Hello,
I have written a very primitive code for porting FFT domain filter. It
accepts only gray8 format images. The output should be a grayscale image,
but the ouput image is coming out to be a black and white image. Also, I am
getting confused when to do the vertical pass. After taking irdft of the
horizontal pass or before it?
I have attached the patch.
From 455a261d7e2b3afba767aac2e73448aeee02d159 Mon Sep 17 00:00:00 2001
From: Arwa Arif <arwaarif1...@gmail.com>
Date: Tue, 24 Feb 2015 12:17:30 +0530
Subject: [PATCH] Port FFT domain filter.
---
libavfilter/Makefile | 1 +
libavfilter/allfilters.c | 1 +
libavfilter/vf_fftfilt.c | 139 ++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 141 insertions(+)
create mode 100644 libavfilter/vf_fftfilt.c
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index 289c63b..b184f07 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -120,6 +120,7 @@ OBJS-$(CONFIG_EDGEDETECT_FILTER) += vf_edgedetect.o
OBJS-$(CONFIG_EQ_FILTER) += vf_eq.o
OBJS-$(CONFIG_EXTRACTPLANES_FILTER) += vf_extractplanes.o
OBJS-$(CONFIG_FADE_FILTER) += vf_fade.o
+OBJS-$(CONFIG_FFTFILT_FILTER) += vf_fftfilt.o
OBJS-$(CONFIG_FIELD_FILTER) += vf_field.o
OBJS-$(CONFIG_FIELDMATCH_FILTER) += vf_fieldmatch.o
OBJS-$(CONFIG_FIELDORDER_FILTER) += vf_fieldorder.o
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index 55de154..043ac56 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -136,6 +136,7 @@ void avfilter_register_all(void)
REGISTER_FILTER(EQ, eq, vf);
REGISTER_FILTER(EXTRACTPLANES, extractplanes, vf);
REGISTER_FILTER(FADE, fade, vf);
+ REGISTER_FILTER(FFTFILT, fftfilt, vf);
REGISTER_FILTER(FIELD, field, vf);
REGISTER_FILTER(FIELDMATCH, fieldmatch, vf);
REGISTER_FILTER(FIELDORDER, fieldorder, vf);
diff --git a/libavfilter/vf_fftfilt.c b/libavfilter/vf_fftfilt.c
new file mode 100644
index 0000000..753bc8e
--- /dev/null
+++ b/libavfilter/vf_fftfilt.c
@@ -0,0 +1,139 @@
+/*
+ * Copyright (c) 2015 Arwa Arif <arwaarif1...@gmail.com>
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU 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
+ * FFT domain filtering.
+ */
+
+#include "libavfilter/internal.h"
+#include "libavutil/common.h"
+#include "libavutil/imgutils.h"
+#include "libavutil/opt.h"
+#include "libavutil/pixdesc.h"
+#include "libavcodec/avfft.h"
+
+typedef struct {
+ const AVClass *class;
+
+ RDFTContext *rdft;
+ int rdft_bits;
+ FFTSample *rdft_data;
+
+} FFTFILTContext;
+
+static int filter_frame(AVFilterLink *inlink, AVFrame *in)
+{
+ AVFilterContext *ctx = inlink->dst;
+ AVFilterLink *outlink = inlink->dst->outputs[0];
+ FFTFILTContext *fftfilt = ctx->priv;
+ AVFrame *out;
+ int i, j, k, rdft_bits;
+ size_t rdft_len, w, h;
+
+ w = inlink->w;
+ h = inlink->h;
+
+ /* RDFT window size (precision) according to the requested output frame height */
+ for (rdft_bits = 1; 1 << rdft_bits < 2 * w; rdft_bits++);
+ rdft_len = 1 << rdft_bits;
+ fftfilt->rdft_data = av_malloc_array(h, rdft_len * sizeof(FFTSample));
+ memset(fftfilt->rdft_data, 0, rdft_len * h * sizeof(FFTSample));
+
+ out = ff_get_video_buffer(outlink, inlink->w, inlink->h);
+ if (!out)
+ return AVERROR(ENOMEM);
+
+ av_frame_copy_props(out, in);
+
+ /*Horizontal pass - RDFT*/
+ fftfilt->rdft = av_rdft_init(rdft_bits, DFT_R2C);
+ k = 0;
+ for (i = 0; i < h; i++)
+ for (j = 0; j < w; j++)
+ {
+ fftfilt->rdft_data[k] = *(in->data[0] + in->linesize[0] * i + j);
+ k++;
+ }
+
+ for (i = 0; i < h; i++)
+ av_rdft_calc(fftfilt->rdft, fftfilt->rdft_data + i * rdft_len);
+
+ av_rdft_end(fftfilt->rdft);
+
+ /*Horizontal pass - IRDFT*/
+ fftfilt->rdft = av_rdft_init(rdft_bits, IDFT_C2R);
+
+ for (i = 0; i < h; i++)
+ av_rdft_calc(fftfilt->rdft, fftfilt->rdft_data + i * rdft_len);
+
+ k = 0;
+ for (i = 0; i < h; i++)
+ for (j = 0; j < w; j++)
+ {
+ *(out->data[0] + out->linesize[0] * i + j) = fftfilt->rdft_data[k];
+ k++;
+ }
+
+ av_rdft_end(fftfilt->rdft);
+ av_free(fftfilt->rdft_data);
+
+ av_frame_free(&in);
+
+ return ff_filter_frame(outlink, out);
+}
+
+static int query_formats(AVFilterContext *ctx)
+{
+ static const enum AVPixelFormat pixel_fmts_fftfilt[] = {
+ AV_PIX_FMT_GRAY8,
+ AV_PIX_FMT_NONE
+ };
+
+ ff_set_common_formats(ctx, ff_make_format_list(pixel_fmts_fftfilt));
+
+ return 0;
+}
+
+static const AVFilterPad fftfilt_inputs[] = {
+ {
+ .name = "default",
+ .type = AVMEDIA_TYPE_VIDEO,
+ .filter_frame = filter_frame,
+ },
+ { NULL }
+};
+
+static const AVFilterPad fftfilt_outputs[] = {
+ {
+ .name = "default",
+ .type = AVMEDIA_TYPE_VIDEO,
+ },
+ { NULL }
+};
+
+AVFilter ff_vf_fftfilt = {
+ .name = "fftfilt",
+ .description = NULL_IF_CONFIG_SMALL("Adjust gain."),
+ .priv_size = sizeof(FFTFILTContext),
+ .inputs = fftfilt_inputs,
+ .outputs = fftfilt_outputs,
+ .query_formats = query_formats,
+};
--
1.7.9.5
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