On Tue, Aug 24, 2021 at 8:51 PM Paul Buxton <paulbuxton.m...@googlemail.com>
wrote:
> Thanks, will resolve these issues, the alphabetical issues are mostly
> because I originally was calling it underwater filter.
>
> Regarding the iteration over the buffer, I wasn't sure that buffer would
> always be planar, can tidy this up. I assume it may be strided however?
>
use linesize, there are other filters that operate on planar gbrp format,
GBRP, so see how it is done.
Basically what you have done is for packed formats only.
>
> Paul
>
> On Tue, Aug 24, 2021 at 7:28 PM Paul B Mahol <one...@gmail.com> wrote:
>
>>
>>
>> On Tue, Aug 24, 2021 at 6:58 PM Paul Buxton <
>> paulbuxton.m...@googlemail.com> wrote:
>>
>>> Signed-off-by: Paul Buxton <paulbuxton.m...@googlemail.com>
>>> ---
>>> MAINTAINERS | 1 +
>>> doc/filters.texi | 14 ++
>>> libavfilter/Makefile | 1 +
>>> libavfilter/allfilters.c | 1 +
>>> libavfilter/version.h | 2 +-
>>> libavfilter/vf_grayworld.c | 401 +++++++++++++++++++++++++++++++++++++
>>> 6 files changed, 419 insertions(+), 1 deletion(-)
>>> create mode 100644 libavfilter/vf_grayworld.c
>>>
>>> diff --git a/MAINTAINERS b/MAINTAINERS
>>> index dcac46003e..207a53871b 100644
>>> --- a/MAINTAINERS
>>> +++ b/MAINTAINERS
>>> @@ -369,6 +369,7 @@ Filters:
>>> vf_tonemap_opencl.c Ruiling Song
>>> vf_yadif.c Michael Niedermayer
>>> vf_zoompan.c Paul B Mahol
>>> + vf_grayworld.c Paul Buxton (CC
>>> paulbuxton.m...@googlemail.com)
>>>
>>
>> alphabetical order
>>
>>
>>>
>>> Sources:
>>> vsrc_mandelbrot.c Michael Niedermayer
>>> diff --git a/doc/filters.texi b/doc/filters.texi
>>> index b902aca12d..06d2eb3a5a 100644
>>> --- a/doc/filters.texi
>>> +++ b/doc/filters.texi
>>> @@ -13087,6 +13087,20 @@ greyedge=difford=1:minknorm=0:sigma=2
>>>
>>> @end itemize
>>>
>>> +
>>> +@section greyworld
>>> +A color constancy filter that applies color correction based on the
>>> grayworld assumption
>>> +
>>> +See: @url{
>>> https://www.researchgate.net/publication/275213614_A_New_Color_Correction_Method_for_Underwater_Imaging
>>> }
>>> +
>>> +The algorithm linear light, so input
>>
>>
>> missing word(s)
>>
>>
>>> +data should be linearized beforehand (and possibly correctly tagged).
>>> +
>>> +@example
>>> +ffmpeg -i INPUT -vf
>>> zscale=transfer=linear,grayworld,zscale=transfer=bt709,format=yuv420p OUTPUT
>>> +@end example
>>> +
>>> +
>>> @section guided
>>> Apply guided filter for edge-preserving smoothing, dehazing and so on.
>>>
>>> diff --git a/libavfilter/Makefile b/libavfilter/Makefile
>>> index 102ce7beff..84ba69bba7 100644
>>> --- a/libavfilter/Makefile
>>> +++ b/libavfilter/Makefile
>>> @@ -464,6 +464,7 @@ OBJS-$(CONFIG_TRANSPOSE_NPP_FILTER) +=
>>> vf_transpose_npp.o
>>> OBJS-$(CONFIG_TRANSPOSE_OPENCL_FILTER) += vf_transpose_opencl.o
>>> opencl.o opencl/transpose.o
>>> OBJS-$(CONFIG_TRANSPOSE_VAAPI_FILTER) += vf_transpose_vaapi.o
>>> vaapi_vpp.o
>>> OBJS-$(CONFIG_TRIM_FILTER) += trim.o
>>> +OBJS-$(CONFIG_GRAYWORLD_FILTER) += vf_grayworld.o
>>>
>>
>> alphabetical order
>>
>>
>>> OBJS-$(CONFIG_UNPREMULTIPLY_FILTER) += vf_premultiply.o
>>> framesync.o
>>> OBJS-$(CONFIG_UNSHARP_FILTER) += vf_unsharp.o
>>> OBJS-$(CONFIG_UNSHARP_OPENCL_FILTER) += vf_unsharp_opencl.o
>>> opencl.o \
>>> diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
>>> index 73040d2824..bf9356cee5 100644
>>> --- a/libavfilter/allfilters.c
>>> +++ b/libavfilter/allfilters.c
>>> @@ -442,6 +442,7 @@ extern const AVFilter ff_vf_transpose_npp;
>>> extern const AVFilter ff_vf_transpose_opencl;
>>> extern const AVFilter ff_vf_transpose_vaapi;
>>> extern const AVFilter ff_vf_trim;
>>> +extern const AVFilter ff_vf_grayworld;
>>>
>>
>> alphabetical order
>>
>>
>>> extern const AVFilter ff_vf_unpremultiply;
>>> extern const AVFilter ff_vf_unsharp;
>>> extern const AVFilter ff_vf_unsharp_opencl;
>>> diff --git a/libavfilter/version.h b/libavfilter/version.h
>>> index bcd27aa6e8..e9a76c5ac3 100644
>>> --- a/libavfilter/version.h
>>> +++ b/libavfilter/version.h
>>> @@ -30,7 +30,7 @@
>>> #include "libavutil/version.h"
>>>
>>> #define LIBAVFILTER_VERSION_MAJOR 8
>>> -#define LIBAVFILTER_VERSION_MINOR 3
>>> +#define LIBAVFILTER_VERSION_MINOR 4
>>> #define LIBAVFILTER_VERSION_MICRO 100
>>>
>>>
>>> diff --git a/libavfilter/vf_grayworld.c b/libavfilter/vf_grayworld.c
>>> new file mode 100644
>>> index 0000000000..d41b116576
>>> --- /dev/null
>>> +++ b/libavfilter/vf_grayworld.c
>>> @@ -0,0 +1,401 @@
>>> +/*
>>> + * Copyright (c) 2021 Paul Buxton
>>> + *
>>> + * 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
>>> + * Color correction filter based on
>>> + *
>>> https://www.researchgate.net/publication/275213614_A_New_Color_Correction_Method_for_Underwater_Imaging
>>> + *
>>> + */
>>> +
>>> +#include "libavutil/imgutils.h"
>>> +#include "libavutil/opt.h"
>>> +#include "libavutil/pixdesc.h"
>>> +#include "libavutil/intreadwrite.h"
>>> +
>>> +#include "avfilter.h"
>>> +#include "drawutils.h"
>>> +#include "formats.h"
>>> +#include "internal.h"
>>> +#include "video.h"
>>> +
>>> +typedef struct ThreadData {
>>> + AVFrame* in, * out;
>>> + float l_avg;
>>> + float a_avg;
>>> + float b_avg;
>>> + const AVPixFmtDescriptor* desc;
>>> + const AVPixFmtDescriptor* odesc;
>>> +} ThreadData;
>>> +
>>> +typedef struct GrayWorldContext {
>>> + const AVClass* class;
>>> + int64_t stretch_histogram;
>>> + int64_t smoothing_frames;
>>> + int64_t correction_type;
>>> +
>>> + float* tmppl;
>>> + float* tmppa;
>>> + float* tmppb;
>>>
>>
>> float *tmppl,
>> and so on.
>>
>>
>>> +
>>> + float* line_suml;
>>> + float* line_suma;
>>> + float* line_sumb;
>>> +
>>> + int* line_count_pels;
>>> +} GrayWorldContext;
>>> +
>>> +#define OFFSET(x) offsetof(GrayWorldContext, x)
>>> +#define FLAGS AV_OPT_FLAG_FILTERING_PARAM | AV_OPT_FLAG_VIDEO_PARAM |
>>> AV_OPT_FLAG_RUNTIME_PARAM
>>> +static const AVOption grayworld_options[] = {
>>> + {NULL} };
>>> +
>>> +AVFILTER_DEFINE_CLASS(grayworld);
>>> +
>>> +void compute_correction(GrayWorldContext* s, ThreadData* td);
>>> +void apply_matrix(float matrix[3][3], float input[3], float output[3]);
>>> +void rgb2lab(float rgb[3], float lab[3]);
>>> +void lab2rgb(float lab[3], float rgb[3]);
>>> +
>>>
>>
>> no need for several new lines, keep just one empty line.
>>
>>> +
>>> +
>>> +static int query_formats(AVFilterContext* ctx)
>>> +{
>>> + static const enum AVPixelFormat pix_fmts[] = {
>>> + AV_PIX_FMT_GBRPF32,
>>> + AV_PIX_FMT_GBRAPF32,
>>> + 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);
>>> +}
>>>
>>
>> There is now new function to handle this, formats_from_list IIRC.
>>
>>
>>> +
>>> +void apply_matrix(float matrix[3][3], float input[3], float output[3])
>>> +{
>>> + for (int row = 0; row < 3; ++row) {
>>> + output[row] = matrix[row][0] * input[0] + matrix[row][1] *
>>> input[1] + matrix[row][2] * input[2];
>>> + }
>>> +}
>>> +
>>> +
>>> +float lms2lab[3][3] = {
>>> + {0.5774, 0.5774, 0.5774},
>>> + {0.40825, 0.40825, -0.816458},
>>> + {0.707, -0.707, 0}
>>> +};
>>> +
>>> +float lab2lms[3][3] = {
>>> + {0.57735, 0.40825, 0.707},
>>> + {0.57735, 0.40825, -0.707},
>>> + {0.57735, -0.8165, 0}
>>> +};
>>> +
>>> +float rgb2lms[3][3] = {
>>> + {0.3811, 0.5783, 0.0402},
>>> + {0.1967, 0.7244, 0.0782},
>>> + {0.0241, 0.1288, 0.8444}
>>> +};
>>> +
>>> +float lms2rgb[3][3] = {
>>> + {4.4679, -3.5873, 0.1193},
>>> + {-1.2186, 2.3809, -0.1624},
>>> + {0.0497, -0.2439, 1.2045}
>>> +};
>>> +
>>> +/**
>>> + * Convert from Linear RGB to logspace LAB
>>> + *
>>> + * @param rgb Input array of rgb components
>>> + * @param lab output array of lab components
>>> + */
>>> +void rgb2lab(float rgb[3], float lab[3])
>>> +{
>>> + float lms[3];
>>> + apply_matrix(rgb2lms, rgb, lms);
>>> + lms[0] = log(lms[0]);
>>>
>>
>> what about using logf, float variant of functions in all cases?
>>
>>
>>> + lms[1] = log(lms[1]);
>>> + lms[2] = log(lms[2]);
>>> + apply_matrix(lms2lab, lms, lab);
>>> +}
>>> +
>>> +
>>> +/**
>>> + * Convert from Logspace LAB to Linear RGB
>>> + *
>>> + * @param lab input array of lab components
>>> + * @param rgb output array of rgb components
>>> + */
>>> +void lab2rgb(float lab[3], float rgb[3])
>>> +{
>>> + float lms[3];
>>> + apply_matrix(lab2lms, lab, lms);
>>> + lms[0] = exp(lms[0]);
>>>
>>
>> same as above.
>>
>>
>>> + lms[1] = exp(lms[1]);
>>> + lms[2] = exp(lms[2]);
>>> + apply_matrix(lms2rgb, lms, rgb);
>>> +}
>>> +
>>> +/**
>>> + *
>>
>>
>> excessive line
>>
>>
>>>
>>> + * Convert a frame from linear RGB to logspace LAB, and accumulate
>>> channel totals for each row
>>> + * Convert from RGB -> lms using equation 4 in color transfer paper.
>>> + *
>>> + * @param ctx Filter context
>>> + * @param arg Thread data pointer
>>> + * @param jobnr job number
>>> + * @param nb_jobs number of jobs
>>> + */
>>> +static int convert_frame(AVFilterContext* ctx, void* arg, int jobnr,
>>> int nb_jobs)
>>> +{
>>> + GrayWorldContext* s = ctx->priv;
>>> + ThreadData* td = arg;
>>> + AVFrame* in = td->in;
>>> + AVFrame* out = td->out;
>>> + AVFilterLink* outlink = ctx->outputs[0];
>>> + const int slice_start = (out->height * jobnr) / nb_jobs;
>>> + const int slice_end = (out->height * (jobnr + 1)) / nb_jobs;
>>> + float rgb[3];
>>> + float lab[3];
>>> +
>>> +
>>>
>>
>> again.
>>
>>
>>> +
>>> + for (unsigned int i = slice_start; i < slice_end; i++) {
>>> + float* g_in_row = (float*)(in->data[0] + i * in->linesize[0]);
>>> + float* b_in_row = (float*)(in->data[1] + i * in->linesize[1]);
>>> + float* r_in_row = (float*)(in->data[2] + i * in->linesize[2]);
>>> + float* lcur = s->tmppl + (i * outlink->w);
>>> + float* acur = s->tmppa + (i * outlink->w);
>>> + float* bcur = s->tmppb + (i * outlink->w);
>>> +
>>> + s->line_suml[i] = 0.0;
>>> + s->line_suma[i] = 0.0;
>>> + s->line_sumb[i] = 0.0;
>>> + s->line_count_pels[i] = 0;
>>> +
>>> + for (unsigned int j = 0; j < outlink->w; j++) {
>>> + rgb[0] = r_in_row[j * td->desc->comp[0].step /
>>> sizeof(float)];
>>> + rgb[1] = g_in_row[j * td->desc->comp[0].step /
>>> sizeof(float)];
>>> + rgb[2] = b_in_row[j * td->desc->comp[0].step /
>>> sizeof(float)];
>>> + rgb2lab(rgb, lab);
>>> + *(lcur++) = lab[0];
>>> + *(acur++) = lab[1];
>>> + *(bcur++) = lab[2];
>>> + s->line_suml[i] += lab[0];
>>> + s->line_suma[i] += lab[1];
>>> + s->line_sumb[i] += lab[2];
>>> + s->line_count_pels[i]++;
>>> + }
>>> + }
>>> + return 0;
>>> +}
>>> +
>>> +/**
>>> + *
>>
>>
>> excessive line
>>
>>
>>>
>>> + * Sum the channel totals and compute the median for each channel
>>> + *
>>> + * @param s Frame context
>>> + * @param td thread data
>>> + */
>>> +void compute_correction(GrayWorldContext* s, ThreadData* td)
>>> +{
>>> + float lsum = 0.0;
>>> + float asum = 0.0;
>>> + float bsum = 0.0;
>>> + float pixels = 0;
>>>
>>
>> please initialize floats with 0.f;
>>
>>
>> + for (int y = 0; y < td->out->height; ++y) {
>>> + lsum += s->line_suml[y];
>>> + asum += s->line_suma[y];
>>> + bsum += s->line_sumb[y];
>>> + pixels += s->line_count_pels[y];
>>> + }
>>> + td->l_avg = lsum / pixels;
>>> + td->a_avg = asum / pixels;
>>> + td->b_avg = bsum / pixels;
>>> +}
>>> +
>>> +
>>> +/**
>>> + *
>>> + * Subtract the median logspace AB values from each pixel.
>>>
>>
>> mean, median is something else.
>>
>>
>>> + *
>>> + * @param ctx Filter context
>>> + * @param arg Thread data pointer
>>> + * @param jobnr job number
>>> + * @param nb_jobs number of jobs
>>> + */
>>> +static int correct_frame(AVFilterContext* ctx, void* arg, int jobnr,
>>> int nb_jobs)
>>>
>>
>> Please keep style to match with rest of lavfi codebase, thus pointers are
>> written in another way.
>>
>>
>>> +{
>>> + GrayWorldContext* s = ctx->priv;
>>> + ThreadData* td = arg;
>>> + AVFrame* out = td->out;
>>> + AVFilterLink* outlink = ctx->outputs[0];
>>> + const int slice_start = (out->height * jobnr) / nb_jobs;
>>> + const int slice_end = (out->height * (jobnr + 1)) / nb_jobs;
>>> +
>>>
>>
>> excessive empty line.
>>
>>
>>> + float rgb[3];
>>> + float lab[3];
>>> +
>>> + for (int i = slice_start; i < slice_end; i++) {
>>> + float* g_out_row = (float*)(out->data[0] + i *
>>> out->linesize[0]);
>>> + float* b_out_row = (float*)(out->data[1] + i *
>>> out->linesize[1]);
>>> + float* r_out_row = (float*)(out->data[2] + i *
>>> out->linesize[2]);
>>> + float* lcur = s->tmppl + (i * outlink->w);
>>> + float* acur = s->tmppa + (i * outlink->w);
>>> + float* bcur = s->tmppb + (i * outlink->w);
>>> +
>>> + for (int j = 0; j < outlink->w; j++) {
>>> + lab[0] = *lcur++;
>>>
>>
>> IIUC first component is unchanged, thus this step can be skipped
>> completely.
>>
>>
>>> + lab[1] = *acur++;
>>> + lab[2] = *bcur++;
>>> +
>>> + // subtract the average for the color channels
>>> + lab[1] -= td->a_avg;
>>> + lab[2] -= td->b_avg;
>>> +
>>> + //convert back to linear rgb
>>> + lab2rgb(lab, rgb);
>>> + r_out_row[j * td->odesc->comp[0].step / sizeof(float)] =
>>> rgb[0];
>>> + g_out_row[j * td->odesc->comp[1].step / sizeof(float)] =
>>> rgb[1];
>>> + b_out_row[j * td->odesc->comp[2].step / sizeof(float)] =
>>> rgb[2];
>>>
>>
>> This can be written in better way, format is planar, so this can be
>> dramatically simplified.
>>
>>
>>> + }
>>> + }
>>> + return 0;
>>> +}
>>> +
>>> +
>>> +static int config_input(AVFilterLink* inlink)
>>> +{
>>> + GrayWorldContext* s = inlink->dst->priv;
>>> +
>>> + s->tmppl = av_malloc(inlink->h * inlink->w * sizeof(float));
>>> + s->tmppa = av_malloc(inlink->h * inlink->w * sizeof(float));
>>> + s->tmppb = av_malloc(inlink->h * inlink->w * sizeof(float));
>>>
>>
>> use av_malloc_array. And checking of return value is mandatory.
>>
>>
>>> +
>>> + s->line_count_pels = av_malloc(inlink->h * sizeof(int));
>>> +
>>> + s->line_suml = av_malloc(inlink->h * sizeof(float));
>>> + s->line_suma = av_malloc(inlink->h * sizeof(float));
>>> + s->line_sumb = av_malloc(inlink->h * sizeof(float));
>>>
>>
>> ditto.
>>
>>
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +static av_cold void uninit(AVFilterContext* ctx)
>>> +{
>>> + GrayWorldContext* s = ctx->priv;
>>> +
>>> + av_freep(&s->tmppl);
>>> + av_freep(&s->tmppa);
>>> + av_freep(&s->tmppb);
>>> +
>>> + av_freep(&s->line_count_pels);
>>> +
>>> + av_freep(&s->line_suml);
>>> + av_freep(&s->line_suma);
>>> + av_freep(&s->line_sumb);
>>> +}
>>> +
>>> +static int filter_frame(AVFilterLink* inlink, AVFrame* in)
>>> +{
>>> + AVFilterContext* ctx = inlink->dst;
>>> + GrayWorldContext* s = ctx->priv;
>>> + AVFilterLink* outlink = ctx->outputs[0];
>>> + ThreadData td;
>>> + AVFrame* out;
>>> + const AVPixFmtDescriptor* desc =
>>> av_pix_fmt_desc_get(inlink->format);
>>> + const AVPixFmtDescriptor* odesc =
>>> av_pix_fmt_desc_get(outlink->format);
>>> +
>>> +
>>> + if (av_frame_is_writable(in)) {
>>> + out = in;
>>> + } else {
>>> + out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
>>> + if (!out) {
>>> + av_frame_free(&in);
>>> + return AVERROR(ENOMEM);
>>> + }
>>> + av_frame_copy_props(out, in);
>>> + }
>>> + /* input and output transfer will be linear */
>>> + if (in->color_trc == AVCOL_TRC_UNSPECIFIED) {
>>> + av_log(s, AV_LOG_WARNING, "Untagged transfer, assuming linear
>>> light\n");
>>> + out->color_trc = AVCOL_TRC_LINEAR;
>>> + } else if (in->color_trc != AVCOL_TRC_LINEAR) {
>>> + av_log(s, AV_LOG_WARNING, "Tonemapping works on linear light
>>> only\n");
>>> + }
>>> +
>>> + td.in = in;
>>> + td.out = out;
>>> + td.desc = desc;
>>> + td.odesc = odesc;
>>> +
>>> + ctx->internal->execute(ctx, convert_frame, &td, NULL,
>>> FFMIN(outlink->h, ff_filter_get_nb_threads(ctx)));
>>> + compute_correction(s, &td);
>>> + ctx->internal->execute(ctx, correct_frame, &td, NULL,
>>> FFMIN(outlink->h, ff_filter_get_nb_threads(ctx)));
>>> +
>>> + if (desc->flags & AV_PIX_FMT_FLAG_ALPHA && desc->flags &
>>> AV_PIX_FMT_FLAG_ALPHA) {
>>> + av_image_copy_plane(out->data[3], out->linesize[3],
>>> + in->data[3], in->linesize[3],
>>> + out->linesize[3], outlink->h);
>>> + } else if (desc->flags & AV_PIX_FMT_FLAG_ALPHA) {
>>> + for (int y = 0; y < out->height; y++) {
>>> + for (int x = 0; x < out->width; x++) {
>>> + AV_WN32(out->data[3] + x * desc->comp[3].step + y *
>>> out->linesize[3],
>>> + av_float2int(1.0f));
>>> + }
>>> + }
>>> + }
>>> +
>>> + if (in != out)
>>> + av_frame_free(&in);
>>> + return ff_filter_frame(outlink, out);
>>> +}
>>> +
>>> +static const AVFilterPad grayworld_inputs[] = {
>>> + {
>>> + .name = "default",
>>> + .type = AVMEDIA_TYPE_VIDEO,
>>> + .filter_frame = filter_frame,
>>> + .config_props = config_input,
>>> + },
>>> + {NULL} };
>>> +
>>> +static const AVFilterPad grayworld_outputs[] = {
>>> + {
>>> + .name = "default",
>>> + .type = AVMEDIA_TYPE_VIDEO,
>>> + },
>>> + {NULL} };
>>>
>>
>> {NULL} is not needed any more on master ffmpeg version.
>>
>> +
>>> +const AVFilter ff_vf_grayworld = {
>>> + .name = "grayworld",
>>> + .description = NULL_IF_CONFIG_SMALL("Adjust white balance using LAB
>>> gray world algorithm"),
>>> + .priv_size = sizeof(GrayWorldContext),
>>> + .priv_class = &grayworld_class,
>>> + .query_formats = query_formats,
>>> + .inputs = grayworld_inputs,
>>> + .outputs = grayworld_outputs,
>>>
>>
>> This have been recently changed. Look at other filters for example how it
>> is done now.
>>
>>
>>
>>> + .flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC |
>>> AVFILTER_FLAG_SLICE_THREADS,
>>> + .process_command = ff_filter_process_command,
>>>
>>
>> This one is pointless, since filter have 0 options to configure from
>> userspace.
>>
>>
>>> + .uninit = uninit,
>>> +};
>>> --
>>> 2.17.1
>>>
>>> _______________________________________________
>>> ffmpeg-devel mailing list
>>> ffmpeg-devel@ffmpeg.org
>>> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>>>
>>> To unsubscribe, visit link above, or email
>>> ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
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>>
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