[FFmpeg-devel] [PATCH] lavfi: add smartblur filter

Stefano Sabatini stefasab at gmail.com
Mon Aug 27 14:48:37 CEST 2012


On date Saturday 2012-08-25 02:16:04 +0200, Jérémy Tran encoded:
> This is a port of the MPlayer smartblur filter (libmpcodecs/vf_smartblur.c)
> by Michael Niedermayer.

Also mention that the filter code was relicensed with permission of
the original author.

> ---
>  doc/filters.texi           |  26 ++++
>  libavfilter/Makefile       |   1 +
>  libavfilter/allfilters.c   |   1 +
>  libavfilter/vf_smartblur.c | 313 +++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 341 insertions(+)
>  create mode 100644 libavfilter/vf_smartblur.c
> 
> diff --git a/doc/filters.texi b/doc/filters.texi
> index bef95f7..bcdef2e 100644
> --- a/doc/filters.texi
> +++ b/doc/filters.texi
> @@ -3253,6 +3253,32 @@ not specified it will use the default value of 16.
>  Adding this in the beginning of filter chains should make filtering
>  faster due to better use of the memory cache.
>  
> + at section smartblur
> +
> +Blur the input video without impacting the outlines.
> +
> +The filter accepts the following parameters:
> + at var{luma_radius}:@var{luma_strength}:@var{luma_threshold}[:@var{chroma_radius}:@var{chroma_strength}:@var{chroma_threshold}]
> +
> +Parameters prefixed by @var{luma} indicates that it works on the luminance of the

indicate?

> +pixels whereas parameters prefixed by @var{chroma} refer to the chrominance of
> +the pixels.
> +
> +If the chroma parameters are not set, the luma parameters are used for
> +either the luminance and the chrominance of the pixels.
> +

> + at var{luma_radius} or @var{chroma_radius} must be a float number in the range [0.1,5.0] that specifies
> +the blur filter strength (slower if larger).

This is a bit confusing, since "strength" is referenced below. Indeed
radius is the variance of the Gaussian filter used to blur the image.

> + at var{luma_strength} or @var{chroma_strength} must be a float number in the range [-1.0,1.0] that
> +configures the blurring. A value included in [0.0,1.0] will blur the image
> +whereas a value included in [-1.0,0.0] will sharpen the image.
> +
> + at var{luma_threshold} or @var{chroma_threshold} must be an integer in the range [-30,30] that is used as a
> +coefficient to determine whether a pixel should be blurred or not. A value of
> +0 will filter all the image, a value included in [0-30] will filter flat areas
> +and a value included in [-30,0] will filter edges.
> +
>  @section split
>  
>  Split input video into several identical outputs.
> diff --git a/libavfilter/Makefile b/libavfilter/Makefile
> index 3270232..e2fdb8e 100644
> --- a/libavfilter/Makefile
> +++ b/libavfilter/Makefile
> @@ -125,6 +125,7 @@ OBJS-$(CONFIG_SETSAR_FILTER)                 += vf_aspect.o
>  OBJS-$(CONFIG_SETTB_FILTER)                  += f_settb.o
>  OBJS-$(CONFIG_SHOWINFO_FILTER)               += vf_showinfo.o
>  OBJS-$(CONFIG_SLICIFY_FILTER)                += vf_slicify.o

> +OBJS-$(CONFIG_SMARTBLUR_FILTER)              += lswsutils.o vf_smartblur.o

FFLIBS-$(CONFIG_SMARTBLUR_FILTER)            += swscale

>  OBJS-$(CONFIG_SPLIT_FILTER)                  += split.o
>  OBJS-$(CONFIG_SUPER2XSAI_FILTER)             += vf_super2xsai.o
>  OBJS-$(CONFIG_SWAPUV_FILTER)                 += vf_swapuv.o
> diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
> index 0bc5a4a..cd9bef8 100644
> --- a/libavfilter/allfilters.c
> +++ b/libavfilter/allfilters.c
> @@ -116,6 +116,7 @@ void avfilter_register_all(void)
>      REGISTER_FILTER (SETTB,       settb,       vf);
>      REGISTER_FILTER (SHOWINFO,    showinfo,    vf);
>      REGISTER_FILTER (SLICIFY,     slicify,     vf);
> +    REGISTER_FILTER (SMARTBLUR,   smartblur,   vf);
>      REGISTER_FILTER (SPLIT,       split,       vf);
>      REGISTER_FILTER (SUPER2XSAI,  super2xsai,  vf);
>      REGISTER_FILTER (SWAPUV,      swapuv,      vf);
> diff --git a/libavfilter/vf_smartblur.c b/libavfilter/vf_smartblur.c
> new file mode 100644
> index 0000000..9bae193
> --- /dev/null
> +++ b/libavfilter/vf_smartblur.c
> @@ -0,0 +1,313 @@
> +/*
> + * Copyright (c) 2002 Michael Niedermayer <michaelni at gmx.at>
> + * Copyright (c) 2012 Jeremy Tran
> + *
> + * 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
> + * Apply a smartblur filter to the input video
> + * Ported from MPlayer libmpcodecs/vf_smartblur.c.

by ..., so it is clear who is the original author.

> + */
> +
> +#include "libavutil/pixdesc.h"
> +
> +#include "libswscale/swscale.h"
> +
> +#include "avfilter.h"
> +#include "formats.h"
> +#include "internal.h"
> +

> +#define RAD_MIN 0.1
> +#define RAD_MAX 5.0
> +
> +#define STRENGTH_MIN -1.0
> +#define STRENGTH_MAX 1.0
> +
> +#define THRES_MIN -30
> +#define THRES_MAX 30

Nit: RADIUS, THRESHOLD, more grep friendly.

> +typedef struct {
> +    float              radius;
> +    float              strength;
> +    int                threshold;
> +    float              quality;
> +    struct SwsContext *filter_context;
> +} FilterParam;
> +
> +typedef struct {
> +    FilterParam  luma;
> +    FilterParam  chroma;
> +    int          hsub;
> +    int          vsub;
> +    unsigned int flags; // sws flags
> +} SmartblurContext;
> +
> +
> +#define CHECK_PARAM(param, name, min, max, format, ret)                       \
> +    if (param < min || param > max) {                                         \
> +        av_log(ctx, AV_LOG_ERROR,                                             \
> +               "Invalid " #name " value " #format ": "                        \
> +               "must be included between range " #format " and " #format "\n",\
> +               param, min, max);                                              \
> +        ret = AVERROR(EINVAL);                                                \
> +    }
> +

> +static inline int validate_input(AVFilterContext *ctx, uint8_t validate_chroma,
> +                                 float lradius,    float cradius,
> +                                 float lstrength,  float cstrength,
> +                                 int   lthreshold, int   cthreshold)
> +{
> +    int ret = 0;
> +
> +    CHECK_PARAM(lradius,    luma radius,    RAD_MIN,      RAD_MAX,      %0.1f, ret)
> +    CHECK_PARAM(lstrength,  luma strength,  STRENGTH_MIN, STRENGTH_MAX, %0.1f, ret)
> +    CHECK_PARAM(lthreshold, luma threshold, THRES_MIN,    THRES_MAX,    %d,    ret)
> +
> +    if (validate_chroma) {
> +        CHECK_PARAM(cradius,    chroma radius,    RAD_MIN,      RAD_MAX,      %0.1f, ret)
> +        CHECK_PARAM(cstrength,  chroma strength,  STRENGTH_MIN, STRENGTH_MAX, %0.1f, ret)
> +        CHECK_PARAM(cthreshold, chroma threshold, THRES_MIN,    THRES_MAX,    %d,    ret)
> +    }
> +
> +    return ret;
> +}

Nit: this code could be moved to init().

> +
> +static av_cold int init(AVFilterContext *ctx, const char *args)
> +{
> +    SmartblurContext *sblur = ctx->priv;
> +    int n = 0;
> +    float lradius, lstrength, cradius, cstrength;
> +    int lthreshold, cthreshold;
> +
> +    if (args)
> +        n = sscanf(args, "%f:%f:%d:%f:%f:%d",
> +                   &lradius,
> +                   &lstrength,
> +                   &lthreshold,
> +                   &cradius,
> +                   &cstrength,
> +                   &cthreshold);
> +
> +    if (n != 3 && n != 6) {
> +        av_log(ctx, AV_LOG_ERROR,
> +               "Incorrect number of parameters or invalid syntax: "
> +               "must be luma_radius:luma_strength:luma_threshold"
> +               "[:chroma_radius:chroma_strength:chroma_threshold]\n");
> +        return AVERROR(EINVAL);
> +    }
> +
> +    sblur->luma.radius    = lradius;
> +    sblur->luma.strength  = lstrength;
> +    sblur->luma.threshold = lthreshold;
> +
> +    if (n == 3) {
> +        sblur->chroma.radius    = sblur->luma.radius;
> +        sblur->chroma.strength  = sblur->luma.strength;
> +        sblur->chroma.threshold = sblur->luma.threshold;
> +    } else {
> +        sblur->chroma.radius    = cradius;
> +        sblur->chroma.strength  = cstrength;
> +        sblur->chroma.threshold = cthreshold;
> +    }
> +
> +    sblur->luma.quality = sblur->chroma.quality = 3.0;
> +    sblur->flags = SWS_BICUBIC;
> +
> +    return validate_input(ctx, n != 3,
> +                          sblur->luma.radius,    sblur->chroma.radius,
> +                          sblur->luma.strength,  sblur->chroma.strength,
> +                          sblur->luma.threshold, sblur->chroma.threshold);
> +}
> +
> +static av_cold void uninit(AVFilterContext *ctx)
> +{
> +    SmartblurContext *sblur = ctx->priv;
> +
> +    sws_freeContext(sblur->luma.filter_context);
> +    sws_freeContext(sblur->chroma.filter_context);
> +}
> +
> +static int query_formats(AVFilterContext *ctx)
> +{
> +    static const enum PixelFormat pix_fmts[] = {
> +        PIX_FMT_YUV444P,      PIX_FMT_YUV422P,
> +        PIX_FMT_YUV420P,      PIX_FMT_YUV411P,
> +        PIX_FMT_YUV410P,      PIX_FMT_YUV440P,
> +        PIX_FMT_GRAY8,
> +        PIX_FMT_NONE
> +    };
> +
> +    ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
> +
> +    return 0;
> +}
> +

> +static int alloc_sws_context(FilterParam *f, int width, int height, unsigned int flags)
> +{
> +    SwsVector *vec;
> +    SwsFilter sws_filter;
> +
> +    vec = sws_getGaussianVec(f->radius, f->quality);

Missing NULL check?

> +    sws_scaleVec(vec, f->strength);
> +    vec->coeff[vec->length / 2] += 1.0 - f->strength;
> +    sws_filter.lumH = sws_filter.lumV = vec;
> +    sws_filter.chrH = sws_filter.chrV = NULL;
> +    f->filter_context = sws_getCachedContext(NULL,
> +                                             width, height, PIX_FMT_GRAY8,
> +                                             width, height, PIX_FMT_GRAY8,
> +                                             flags, &sws_filter, NULL, NULL);
> +
> +    sws_freeVec(vec);
> +
> +    if (!f->filter_context)
> +        return AVERROR(EINVAL);
> +
> +    return 0;
> +}
> +
> +static int config_props(AVFilterLink *inlink)
> +{
> +    SmartblurContext *sblur = inlink->dst->priv;
> +    const AVPixFmtDescriptor *desc = &av_pix_fmt_descriptors[inlink->format];
> +
> +    sblur->hsub = desc->log2_chroma_w;
> +    sblur->vsub = desc->log2_chroma_h;
> +
> +    alloc_sws_context(&sblur->luma, inlink->w, inlink->h, sblur->flags);
> +    alloc_sws_context(&sblur->chroma, inlink->w >> sblur->hsub, inlink->h >> sblur->vsub, sblur->flags);
> +
> +    return 0;
> +}
> +
> +static void blur(uint8_t *dst, int dst_linesize,
> +                 uint8_t *src, int src_linesize,

const? (possibly faster)

> +                 int w, int h, int threshold,
> +                 struct SwsContext *filter_context)
> +{
> +    int x, y;
> +    int orig, filtered;
> +    int diff;
> +    /* Declare arrays of 4 to get aligned data */
> +    const uint8_t* const src_array[4] = {src};
> +    uint8_t *dst_array[4]             = {dst};
> +    int src_linesize_array[4] = {src_linesize};
> +    int dst_linesize_array[4] = {dst_linesize};
> +
> +    sws_scale(filter_context, src_array, src_linesize_array, 0, h, dst_array, dst_linesize_array);
> +
> +    if (threshold > 0) {

> +        for (y = 0; y < h; ++y)

Nit: "{" so it's easer to spot where the block ends, same below.

> +            for (x = 0; x < w; ++x) {
> +                orig     = src[x + y * src_linesize];
> +                filtered = dst[x + y * dst_linesize];
> +                diff     = orig - filtered;
> +
> +                if (diff > 0) {
> +                    if (diff > 2 * threshold)
> +                        dst[x + y * dst_linesize] = orig;
> +                    else if (diff > threshold)
> +                        /* add 'diff' and substract 'threshold' from 'filtered' */
> +                        dst[x + y * dst_linesize] = orig - threshold;
> +                } else {
> +                    if (-diff > 2 * threshold)
> +                        dst[x + y * dst_linesize] = orig;
> +                    else if (-diff > threshold)
> +                        /* add 'diff' and 'threshold' to 'filtered' */
> +                        dst[x + y * dst_linesize] = orig + threshold;
> +                }
> +            }
> +    } else if (threshold < 0) {
> +        for (y = 0; y < h; ++y)
> +            for (x = 0; x < w; ++x) {
> +                orig     = src[x + y * src_linesize];
> +                filtered = dst[x + y * dst_linesize];
> +                diff     = orig - filtered;
> +
> +                if (diff > 0) {
> +                    if (diff <= -threshold)
> +                        dst[x + y * dst_linesize] = orig;
> +                    else if (diff <= -2 * threshold)
> +                        /* substract 'diff' and 'threshold' from 'orig' */
> +                        dst[x + y * dst_linesize] = filtered - threshold;
> +                } else {
> +                    if (diff >= threshold)
> +                        dst[x + y * dst_linesize] = orig;
> +                    else if (diff >= 2 * threshold)
> +                        /* add 'threshold' and substract 'diff' from 'orig' */
> +                        dst[x + y * dst_linesize] = filtered + threshold;
> +                }
> +            }
> +    }
> +}
> +
> +static int end_frame(AVFilterLink *inlink)
> +{
> +    SmartblurContext  *sblur  = inlink->dst->priv;
> +    AVFilterBufferRef *inpic  = inlink->cur_buf;
> +    AVFilterBufferRef *outpic = inlink->dst->outputs[0]->out_buf;
> +    int cw = inlink->w >> sblur->hsub;
> +    int ch = inlink->h >> sblur->vsub;
> +
> +    blur(outpic->data[0], outpic->linesize[0],
> +         inpic->data[0],  inpic->linesize[0],
> +         inlink->w, inlink->h, sblur->luma.threshold,
> +         sblur->luma.filter_context);
> +

> +    if (inlink->format != PIX_FMT_GRAY8) {

This could be made more robust, checking on inpic->data[2] != NULL.

> +        blur(outpic->data[1], outpic->linesize[1],
> +             inpic->data[1],  inpic->linesize[1],
> +             cw, ch, sblur->chroma.threshold,
> +             sblur->chroma.filter_context);
> +        blur(outpic->data[2], outpic->linesize[2],
> +             inpic->data[2],  inpic->linesize[2],
> +             cw, ch, sblur->chroma.threshold,
> +             sblur->chroma.filter_context);
> +    }
> +
> +    return ff_end_frame(inlink->dst->outputs[0]);
> +}
> +
> +AVFilter avfilter_vf_smartblur = {
> +    .name        = "smartblur",
> +    .description = NULL_IF_CONFIG_SMALL("Blur the input video without impacting the outlines."),
> +
> +    .priv_size = sizeof(SmartblurContext),
> +
> +    .init          = init,
> +    .uninit        = uninit,
> +    .query_formats = query_formats,
> +
> +    .inputs = (const AVFilterPad[]) {
> +        {
> +            .name         = "default",
> +            .type         = AVMEDIA_TYPE_VIDEO,
> +            .end_frame    = end_frame,
> +            .config_props = config_props,
> +            .min_perms    = AV_PERM_READ,
> +        },
> +        { .name = NULL }
> +    },
> +    .outputs = (const AVFilterPad[]) {
> +        {
> +            .name         = "default",
> +            .type         = AVMEDIA_TYPE_VIDEO,
> +        },
> +        { .name = NULL }
> +    }
> +};
> -- 
> 1.7.11.3

Should be good otherwise.

Did you check that the mp=smartblur returns the same output? What was
the issue?
-- 
FFmpeg = Faithful & Fostering Mere Political Easy Genius


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