0]->w;
+    ctx->outputs[0]->h = ctx->inputs[0]->h;
+    ctx->outputs[1]->w = s->w;
+    ctx->outputs[1]->h = s->h;
+
+    return 0;
+}
+
+static int query_formats(AVFilterContext *ctx)
+{
+    return ff_set_common_formats(ctx, ff_formats_pixdesc_filter(0, AV_PIX_FMT_FLAG_BITSTREAM |
+                                                                   AV_PIX_FMT_FLAG_HWACCEL |
+                                                                   AV_PIX_FMT_FLAG_PAL));
+}
+
+static int activate(AVFilterContext *ctx)
+{
+    FeedbackContext *s = ctx->priv;
+    int status, ret;
+    int64_t pts;
+
+    adjust_pos(ctx, s);
+
+    for (int i = 0; i < ctx->nb_outputs; i++)
+        FF_FILTER_FORWARD_STATUS_BACK_ALL(ctx->outputs[i], ctx);
+
+    if (!s->feed) {
+        ret = ff_inlink_consume_frame(ctx->inputs[1], &s->feed);
+        if (ret < 0)
+            return ret;
+    }
+
+    if (s->feed && av_fifo_can_read(s->fifo)) {
+        AVFrame *src = s->feed;
+        AVFrame *dst = NULL;
+
+        av_fifo_read(s->fifo, &dst, 1);
+        if (!dst)
+            return AVERROR_BUG;
+
+        for (int y = 0; y < src->height; y++) {
+            memmove(dst->data[0] + (s->y + y) * dst->linesize[0] + s->x * s->max_step[0],
+                    src->data[0] + y * src->linesize[0], src->width * s->max_step[0]);
+        }
+
+        for (int i = 1; i < 3; i ++) {
+            if (dst->data[i]) {
+                for (int y = 0; y < src->height; y++) {
+                    memmove(dst->data[i] + ((s->y + y) >> s->vsub) * dst->linesize[i] + ((s->x * s->max_step[i]) >> s->hsub),
+                            src->data[i] + (y >> s->vsub) * src->linesize[i], (src->width * s->max_step[i]) >> s->hsub);
+                }
+            }
+        }
+
+        if (dst->data[3]) {
+            for (int y = 0; y < src->height; y++) {
+                memmove(dst->data[3] + (s->y + y) * dst->linesize[3] + s->x * s->max_step[3],
+                        src->data[3] + y * src->linesize[3], src->width * s->max_step[3]);
+            }
+        }
+
+        ret = ff_filter_frame(ctx->outputs[0], dst);
+        av_frame_free(&s->feed);
+        return ret;
+    }
+
+    if (!s->feed) {
+        AVFrame *in = NULL;
+
+        ret = ff_inlink_consume_frame(ctx->inputs[0], &in);
+        if (ret < 0)
+            return ret;
+
+        if (ret > 0) {
+            AVFrame *frame;
+
+            ret = av_fifo_write(s->fifo, &in, 1);
+            if (ret < 0) {
+                av_frame_free(&in);
+                return ret;
+            }
+
+            frame = av_frame_clone(in);
+            if (!frame)
+                return AVERROR(ENOMEM);
+
+            frame->width  = s->w;
+            frame->height = s->h;
+
+            frame->data[0] += s->y * frame->linesize[0];
+            frame->data[0] += s->x * s->max_step[0];
+
+            for (int i = 1; i < 3; i ++) {
+                if (frame->data[i]) {
+                    frame->data[i] += (s->y >> s->vsub) * frame->linesize[i];
+                    frame->data[i] += (s->x * s->max_step[i]) >> s->hsub;
+                }
+            }
+
+            if (frame->data[3]) {
+                frame->data[3] += s->y * frame->linesize[3];
+                frame->data[3] += s->x * s->max_step[3];
+            }
+
+            return ff_filter_frame(ctx->outputs[1], frame);
+        }
+    }
+
+    if (ff_inlink_acknowledge_status(ctx->inputs[0], &status, &pts)) {
+        ff_outlink_set_status(ctx->outputs[0], status, pts);
+        ff_outlink_set_status(ctx->outputs[1], status, pts);
+        return 0;
+    }
+
+    if (ff_inlink_acknowledge_status(ctx->inputs[1], &status, &pts)) {
+        ff_outlink_set_status(ctx->outputs[0], status, pts);
+        ff_outlink_set_status(ctx->outputs[1], status, pts);
+        return 0;
+    }
+
+    if (!s->feed) {
+        if (ff_outlink_frame_wanted(ctx->outputs[0])) {
+            ff_inlink_request_frame(ctx->inputs[0]);
+            ff_inlink_request_frame(ctx->inputs[1]);
+            return 0;
+        }
+    }
+
+    return FFERROR_NOT_READY;
+}
+
+static av_cold int init(AVFilterContext *ctx)
+{
+    FeedbackContext *s = ctx->priv;
+
+    s->fifo = av_fifo_alloc2(8, sizeof(AVFrame *), AV_FIFO_FLAG_AUTO_GROW);
+    if (!s->fifo)
+        return AVERROR(ENOMEM);
+
+    return 0;
+}
+
+static av_cold void uninit(AVFilterContext *ctx)
+{
+    FeedbackContext *s = ctx->priv;
+    if (s->fifo) {
+        size_t size = av_fifo_can_read(s->fifo);
+
+        for (size_t n = 0; n < size; n++) {
+            AVFrame *frame = NULL;
+
+            av_fifo_read(s->fifo, &frame, 1);
+
+            av_frame_free(&frame);
+        }
+
+        av_fifo_freep2(&s->fifo);
+    }
+}
+
+static const AVFilterPad inputs[] = {
+    {
+        .name         = "default",
+        .type         = AVMEDIA_TYPE_VIDEO,
+        .config_props = config_input,
+    },
+    {
+        .name         = "feedin",
+        .type         = AVMEDIA_TYPE_VIDEO,
+        .config_props = config_input,
+    },
+};
+
+static const AVFilterPad outputs[] = {
+    {
+        .name         = "default",
+        .type         = AVMEDIA_TYPE_VIDEO,
+        .config_props = config_output,
+    },
+    {
+        .name         = "feedout",
+        .type         = AVMEDIA_TYPE_VIDEO,
+        .config_props = config_output,
+    },
+};
+
+#define OFFSET(x) offsetof(FeedbackContext, x)
+#define FLAGS (AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_FILTERING_PARAM)
+#define TFLAGS (AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_FILTERING_PARAM | AV_OPT_FLAG_RUNTIME_PARAM)
+
+static const AVOption feedback_options[] = {
+    { "x", "set top left crop position", OFFSET(x), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, TFLAGS },
+    { "y", "set top left crop position", OFFSET(y), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, TFLAGS },
+    { "w", "set crop size",              OFFSET(w), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, FLAGS },
+    { "h", "set crop size",              OFFSET(h), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, FLAGS },
+    { NULL }
+};
+
+AVFILTER_DEFINE_CLASS(feedback);
+
+const AVFilter ff_vf_feedback = {
+    .name        = "feedback",
+    .description = NULL_IF_CONFIG_SMALL("Apply feedback video filter."),
+    .priv_class  = &feedback_class,
+    .priv_size   = sizeof(FeedbackContext),
+    .activate    = activate,
+    .init        = init,
+    .uninit      = uninit,
+    FILTER_INPUTS(inputs),
+    FILTER_OUTPUTS(outputs),
+    FILTER_QUERY_FUNC(query_formats),
+};
-- 
2.35.1

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