[FFmpeg-devel] [PATCH 1/3] lavc/pgs_frame_merge_bsf: add bsf to merge PGS segments

John Stebbins jstebbins at jetheaddev.com
Fri Apr 17 02:06:06 EEST 2020


On Thu, 2020-04-16 at 15:59 -0700, John Stebbins wrote:
> On Thu, 2020-04-16 at 16:57 -0600, John Stebbins wrote:
> > Required to remux m2ts to mkv
> > ---
> >  libavcodec/Makefile              |   1 +
> >  libavcodec/bitstream_filters.c   |   1 +
> >  libavcodec/pgs_frame_merge_bsf.c | 164
> > +++++++++++++++++++++++++++++++
> >  3 files changed, 166 insertions(+)
> >  create mode 100644 libavcodec/pgs_frame_merge_bsf.c
> > 
> 
> Ugh!  I forgot the version bump.  Will get on that...

A question about this.  I have 2 bsf submitted for review.  Should I
just do a separate patch that updates the minor version once.  Or do
you require it to be bumped with each change separately?

> 
> > diff --git a/libavcodec/Makefile b/libavcodec/Makefile
> > index c1c9a44f2b..c7d8fbebaa 100644
> > --- a/libavcodec/Makefile
> > +++ b/libavcodec/Makefile
> > @@ -1110,6 +1110,7 @@ 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..d1bb3a60c2
> > --- /dev/null
> > +++ b/libavcodec/pgs_frame_merge_bsf.c
> > @@ -0,0 +1,164 @@
> > +/*
> > + * 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 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);
> > +}
> > +
> > +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
> > +            break;
> > +        if (segment_type == PRESENTATION_SEGMENT && !ctx-
> > > presentation_found) {
> > +            int object_count;
> > +            ctx->presentation_found = 1;
> > +            ret = av_packet_copy_props(pkt, in);
> > +            if (ret < 0)
> > +                goto fail;
> > +            object_count  = in->data[i + 13];
> > +            pkt->flags = !!object_count * AV_PKT_FLAG_KEY;
> > +        }
> > +        i += segment_len;
> > +        if (segment_type == DISPLAY_SEGMENT) {
> > +            size = display = i;
> > +            break;
> > +        }
> > +    }
> > +    if (display && pkt->size == 0 && size == in->size) { //
> > passthrough
> > +        av_packet_move_ref(out, in);
> > +        return 0;
> > +    }
> > +    if ((!display && i != in->size) || size > in->size) {
> > +        av_log(bsf, AV_LOG_WARNING, "Failed to parse PGS
> > segments.\n");
> > +        // force output what we have
> > +        display = size = in->size;
> > +    }
> > +
> > +    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;
> > +        av_packet_move_ref(out, pkt);
> > +        return 0;
> > +    }
> > +    return AVERROR(EAGAIN);
> > +
> > +fail:
> > +    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,
> > +};


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