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[FFmpeg-devel,2/5] lavc/pgs_frame_split_bsf: add bsf to split PGS segments

Message ID 20200508141128.2684843-3-jstebbins@jetheaddev.com
State New
Headers show
Series [FFmpeg-devel,1/5] lavc/pgs_frame_merge_bsf: add bsf to merge PGS segments
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Commit Message

John Stebbins May 8, 2020, 2:11 p.m. UTC
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 | 179 +++++++++++++++++++++++++++++++
 5 files changed, 190 insertions(+)
 create mode 100644 libavcodec/pgs_frame_split_bsf.c
diff mbox series

Patch

diff --git a/Changelog b/Changelog
index 0b108e548f..7564a55220 100644
--- a/Changelog
+++ b/Changelog
@@ -67,6 +67,7 @@  version <next>:
 - Pro Pinball Series Soundbank demuxer
 - pcm_rechunk bitstream filter
 - 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 de2ddcacc4..5b992b1a5d 100644
--- a/doc/bitstream_filters.texi
+++ b/doc/bitstream_filters.texi
@@ -586,6 +586,14 @@  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 1a3c411a81..a011e7c3ba 100644
--- a/libavcodec/Makefile
+++ b/libavcodec/Makefile
@@ -1119,6 +1119,7 @@  OBJS-$(CONFIG_NULL_BSF)                   += null_bsf.o
 OBJS-$(CONFIG_OPUS_METADATA_BSF)          += opus_metadata_bsf.o
 OBJS-$(CONFIG_PCM_RECHUNK_BSF)            += pcm_rechunk_bsf.o
 OBJS-$(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 b4a9388ee2..7c79bc3e4b 100644
--- a/libavcodec/bitstream_filters.c
+++ b/libavcodec/bitstream_filters.c
@@ -52,6 +52,7 @@  extern const AVBitStreamFilter ff_null_bsf;
 extern const AVBitStreamFilter ff_opus_metadata_bsf;
 extern const AVBitStreamFilter ff_pcm_rechunk_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..cb60f59a87
--- /dev/null
+++ b/libavcodec/pgs_frame_split_bsf.c
@@ -0,0 +1,179 @@ 
+/*
+ * 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 "libavutil/log.h"
+#include "avcodec.h"
+#include "bsf.h"
+#include "libavutil/intreadwrite.h"
+
+enum PGSSegmentType {
+    PALETTE_SEGMENT         = 0x14,
+    OBJECT_SEGMENT          = 0x15,
+    PRESENTATION_SEGMENT    = 0x16,
+    WINDOW_SEGMENT          = 0x17,
+    END_DISPLAY_SET_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 ret;
+    unsigned int i;
+    uint8_t segment_type;
+    int 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);
+        out->flags |= AV_PKT_FLAG_CORRUPT;
+        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 END_DISPLAY_SET_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,
+};