| Message ID | 20200418142547.21299-4-jstebbins@jetheaddev.com |
|---|---|
| State | New |
| Headers | show |
| Series | [FFmpeg-devel,1/4] lavc/pgs_frame_merge_bsf: add bsf to merge PGS segments | expand |
| Context | Check | Description |
|---|---|---|
| andriy/default | pending | |
| andriy/configure | warning | Failed to apply patch |
John Stebbins: > 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}). > > +@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}). Is there a reason you don't add this bsf automatically for ts? > + > @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@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; uint16_t is not enough for segment_len. Also you are possibly overreading here. > + i += segment_len; Possible overflow. > + } > + if (i != in->size) { > + av_log(bsf, AV_LOG_WARNING, "Failed to parse PGS segments.\n"); If you output invalid data, you need to set the AV_PKT_FLAG_CORRUPT flag. > + 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 Where does this number come from? > + 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, > +}; >
On Sat, 2020-05-02 at 23:05 +0200, Andreas Rheinhardt wrote: > John Stebbins: > > 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}). > > > > +@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}). > > Is there a reason you don't add this bsf automatically for ts? Yes, it is dependent on: http://ffmpeg.org/pipermail/ffmpeg-devel/2020-April/261598.html I have a patch ready for when the above gets approved and committed > > > + > > @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@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; > > uint16_t is not enough for segment_len. Also you are possibly > overreading here. > Ugh, originally I didn't add the "+ 3" and then forgot about the type Will fix > > + i += segment_len; > > Possible overflow. > Similar to my comment in the pgs merge review. The conditions of the overflow are pretty extreme. I.e. A very large input packet and more than 32768 segments in the packet and the last segment size > 2^31 - in->size. I could make i unsigned similar to your suggestion for merge. Just making sure I'm not missing something else. There you suggested makeing segment_len unisigned, but making i unsigned works just as well in merge. > > + } > > + if (i != in->size) { > > + av_log(bsf, AV_LOG_WARNING, "Failed to parse PGS > > segments.\n"); > > If you output invalid data, you need to set the AV_PKT_FLAG_CORRUPT > flag. > > > + 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 > > Where does this number come from? There is no spec beyond A must be > B which is > C type wording and some segments are specified to have no DTS. I looked at some real BD data to determine a good nominal value. > > > + 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, > > +}; > > >
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}). +@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@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, +};