lavfi: add elbg filter

Changelog

@@ -6,6 +6,7 @@ version <next>
 - HNM version 4 demuxer and video decoder
 - Live HDS muxer
 - setsar/setdar filters now support variables in ratio expressions
+- elbg filter
 
 
 version 2.1:

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
 
+@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.
+
+@table @option
+@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.
+
+@item nb_steps, n
+Set the maximum number of iterations 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.
+
+@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.
+@end table
+
 @section fade
 
 Apply fade-in/out effect to input video.

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

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);

libavfilter/version.h

@@ -30,8 +30,8 @@
 #include "libavutil/avutil.h"
 
 #define LIBAVFILTER_VERSION_MAJOR  3
-#define LIBAVFILTER_VERSION_MINOR  90
-#define LIBAVFILTER_VERSION_MICRO 102
+#define LIBAVFILTER_VERSION_MINOR  91
+#define LIBAVFILTER_VERSION_MICRO 100
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \
                                                LIBAVFILTER_VERSION_MINOR, \

libavfilter/vf_elbg.c

@@ -0,0 +1,212 @@
+/*
+ * 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 }, 1, INT_MAX, FLAGS },
+    { "nb_steps", "set max number of steps used to compute the mapping", OFFSET(max_steps_nb), AV_OPT_TYPE_INT, { .i64 = 1 }, 1, INT_MAX, FLAGS },
+    { "n",        "set max number of steps used to compute the mapping", 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 },
+    { 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(*elbg->codeword));
+    if (!elbg->codeword)
+        return AVERROR(ENOMEM);
+
+    elbg->codeword_closest_codebook_idxs =
+        av_realloc_f(elbg->codeword_closest_codebook_idxs, elbg->codeword_length,
+                     sizeof(*elbg->codeword_closest_codebook_idxs));
+    if (!elbg->codeword_closest_codebook_idxs)
+        return AVERROR(ENOMEM);
+
+    elbg->codebook = av_realloc_f(elbg->codebook, elbg->codebook_length,
+                                  NB_COMPONENTS * sizeof(*elbg->codebook));
+    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
+
+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];
+    k = 0;
+    for (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 */
+    avpriv_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);
+    avpriv_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);
+
+    /* fill the output with the codebook values */
+    p0 = frame->data[0];
+
+    k = 0;
+    for (i = 0; i < inlink->h; i++) {
+        p = p0;
+        for (j = 0; j < inlink->w; j++) {
+            int cb_idx = NB_COMPONENTS * elbg->codeword_closest_codebook_idxs[k++];
+            p[r_idx] = elbg->codebook[cb_idx];
+            p[g_idx] = elbg->codebook[cb_idx+1];
+            p[b_idx] = elbg->codebook[cb_idx+2];
+            p += elbg->pix_desc->nb_components;
+        }
+        p0 += frame->linesize[0];
+    }
+
+    return ff_filter_frame(inlink->dst->outputs[0], frame);
+}
+
+static av_cold void uninit(AVFilterContext *ctx)
+{
+    ELBGContext *elbg = ctx->priv;
+
+    av_freep(&elbg->codebook);
+    av_freep(&elbg->codeword);
+    av_freep(&elbg->codeword_closest_codebook_idxs);
+}
+
+static const AVFilterPad elbg_inputs[] = {
+    {
+        .name           = "default",
+        .type           = AVMEDIA_TYPE_VIDEO,
+        .config_props   = config_input,
+        .filter_frame   = filter_frame,
+        .needs_writable = 1,
+    },
+    { NULL }
+};
+
+static const AVFilterPad elbg_outputs[] = {
+    {
+        .name = "default",
+        .type = AVMEDIA_TYPE_VIDEO,
+    },
+    { NULL }
+};
+
+AVFilter ff_vf_elbg = {
+    .name          = "elbg",
+    .description   = NULL_IF_CONFIG_SMALL("Apply posterize effect, using the ELBG algorithm."),
+    .priv_size     = sizeof(ELBGContext),
+    .priv_class    = &elbg_class,
+    .query_formats = query_formats,
+    .init          = init,
+    .uninit        = uninit,
+    .inputs        = elbg_inputs,
+    .outputs       = elbg_outputs,
+};