On Tue, Feb 24, 2015 at 02:27:01PM +0530, arwa arif wrote: > 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?
you can do both rdft first and then the 2 irdft passes, this should
give more possibilities in filtering but it could be done the other
way around too
>
> I have attached the patch.
> Makefile | 1
> allfilters.c | 1
> vf_fftfilt.c | 139
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 141 insertions(+)
> d4b25d6a204534a66400f52c1f5312652e8208af 0001-Port-FFT-domain-filter.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++;
> + }
the copied data must line up with the rdft applied to them
also its better to only clear the space between than the whole, as its
faster, so the memset above is not needed if the memset below is used
for (i = 0; i < h; i++) {
for (j = 0; j < w; j++)
fftfilt->rdft_data[i*rdft_len + j] = *(in->data[0] +
in->linesize[0] * i + j);
memset(fftfilt->rdft_data + i*rdft_len + j, 0,
(rdft_len-w)*sizeof(*fftfilt->rdft_data));
}
> +
> + 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++;
> + }
this needs cliping and scaling
for (i = 0; i < h; i++)
for (j = 0; j < w; j++)
*(out->data[0] + out->linesize[0] * i + j) =
av_clip(fftfilt->rdft_data[i*rdft_len + j] * 2 / rdft_len, 0, 255);
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
While the State exists there can be no freedom; when there is freedom there
will be no State. -- Vladimir Lenin
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