@@ -25024,6 +25024,30 @@ existing filters using @code{--disable-filters}.
Below is a description of the currently available subtitle filters.
+@section stripstyles
+
+Remove all inline styles from subtitle events.
+
+It accepts the following parameters:
+
+@table @option
+@item remove_animated
+Also remove text which is subject to animation (default: true)
+Usually, animated text elements are used used in addition to static subtitle lines for creating effects, so in most cases it is safe to remove the animation content.
+If subtitle text is missing, try setting this to false.
+
+@end table
+
+@subsection Examples
+
+@itemize
+@item
+Change all characters to upper case while keeping all styles and animations:
+@example
+ffmpeg -i "https://streams.videolan.org/samples/sub/SSA/subtitle_testing_complex.mkv" -filter_complex "[0:1]stripstyles" -map 0 output.mkv
+@end example
+@end itemize
+
@section textmod
Modify subtitle text in a number of ways.
@@ -536,6 +536,7 @@ OBJS-$(CONFIG_NULLSINK_FILTER) += vsink_nullsink.o
# subtitle filters
OBJS-$(CONFIG_TEXTMOD_FILTER) += sf_textmod.o
+OBJS-$(CONFIG_STRIPSTYLES_FILTER) += sf_stripstyles.o
# multimedia filters
OBJS-$(CONFIG_ABITSCOPE_FILTER) += avf_abitscope.o
@@ -524,6 +524,7 @@ extern const AVFilter ff_avf_showvolume;
extern const AVFilter ff_avf_showwaves;
extern const AVFilter ff_avf_showwavespic;
extern const AVFilter ff_vaf_spectrumsynth;
+extern const AVFilter ff_sf_stripstyles;
extern const AVFilter ff_sf_textmod;
extern const AVFilter ff_svf_graphicsub2video;
extern const AVFilter ff_svf_textsub2video;
new file mode 100644
@@ -0,0 +1,215 @@
+/*
+ * 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
+ * text subtitle filter which removes inline-styles from subtitles
+ */
+
+#include <libavcodec/ass.h>
+
+#include "libavutil/avassert.h"
+#include "libavutil/opt.h"
+#include "avfilter.h"
+#include "internal.h"
+#include "libavcodec/avcodec.h"
+#include "libavcodec/ass_split.h"
+
+typedef struct StripStylesContext {
+ const AVClass *class;
+ enum AVSubtitleType format;
+ int remove_animated;
+} StripStylesContext;
+
+typedef struct DialogContext {
+ const AVClass *class;
+ const StripStylesContext* ss_ctx;
+ AVBPrint buffer;
+ int drawing_scale;
+ int is_animated;
+} DialogContext;
+
+static void dialog_text_cb(void *priv, const char *text, int len)
+{
+ DialogContext *s = priv;
+ if (!s->drawing_scale && (!s->is_animated || !s->ss_ctx->remove_animated))
+ av_bprint_append_data(&s->buffer, text, len);
+}
+
+static void dialog_new_line_cb(void *priv, int forced)
+{
+ DialogContext *s = priv;
+ if (!s->drawing_scale && !s->is_animated)
+ av_bprint_append_data(&s->buffer, forced ? "\\N" : "\\n", 2);
+}
+
+static void dialog_drawing_mode_cb(void *priv, int scale)
+{
+ DialogContext *s = priv;
+ s->drawing_scale = scale;
+}
+
+static void dialog_animate_cb(void *priv, int t1, int t2, int accel, char *style)
+{
+ DialogContext *s = priv;
+ s->is_animated = 1;
+}
+
+static void dialog_move_cb(void *priv, int x1, int y1, int x2, int y2, int t1, int t2)
+{
+ DialogContext *s = priv;
+ if (t1 >= 0 || t2 >= 0)
+ s->is_animated = 1;
+}
+
+static const ASSCodesCallbacks dialog_callbacks = {
+ .text = dialog_text_cb,
+ .new_line = dialog_new_line_cb,
+ .drawing_mode = dialog_drawing_mode_cb,
+ .animate = dialog_animate_cb,
+ .move = dialog_move_cb,
+};
+
+static int query_formats(AVFilterContext *ctx)
+{
+ AVFilterFormats *formats;
+ AVFilterLink *inlink = ctx->inputs[0];
+ AVFilterLink *outlink = ctx->outputs[0];
+ static const enum AVSubtitleType subtitle_fmts[] = { AV_SUBTITLE_FMT_ASS, AV_SUBTITLE_FMT_NONE };
+ int ret;
+
+ /* set input subtitle format */
+ formats = ff_make_format_list(subtitle_fmts);
+ if ((ret = ff_formats_ref(formats, &inlink->outcfg.formats)) < 0)
+ return ret;
+
+ /* set output video format */
+ if ((ret = ff_formats_ref(formats, &outlink->incfg.formats)) < 0)
+ return ret;
+
+ return 0;
+}
+
+static char *ass_get_line(int readorder, int layer, const char *style,
+ const char *speaker, const char *effect, const char *text)
+{
+ return av_asprintf("%d,%d,%s,%s,0,0,0,%s,%s",
+ readorder, layer, style ? style : "Default",
+ speaker ? speaker : "", effect, text);
+}
+
+static char *process_dialog(StripStylesContext *s, const char *ass_line)
+{
+ ASSDialog *dialog = ff_ass_split_dialog(NULL, ass_line);
+ char *result = NULL, *text;
+ DialogContext dlg_ctx = { 0 };
+
+ if (!dialog)
+ return NULL;
+
+ dlg_ctx.ss_ctx = s;
+
+ av_bprint_init(&dlg_ctx.buffer, 0, AV_BPRINT_SIZE_UNLIMITED);
+
+ ff_ass_split_override_codes(&dialog_callbacks, &dlg_ctx, dialog->text);
+
+ av_bprint_finalize(&dlg_ctx.buffer, &text);
+
+ if (text && strlen(text) > 0)
+ result = ass_get_line(dialog->readorder, dialog->layer, dialog->style, dialog->name, dialog->effect, text);
+
+ av_free(text);
+ ff_ass_free_dialog(&dialog);
+
+ return result;
+}
+
+static int filter_frame(AVFilterLink *inlink, AVFrame *src_frame)
+{
+ StripStylesContext *s = inlink->dst->priv;
+ AVFilterLink *outlink = inlink->dst->outputs[0];
+ AVFrame *out;
+
+ outlink->format = inlink->format;
+
+ out = av_frame_clone(src_frame);
+ if (!out)
+ return AVERROR(ENOMEM);
+
+ for (unsigned i = 0; i < out->num_subtitle_rects; i++) {
+
+ AVSubtitleRect *rect = out->subtitle_rects[i];
+
+ if (rect->ass) {
+ if (rect->ass) {
+ char *tmp = rect->ass;
+ rect->ass = process_dialog(s, rect->ass);
+
+ if (rect->ass) {
+ av_log(inlink->dst, AV_LOG_DEBUG, "original: %s\n", tmp);
+ av_log(inlink->dst, AV_LOG_DEBUG, "stripped: %s\n", rect->ass);
+ }
+ else
+ rect->ass = av_strdup("");
+
+ av_free(tmp);
+ }
+ }
+ }
+
+ av_frame_free(&src_frame);
+ return ff_filter_frame(outlink, out);
+}
+
+#define OFFSET(x) offsetof(StripStylesContext, x)
+#define FLAGS (AV_OPT_FLAG_SUBTITLE_PARAM | AV_OPT_FLAG_FILTERING_PARAM)
+
+static const AVOption stripstyles_options[] = {
+ { "remove_animated", "remove animated text (default: yes)", OFFSET(remove_animated), AV_OPT_TYPE_BOOL, {.i64 = 1 }, 0, 1, FLAGS, 0 },
+ { NULL },
+};
+
+AVFILTER_DEFINE_CLASS(stripstyles);
+
+static const AVFilterPad inputs[] = {
+ {
+ .name = "default",
+ .type = AVMEDIA_TYPE_SUBTITLE,
+ .filter_frame = filter_frame,
+ },
+};
+
+static const AVFilterPad outputs[] = {
+ {
+ .name = "default",
+ .type = AVMEDIA_TYPE_SUBTITLE,
+ },
+};
+
+const AVFilter ff_sf_stripstyles = {
+ .name = "stripstyles",
+ .description = NULL_IF_CONFIG_SMALL("Strip subtitle inline styles"),
+ .query_formats = query_formats,
+ .priv_size = sizeof(StripStylesContext),
+ .priv_class = &stripstyles_class,
+ FILTER_INPUTS(inputs),
+ FILTER_OUTPUTS(outputs),
+};
+
Signed-off-by: softworkz <softworkz@hotmail.com> --- doc/filters.texi | 24 ++++ libavfilter/Makefile | 1 + libavfilter/allfilters.c | 1 + libavfilter/sf_stripstyles.c | 215 +++++++++++++++++++++++++++++++++++ 4 files changed, 241 insertions(+) create mode 100644 libavfilter/sf_stripstyles.c