John Stebbins: > Required to remux m2ts to mkv > --- > Changelog | 1 + > doc/bitstream_filters.texi | 8 ++ > libavcodec/Makefile | 1 + > libavcodec/bitstream_filters.c | 1 + > libavcodec/pgs_frame_merge_bsf.c | 168 +++++++++++++++++++++++++++++++ > 5 files changed, 179 insertions(+) > create mode 100644 libavcodec/pgs_frame_merge_bsf.c > > diff --git a/Changelog b/Changelog > index d9fcd8bb0a..fec4867488 100644 > --- a/Changelog > +++ b/Changelog > @@ -59,6 +59,7 @@ version <next>: > - mv30 decoder > - Expanded styling support for 3GPP Timed Text Subtitles (movtext) > - WebP parser > +- PGS subtitle frame merge bitstream filter > > > version 4.2: > diff --git a/doc/bitstream_filters.texi b/doc/bitstream_filters.texi > index 8fe5b3ad75..21ed09986c 100644 > --- a/doc/bitstream_filters.texi > +++ b/doc/bitstream_filters.texi > @@ -548,6 +548,14 @@ ffmpeg -i INPUT -c copy -bsf noise[=1] output.mkv > @section null > This bitstream filter passes the packets through unchanged. > > +@section pgs_frame_merge > + > +Merge a sequence of PGS Subtitle segments ending with an "end of display set" > +segment into a single packet. > + > +This is required by some containers that support PGS subtitles > +(muxer @code{matroska}). > + > @section prores_metadata > > Modify color property metadata embedded in prores stream. > diff --git a/libavcodec/Makefile b/libavcodec/Makefile > index 88944d9a3a..b630de21bc 100644 > --- a/libavcodec/Makefile > +++ b/libavcodec/Makefile > @@ -1115,6 +1115,7 @@ OBJS-$(CONFIG_MP3_HEADER_DECOMPRESS_BSF) += > mp3_header_decompress_bsf.o \ > OBJS-$(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_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 6b5ffe4d70..92619225f0 100644 > --- a/libavcodec/bitstream_filters.c > +++ b/libavcodec/bitstream_filters.c > @@ -49,6 +49,7 @@ extern const AVBitStreamFilter ff_mpeg4_unpack_bframes_bsf; > 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_prores_metadata_bsf; > extern const AVBitStreamFilter ff_remove_extradata_bsf; > extern const AVBitStreamFilter ff_text2movsub_bsf; > diff --git a/libavcodec/pgs_frame_merge_bsf.c > b/libavcodec/pgs_frame_merge_bsf.c > new file mode 100644 > index 0000000000..cae5c75655 > --- /dev/null > +++ b/libavcodec/pgs_frame_merge_bsf.c > @@ -0,0 +1,168 @@ > +/* > + * Copyright (c) 2020 John Stebbins <jstebbins...@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 merges PGS subtitle packets containing incomplete > + * set of segments into a single packet > + * > + * Packets already containing a complete set of segments 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 PGSMergeContext { > + AVPacket *buffer_pkt, *in; > + int presentation_found; > +} PGSMergeContext; > + > +static void frame_merge_flush(AVBSFContext *bsf) > +{ > + PGSMergeContext *ctx = bsf->priv_data; > + > + av_packet_unref(ctx->in); > + av_packet_unref(ctx->buffer_pkt);
flush should reset ctx->presentation_found, shouldn't it? > +} > + > +static int frame_merge_filter(AVBSFContext *bsf, AVPacket *out) > +{ > + PGSMergeContext *ctx = bsf->priv_data; > + AVPacket *in = ctx->in, *pkt = ctx->buffer_pkt; > + int ret, i, size, pos, display = 0; > + > + 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 and find display_end segment > + size = in->size; > + i = 0; > + while (i + 3 <= in->size) { > + uint8_t segment_type; > + int segment_len; > + > + segment_type = in->data[i]; > + segment_len = AV_RB16(in->data + i + 1) + 3; > + if (i + segment_len > in->size) // Invalid data Possible overflow. Use an unsigned as segment_len to avoid it. > + break; > + if (segment_type == PRESENTATION_SEGMENT && i + 10 < in->size && > + !ctx->presentation_found) { > + uint8_t state; > + ctx->presentation_found = 1; > + ret = av_packet_copy_props(pkt, in); This will copy the properties even if it eventually turns out that one can just pass through the packet. Even worse: Imagine the input packet having side-data. Then pkt contains side-data, yet the code thinks that this packet is blank. This side data will then leak when the properties of the next presentation segment are copied. Furthermore, I would actually have expected the pts of the display segment to be used. Or are they guaranteed to be identical? > + if (ret < 0) > + goto fail; > + state = in->data[i + 10] & 0xc0; This amounts to the composition_state of the composition_descriptor(), doesn't it? > + if (state) > + pkt->flags |= AV_PKT_FLAG_KEY; The keyframe flag will be ignored on passthrough. Also, should the flag be cleared if state == 0? > + } > + i += segment_len; > + if (segment_type == DISPLAY_SEGMENT) { > + size = display = i; > + break; > + } > + } > + if (display && pkt->size == 0 && size == in->size) { // passthrough > + ctx->presentation_found = 0; > + av_packet_move_ref(out, in); > + return 0; > + } > + if ((!display && i != in->size) || size > in->size) { I don't see how size > in->size can ever be true. > + av_log(bsf, AV_LOG_WARNING, "Failed to parse PGS segments.\n"); > + // force output what we have > + display = size = in->size; If you output a corrupt packet, you should set the AV_PKT_FLAG_CORRUPT flag. > + } > + > + pos = pkt->size; > + ret = av_grow_packet(pkt, size); > + if (ret < 0) > + goto fail; > + memcpy(pkt->data + pos, in->data, size); > + > + if (size == in->size) > + av_packet_unref(in); > + else { > + in->data += size; > + in->size -= size; > + } > + > + if (display) { > + ctx->presentation_found = 0; I don't see anything in the code that actually enforces that a presentation segment has been found at this point; the properties of the output packet would then still be blank. Is this intended? If it is spec-incompliant, then one should add the AV_PKT_FLAG_CORRUPT flag. > + av_packet_move_ref(out, pkt); > + return 0; > + } > + return AVERROR(EAGAIN); > + > +fail: > + ctx->presentation_found = 0; > + frame_merge_flush(bsf); > + return ret; > +} > + > +static int frame_merge_init(AVBSFContext *bsf) > +{ > + PGSMergeContext *ctx = bsf->priv_data; > + > + ctx->in = av_packet_alloc(); > + ctx->buffer_pkt = av_packet_alloc(); > + if (!ctx->in || !ctx->buffer_pkt) > + return AVERROR(ENOMEM); > + > + return 0; > +} > + > +static void frame_merge_close(AVBSFContext *bsf) > +{ > + PGSMergeContext *ctx = bsf->priv_data; > + > + av_packet_free(&ctx->in); > + av_packet_free(&ctx->buffer_pkt); > +} > + > +static const enum AVCodecID frame_merge_codec_ids[] = { > + AV_CODEC_ID_HDMV_PGS_SUBTITLE, AV_CODEC_ID_NONE, > +}; > + > +const AVBitStreamFilter ff_pgs_frame_merge_bsf = { > + .name = "pgs_frame_merge", > + .priv_data_size = sizeof(PGSMergeContext), > + .init = frame_merge_init, > + .flush = frame_merge_flush, > + .close = frame_merge_close, > + .filter = frame_merge_filter, > + .codec_ids = frame_merge_codec_ids, > +}; > _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".