[FFmpeg-devel] [PATCH v2 18/26] avfilter/subscale: Add filter for scaling and/or re-arranging graphical subtitles
ffmpegagent
ffmpegagent at gmail.com
Thu Jan 20 04:48:28 EET 2022
From: softworkz <softworkz at hotmail.com>
Signed-off-by: softworkz <softworkz at hotmail.com>
---
configure | 1 +
doc/filters.texi | 164 +++++++
libavfilter/Makefile | 1 +
libavfilter/allfilters.c | 1 +
libavfilter/sf_subscale.c | 884 ++++++++++++++++++++++++++++++++++++++
5 files changed, 1051 insertions(+)
create mode 100644 libavfilter/sf_subscale.c
diff --git a/configure b/configure
index ee7afffb05..a8b7ce8a26 100755
--- a/configure
+++ b/configure
@@ -3731,6 +3731,7 @@ sr_filter_deps="avformat swscale"
sr_filter_select="dnn"
stereo3d_filter_deps="gpl"
splitcc_filter_deps="avcodec"
+subscale_filter_deps="swscale avcodec"
subtitles_filter_deps="avformat avcodec libass"
super2xsai_filter_deps="gpl"
pixfmts_super2xsai_test_deps="super2xsai_filter"
diff --git a/doc/filters.texi b/doc/filters.texi
index 9311714f82..b3d11c0ac0 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -26303,6 +26303,170 @@ Set the rendering margin in pixels.
For rendering, alway use the latest event only, which is covering the given point in time.
@end table
+ at section subscale
+
+Provides high-quality scaling and rearranging functionality for graphical subtitles.
+
+The subscale filter provides multiple approaches for manipulating
+the size and position of graphical subtitle rectangles wich can
+be combined or used separately.
+Scaling is performed by converting the palettized subtitle bitmaps
+to RGBA and re-quantization to palette colors afterwards via elbg algorithm.
+
+The two major operations are 'scale' and 're-arrange' with the
+latter being separated as 'arrange_h' and 'arrange_v'.
+
+
+Inputs:
+- 0: Subtitles [bitmap]
+
+Outputs:
+- 0: Subtitles [bitmap]
+
+It accepts the following parameters:
+
+ at table @option
+
+ at item w, width
+Set the width of the output.
+Width and height in case of graphical subtitles are just indicating
+a virtual size for which the output (consisting of 0-n bitmap rectangles)
+is intended to be displayed on.
+
+ at item h, height
+Set the height of the output.
+
+ at item margin_h
+Sets a horizontal margin to be preserverved when using any
+of the arrange modes.
+
+ at item margin_v
+Sets a vertical margin to be preserverved when using any
+of the arrange modes.
+
+ at item force_original_aspect_ratio
+Enable decreasing or increasing output video width or height if necessary to
+keep the original aspect ratio. Possible values:
+
+ at table @samp
+ at item disable
+Scale the video as specified and disable this feature.
+
+ at item decrease
+The output video dimensions will automatically be decreased if needed.
+
+ at item increase
+The output video dimensions will automatically be increased if needed.
+
+ at end table
+
+
+ at item scale_mode
+Specifies how subtitle bitmaps should be scaled.
+The scale factor is determined by the the factor between input
+and output size.
+
+ at table @samp
+ at item none
+Do not apply any common scaling.
+
+ at item uniform
+Uniformly scale all subtitle bitmaps including their positions.
+
+ at item uniform_no_reposition
+Uniformly scale all subtitle bitmaps without changing positions.
+
+ at end table
+
+
+ at item arrange_h
+Specifies how subtitle bitmaps should be arranged horizontally.
+
+ at item arrange_v
+Specifies how subtitle bitmaps should be arranged vertically.
+
+
+ at table @samp
+ at item none
+Do not rearrange subtitle bitmaps.
+
+ at item margin_no_scale
+Move subtitle bitmaps to be positioned inside the specified
+margin (margin_h or margin_v) when possible and without scaling.
+
+ at item margin_and_scale
+Move subtitle bitmaps to be positioned inside the specified
+margin (margin_h or margin_v) and scale in case it doesn't fit.
+
+ at item snapalign_no_scale
+Categorize subtitle bitmap positions as one of left/center/right
+or top/bottom/middle based on original positioning and apply
+these alignments for the target positioning.
+No scaling will be applied.
+
+ at item snapalign_and_scale
+Categorize subtitle bitmap positions as one of left/center/right
+or top/bottom/middle based on original positioning and apply
+these alignments for the target positioning.
+Bitmaps that do not fit inside the margins borders are
+scaled to fit.
+ at end table
+
+ at item eval
+Set evaluation mode for the expressions (@option{width}, @option{height}).
+
+It accepts the following values:
+ at table @samp
+ at item init
+Evaluate expressions only once during the filter initialization.
+
+ at item frame
+Evaluate expressions for each incoming frame. This is way slower than the
+ at samp{init} mode since it requires all the scalers to be re-computed, but it
+allows advanced dynamic expressions.
+ at end table
+
+Default value is @samp{init}.
+
+
+ at item num_colors
+Set the number of palette colors for output images.
+Choose the maximum (256) when further processing is done (e.g.
+overlaying on a video).
+When subtitles will be encoded as bitmap subtitles (e.g. dvbsub),
+a smaller number of palette colors (e.g. 4-16) might need to be used, depending
+on the target format and codec.
+
+ at item bitmap_width_align
+ at item bitmap_height_align
+Make sure that subtitle bitmap sizes are a multiple of this
+value. Default is 2.
+
+ at end table
+
+ at subsection Examples
+
+ at itemize
+ at item
+Uniformly scale down video and bitmap subtitles and encode
+subtitles as dvbsub.
+ at example
+ffmpeg -y -loglevel verbose -ss 32 -i "https://streams.videolan.org/samples/sub/largeres_vobsub.mkv" -filter_complex "[0:0]scale=480x270[vid1];[0:10]subscale=w=480:h=270:num_colors=16[sub1]" -map [vid1] -map [sub1] -c:s dvbsub -c:v libx265 output.ts
+ at end example
+ at item
+Squeeze video vertically and arrange subtitle bitmaps
+inside the video area without scaling, then overlay
+subtitles onto the video.
+ at example
+ffmpeg -y -loglevel verbose -ss 32 -i "https://streams.videolan.org/samples/sub/largeres_vobsub.mkv" -filter_complex "[0:0]scale=1920x400,setsar=1[vid1];[0:10]subscale=w=1920:h=400:scale_mode=none:margin_h=50:arrange_h=margin_no_scale:arrange_v=margin_no_scale:margin_v=50:num_colors=256[sub1];[vid1][sub1]overlay_graphicsubs" -c:v libx265 output.ts
+ at end example
+ at item
+Scale both, a video and its embedded VOB subs, then encode them as separate streams into an MKV.
+ at example
+ffmpeg -y -y -loglevel verbose -i "https://streams.videolan.org/samples/sub/largeres_vobsub.mkv" -filter_complex "[0:0]scale=720x576[vid1];[0:7]subscale=w=720:h=576:num_colors=16[sub1]" -map [vid1] -map [sub1] -c:s dvdsub out.mkv
+ at end example
+ at end itemize
+
@c man end SUBTITLE FILTERS
@chapter Multimedia Filters
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index ead3e38507..0e3e48613e 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -569,6 +569,7 @@ OBJS-$(CONFIG_SHOW_SPEAKER_FILTER) += sf_textmod.o
OBJS-$(CONFIG_TEXTMOD_FILTER) += sf_textmod.o
OBJS-$(CONFIG_SPLITCC_FILTER) += sf_splitcc.o
OBJS-$(CONFIG_STRIPSTYLES_FILTER) += sf_stripstyles.o
+OBJS-$(CONFIG_SUBSCALE_FILTER) += sf_subscale.o
# multimedia filters
OBJS-$(CONFIG_ABITSCOPE_FILTER) += avf_abitscope.o
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index 34576016ce..8e4f2feca3 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -552,6 +552,7 @@ extern const AVFilter ff_sf_graphicsub2text;
extern const AVFilter ff_sf_showspeaker;
extern const AVFilter ff_sf_splitcc;
extern const AVFilter ff_sf_stripstyles;
+extern const AVFilter ff_sf_subscale;
extern const AVFilter ff_sf_textmod;
extern const AVFilter ff_svf_graphicsub2video;
extern const AVFilter ff_svf_textsub2video;
diff --git a/libavfilter/sf_subscale.c b/libavfilter/sf_subscale.c
new file mode 100644
index 0000000000..04f0f16c27
--- /dev/null
+++ b/libavfilter/sf_subscale.c
@@ -0,0 +1,884 @@
+/*
+ * Copyright (c) 2021 softworkz
+ *
+ * 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
+ * scale graphical subtitles filter
+ */
+
+#include <string.h>
+
+#include "drawutils.h"
+#include "internal.h"
+#include "scale_eval.h"
+#include "libavutil/eval.h"
+#include "libavutil/opt.h"
+#include "libswscale/swscale.h"
+
+#include "libavcodec/elbg.h"
+
+static const char *const var_names[] = {
+ "in_w", "iw",
+ "in_h", "ih",
+ "out_w", "ow",
+ "out_h", "oh",
+ "a",
+ "sar",
+ "dar",
+ "margin_h",
+ "margin_v",
+ NULL
+};
+
+enum var_name {
+ VAR_IN_W, VAR_IW,
+ VAR_IN_H, VAR_IH,
+ VAR_OUT_W, VAR_OW,
+ VAR_OUT_H, VAR_OH,
+ VAR_A,
+ VAR_SAR,
+ VAR_DAR,
+ VARS_B_H,
+ VARS_B_V,
+ VARS_NB
+};
+
+enum EvalMode {
+ EVAL_MODE_INIT,
+ EVAL_MODE_FRAME,
+ EVAL_MODE_NB
+};
+
+enum SubScaleMode {
+ SSM_NONE,
+ SSM_UNIFORM,
+ SSM_UNIFORM_NO_REPOSITION,
+};
+
+enum SubArrangeMode {
+ SAM_NONE,
+ SAM_ENSUREMARGIN_NO_SCALE,
+ SAM_ENSUREMARGIN_AND_SCALE,
+ SAM_SNAPALIGNMENT_NO_SCALE,
+ SAM_SNAPALIGNMENT_AND_SCALE,
+};
+
+typedef struct SubScaleContext {
+ const AVClass *class;
+ struct SwsContext *sws;
+ AVDictionary *opts;
+
+ int w, h;
+
+ char *w_expr; ///< width expression string
+ char *h_expr; ///< height expression string
+ AVExpr *w_pexpr;
+ AVExpr *h_pexpr;
+ double var_values[VARS_NB];
+
+ int force_original_aspect_ratio;
+ int eval_mode; ///< expression evaluation mode
+
+ int use_caching;
+
+ // Scale Options
+ enum SubScaleMode scale_mode;
+
+ // Arrange Options
+ enum SubArrangeMode arrange_mode_h;
+ enum SubArrangeMode arrange_mode_v;
+ int margin_h;
+ int margin_v;
+ char *margin_h_expr;
+ char *margin_v_expr;
+ AVExpr *margin_h_pexpr;
+ AVExpr *margin_v_pexpr;
+
+ // Bitmap Options
+ int num_output_colors;
+ int bitmap_width_align;
+ int bitmap_height_align;
+
+ // Color Quantization Fields
+ struct ELBGContext *ctx;
+ AVLFG lfg;
+ int *codeword;
+ int *codeword_closest_codebook_idxs;
+ int *codebook;
+ int r_idx, g_idx, b_idx, a_idx;
+ AVFrame *cache_frame;
+} SubScaleContext;
+
+
+static int config_output(AVFilterLink *outlink);
+
+static int check_exprs(AVFilterContext *ctx)
+{
+ const SubScaleContext *s = ctx->priv;
+ unsigned vars_w[VARS_NB] = { 0 }, vars_h[VARS_NB] = { 0 };
+
+ if (!s->w_pexpr && !s->h_pexpr)
+ return AVERROR(EINVAL);
+
+ if (s->w_pexpr)
+ av_expr_count_vars(s->w_pexpr, vars_w, VARS_NB);
+ if (s->h_pexpr)
+ av_expr_count_vars(s->h_pexpr, vars_h, VARS_NB);
+
+ if (vars_w[VAR_OUT_W] || vars_w[VAR_OW]) {
+ av_log(ctx, AV_LOG_ERROR, "Width expression cannot be self-referencing: '%s'.\n", s->w_expr);
+ return AVERROR(EINVAL);
+ }
+
+ if (vars_h[VAR_OUT_H] || vars_h[VAR_OH]) {
+ av_log(ctx, AV_LOG_ERROR, "Height expression cannot be self-referencing: '%s'.\n", s->h_expr);
+ return AVERROR(EINVAL);
+ }
+
+ if ((vars_w[VAR_OUT_H] || vars_w[VAR_OH]) &&
+ (vars_h[VAR_OUT_W] || vars_h[VAR_OW])) {
+ av_log(ctx, AV_LOG_WARNING, "Circular references detected for width '%s' and height '%s' - possibly invalid.\n", s->w_expr, s->h_expr);
+ }
+
+ if (s->margin_h_pexpr)
+ av_expr_count_vars(s->margin_h_pexpr, vars_w, VARS_NB);
+ if (s->margin_v_pexpr)
+ av_expr_count_vars(s->margin_v_pexpr, vars_h, VARS_NB);
+
+ return 0;
+}
+
+static int scale_parse_expr(AVFilterContext *ctx, char *str_expr, AVExpr **pexpr_ptr, const char *var, const char *args)
+{
+ SubScaleContext *s = ctx->priv;
+ int ret, is_inited = 0;
+ char *old_str_expr = NULL;
+ AVExpr *old_pexpr = NULL;
+
+ if (str_expr) {
+ old_str_expr = av_strdup(str_expr);
+ if (!old_str_expr)
+ return AVERROR(ENOMEM);
+ av_opt_set(s, var, args, 0);
+ }
+
+ if (*pexpr_ptr) {
+ old_pexpr = *pexpr_ptr;
+ *pexpr_ptr = NULL;
+ is_inited = 1;
+ }
+
+ ret = av_expr_parse(pexpr_ptr, args, var_names,
+ NULL, NULL, NULL, NULL, 0, ctx);
+ if (ret < 0) {
+ av_log(ctx, AV_LOG_ERROR, "Cannot parse expression for %s: '%s'\n", var, args);
+ goto revert;
+ }
+
+ ret = check_exprs(ctx);
+ if (ret < 0)
+ goto revert;
+
+ if (is_inited && (ret = config_output(ctx->outputs[0])) < 0)
+ goto revert;
+
+ av_expr_free(old_pexpr);
+ av_freep(&old_str_expr);
+
+ return 0;
+
+revert:
+ av_expr_free(*pexpr_ptr);
+ *pexpr_ptr = NULL;
+ if (old_str_expr) {
+ av_opt_set(s, var, old_str_expr, 0);
+ av_free(old_str_expr);
+ }
+ if (old_pexpr)
+ *pexpr_ptr = old_pexpr;
+
+ return ret;
+}
+
+static av_cold int init_dict(AVFilterContext *ctx, AVDictionary **opts)
+{
+ SubScaleContext *s = ctx->priv;
+ uint8_t rgba_map[4];
+ int ret;
+
+ if (!s->w_expr)
+ av_opt_set(s, "w", "iw", 0);
+ if (!s->h_expr)
+ av_opt_set(s, "h", "ih", 0);
+
+ ret = scale_parse_expr(ctx, NULL, &s->w_pexpr, "width", s->w_expr);
+ if (ret < 0)
+ return ret;
+
+ ret = scale_parse_expr(ctx, NULL, &s->h_pexpr, "height", s->h_expr);
+ if (ret < 0)
+ return ret;
+
+ av_log(ctx, AV_LOG_VERBOSE, "w:%s h:%s\n",
+ s->w_expr, s->h_expr);
+
+ if (!s->margin_h_expr)
+ av_opt_set(s, "margin_h", "0", 0);
+ if (!s->margin_v_expr)
+ av_opt_set(s, "margin_v", "0", 0);
+
+ ret = scale_parse_expr(ctx, NULL, &s->margin_h_pexpr, "margin_h", s->margin_h_expr);
+ if (ret < 0)
+ return ret;
+
+ ret = scale_parse_expr(ctx, NULL, &s->margin_v_pexpr, "margin_v", s->margin_v_expr);
+ if (ret < 0)
+ return ret;
+
+ s->opts = *opts;
+ *opts = NULL;
+
+ ff_fill_rgba_map(&rgba_map[0], AV_PIX_FMT_RGB32);
+
+ s->r_idx = rgba_map[0]; // R
+ s->g_idx = rgba_map[1]; // G
+ s->b_idx = rgba_map[2]; // B
+ s->a_idx = rgba_map[3]; // A
+
+ av_lfg_init(&s->lfg, 123456789);
+
+
+ return 0;
+}
+
+static av_cold void uninit(AVFilterContext *ctx)
+{
+ SubScaleContext *s = ctx->priv;
+
+ av_frame_free(&s->cache_frame);
+
+ av_expr_free(s->w_pexpr);
+ av_expr_free(s->h_pexpr);
+ s->w_pexpr = s->h_pexpr = NULL;
+
+ av_expr_free(s->margin_h_pexpr);
+ av_expr_free(s->margin_v_pexpr);
+ s->margin_h_pexpr = s->margin_v_pexpr = NULL;
+
+ sws_freeContext(s->sws);
+ s->sws = NULL;
+ av_dict_free(&s->opts);
+
+ avpriv_elbg_free(&s->ctx);
+
+ av_freep(&s->codebook);
+ av_freep(&s->codeword);
+ av_freep(&s->codeword_closest_codebook_idxs);
+}
+
+static int config_input(AVFilterLink *inlink)
+{
+ ////const AVFilterContext *ctx = inlink->dst;
+ ////SubScaleContext *s = ctx->priv;
+
+ ////if (s->w <= 0 || s->h <= 0) {
+ //// s->w = inlink->w;
+ //// s->h = inlink->h;
+ ////}
+ return 0;
+}
+
+static int scale_eval_dimensions(AVFilterContext *ctx)
+{
+ SubScaleContext *s = ctx->priv;
+ const AVFilterLink *inlink = ctx->inputs[0];
+ char *expr;
+ int eval_w, eval_h, margin_h, margin_v;
+ int ret;
+ double res;
+
+ s->var_values[VAR_IN_W] = s->var_values[VAR_IW] = inlink->w;
+ s->var_values[VAR_IN_H] = s->var_values[VAR_IH] = inlink->h;
+ s->var_values[VAR_OUT_W] = s->var_values[VAR_OW] = NAN;
+ s->var_values[VAR_OUT_H] = s->var_values[VAR_OH] = NAN;
+ s->var_values[VARS_B_H] = s->var_values[VARS_B_V] = 0;
+ s->var_values[VAR_A] = (double) inlink->w / inlink->h;
+ s->var_values[VAR_SAR] = inlink->sample_aspect_ratio.num ?
+ (double) inlink->sample_aspect_ratio.num / inlink->sample_aspect_ratio.den : 1;
+ s->var_values[VAR_DAR] = s->var_values[VAR_A] * s->var_values[VAR_SAR];
+
+ res = av_expr_eval(s->w_pexpr, s->var_values, NULL);
+ s->var_values[VAR_OUT_W] = s->var_values[VAR_OW] = (int) res == 0 ? inlink->w : (int) res;
+
+ res = av_expr_eval(s->h_pexpr, s->var_values, NULL);
+ if (isnan(res)) {
+ expr = s->h_expr;
+ ret = AVERROR(EINVAL);
+ goto fail;
+ }
+ eval_h = s->var_values[VAR_OUT_H] = s->var_values[VAR_OH] = (int) res == 0 ? inlink->h : (int) res;
+
+ res = av_expr_eval(s->w_pexpr, s->var_values, NULL);
+ if (isnan(res)) {
+ expr = s->w_expr;
+ ret = AVERROR(EINVAL);
+ goto fail;
+ }
+ eval_w = s->var_values[VAR_OUT_W] = s->var_values[VAR_OW] = (int) res == 0 ? inlink->w : (int) res;
+
+ s->w = eval_w;
+ s->h = eval_h;
+
+ res = av_expr_eval(s->margin_h_pexpr, s->var_values, NULL);
+ s->var_values[VARS_B_H] = (int)res;
+
+ res = av_expr_eval(s->margin_v_pexpr, s->var_values, NULL);
+ if (isnan(res)) {
+ expr = s->margin_v_expr;
+ ret = AVERROR(EINVAL);
+ goto fail;
+ }
+ margin_v = s->var_values[VARS_B_V] = (int)res;
+
+ res = av_expr_eval(s->margin_h_pexpr, s->var_values, NULL);
+ if (isnan(res)) {
+ expr = s->margin_h_expr;
+ ret = AVERROR(EINVAL);
+ goto fail;
+ }
+ margin_h = s->var_values[VARS_B_H] = (int)res;
+
+ s->margin_h = margin_h;
+ s->margin_v = margin_v;
+
+ return 0;
+
+fail:
+ av_log(ctx, AV_LOG_ERROR,
+ "Error when evaluating the expression '%s'.\n", expr);
+ return ret;
+}
+
+static int config_output(AVFilterLink *outlink)
+{
+ AVFilterContext *ctx = outlink->src;
+ AVFilterLink *inlink = outlink->src->inputs[0];
+ SubScaleContext *s = ctx->priv;
+ int ret;
+
+ outlink->format = AV_SUBTITLE_FMT_BITMAP;
+ outlink->time_base = ctx->inputs[0]->time_base;
+ outlink->frame_rate = ctx->inputs[0]->frame_rate;
+
+ if ((ret = scale_eval_dimensions(ctx)) < 0)
+ goto fail;
+
+ ff_scale_adjust_dimensions(inlink, &s->w, &s->h,
+ s->force_original_aspect_ratio, 2);
+
+ if (s->w > INT_MAX ||
+ s->h > INT_MAX ||
+ (s->h * inlink->w) > INT_MAX ||
+ (s->w * inlink->h) > INT_MAX)
+ av_log(ctx, AV_LOG_ERROR, "Rescaled value for width or height is too big.\n");
+
+ outlink->w = s->w;
+ outlink->h = s->h;
+
+ if (s->sws)
+ sws_freeContext(s->sws);
+
+ s->sws = sws_alloc_context();
+ if (!s->sws)
+ return AVERROR(ENOMEM);
+
+ av_opt_set_pixel_fmt(s->sws, "src_format", AV_PIX_FMT_PAL8, 0);
+ av_opt_set_int(s->sws, "dst_format", AV_PIX_FMT_RGB32, 0);
+ av_opt_set_int(s->sws, "threads", ff_filter_get_nb_threads(ctx), 0);
+
+ if (s->opts) {
+ const AVDictionaryEntry *e = NULL;
+ while ((e = av_dict_get(s->opts, "", e, AV_DICT_IGNORE_SUFFIX))) {
+ if ((ret = av_opt_set(s->sws, e->key, e->value, 0)) < 0)
+ return ret;
+ }
+ }
+
+ if ((ret = sws_init_context(s->sws, NULL, NULL)) < 0)
+ return ret;
+
+ if (inlink->sample_aspect_ratio.num){
+ outlink->sample_aspect_ratio = av_mul_q((AVRational){outlink->h * inlink->w, outlink->w * inlink->h}, inlink->sample_aspect_ratio);
+ } else
+ outlink->sample_aspect_ratio = inlink->sample_aspect_ratio;
+
+ av_log(ctx, AV_LOG_VERBOSE, "Output size set to %dx%d.\n", outlink->w, outlink->h);
+
+ return 0;
+fail:
+ return ret;
+}
+
+static int palettize_image(SubScaleContext *const s, const int w, const int h, const int src_linesize, uint8_t *src_data,
+ int dst_linesize, uint8_t *dst_data, uint32_t *dst_pal)
+{
+ int k, ret;
+ const int codeword_length = w * h;
+
+ /* Re-Initialize */
+ s->codeword = av_realloc_f(s->codeword, codeword_length, 4 * sizeof(*s->codeword));
+ if (!s->codeword)
+ return AVERROR(ENOMEM);
+
+ s->codeword_closest_codebook_idxs =
+ av_realloc_f(s->codeword_closest_codebook_idxs, codeword_length,
+ sizeof(*s->codeword_closest_codebook_idxs));
+ if (!s->codeword_closest_codebook_idxs)
+ return AVERROR(ENOMEM);
+
+ s->codebook = av_realloc_f(s->codebook, s->num_output_colors, 4 * sizeof(*s->codebook));
+ if (!s->codebook)
+ return AVERROR(ENOMEM);
+
+ /* build the codeword */
+ k = 0;
+ for (int i = 0; i < h; i++) {
+ uint8_t *p = src_data;
+ for (int j = 0; j < w; j++) {
+ s->codeword[k++] = p[s->b_idx];
+ s->codeword[k++] = p[s->g_idx];
+ s->codeword[k++] = p[s->r_idx];
+ s->codeword[k++] = p[s->a_idx];
+ p += 4;
+ }
+ src_data += src_linesize;
+ }
+
+ /* compute the codebook */
+ ret = avpriv_elbg_do(&s->ctx, s->codeword, 4,
+ codeword_length, s->codebook,
+ s->num_output_colors, 1,
+ s->codeword_closest_codebook_idxs, &s->lfg, 0);
+
+ if (ret < 0)
+ return ret;
+
+ /* Write Palette */
+ for (int i = 0; i < s->num_output_colors; i++) {
+ dst_pal[i] = s->codebook[i*4+3] << 24 |
+ (s->codebook[i*4+2] << 16) |
+ (s->codebook[i*4+1] << 8) |
+ s->codebook[i*4 ];
+ }
+
+ /* Write Image */
+ k = 0;
+ for (int i = 0; i < h; i++) {
+ uint8_t *p = dst_data;
+ for (int j = 0; j < w; j++, p++) {
+ p[0] = s->codeword_closest_codebook_idxs[k++];
+ }
+
+ dst_data += dst_linesize;
+ }
+
+ return ret;
+}
+
+static int rescale_size(int64_t a, AVRational factor)
+{
+ const int64_t res = av_rescale_rnd(a, factor.num, factor.den, AV_ROUND_NEAR_INF);
+ if (res > INT32_MAX || res < 0)
+ return 0;
+
+ return (int)res;
+}
+
+
+static int scale_area(AVFilterLink *link, AVSubtitleArea *area, const int target_width, const int target_height)
+{
+ const AVFilterContext *ctx = link->dst;
+ SubScaleContext *s = ctx->priv;
+ int ret;
+
+ AVBufferRef *dst_buffer;
+ const uint8_t* data[2] = { area->buf[0]->data, (uint8_t *)&area->pal };
+ const int dstW = FFALIGN(target_width, s->bitmap_width_align);
+ const int dstH = FFALIGN(target_height, s->bitmap_height_align);
+ const int tmp_linesize[2] = { FFALIGN(dstW * 4, 32), 0 };
+ const int dst_linesize[2] = { dstW, 0 };
+ uint8_t* tmp[2] = { 0, 0 };
+
+ AVBufferRef *tmp_buffer = av_buffer_allocz(tmp_linesize[0] * dstH);
+ if (!tmp_buffer)
+ return AVERROR(ENOMEM);
+
+ if (!s->sws)
+ return 0;
+
+ tmp[0] = tmp_buffer->data;
+
+ s->sws = sws_getCachedContext(s->sws, area->w, area->h, AV_PIX_FMT_PAL8,
+ dstW, dstH, AV_PIX_FMT_RGB32, SWS_BICUBIC, NULL, NULL, NULL);
+ if (!s->sws) {
+ av_log(NULL, AV_LOG_FATAL, "Cannot initialize the conversion context. dstW=%d dstH=%d\n", dstW, dstH);
+ return AVERROR(EINVAL);
+ }
+
+ // Rescale to ARGB
+ ret = sws_scale(s->sws, data, area->linesize, 0, area->h, tmp, tmp_linesize);
+ if (ret < 0) {
+ av_buffer_unref(&tmp_buffer);
+ return ret;
+ }
+
+ // Alloc output buffer
+ dst_buffer = av_buffer_allocz(dst_linesize[0] * dstH);
+ if (!dst_buffer) {
+ av_buffer_unref(&tmp_buffer);
+ return AVERROR(ENOMEM);
+ }
+
+ // Quantize to palettized image
+ ret = palettize_image(s, dstW, dstH, tmp_linesize[0], tmp[0], dst_linesize[0], dst_buffer->data, area->pal);
+ av_buffer_unref(&tmp_buffer);
+
+ if (ret < 0) {
+ av_buffer_unref(&dst_buffer);
+ return ret;
+ }
+
+ av_buffer_unref(&area->buf[0]);
+ ret = av_buffer_replace(&area->buf[0], dst_buffer);
+ if (ret < 0) {
+ av_buffer_unref(&dst_buffer);
+ return ret;
+ }
+
+ area->w = dstW;
+ area->h = dstH;
+ area->linesize[0] = dst_linesize[0];
+ area->nb_colors = s->num_output_colors;
+
+ return ret;
+}
+
+static int process_area(AVFilterLink *inlink, AVSubtitleArea *area, AVRational x_factor, AVRational y_factor)
+{
+ AVFilterContext *ctx = inlink->dst;
+ const SubScaleContext *s = ctx->priv;
+ int target_w, target_h, target_x, target_y;
+ const int border_l = s->margin_h;
+ const int border_r = s->w - s->margin_h;
+ const int border_t = s->margin_v;
+ const int border_b = s->h - s->margin_v;
+
+ av_log(ctx, AV_LOG_DEBUG, "process_area - start: x/y: (%d:%d) size: %dx%d scale_mode: %d x-factor: %d:%d y-factor: %d:%d\n",
+ area->x, area->y, area->w, area->h, s->scale_mode, x_factor.num, x_factor.den, y_factor.num, y_factor.den);
+
+ switch (s->scale_mode) {
+ case SSM_NONE:
+ target_w = area->w;
+ target_h = area->h;
+ target_x = area->x;
+ target_y = area->y;
+ break;
+ case SSM_UNIFORM:
+ target_w = rescale_size(area->w, x_factor);
+ target_h = rescale_size(area->h, y_factor);
+ target_x = rescale_size(area->x, x_factor);
+ target_y = rescale_size(area->y, y_factor);
+ break;
+ case SSM_UNIFORM_NO_REPOSITION:
+ target_w = rescale_size(area->w, x_factor);
+ target_h = rescale_size(area->h, y_factor);
+ target_x = area->x;
+ target_y = area->y;
+ break;
+ default:
+ av_log(ctx, AV_LOG_ERROR, "Invalid scale_mode: %d\n", s->scale_mode);
+ return AVERROR(EINVAL);
+ }
+
+ av_log(ctx, AV_LOG_DEBUG, "process_area - scaled: x/y: (%d:%d) size: %dx%d.\n", target_x, target_y, target_w, target_h);
+
+
+ switch (s->arrange_mode_h) {
+ case SAM_ENSUREMARGIN_AND_SCALE:
+ case SAM_SNAPALIGNMENT_AND_SCALE:
+ {
+ // IF it doesn't fit - scale it
+ int max_width = s->w - 2 * s->margin_h;
+
+ if (max_width < 2)
+ max_width = 2;
+
+ if (target_w > max_width) {
+ target_h = (int)av_rescale(target_h, max_width, target_w);
+ target_w = max_width;
+ target_x = s->margin_h;
+ }
+ }
+ break;
+ }
+
+ switch (s->arrange_mode_h) {
+ case SAM_NONE:
+ break;
+ case SAM_ENSUREMARGIN_NO_SCALE:
+ case SAM_ENSUREMARGIN_AND_SCALE:
+ // Left border
+ if (target_x < border_l)
+ target_x = border_l;
+
+ // Right border
+ if (target_x + target_w > border_r)
+ target_x = border_r - target_w;
+
+ break;
+ case SAM_SNAPALIGNMENT_NO_SCALE:
+ case SAM_SNAPALIGNMENT_AND_SCALE:
+ {
+ // Use original values to detect alignment
+ const int left_margin = area->x;
+ const int right_margin = inlink->w - area->x - area->w;
+ const AVRational diff_factor_r = { left_margin - right_margin, area->w };
+ const float diff_factor = (float)av_q2d(diff_factor_r);
+
+ if (diff_factor > 0.2f) {
+ // Right aligned
+ target_x = border_r - target_w;
+ } else if (diff_factor < -0.2f) {
+ // Left aligned
+ target_x = border_l;
+ } else {
+ // Centered
+ target_x = (inlink->w - area->w) / 2;
+ }
+ }
+
+ break;
+ default:
+ av_log(ctx, AV_LOG_ERROR, "Invalid arrange_mode_h: %d\n", s->arrange_mode_h);
+ return AVERROR(EINVAL);
+ }
+
+ av_log(ctx, AV_LOG_DEBUG, "process_area - arr_h: x/y: (%d:%d) size: %dx%d.\n", target_x, target_y, target_w, target_h);
+
+
+ switch (s->arrange_mode_v) {
+ case SAM_ENSUREMARGIN_AND_SCALE:
+ case SAM_SNAPALIGNMENT_AND_SCALE:
+ {
+ // IF it doesn't fit - scale it
+ int max_height = s->h - 2 * s->margin_v;
+
+ if (max_height < 2)
+ max_height = 2;
+
+ if (target_h > max_height) {
+ target_w = (int)av_rescale(target_w, max_height, target_h);
+ target_h = max_height;
+ target_y = s->margin_v;
+ }
+ }
+ break;
+ }
+
+ switch (s->arrange_mode_v) {
+ case SAM_NONE:
+ break;
+ case SAM_ENSUREMARGIN_NO_SCALE:
+ case SAM_ENSUREMARGIN_AND_SCALE:
+ // Top border
+ if (target_y < border_t)
+ target_y = border_t;
+
+ // Bottom border
+ if (target_y + target_h > border_b)
+ target_y = border_b - target_h;
+
+ break;
+ case SAM_SNAPALIGNMENT_NO_SCALE:
+ case SAM_SNAPALIGNMENT_AND_SCALE:
+ {
+ // Use original values to detect alignment
+ const int top_margin = area->y;
+ const int bottom_margin = inlink->h - area->y - area->h;
+ const AVRational diff_factor_r = { top_margin - bottom_margin, area->h };
+ const float diff_factor = (float)av_q2d(diff_factor_r);
+
+ if (diff_factor > 0.2f) {
+ // Bottom aligned
+ target_y = border_b - target_h;
+ } else if (diff_factor < -0.2f) {
+ // Top aligned
+ target_y = border_t;
+ } else {
+ // Centered
+ target_y = (inlink->h - area->h) / 2;
+ }
+ }
+
+ break;
+ default:
+ av_log(ctx, AV_LOG_ERROR, "Invalid arrange_mode_v: %d\n", s->arrange_mode_v);
+ return AVERROR(EINVAL);
+ }
+
+ av_log(ctx, AV_LOG_VERBOSE, "process_area - arr_v: x/y: (%d:%d) size: %dx%d.\n", target_x, target_y, target_w, target_h);
+
+ area->x = target_x;
+ area->y = target_y;
+
+ if (area->w != target_w || area->h != target_h)
+ return scale_area(inlink, area, target_w, target_h);
+
+ return 0;
+}
+
+static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
+{
+ const AVFilterContext *ctx = inlink->dst;
+ SubScaleContext *s = ctx->priv;
+ AVFilterLink *outlink = ctx->outputs[0];
+ int ret;
+
+ // just forward empty frames
+ if (frame->num_subtitle_areas == 0) {
+ av_frame_free(&s->cache_frame);
+ return ff_filter_frame(outlink, frame);
+ }
+
+ if (s->use_caching && s->cache_frame && frame->repeat_sub
+ && s->cache_frame->subtitle_timing.start_pts == frame->subtitle_timing.start_pts) {
+ AVFrame *out = av_frame_clone(s->cache_frame);
+ if (!out)
+ return AVERROR(ENOMEM);
+
+ ret = av_frame_copy_props(out, frame);
+ if (ret < 0)
+ return ret;
+
+ av_log(inlink->dst, AV_LOG_DEBUG, "subscale CACHED - size %dx%d pts: %"PRId64" areas: %d\n", frame->width, frame->height, frame->subtitle_timing.start_pts, frame->num_subtitle_areas);
+ av_frame_free(&frame);
+ return ff_filter_frame(outlink, out);
+ }
+
+ ret = av_frame_make_writable(frame);
+ if (ret >= 0) {
+ const AVRational x_factor = { .num = outlink->w, .den = inlink->w} ;
+ const AVRational y_factor = { .num = outlink->h, .den = inlink->h} ;
+
+ for (unsigned i = 0; i < frame->num_subtitle_areas; ++i) {
+ AVSubtitleArea *area = frame->subtitle_areas[i];
+
+ ret = process_area(inlink, area, x_factor, y_factor);
+ if (ret < 0)
+ return ret;
+ }
+
+ av_log(inlink->dst, AV_LOG_DEBUG, "subscale output - size %dx%d pts: %"PRId64" areas: %d\n", frame->width, frame->height, frame->subtitle_timing.start_pts, frame->num_subtitle_areas);
+
+ if (s->use_caching) {
+ av_frame_free(&s->cache_frame);
+ s->cache_frame = av_frame_clone(frame);
+ }
+
+ return ff_filter_frame(outlink, frame);
+ }
+
+ return ret;
+}
+
+#define OFFSET(x) offsetof(SubScaleContext, x)
+#define FLAGS (AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM)
+
+static const AVOption subscale_options[] = {
+ { "margin_h", "horizontal border", OFFSET(margin_h_expr), AV_OPT_TYPE_STRING, .flags = FLAGS },
+ { "margin_v", "vertical border", OFFSET(margin_v_expr), AV_OPT_TYPE_STRING, .flags = FLAGS },
+ { "w", "Output video width", OFFSET(w_expr), AV_OPT_TYPE_STRING, .flags = FLAGS },
+ { "width", "Output video width", OFFSET(w_expr), AV_OPT_TYPE_STRING, .flags = FLAGS },
+ { "h", "Output video height", OFFSET(h_expr), AV_OPT_TYPE_STRING, .flags = FLAGS },
+ { "height","Output video height", OFFSET(h_expr), AV_OPT_TYPE_STRING, .flags = FLAGS },
+ { "force_original_aspect_ratio", "decrease or increase w/h if necessary to keep the original AR", OFFSET(force_original_aspect_ratio), AV_OPT_TYPE_INT, { .i64 = 0}, 0, 2, FLAGS, "force_oar" },
+ { "disable", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = 0 }, 0, 0, FLAGS, "force_oar" },
+ { "decrease", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = 1 }, 0, 0, FLAGS, "force_oar" },
+ { "increase", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = 2 }, 0, 0, FLAGS, "force_oar" },
+ { "scale_mode", "specify how to scale subtitles", OFFSET(scale_mode), AV_OPT_TYPE_INT, {.i64 = SSM_UNIFORM}, 0, SSM_UNIFORM_NO_REPOSITION, FLAGS, "scale_mode" },
+ { "none", "no common scaling", 0, AV_OPT_TYPE_CONST, {.i64=SSM_NONE}, .flags = FLAGS, .unit = "scale_mode" },
+ { "uniform", "uniformly scale and reposition", 0, AV_OPT_TYPE_CONST, {.i64=SSM_UNIFORM}, .flags = FLAGS, .unit = "scale_mode" },
+ { "uniform_no_reposition", "uniformly scale but keep positions", 0, AV_OPT_TYPE_CONST, {.i64=SSM_UNIFORM_NO_REPOSITION}, .flags = FLAGS, .unit = "scale_mode" },
+ { "use_caching", "Cache output frames", OFFSET(use_caching), AV_OPT_TYPE_BOOL, { .i64 = 1}, 0, 1, .flags = FLAGS },
+
+ { "arrange_h", "specify how to arrange subtitles horizontally", OFFSET(arrange_mode_h), AV_OPT_TYPE_INT, {.i64 = SAM_NONE}, 0, SAM_SNAPALIGNMENT_AND_SCALE, FLAGS, "arrange" },
+ { "arrange_v", "specify how to arrange subtitles vertically", OFFSET(arrange_mode_v), AV_OPT_TYPE_INT, {.i64 = SAM_NONE}, 0, SAM_SNAPALIGNMENT_AND_SCALE, FLAGS, "arrange" },
+ { "none", "no repositioning", 0, AV_OPT_TYPE_CONST, {.i64=SAM_NONE}, .flags = FLAGS, .unit = "arrange" },
+ { "margin_no_scale", "move subs inside border when possible", 0, AV_OPT_TYPE_CONST, {.i64=SAM_ENSUREMARGIN_NO_SCALE,}, .flags = FLAGS, .unit = "arrange" },
+ { "margin_and_scale", "move subs inside border and scale as needed", 0, AV_OPT_TYPE_CONST, {.i64=SAM_ENSUREMARGIN_AND_SCALE,}, .flags = FLAGS, .unit = "arrange" },
+ { "snapalign_no_scale", "snap subs to near/far/center when possible", 0, AV_OPT_TYPE_CONST, {.i64=SAM_SNAPALIGNMENT_NO_SCALE,}, .flags = FLAGS, .unit = "arrange" },
+ { "snapalign_and_scale", "snap subs to near/far/center and scale as needed", 0, AV_OPT_TYPE_CONST, {.i64=SAM_SNAPALIGNMENT_AND_SCALE,}, .flags = FLAGS, .unit = "arrange" },
+
+ { "eval", "specify when to evaluate expressions", OFFSET(eval_mode), AV_OPT_TYPE_INT, {.i64 = EVAL_MODE_INIT}, 0, EVAL_MODE_NB-1, FLAGS, "eval" },
+ { "init", "eval expressions once during initialization", 0, AV_OPT_TYPE_CONST, {.i64=EVAL_MODE_INIT}, .flags = FLAGS, .unit = "eval" },
+ { "frame", "eval expressions during initialization and per-frame", 0, AV_OPT_TYPE_CONST, {.i64=EVAL_MODE_FRAME}, .flags = FLAGS, .unit = "eval" },
+ { "num_colors", "number of palette colors in output", OFFSET(num_output_colors), AV_OPT_TYPE_INT, {.i64 = 256 }, 2, 256, .flags = FLAGS },
+ { "bitmap_width_align", "Bitmap width alignment", OFFSET(bitmap_width_align), AV_OPT_TYPE_INT, {.i64 = 2 }, 1, 256, .flags = FLAGS },
+ { "bitmap_height_align", "Bitmap height alignment", OFFSET(bitmap_height_align), AV_OPT_TYPE_INT, {.i64 = 2 }, 1, 256, .flags = FLAGS },
+ { .name = NULL }
+};
+
+static const AVClass subscale_class = {
+ .class_name = "subscale",
+ .item_name = av_default_item_name,
+ .option = subscale_options,
+ .version = LIBAVUTIL_VERSION_INT,
+ .category = AV_CLASS_CATEGORY_FILTER,
+};
+
+static const AVFilterPad inputs[] = {
+ {
+ .name = "default",
+ .type = AVMEDIA_TYPE_SUBTITLE,
+ .filter_frame = filter_frame,
+ .config_props = config_input,
+ },
+};
+
+static const AVFilterPad outputs[] = {
+ {
+ .name = "default",
+ .type = AVMEDIA_TYPE_SUBTITLE,
+ .config_props = config_output,
+ },
+};
+
+const AVFilter ff_sf_subscale = {
+ .name = "subscale",
+ .description = NULL_IF_CONFIG_SMALL("Scale graphical subtitles."),
+ .init_dict = init_dict,
+ .uninit = uninit,
+ .priv_size = sizeof(SubScaleContext),
+ .priv_class = &subscale_class,
+ FILTER_INPUTS(inputs),
+ FILTER_OUTPUTS(outputs),
+ FILTER_SINGLE_SUBFMT(AV_SUBTITLE_FMT_BITMAP),
+};
+
--
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