mirror of
https://git.ffmpeg.org/ffmpeg.git
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192 lines
5.5 KiB
C
192 lines
5.5 KiB
C
/*
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* Copyright (c) 2020 John Stebbins <jstebbins.hb@gmail.com>
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* This bitstream filter merges PGS subtitle packets containing incomplete
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* set of segments into a single packet
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*
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* Packets already containing a complete set of segments will be passed through
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* unchanged.
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*/
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#include "libavutil/attributes.h"
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#include "libavutil/intreadwrite.h"
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#include "libavutil/log.h"
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#include "bsf.h"
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#include "bsf_internal.h"
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enum PGSSegmentType {
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PALETTE_SEGMENT = 0x14,
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OBJECT_SEGMENT = 0x15,
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PRESENTATION_SEGMENT = 0x16,
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WINDOW_SEGMENT = 0x17,
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END_DISPLAY_SET_SEGMENT = 0x80,
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};
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typedef struct PGSMergeContext {
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AVPacket *buffer_pkt, *in;
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int presentation_found;
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int pkt_flags;
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} PGSMergeContext;
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static av_cold void frame_merge_flush(AVBSFContext *bsf)
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{
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PGSMergeContext *ctx = bsf->priv_data;
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ctx->presentation_found = ctx->pkt_flags = 0;
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av_packet_unref(ctx->in);
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av_packet_unref(ctx->buffer_pkt);
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}
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static int frame_merge_output(PGSMergeContext *ctx, AVPacket *dst, AVPacket *src)
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{
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if (!ctx->presentation_found)
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ctx->pkt_flags |= AV_PKT_FLAG_CORRUPT;
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ctx->presentation_found = 0;
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src->flags |= ctx->pkt_flags;
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ctx->pkt_flags = 0;
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av_packet_move_ref(dst, src);
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return 0;
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}
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static int frame_merge_filter(AVBSFContext *bsf, AVPacket *out)
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{
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PGSMergeContext *ctx = bsf->priv_data;
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AVPacket *in = ctx->in, *pkt = ctx->buffer_pkt;
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int ret, size, pos, display = 0, presentation = 0;
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unsigned int i;
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if (!in->data) {
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ret = ff_bsf_get_packet_ref(bsf, in);
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if (ret == AVERROR_EOF && pkt->data) {
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// Output remaining data
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ctx->pkt_flags |= AV_PKT_FLAG_CORRUPT;
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return frame_merge_output(ctx, out, pkt);
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}
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if (ret < 0)
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return ret;
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}
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if (!in->size) {
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av_packet_unref(in);
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return AVERROR(EAGAIN);
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}
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in->flags &= ~AV_PKT_FLAG_KEY; // Will be detected in the stream
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// Validate packet data and find display_end segment
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size = in->size;
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i = 0;
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while (i + 3 <= in->size) {
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uint8_t segment_type = in->data[i];
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int segment_len = AV_RB16(in->data + i + 1) + 3;
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if (i + segment_len > in->size)
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break; // Invalid, segments can't span packets
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if (segment_type == PRESENTATION_SEGMENT && ctx->presentation_found)
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break; // Invalid, there can be only one
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if (segment_type == PRESENTATION_SEGMENT) {
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uint8_t state;
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if (segment_len < 11)
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break; // Invalid presentation segment length
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ctx->presentation_found = presentation = 1;
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state = in->data[i + 10] & 0xc0;
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if (state)
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ctx->pkt_flags |= AV_PKT_FLAG_KEY;
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else
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ctx->pkt_flags &= ~AV_PKT_FLAG_KEY;
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}
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i += segment_len;
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if (segment_type == END_DISPLAY_SET_SEGMENT) {
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size = i;
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display = 1;
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break;
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}
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}
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if (display && pkt->size == 0 && size == in->size) // passthrough
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return frame_merge_output(ctx, out, in);
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if (!display && i != in->size) {
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av_log(bsf, AV_LOG_WARNING, "Failed to parse PGS segments.\n");
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// force output what we have
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size = in->size;
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display = 1;
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ctx->pkt_flags |= AV_PKT_FLAG_CORRUPT;
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}
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if (presentation) {
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ret = av_packet_copy_props(pkt, in);
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if (ret < 0)
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goto fail;
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}
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pos = pkt->size;
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ret = av_grow_packet(pkt, size);
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if (ret < 0)
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goto fail;
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memcpy(pkt->data + pos, in->data, size);
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if (size == in->size)
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av_packet_unref(in);
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else {
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in->data += size;
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in->size -= size;
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}
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if (display)
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return frame_merge_output(ctx, out, pkt);
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return AVERROR(EAGAIN);
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fail:
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frame_merge_flush(bsf);
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return ret;
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}
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static av_cold int frame_merge_init(AVBSFContext *bsf)
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{
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PGSMergeContext *ctx = bsf->priv_data;
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ctx->in = av_packet_alloc();
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ctx->buffer_pkt = av_packet_alloc();
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if (!ctx->in || !ctx->buffer_pkt)
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return AVERROR(ENOMEM);
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return 0;
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}
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static av_cold void frame_merge_close(AVBSFContext *bsf)
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{
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PGSMergeContext *ctx = bsf->priv_data;
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av_packet_free(&ctx->in);
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av_packet_free(&ctx->buffer_pkt);
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}
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static const enum AVCodecID frame_merge_codec_ids[] = {
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AV_CODEC_ID_HDMV_PGS_SUBTITLE, AV_CODEC_ID_NONE,
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};
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const FFBitStreamFilter ff_pgs_frame_merge_bsf = {
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.p.name = "pgs_frame_merge",
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.p.codec_ids = frame_merge_codec_ids,
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.priv_data_size = sizeof(PGSMergeContext),
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.init = frame_merge_init,
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.flush = frame_merge_flush,
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.close = frame_merge_close,
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.filter = frame_merge_filter,
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};
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