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

Clément Bœsch u at pkh.me
Mon Nov 11 16:48:39 CET 2013


On Mon, Nov 11, 2013 at 01:04:21AM +0100, Stefano Sabatini wrote:
> TODO: bump minor, add Changelog entry
> ---
>  doc/filters.texi         |  26 ++++++
>  libavfilter/Makefile     |   2 +
>  libavfilter/allfilters.c |   1 +
>  libavfilter/vf_elbg.c    | 210 +++++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 239 insertions(+)
>  create mode 100644 libavfilter/vf_elbg.c
> 
> diff --git a/doc/filters.texi b/doc/filters.texi
> index 9fae339..978978c 100644
> --- a/doc/filters.texi
> +++ b/doc/filters.texi
> @@ -3790,6 +3790,32 @@ ffmpeg -i video.avi -filter_complex 'extractplanes=y+u+v[y][u][v]' -map '[y]' y.
>  @end example
>  @end itemize
>  
> + at section elbg
> +
> +Apply a posterize effect using the ELBG (Enhanced LBG) algorithm.
> +
> +For each input image, the filter will compute the optimal mapping from
> +the input to the output given the codebook length, that is the number
> +of distinct output colors.
> +
> +This filter accepts the following options.
> +
> + at table @option
> + at item codebook_length, l
> +Set codebook length. The value must be a positive integer, and
> +represents the number of distinct output colors. Default value is 256.
> +
> + at item nb_steps, n
> +Set the maximum number of iteration to apply for computing the optimal
> +mapping. The higher the value the better the result and the higher the
> +computation time. Default value is 1.
> +
> + at item seed, s
> +Set a random seed, must be an integer included between 0 and
> +UINT32_MAX. If not specified, or if explicitly set to -1, the filter
> +will try to use a good random seed on a best effort basis.
> + at end table
> +
>  @section fade
>  
>  Apply fade-in/out effect to input video.
> diff --git a/libavfilter/Makefile b/libavfilter/Makefile
> index 3fcccf8..7bd4323 100644
> --- a/libavfilter/Makefile
> +++ b/libavfilter/Makefile
> @@ -9,6 +9,7 @@ FFLIBS-$(CONFIG_ASYNCTS_FILTER)              += avresample
>  FFLIBS-$(CONFIG_ATEMPO_FILTER)               += avcodec
>  FFLIBS-$(CONFIG_DECIMATE_FILTER)             += avcodec
>  FFLIBS-$(CONFIG_DESHAKE_FILTER)              += avcodec
> +FFLIBS-$(CONFIG_ELBG_FILTER)                 += avcodec
>  FFLIBS-$(CONFIG_MCDEINT_FILTER)              += avcodec
>  FFLIBS-$(CONFIG_MOVIE_FILTER)                += avformat avcodec
>  FFLIBS-$(CONFIG_MP_FILTER)                   += avcodec
> @@ -130,6 +131,7 @@ OBJS-$(CONFIG_DESHAKE_FILTER)                += vf_deshake.o
>  OBJS-$(CONFIG_DRAWBOX_FILTER)                += vf_drawbox.o
>  OBJS-$(CONFIG_DRAWGRID_FILTER)               += vf_drawbox.o
>  OBJS-$(CONFIG_DRAWTEXT_FILTER)               += vf_drawtext.o
> +OBJS-$(CONFIG_ELBG_FILTER)                   += vf_elbg.o
>  OBJS-$(CONFIG_EDGEDETECT_FILTER)             += vf_edgedetect.o
>  OBJS-$(CONFIG_EXTRACTPLANES_FILTER)          += vf_extractplanes.o
>  OBJS-$(CONFIG_FADE_FILTER)                   += vf_fade.o
> diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
> index a61ca0e..487946f 100644
> --- a/libavfilter/allfilters.c
> +++ b/libavfilter/allfilters.c
> @@ -127,6 +127,7 @@ void avfilter_register_all(void)
>      REGISTER_FILTER(DRAWGRID,       drawgrid,       vf);
>      REGISTER_FILTER(DRAWTEXT,       drawtext,       vf);
>      REGISTER_FILTER(EDGEDETECT,     edgedetect,     vf);
> +    REGISTER_FILTER(ELBG,           elbg,           vf);
>      REGISTER_FILTER(EXTRACTPLANES,  extractplanes,  vf);
>      REGISTER_FILTER(FADE,           fade,           vf);
>      REGISTER_FILTER(FIELD,          field,          vf);
> diff --git a/libavfilter/vf_elbg.c b/libavfilter/vf_elbg.c
> new file mode 100644
> index 0000000..3b6f600
> --- /dev/null
> +++ b/libavfilter/vf_elbg.c
> @@ -0,0 +1,210 @@
> +/*
> + * Copyright (c) 2013 Stefano Sabatini
> + *
> + * 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
> + * video quantizer filter based on ELBG
> + */
> +
> +#include "libavcodec/elbg.h"
> +#include "libavutil/opt.h"
> +#include "libavutil/pixdesc.h"
> +#include "libavutil/random_seed.h"
> +
> +#include "avfilter.h"
> +#include "drawutils.h"
> +#include "internal.h"
> +#include "video.h"
> +
> +typedef struct {
> +    const AVClass *class;
> +    AVLFG lfg;
> +    int lfg_seed;
> +    int max_steps_nb;
> +    int *codeword;
> +    int codeword_length;
> +    int *codeword_closest_codebook_idxs;
> +    int *codebook;
> +    int codebook_length;
> +    const AVPixFmtDescriptor *pix_desc;
> +    uint8_t rgba_map[4];
> +} ELBGContext;
> +
> +#define OFFSET(x) offsetof(ELBGContext, x)
> +#define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
> +
> +static const AVOption elbg_options[] = {
> +    { "codebook_length", "set codebook length", OFFSET(codebook_length), AV_OPT_TYPE_INT, { .i64 = 256 }, 1, INT_MAX, FLAGS },
> +    { "l",               "set codebook length", OFFSET(codebook_length), AV_OPT_TYPE_INT, { .i64 = 256 }, 0, INT_MAX, FLAGS },
> +    { "nb_steps", "set max number of steps to apply the grouping algorithm", OFFSET(max_steps_nb), AV_OPT_TYPE_INT, { .i64 = 1 }, 1, INT_MAX, FLAGS },
> +    { "n",        "set max number of steps to apply the grouping algorithm", OFFSET(max_steps_nb), AV_OPT_TYPE_INT, { .i64 = 1 }, 1, INT_MAX, FLAGS },

> +    { "seed", "set the random seed", OFFSET(lfg_seed), AV_OPT_TYPE_INT, {.i64 = -1}, -1, UINT32_MAX, FLAGS },
> +    { "s",    "set the random seed", OFFSET(lfg_seed), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, INT_MAX, FLAGS },

Those 2 are not the same

> +    { NULL }
> +};
> +
> +AVFILTER_DEFINE_CLASS(elbg);
> +
> +static av_cold int init(AVFilterContext *ctx)
> +{
> +    ELBGContext *elbg = ctx->priv;
> +
> +    if (elbg->lfg_seed == -1)
> +        elbg->lfg_seed = av_get_random_seed();
> +
> +    av_lfg_init(&elbg->lfg, elbg->lfg_seed);
> +    return 0;
> +}
> +
> +static int query_formats(AVFilterContext *ctx)
> +{
> +    static const enum PixelFormat pix_fmts[] = {
> +        AV_PIX_FMT_ARGB, AV_PIX_FMT_RGBA, AV_PIX_FMT_ABGR, AV_PIX_FMT_BGRA,
> +        AV_PIX_FMT_RGB24, AV_PIX_FMT_BGR24,
> +        AV_PIX_FMT_NONE
> +    };
> +
> +    ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
> +
> +    return 0;
> +}
> +
> +#define NB_COMPONENTS 3
> +
> +static int config_input(AVFilterLink *inlink)
> +{
> +    AVFilterContext *ctx = inlink->dst;
> +    ELBGContext *elbg = ctx->priv;
> +
> +    elbg->pix_desc = av_pix_fmt_desc_get(inlink->format);
> +    elbg->codeword_length = inlink->w * inlink->h;
> +    elbg->codeword = av_realloc_f(elbg->codeword,
> +                                  elbg->codeword_length, NB_COMPONENTS * sizeof(int));

sizeof(*elbg->codeword)

a few more below

> +    if (!elbg->codeword)
> +        return AVERROR(ENOMEM);
> +
> +    elbg->codeword_closest_codebook_idxs = av_realloc_f(elbg->codeword_closest_codebook_idxs,
> +                                                        elbg->codeword_length, sizeof(int));
> +    if (!elbg->codeword_closest_codebook_idxs)
> +        return AVERROR(ENOMEM);
> +
> +    elbg->codebook = av_realloc_f(elbg->codebook,
> +                                  elbg->codebook_length, NB_COMPONENTS * sizeof(int));
> +    if (!elbg->codebook)
> +        return AVERROR(ENOMEM);
> +
> +    ff_fill_rgba_map(elbg->rgba_map, inlink->format);
> +
> +    return 0;
> +}
> +
> +#define R 0
> +#define G 1
> +#define B 2
> +#define A 3
> +
> +static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
> +{
> +    ELBGContext *elbg = inlink->dst->priv;
> +    int i, j, k;
> +    uint8_t *p, *p0;
> +
> +    const uint8_t r_idx  = elbg->rgba_map[R];
> +    const uint8_t g_idx  = elbg->rgba_map[G];
> +    const uint8_t b_idx  = elbg->rgba_map[B];
> +
> +    /* build the codeword */
> +    p0 = frame->data[0];
> +    for (k = 0, i = 0; i < inlink->h; i++) {
> +        p = p0;
> +        for (j = 0; j < inlink->w; j++) {
> +            elbg->codeword[k++] = p[r_idx];
> +            elbg->codeword[k++] = p[g_idx];
> +            elbg->codeword[k++] = p[b_idx];
> +            p += elbg->pix_desc->nb_components;
> +        }
> +        p0 += frame->linesize[0];
> +    }
> +

> +    /* compute the codebook */
> +    ff_init_elbg(elbg->codeword, NB_COMPONENTS, elbg->codeword_length,
> +                 elbg->codebook, elbg->codebook_length, elbg->max_steps_nb,
> +                 elbg->codeword_closest_codebook_idxs, &elbg->lfg);
> +    ff_do_elbg(elbg->codeword, NB_COMPONENTS, elbg->codeword_length,
> +               elbg->codebook, elbg->codebook_length, elbg->max_steps_nb,
> +               elbg->codeword_closest_codebook_idxs, &elbg->lfg);
> +

This will not work with a shared build (ff_ syms are not exported)

> +    /* fill the output with the codebook values */
> +    p0 = frame->data[0];
> +
> +    for (i = 0, k = 0; i < inlink->h; i++) {

Please take the k out of the loop

> +        p = p0;
> +        for (j = 0; j < inlink->w; j++, k++) {

...and out of this one (increment in the following line)

> +            int cb_idx = NB_COMPONENTS* elbg->codeword_closest_codebook_idxs[k];

*-style

> +            p[r_idx] = elbg->codebook[cb_idx+r_idx];
> +            p[g_idx] = elbg->codebook[cb_idx+g_idx];
> +            p[b_idx] = elbg->codebook[cb_idx+b_idx];
> +            p += elbg->pix_desc->nb_components;
> +        }
> +        p0 += frame->linesize[0];
> +    }
> +
> +    return ff_filter_frame(inlink->dst->outputs[0], frame);
> +}
[...]

-- 
Clément B.
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