[FFmpeg-devel] [PATCH v18 17/19] avfilter/splitcc: Add splitcc filter for closed caption handling
Soft Works
softworkz at hotmail.com
Mon Nov 29 21:48:41 EET 2021
- splitcc {V -> VS)
Extract closed-caption (A53) data from video
frames as subtitle Frames
ffmpeg -y -loglevel verbose -i "https://streams.videolan.org/streams/ts/CC/NewsStream-608-ac3.ts" -filter_complex "[0:v]splitcc[vid1],textmod=mode=remove_chars:find='@',[vid1]overlay_textsubs" output.mkv
Signed-off-by: softworkz <softworkz at hotmail.com>
---
configure | 1 +
doc/filters.texi | 63 ++++++++
libavfilter/Makefile | 1 +
libavfilter/allfilters.c | 1 +
libavfilter/sf_splitcc.c | 328 +++++++++++++++++++++++++++++++++++++++
5 files changed, 394 insertions(+)
create mode 100644 libavfilter/sf_splitcc.c
diff --git a/configure b/configure
index 8c0d5a6620..fc7cc2163e 100755
--- a/configure
+++ b/configure
@@ -3700,6 +3700,7 @@ spp_filter_select="fft idctdsp fdctdsp me_cmp pixblockdsp"
sr_filter_deps="avformat swscale"
sr_filter_select="dnn"
stereo3d_filter_deps="gpl"
+splitcc_filter_deps="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 10d132c23b..7350fa2a7e 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -25970,6 +25970,69 @@ ffmpeg -i INPUT -filter_complex "showspeaker=format=colon:style='@{\\c&HDD0000&\
@end example
@end itemize
+
+ at section splitcc
+
+Split-out closed-caption/A53 subtitles from video frame side data.
+
+This filter provides an input and an output for video frames, which are just passed through without modification.
+The second out provides subtitle frames which are extracted from video frame side data.
+
+Inputs:
+ at itemize
+ at item 0: Video [ALL]
+ at end itemize
+
+Outputs:
+ at itemize
+ at item 0: Video (same as input)
+ at item 1: Subtitles [TEXT]
+ at end itemize
+
+It accepts the following parameters:
+
+ at table @option
+
+ at item use_cc_styles
+Emit closed caption style header.
+This will make closed captions appear in white font with a black rectangle background.
+
+ at item real_time
+Emit subtitle events as they are decoded for real-time display.
+
+ at item real_time_latency_msec
+Minimum elapsed time between emitting real-time subtitle events.
+Only applies to real_time mode.
+
+ at item data_field
+Select data field. Possible values:
+
+ at table @samp
+ at item auto
+Pick first one that appears.
+ at item first
+ at item second
+ at end table
+
+ at end table
+
+ at subsection Examples
+
+ at itemize
+ at item
+Extract closed captions as text subtitle stream and overlay it onto the video in cc style (black bar background):
+ at example
+ffmpeg -i "https://streams.videolan.org/streams/ts/CC/NewsStream-608-ac3.ts" -filter_complex "[0:v:0]splitcc=use_cc_styles=1[vid1][sub1];[vid1][sub1]overlaytextsubs" output.mkv
+ at end example
+
+ at item
+A nicer variant, using realtime output from cc_dec and rendering it with the render_latest_only parameter from overlaytextsubs to avoid ghosting by timely overlap.
+ at example
+ffmpeg -i "https://streams.videolan.org/streams/ts/CC/NewsStream-608-ac3.ts" -filter_complex "[0:v:0]splitcc=real_time=1:real_time_latency_msec=200[vid1][sub1];[vid1][sub1]overlaytextsubs=render_latest_only=1" output.mkv
+ at end example
+ at end itemize
+
+
@section textsub2video
Converts text subtitles to video frames.
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index 599ca0e54a..5364e11491 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -555,6 +555,7 @@ 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-$(CONFIG_SPLITCC_FILTER) += sf_splitcc.o
OBJS-$(CONFIG_STRIPSTYLES_FILTER) += sf_stripstyles.o
# multimedia filters
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index 378d1dcaac..1444ca873a 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -543,6 +543,7 @@ 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_splitcc;
extern const AVFilter ff_sf_stripstyles;
extern const AVFilter ff_sf_textmod;
extern const AVFilter ff_svf_graphicsub2video;
diff --git a/libavfilter/sf_splitcc.c b/libavfilter/sf_splitcc.c
new file mode 100644
index 0000000000..65321a38d7
--- /dev/null
+++ b/libavfilter/sf_splitcc.c
@@ -0,0 +1,328 @@
+/*
+ * 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
+ * subtitle filter for splitting out closed-caption/A53 subtitles from video frame side data
+ */
+
+#include "libavutil/opt.h"
+#include "subtitles.h"
+#include "libavcodec/avcodec.h"
+
+typedef struct SplitCaptionsContext {
+ const AVClass *class;
+ enum AVSubtitleType format;
+ AVCodecContext *cc_dec;
+ int eof;
+ AVFrame *next_sub_frame;
+ int new_frame;
+ AVBufferRef *subtitle_header;
+ int use_cc_styles;
+ int real_time;
+ int real_time_latency_msec;
+ int data_field;
+} SplitCaptionsContext;
+
+static int init(AVFilterContext *ctx)
+{
+ SplitCaptionsContext *s = ctx->priv;
+ AVDictionary *options = NULL;
+
+ int ret;
+ const AVCodec *codec = avcodec_find_decoder(AV_CODEC_ID_EIA_608);
+ if (!codec) {
+ av_log(ctx, AV_LOG_ERROR, "failed to find EIA-608/708 decoder\n");
+ return AVERROR_DECODER_NOT_FOUND;
+ }
+
+ if (!((s->cc_dec = avcodec_alloc_context3(codec)))) {
+ av_log(ctx, AV_LOG_ERROR, "failed to allocate EIA-608/708 decoder\n");
+ return AVERROR(ENOMEM);
+ }
+
+ av_dict_set_int(&options, "real_time", s->real_time, 0);
+ av_dict_set_int(&options, "real_time_latency_msec", s->real_time_latency_msec, 0);
+ av_dict_set_int(&options, "data_field", s->data_field, 0);
+
+ if ((ret = avcodec_open2(s->cc_dec, codec, &options)) < 0) {
+ av_log(ctx, AV_LOG_ERROR, "failed to open EIA-608/708 decoder: %i\n", ret);
+ return ret;
+ }
+
+ if (s->use_cc_styles && s->cc_dec->subtitle_header && s->cc_dec->subtitle_header[0] != 0) {
+ char* subtitle_header = av_strdup((char *)s->cc_dec->subtitle_header);
+ if (!subtitle_header)
+ return AVERROR(ENOMEM);
+ s->subtitle_header = av_buffer_create((uint8_t *)subtitle_header, strlen(subtitle_header) + 1, NULL, NULL, 0);
+ if (!s->subtitle_header) {
+ av_free(subtitle_header);
+ return AVERROR(ENOMEM);
+ }
+ }
+
+ return 0;
+}
+
+static void uninit(AVFilterContext *ctx)
+{
+ SplitCaptionsContext *s = ctx->priv;
+ av_frame_free(&s->next_sub_frame);
+ av_buffer_unref(&s->subtitle_header);
+}
+
+static int config_input(AVFilterLink *link)
+{
+ const SplitCaptionsContext *context = link->dst->priv;
+
+ if (context->cc_dec)
+ context->cc_dec->pkt_timebase = link->time_base;
+
+ return 0;
+}
+
+static int query_formats(AVFilterContext *ctx)
+{
+ AVFilterFormats *formats;
+ AVFilterLink *inlink0 = ctx->inputs[0];
+ AVFilterLink *outlink0 = ctx->outputs[0];
+ AVFilterLink *outlink1 = ctx->outputs[1];
+ static const enum AVSubtitleType subtitle_fmts[] = { AV_SUBTITLE_FMT_ASS, AV_SUBTITLE_FMT_NB };
+ int ret;
+
+ /* set input0 video formats */
+ formats = ff_all_formats(AVMEDIA_TYPE_VIDEO);
+ if ((ret = ff_formats_ref(formats, &inlink0->outcfg.formats)) < 0)
+ return ret;
+
+ /* set output0 video formats */
+ if ((ret = ff_formats_ref(formats, &outlink0->incfg.formats)) < 0)
+ return ret;
+
+ /* set output1 subtitle formats */
+ formats = ff_make_format_list(subtitle_fmts);
+ if ((ret = ff_formats_ref(formats, &outlink1->incfg.formats)) < 0)
+ return ret;
+
+ return 0;
+}
+
+static int config_video_output(AVFilterLink *outlink)
+{
+ const AVFilterLink *inlink = outlink->src->inputs[0];
+
+ if (inlink->hw_frames_ctx)
+ outlink->hw_frames_ctx = av_buffer_ref(inlink->hw_frames_ctx);
+
+ return 0;
+}
+
+static int config_sub_output(AVFilterLink *outlink)
+{
+ const AVFilterLink *inlink = outlink->src->inputs[0];
+
+ outlink->time_base = inlink->time_base;
+ outlink->format = AV_SUBTITLE_FMT_ASS;
+
+ return 0;
+}
+
+static int request_sub_frame(AVFilterLink *outlink)
+{
+ SplitCaptionsContext *s = outlink->src->priv;
+
+ if (s->eof)
+ return AVERROR_EOF;
+
+ if (s->next_sub_frame && s->new_frame) {
+ AVFrame *out;
+ s->next_sub_frame->pts++;
+
+ out = av_frame_clone(s->next_sub_frame);
+ if (!out)
+ return AVERROR(ENOMEM);
+
+ out->subtitle_pts = av_rescale_q(s->next_sub_frame->pts, outlink->time_base, AV_TIME_BASE_Q);
+ s->new_frame = 0;
+
+ return ff_filter_frame(outlink, out);
+ }
+
+ return 0;
+}
+
+static int decode(AVCodecContext *avctx, AVFrame *frame, int *got_frame, AVPacket *pkt)
+{
+ int ret;
+
+ *got_frame = 0;
+
+ if (pkt) {
+ ret = avcodec_send_packet(avctx, pkt);
+ // In particular, we don't expect AVERROR(EAGAIN), because we read all
+ // decoded frames with avcodec_receive_frame() until done.
+ if (ret < 0 && ret != AVERROR_EOF)
+ return ret;
+ }
+
+ ret = avcodec_receive_frame(avctx, frame);
+ if (ret < 0 && ret != AVERROR(EAGAIN))
+ return ret;
+ if (ret >= 0)
+ *got_frame = 1;
+
+ return 0;
+}
+
+static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
+{
+ AVFrameSideData *sd;
+ SplitCaptionsContext *s = inlink->dst->priv;
+ AVFilterLink *outlink0 = inlink->dst->outputs[0];
+ AVFilterLink *outlink1 = inlink->dst->outputs[1];
+ AVPacket *pkt = NULL;
+ AVFrame *sub_out = NULL;
+
+ int ret;
+
+ outlink0->format = inlink->format;
+
+ sd = av_frame_get_side_data(frame, AV_FRAME_DATA_A53_CC);
+
+ if (sd) {
+ int got_output = 0;
+
+ pkt = av_packet_alloc();
+ pkt->buf = av_buffer_ref(sd->buf);
+ if (!pkt->buf) {
+ ret = AVERROR(ENOMEM);
+ goto fail;
+ }
+
+ pkt->data = sd->data;
+ pkt->size = (int)sd->size;
+ pkt->pts = frame->pts;
+
+ sub_out = ff_get_subtitles_buffer(outlink1, AV_SUBTITLE_FMT_ASS);
+ if (!sub_out) {
+ ret = AVERROR(ENOMEM);
+ goto fail;
+ }
+
+ if ((ret = av_buffer_replace(&sub_out->subtitle_header, s->subtitle_header)) < 0)
+ goto fail;
+
+ ret = decode(s->cc_dec, sub_out, &got_output, pkt);
+
+ if (ret < 0)
+ goto fail;
+
+ if (got_output) {
+ sub_out->pts = frame->pts;
+ av_frame_free(&s->next_sub_frame);
+ s->next_sub_frame = sub_out;
+ sub_out = NULL;
+ s->new_frame = 1;
+
+ if ((ret = av_buffer_replace(&s->next_sub_frame->subtitle_header, s->subtitle_header)) < 0)
+ goto fail;
+
+ ret = request_sub_frame(outlink1);
+ if (ret < 0)
+ goto fail;
+ }
+ }
+
+ if (!s->next_sub_frame) {
+ s->next_sub_frame = ff_get_subtitles_buffer(outlink1, outlink1->format);
+ if (!s->next_sub_frame) {
+ ret = AVERROR(ENOMEM);
+ goto fail;
+ }
+
+ s->next_sub_frame->subtitle_end_time = 100;
+ s->next_sub_frame->pts = frame->pts;
+ s->new_frame = 1;
+
+ if ((ret = av_buffer_replace(&s->next_sub_frame->subtitle_header, s->subtitle_header)) < 0)
+ goto fail;
+ }
+ else
+ s->next_sub_frame->pts = frame->pts;
+
+ ret = ff_filter_frame(outlink0, frame);
+
+fail:
+ av_packet_free(&pkt);
+ av_frame_free(&sub_out);
+ return ret;
+}
+
+#define OFFSET(x) offsetof(SplitCaptionsContext, x)
+#define FLAGS (AV_OPT_FLAG_SUBTITLE_PARAM | AV_OPT_FLAG_FILTERING_PARAM)
+
+static const AVOption split_cc_options[] = {
+ { "use_cc_styles", "Emit closed caption style header", OFFSET(use_cc_styles), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS, NULL },
+ { "real_time", "emit subtitle events as they are decoded for real-time display", OFFSET(real_time), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, FLAGS },
+ { "real_time_latency_msec", "minimum elapsed time between emitting real-time subtitle events", OFFSET(real_time_latency_msec), AV_OPT_TYPE_INT, { .i64 = 200 }, 0, 500, FLAGS },
+ { "data_field", "select data field", OFFSET(data_field), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, 1, FLAGS, "data_field" },
+ { "auto", "pick first one that appears", 0, AV_OPT_TYPE_CONST, { .i64 =-1 }, 0, 0, FLAGS, "data_field" },
+ { "first", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = 0 }, 0, 0, FLAGS, "data_field" },
+ { "second", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = 1 }, 0, 0, FLAGS, "data_field" },
+ { NULL },
+};
+
+AVFILTER_DEFINE_CLASS(split_cc);
+
+static const AVFilterPad inputs[] = {
+ {
+ .name = "default",
+ .type = AVMEDIA_TYPE_VIDEO,
+ .filter_frame = filter_frame,
+ .config_props = config_input,
+ },
+};
+
+static const AVFilterPad outputs[] = {
+ {
+ .name = "video_passthrough",
+ .type = AVMEDIA_TYPE_VIDEO,
+ .config_props = config_video_output,
+ },
+ {
+ .name = "subtitles",
+ .type = AVMEDIA_TYPE_SUBTITLE,
+ .request_frame = request_sub_frame,
+ .config_props = config_sub_output,
+ },
+};
+
+const AVFilter ff_sf_splitcc = {
+ .name = "splitcc",
+ .description = NULL_IF_CONFIG_SMALL("Extract closed-caption (A53) data from video as subtitle stream."),
+ .init = init,
+ .uninit = uninit,
+ .priv_size = sizeof(SplitCaptionsContext),
+ .priv_class = &split_cc_class,
+ .flags_internal = FF_FILTER_FLAG_HWFRAME_AWARE,
+ FILTER_INPUTS(inputs),
+ FILTER_OUTPUTS(outputs),
+ FILTER_QUERY_FUNC(query_formats),
+};
--
2.30.2.windows.1
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