> -----Original Message-----
> From: ffmpeg-devel [mailto:ffmpeg-devel-boun...@ffmpeg.org] On Behalf Of
> Mark Thompson
> Sent: Monday, July 08, 2019 3:27 AM
> To: ffmpeg-devel@ffmpeg.org
> Subject: [FFmpeg-devel] [PATCH v4 2/2] lavfi: addroi filter
>
> This can be used to add region of interest side data to video frames.
> ---
> doc/filters.texi | 73 +++++++++++
> libavfilter/Makefile | 1 +
> libavfilter/allfilters.c | 1 +
> libavfilter/vf_addroi.c | 269 +++++++++++++++++++++++++++++++++++++++
> 4 files changed, 344 insertions(+)
> create mode 100644 libavfilter/vf_addroi.c
>
> diff --git a/doc/filters.texi b/doc/filters.texi
> index ee6a93ffbf..f7145532c7 100644
> --- a/doc/filters.texi
> +++ b/doc/filters.texi
> @@ -5876,6 +5876,79 @@ build.
>
> Below is a description of the currently available video filters.
>
> +@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.
> +
> +@table @option
> +@item x
> +Region distance in pixels from the left edge of the frame.
> +@item y
> +Region distance in pixels from the top edge of the frame.
> +@item w
> +Region width in pixels.
> +@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:
> +@table @option
> +@item iw
> +Width of the input frame.
> +@item ih
> +Height of the input frame.
> +@end table
> +
> +@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.
> +@item clear
> +If set to true, remove any existing regions of interest marked on the
> +frame before adding the new one.
> +@end table
> +
> +@subsection Examples
> +
> +@itemize
> +@item
> +Mark the centre quarter of the frame as interesting.
> +@example
> +addroi=iw/4:ih/4:iw/2:ih/2:-1/10
> +@end example
> +@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).
> +@example
> +addroi=0:0:100:ih:+1/5
> +@end example
> +@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 455c809b15..00c402c3bc 100644
> --- a/libavfilter/Makefile
> +++ b/libavfilter/Makefile
> @@ -152,6 +152,7 @@ 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);
> + }
looks good to me, btw, the "{}" here can be removed.
> + 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,
> +};
> --
> 2.20.1
>
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