[FFmpeg-devel] [PATCH 3/4] lavc/pgs_frame_split_bsf: add bsf to split PGS segments
John Stebbins
jstebbins at jetheaddev.com
Sat Apr 18 17:25:45 EEST 2020
Requried to remux mkv to m2ts
---
Changelog | 1 +
doc/bitstream_filters.texi | 8 ++
libavcodec/Makefile | 1 +
libavcodec/bitstream_filters.c | 1 +
libavcodec/pgs_frame_split_bsf.c | 176 +++++++++++++++++++++++++++++++
5 files changed, 187 insertions(+)
create mode 100644 libavcodec/pgs_frame_split_bsf.c
diff --git a/Changelog b/Changelog
index fec4867488..372bb4694c 100644
--- a/Changelog
+++ b/Changelog
@@ -60,6 +60,7 @@ version <next>:
- Expanded styling support for 3GPP Timed Text Subtitles (movtext)
- WebP parser
- PGS subtitle frame merge bitstream filter
+- PGS subtitle frame split bitstream filter
version 4.2:
diff --git a/doc/bitstream_filters.texi b/doc/bitstream_filters.texi
index 21ed09986c..643c419076 100644
--- a/doc/bitstream_filters.texi
+++ b/doc/bitstream_filters.texi
@@ -556,6 +556,14 @@ segment into a single packet.
This is required by some containers that support PGS subtitles
(muxer @code{matroska}).
+ at section pgs_frame_split
+
+Split a packet containing a sequence of PGS Subtitle segments into separate
+packets each containing a single segment.
+
+This is required by some streaming formats, typically the MPEG-2
+transport stream format (muxer @code{mpegts}).
+
@section prores_metadata
Modify color property metadata embedded in prores stream.
diff --git a/libavcodec/Makefile b/libavcodec/Makefile
index b630de21bc..0e5f2db192 100644
--- a/libavcodec/Makefile
+++ b/libavcodec/Makefile
@@ -1116,6 +1116,7 @@ OBJS-$(CONFIG_MPEG2_METADATA_BSF) += mpeg2_metadata_bsf.o
OBJS-$(CONFIG_NOISE_BSF) += noise_bsf.o
OBJS-$(CONFIG_NULL_BSF) += null_bsf.o
OBJS-$(CONFIG_PGS_FRAME_MERGE_BSF) += pgs_frame_merge_bsf.o
+OBJS-$(CONFIG_PGS_FRAME_SPLIT_BSF) += pgs_frame_split_bsf.o
OBJS-$(CONFIG_PRORES_METADATA_BSF) += prores_metadata_bsf.o
OBJS-$(CONFIG_REMOVE_EXTRADATA_BSF) += remove_extradata_bsf.o
OBJS-$(CONFIG_TEXT2MOVSUB_BSF) += movsub_bsf.o
diff --git a/libavcodec/bitstream_filters.c b/libavcodec/bitstream_filters.c
index 92619225f0..02e72c9ca5 100644
--- a/libavcodec/bitstream_filters.c
+++ b/libavcodec/bitstream_filters.c
@@ -50,6 +50,7 @@ extern const AVBitStreamFilter ff_mov2textsub_bsf;
extern const AVBitStreamFilter ff_noise_bsf;
extern const AVBitStreamFilter ff_null_bsf;
extern const AVBitStreamFilter ff_pgs_frame_merge_bsf;
+extern const AVBitStreamFilter ff_pgs_frame_split_bsf;
extern const AVBitStreamFilter ff_prores_metadata_bsf;
extern const AVBitStreamFilter ff_remove_extradata_bsf;
extern const AVBitStreamFilter ff_text2movsub_bsf;
diff --git a/libavcodec/pgs_frame_split_bsf.c b/libavcodec/pgs_frame_split_bsf.c
new file mode 100644
index 0000000000..c983f6acf5
--- /dev/null
+++ b/libavcodec/pgs_frame_split_bsf.c
@@ -0,0 +1,176 @@
+/*
+ * Copyright (c) 2020 John Stebbins <jstebbins.hb at gmail.com>
+ *
+ * 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
+ * This bitstream filter splits PGS subtitle packets into packets containing
+ * just one segment.
+ *
+ * Packets already containing only one segment will be passed through
+ * unchanged.
+ */
+
+#include "avcodec.h"
+#include "bsf.h"
+#include "libavutil/intreadwrite.h"
+
+enum PGSSegmentType {
+ PALETTE_SEGMENT = 0x14,
+ OBJECT_SEGMENT = 0x15,
+ PRESENTATION_SEGMENT = 0x16,
+ WINDOW_SEGMENT = 0x17,
+ DISPLAY_SEGMENT = 0x80,
+};
+
+typedef struct PGSSplitContext {
+ AVPacket *in;
+} PGSSplitContext;
+
+static int frame_split_filter(AVBSFContext *bsf, AVPacket *out)
+{
+ PGSSplitContext *ctx = bsf->priv_data;
+ AVPacket *in = ctx->in;
+ int i, ret;
+ uint8_t segment_type;
+ uint16_t segment_len;
+ int split = !!in->data;
+
+ if (!in->data) {
+ ret = ff_bsf_get_packet_ref(bsf, in);
+ if (ret < 0)
+ return ret;
+ }
+ if (!in->size) {
+ av_packet_unref(in);
+ return AVERROR(EAGAIN);
+ }
+
+ // Validate packet data
+ i = 0;
+ while (i < in->size) {
+ segment_type = in->data[i];
+ segment_len = AV_RB16(in->data + i + 1) + 3;
+ i += segment_len;
+ }
+ if (i != in->size) {
+ av_log(bsf, AV_LOG_WARNING, "Failed to parse PGS segments.\n");
+ av_packet_move_ref(out, in);
+ return 0;
+ }
+
+ segment_type = in->data[0];
+ segment_len = AV_RB16(in->data + 1) + 3;
+ if (split || segment_len < in->size) { // Split
+ int64_t ts_delta, dts;
+
+ ret = av_packet_ref(out, in);
+ if (ret < 0)
+ goto fail;
+ out->size = segment_len;
+ in->data += segment_len;
+ in->size -= segment_len;
+
+ // Update PTS/DTS, Stagger timestamps by 3ms
+ ts_delta = 270; // Assume 90khz tick if no time_base_in
+ if (bsf->time_base_in.num && bsf->time_base_in.den)
+ ts_delta = bsf->time_base_in.den / bsf->time_base_in.num / 333;
+ if (ts_delta == 0)
+ ts_delta = 1;
+
+ // Compute DTS, it's the same for all packets that carry it
+ // Assuming input PTS/DTS come from original presentation_segment
+ if (in->dts <= in->pts - 2 * ts_delta &&
+ in->dts != AV_NOPTS_VALUE)
+ dts = in->dts;
+ else if (in->pts != AV_NOPTS_VALUE)
+ dts = in->pts - 2 * ts_delta;
+
+ switch (segment_type) {
+ case DISPLAY_SEGMENT:
+ if (in->pts != AV_NOPTS_VALUE)
+ out->pts = in->pts - ts_delta;
+ out->dts = AV_NOPTS_VALUE;
+ break;
+ case PALETTE_SEGMENT:
+ if (in->pts != AV_NOPTS_VALUE)
+ out->pts = in->pts - 2 * ts_delta;
+ out->dts = AV_NOPTS_VALUE;
+ break;
+ case PRESENTATION_SEGMENT:
+ out->pts = in->pts;
+ out->dts = dts;
+ break;
+ case WINDOW_SEGMENT:
+ case OBJECT_SEGMENT:
+ default:
+ if (in->pts != AV_NOPTS_VALUE)
+ out->pts = in->pts - ts_delta;
+ out->dts = dts;
+ break;
+ }
+ } else
+ av_packet_move_ref(out, in);
+
+ return 0;
+
+fail:
+ av_packet_unref(in);
+
+ return ret;
+}
+
+static int frame_split_init(AVBSFContext *bsf)
+{
+ PGSSplitContext *ctx = bsf->priv_data;
+
+ ctx->in = av_packet_alloc();
+ if (!ctx->in)
+ return AVERROR(ENOMEM);
+
+ return 0;
+}
+
+static void frame_split_flush(AVBSFContext *bsf)
+{
+ PGSSplitContext *ctx = bsf->priv_data;
+
+ av_packet_unref(ctx->in);
+}
+
+static void frame_split_close(AVBSFContext *bsf)
+{
+ PGSSplitContext *ctx = bsf->priv_data;
+
+ av_packet_free(&ctx->in);
+}
+
+static const enum AVCodecID frame_split_codec_ids[] = {
+ AV_CODEC_ID_HDMV_PGS_SUBTITLE, AV_CODEC_ID_NONE,
+};
+
+const AVBitStreamFilter ff_pgs_frame_split_bsf = {
+ .name = "pgs_frame_split",
+ .priv_data_size = sizeof(PGSSplitContext),
+ .init = frame_split_init,
+ .flush = frame_split_flush,
+ .close = frame_split_close,
+ .filter = frame_split_filter,
+ .codec_ids = frame_split_codec_ids,
+};
--
2.25.2
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