[FFmpeg-cvslog] lavfi: addroi filter
Mark Thompson
git at videolan.org
Mon Jul 29 01:23:19 EEST 2019
ffmpeg | branch: master | Mark Thompson <sw at jkqxz.net> | Sun Jul 7 20:26:50 2019 +0100| [20fed2f0ab197d60801280dfc844f6b29a397ff2] | committer: Mark Thompson
lavfi: addroi filter
This can be used to add region of interest side data to video frames.
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=20fed2f0ab197d60801280dfc844f6b29a397ff2
---
doc/filters.texi | 73 +++++++++++++
libavfilter/Makefile | 1 +
libavfilter/allfilters.c | 1 +
libavfilter/vf_addroi.c | 269 +++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 344 insertions(+)
diff --git a/doc/filters.texi b/doc/filters.texi
index c4ba907981..e081cdc7bc 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -5931,6 +5931,79 @@ build.
Below is a description of the currently available video filters.
+ at section addroi
+
+Mark a region of interest in a video frame.
+
+The frame data is passed through unchanged, but metadata is attached
+to the frame indicating regions of interest which can affect the
+behaviour of later encoding. Multiple regions can be marked by
+applying the filter multiple times.
+
+ at table @option
+ at item x
+Region distance in pixels from the left edge of the frame.
+ at item y
+Region distance in pixels from the top edge of the frame.
+ at item w
+Region width in pixels.
+ at item h
+Region height in pixels.
+
+The parameters @var{x}, @var{y}, @var{w} and @var{h} are expressions,
+and may contain the following variables:
+ at table @option
+ at item iw
+Width of the input frame.
+ at item ih
+Height of the input frame.
+ at end table
+
+ at item qoffset
+Quantisation offset to apply within the region.
+
+This must be a real value in the range -1 to +1. A value of zero
+indicates no quality change. A negative value asks for better quality
+(less quantisation), while a positive value asks for worse quality
+(greater quantisation).
+
+The range is calibrated so that the extreme values indicate the
+largest possible offset - if the rest of the frame is encoded with the
+worst possible quality, an offset of -1 indicates that this region
+should be encoded with the best possible quality anyway. Intermediate
+values are then interpolated in some codec-dependent way.
+
+For example, in 10-bit H.264 the quantisation parameter varies between
+-12 and 51. A typical qoffset value of -1/10 therefore indicates that
+this region should be encoded with a QP around one-tenth of the full
+range better than the rest of the frame. So, if most of the frame
+were to be encoded with a QP of around 30, this region would get a QP
+of around 24 (an offset of approximately -1/10 * (51 - -12) = -6.3).
+An extreme value of -1 would indicate that this region should be
+encoded with the best possible quality regardless of the treatment of
+the rest of the frame - that is, should be encoded at a QP of -12.
+ at item clear
+If set to true, remove any existing regions of interest marked on the
+frame before adding the new one.
+ at end table
+
+ at subsection Examples
+
+ at itemize
+ at item
+Mark the centre quarter of the frame as interesting.
+ at example
+addroi=iw/4:ih/4:iw/2:ih/2:-1/10
+ at end example
+ at item
+Mark the 100-pixel-wide region on the left edge of the frame as very
+uninteresting (to be encoded at much lower quality than the rest of
+the frame).
+ at example
+addroi=0:0:100:ih:+1/5
+ at end example
+ at end itemize
+
@section alphaextract
Extract the alpha component from the input as a grayscale video. This
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index 450d7810ef..efc7bbb153 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -151,6 +151,7 @@ OBJS-$(CONFIG_SINE_FILTER) += asrc_sine.o
OBJS-$(CONFIG_ANULLSINK_FILTER) += asink_anullsink.o
# video filters
+OBJS-$(CONFIG_ADDROI_FILTER) += vf_addroi.o
OBJS-$(CONFIG_ALPHAEXTRACT_FILTER) += vf_extractplanes.o
OBJS-$(CONFIG_ALPHAMERGE_FILTER) += vf_alphamerge.o
OBJS-$(CONFIG_AMPLIFY_FILTER) += vf_amplify.o
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index 04a3df7d56..abd726d616 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -143,6 +143,7 @@ extern AVFilter ff_asrc_sine;
extern AVFilter ff_asink_anullsink;
+extern AVFilter ff_vf_addroi;
extern AVFilter ff_vf_alphaextract;
extern AVFilter ff_vf_alphamerge;
extern AVFilter ff_vf_amplify;
diff --git a/libavfilter/vf_addroi.c b/libavfilter/vf_addroi.c
new file mode 100644
index 0000000000..489998ce73
--- /dev/null
+++ b/libavfilter/vf_addroi.c
@@ -0,0 +1,269 @@
+/*
+ * 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/avassert.h"
+#include "libavutil/eval.h"
+#include "libavutil/opt.h"
+#include "avfilter.h"
+#include "internal.h"
+
+enum {
+ X, Y, W, H,
+ NB_PARAMS,
+};
+static const char *addroi_param_names[] = {
+ "x", "y", "w", "h",
+};
+
+enum {
+ VAR_IW,
+ VAR_IH,
+ NB_VARS,
+};
+static const char *const addroi_var_names[] = {
+ "iw",
+ "ih",
+};
+
+typedef struct AddROIContext {
+ const AVClass *class;
+
+ char *region_str[NB_PARAMS];
+ AVExpr *region_expr[NB_PARAMS];
+
+ int region[NB_PARAMS];
+ AVRational qoffset;
+
+ int clear;
+} AddROIContext;
+
+static int addroi_config_input(AVFilterLink *inlink)
+{
+ AVFilterContext *avctx = inlink->dst;
+ AddROIContext *ctx = avctx->priv;
+ int i;
+ double vars[NB_VARS];
+ double val;
+
+ vars[VAR_IW] = inlink->w;
+ vars[VAR_IH] = inlink->h;
+
+ for (i = 0; i < NB_PARAMS; i++) {
+ int max_value;
+ switch (i) {
+ case X: max_value = inlink->w; break;
+ case Y: max_value = inlink->h; break;
+ case W: max_value = inlink->w - ctx->region[X]; break;
+ case H: max_value = inlink->h - ctx->region[Y]; break;
+ }
+
+ val = av_expr_eval(ctx->region_expr[i], vars, NULL);
+ if (val < 0.0) {
+ av_log(avctx, AV_LOG_WARNING, "Calculated value %g for %s is "
+ "less than zero - using zero instead.\n", val,
+ addroi_param_names[i]);
+ val = 0.0;
+ } else if (val > max_value) {
+ av_log(avctx, AV_LOG_WARNING, "Calculated value %g for %s is "
+ "greater than maximum allowed value %d - "
+ "using %d instead.\n", val, addroi_param_names[i],
+ max_value, max_value);
+ val = max_value;
+ }
+ ctx->region[i] = val;
+ }
+
+ return 0;
+}
+
+static int addroi_filter_frame(AVFilterLink *inlink, AVFrame *frame)
+{
+ AVFilterContext *avctx = inlink->dst;
+ AVFilterLink *outlink = avctx->outputs[0];
+ AddROIContext *ctx = avctx->priv;
+ AVRegionOfInterest *roi;
+ AVFrameSideData *sd;
+ int err;
+
+ if (ctx->clear) {
+ av_frame_remove_side_data(frame, AV_FRAME_DATA_REGIONS_OF_INTEREST);
+ sd = NULL;
+ } else {
+ sd = av_frame_get_side_data(frame, AV_FRAME_DATA_REGIONS_OF_INTEREST);
+ }
+ if (sd) {
+ const AVRegionOfInterest *old_roi;
+ uint32_t old_roi_size;
+ AVBufferRef *roi_ref;
+ int nb_roi, i;
+
+ old_roi = (const AVRegionOfInterest*)sd->data;
+ old_roi_size = old_roi->self_size;
+ av_assert0(old_roi_size && sd->size % old_roi_size == 0);
+ nb_roi = sd->size / old_roi_size + 1;
+
+ roi_ref = av_buffer_alloc(sizeof(*roi) * nb_roi);
+ if (!roi_ref) {
+ err = AVERROR(ENOMEM);
+ goto fail;
+ }
+ roi = (AVRegionOfInterest*)roi_ref->data;
+
+ for (i = 0; i < nb_roi - 1; i++) {
+ old_roi = (const AVRegionOfInterest*)
+ (sd->data + old_roi_size * i);
+
+ roi[i] = (AVRegionOfInterest) {
+ .self_size = sizeof(*roi),
+ .top = old_roi->top,
+ .bottom = old_roi->bottom,
+ .left = old_roi->left,
+ .right = old_roi->right,
+ .qoffset = old_roi->qoffset,
+ };
+ }
+
+ roi[nb_roi - 1] = (AVRegionOfInterest) {
+ .self_size = sizeof(*roi),
+ .top = ctx->region[Y],
+ .bottom = ctx->region[Y] + ctx->region[H],
+ .left = ctx->region[X],
+ .right = ctx->region[X] + ctx->region[W],
+ .qoffset = ctx->qoffset,
+ };
+
+ av_frame_remove_side_data(frame, AV_FRAME_DATA_REGIONS_OF_INTEREST);
+
+ sd = av_frame_new_side_data_from_buf(frame,
+ AV_FRAME_DATA_REGIONS_OF_INTEREST,
+ roi_ref);
+ if (!sd) {
+ av_buffer_unref(&roi_ref);
+ err = AVERROR(ENOMEM);
+ goto fail;
+ }
+
+ } else {
+ sd = av_frame_new_side_data(frame, AV_FRAME_DATA_REGIONS_OF_INTEREST,
+ sizeof(AVRegionOfInterest));
+ if (!sd) {
+ err = AVERROR(ENOMEM);
+ goto fail;
+ }
+ roi = (AVRegionOfInterest*)sd->data;
+ *roi = (AVRegionOfInterest) {
+ .self_size = sizeof(*roi),
+ .top = ctx->region[Y],
+ .bottom = ctx->region[Y] + ctx->region[H],
+ .left = ctx->region[X],
+ .right = ctx->region[X] + ctx->region[W],
+ .qoffset = ctx->qoffset,
+ };
+ }
+
+ return ff_filter_frame(outlink, frame);
+
+fail:
+ av_frame_free(&frame);
+ return err;
+}
+
+static av_cold int addroi_init(AVFilterContext *avctx)
+{
+ AddROIContext *ctx = avctx->priv;
+ int i, err;
+
+ for (i = 0; i < NB_PARAMS; i++) {
+ err = av_expr_parse(&ctx->region_expr[i], ctx->region_str[i],
+ addroi_var_names, NULL, NULL, NULL, NULL,
+ 0, avctx);
+ if (err < 0) {
+ av_log(ctx, AV_LOG_ERROR,
+ "Error parsing %s expression '%s'.\n",
+ addroi_param_names[i], ctx->region_str[i]);
+ return err;
+ }
+ }
+
+ return 0;
+}
+
+static av_cold void addroi_uninit(AVFilterContext *avctx)
+{
+ AddROIContext *ctx = avctx->priv;
+ int i;
+
+ for (i = 0; i < NB_PARAMS; i++) {
+ av_expr_free(ctx->region_expr[i]);
+ ctx->region_expr[i] = NULL;
+ }
+}
+
+#define OFFSET(x) offsetof(AddROIContext, x)
+#define FLAGS AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_FILTERING_PARAM
+static const AVOption addroi_options[] = {
+ { "x", "Region distance from left edge of frame.",
+ OFFSET(region_str[X]), AV_OPT_TYPE_STRING, { .str = "0" }, .flags = FLAGS },
+ { "y", "Region distance from top edge of frame.",
+ OFFSET(region_str[Y]), AV_OPT_TYPE_STRING, { .str = "0" }, .flags = FLAGS },
+ { "w", "Region width.",
+ OFFSET(region_str[W]), AV_OPT_TYPE_STRING, { .str = "0" }, .flags = FLAGS },
+ { "h", "Region height.",
+ OFFSET(region_str[H]), AV_OPT_TYPE_STRING, { .str = "0" }, .flags = FLAGS },
+
+ { "qoffset", "Quantisation offset to apply in the region.",
+ OFFSET(qoffset), AV_OPT_TYPE_RATIONAL, { .dbl = -0.1 }, -1, +1, FLAGS },
+
+ { "clear", "Remove any existing regions of interest before adding the new one.",
+ OFFSET(clear), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, FLAGS },
+
+ { NULL }
+};
+
+AVFILTER_DEFINE_CLASS(addroi);
+
+static const AVFilterPad addroi_inputs[] = {
+ {
+ .name = "default",
+ .type = AVMEDIA_TYPE_VIDEO,
+ .config_props = addroi_config_input,
+ .filter_frame = addroi_filter_frame,
+ },
+ { NULL }
+};
+
+static const AVFilterPad addroi_outputs[] = {
+ {
+ .name = "default",
+ .type = AVMEDIA_TYPE_VIDEO,
+ },
+ { NULL }
+};
+
+AVFilter ff_vf_addroi = {
+ .name = "addroi",
+ .description = NULL_IF_CONFIG_SMALL("Add region of interest to frame."),
+ .init = addroi_init,
+ .uninit = addroi_uninit,
+
+ .priv_size = sizeof(AddROIContext),
+ .priv_class = &addroi_class,
+
+ .inputs = addroi_inputs,
+ .outputs = addroi_outputs,
+};
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