[FFmpeg-devel] [PATCH v22 17/23] avfilter/stripstyles: Add stripstyles filter
Soft Works
softworkz at hotmail.com
Thu Dec 9 14:12:58 EET 2021
- stripstyles {S -> S)
Remove all inline styles from subtitle events
Signed-off-by: softworkz <softworkz at hotmail.com>
---
doc/filters.texi | 37 +++++++
libavfilter/Makefile | 1 +
libavfilter/allfilters.c | 1 +
libavfilter/sf_stripstyles.c | 196 +++++++++++++++++++++++++++++++++++
4 files changed, 235 insertions(+)
create mode 100644 libavfilter/sf_stripstyles.c
diff --git a/doc/filters.texi b/doc/filters.texi
index e87d3993df..241c5d469b 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -25704,6 +25704,43 @@ ffmpeg -i "http://streams.videolan.org/samples/sub/SSA/subtitle_testing_complex.
@end example
@end itemize
+ at section stripstyles
+
+Remove all inline styles from subtitle events.
+
+Inputs:
+ at itemize
+ at item 0: Subtitles[TEXT]
+ at end itemize
+
+Outputs:
+ at itemize
+ at item 0: Subtitles[TEXT]
+ at end itemize
+
+It accepts the following parameters:
+
+ at table @option
+ at 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.
+
+ at item select_layer
+Process only ASS subtitle events from a specific layer. This allows to filter out certain effects where an ASS author duplicates the text onto multiple layers.
+
+ at end table
+
+ at subsection Examples
+
+ at itemize
+ at item
+Remove styles and animations from ASS subtitles and output events from ass layer 0 only. Then convert asn save as SRT stream:
+ at example
+ffmpeg -i "https://streams.videolan.org/samples/sub/SSA/subtitle_testing_complex.mkv" -filter_complex "[0:1]stripstyles=select_layer=0" -map 0 -c:s srt output.mkv
+ at end example
+ at end itemize
+
@section textmod
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index d2995fbec6..7d7da0c59a 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -557,6 +557,7 @@ OBJS-$(CONFIG_NULLSINK_FILTER) += vsink_nullsink.o
OBJS-$(CONFIG_CENSOR_FILTER) += sf_textmod.o
OBJS-$(CONFIG_SHOW_SPEAKER_FILTER) += sf_textmod.o
OBJS-$(CONFIG_TEXTMOD_FILTER) += sf_textmod.o
+OBJS-$(CONFIG_STRIPSTYLES_FILTER) += sf_stripstyles.o
# multimedia filters
OBJS-$(CONFIG_ABITSCOPE_FILTER) += avf_abitscope.o
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index 673f9fb839..27680a2f00 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -546,6 +546,7 @@ extern const AVFilter ff_avf_showwavespic;
extern const AVFilter ff_vaf_spectrumsynth;
extern const AVFilter ff_sf_censor;
extern const AVFilter ff_sf_showspeaker;
+extern const AVFilter ff_sf_stripstyles;
extern const AVFilter ff_sf_textmod;
extern const AVFilter ff_svf_graphicsub2video;
extern const AVFilter ff_svf_textsub2video;
diff --git a/libavfilter/sf_stripstyles.c b/libavfilter/sf_stripstyles.c
new file mode 100644
index 0000000000..82cb9c7647
--- /dev/null
+++ b/libavfilter/sf_stripstyles.c
@@ -0,0 +1,196 @@
+/*
+ * 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 "libavutil/opt.h"
+#include "internal.h"
+#include "libavutil/ass_split_internal.h"
+#include "libavutil/bprint.h"
+
+typedef struct StripStylesContext {
+ const AVClass *class;
+ enum AVSubtitleType format;
+ int remove_animated;
+ int select_layer;
+} StripStylesContext;
+
+typedef struct DialogContext {
+ 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;
+
+ av_log(s->ss_ctx, AV_LOG_DEBUG, "dialog_text_cb: %s\n", text);
+
+ 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 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)
+{
+ DialogContext dlg_ctx = { .ss_ctx = s };
+ ASSDialog *dialog = avpriv_ass_split_dialog(NULL, ass_line);
+ char *result = NULL;
+
+ if (!dialog)
+ return NULL;
+
+ if (s->select_layer >= 0 && dialog->layer != s->select_layer)
+ return NULL;
+
+ dlg_ctx.ss_ctx = s;
+
+ av_bprint_init(&dlg_ctx.buffer, 0, AV_BPRINT_SIZE_UNLIMITED);
+
+ avpriv_ass_split_override_codes(&dialog_callbacks, &dlg_ctx, dialog->text);
+
+ if (av_bprint_is_complete(&dlg_ctx.buffer)
+ && dlg_ctx.buffer.len > 0)
+ result = ass_get_line(dialog->readorder, dialog->layer, dialog->style, dialog->name, dialog->effect, dlg_ctx.buffer.str);
+
+ av_bprint_finalize(&dlg_ctx.buffer, NULL);
+ avpriv_ass_free_dialog(&dialog);
+
+ return result;
+}
+
+static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
+{
+ StripStylesContext *s = inlink->dst->priv;
+ AVFilterLink *outlink = inlink->dst->outputs[0];
+ int ret;
+
+ outlink->format = inlink->format;
+
+ ret = av_frame_make_writable(frame);
+ if (ret <0 ) {
+ av_frame_free(&frame);
+ return AVERROR(ENOMEM);
+ }
+
+ for (unsigned i = 0; i < frame->num_subtitle_areas; i++) {
+
+ AVSubtitleArea *area = frame->subtitle_areas[i];
+
+ if (area->ass) {
+ char *tmp = area->ass;
+ area->ass = process_dialog(s, area->ass);
+
+ if (area->ass) {
+ av_log(inlink->dst, AV_LOG_INFO, "original: %d %s\n", i, tmp);
+ av_log(inlink->dst, AV_LOG_INFO, "stripped: %d %s\n", i, area->ass);
+ }
+ else
+ area->ass = NULL;
+
+ av_free(tmp);
+ }
+ }
+
+ return ff_filter_frame(outlink, frame);
+}
+
+#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 },
+ { "select_layer", "process a specific ass layer only", OFFSET(remove_animated), AV_OPT_TYPE_INT, {.i64 = -1 }, -1, INT_MAX, 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"),
+ .priv_size = sizeof(StripStylesContext),
+ .priv_class = &stripstyles_class,
+ FILTER_INPUTS(inputs),
+ FILTER_OUTPUTS(outputs),
+ FILTER_SINGLE_SUBFMT(AV_SUBTITLE_FMT_ASS),
+};
+
--
2.30.2.windows.1
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