| /* |
| * 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 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 "libavutil/attributes.h" |
| #include "libavutil/intreadwrite.h" |
| #include "libavutil/log.h" |
| #include "bsf.h" |
| #include "bsf_internal.h" |
| |
| enum PGSSegmentType { |
| PALETTE_SEGMENT = 0x14, |
| OBJECT_SEGMENT = 0x15, |
| PRESENTATION_SEGMENT = 0x16, |
| WINDOW_SEGMENT = 0x17, |
| END_DISPLAY_SET_SEGMENT = 0x80, |
| }; |
| |
| typedef struct PGSMergeContext { |
| AVPacket *buffer_pkt, *in; |
| int presentation_found; |
| int pkt_flags; |
| } PGSMergeContext; |
| |
| static av_cold void frame_merge_flush(AVBSFContext *bsf) |
| { |
| PGSMergeContext *ctx = bsf->priv_data; |
| |
| ctx->presentation_found = ctx->pkt_flags = 0; |
| av_packet_unref(ctx->in); |
| av_packet_unref(ctx->buffer_pkt); |
| } |
| |
| static int frame_merge_output(PGSMergeContext *ctx, AVPacket *dst, AVPacket *src) |
| { |
| if (!ctx->presentation_found) |
| ctx->pkt_flags |= AV_PKT_FLAG_CORRUPT; |
| ctx->presentation_found = 0; |
| src->flags |= ctx->pkt_flags; |
| ctx->pkt_flags = 0; |
| av_packet_move_ref(dst, src); |
| return 0; |
| } |
| |
| static int frame_merge_filter(AVBSFContext *bsf, AVPacket *out) |
| { |
| PGSMergeContext *ctx = bsf->priv_data; |
| AVPacket *in = ctx->in, *pkt = ctx->buffer_pkt; |
| int ret, size, pos, display = 0, presentation = 0; |
| unsigned int i; |
| |
| if (!in->data) { |
| ret = ff_bsf_get_packet_ref(bsf, in); |
| if (ret == AVERROR_EOF && pkt->data) { |
| // Output remaining data |
| ctx->pkt_flags |= AV_PKT_FLAG_CORRUPT; |
| return frame_merge_output(ctx, out, pkt); |
| } |
| if (ret < 0) |
| return ret; |
| } |
| if (!in->size) { |
| av_packet_unref(in); |
| return AVERROR(EAGAIN); |
| } |
| in->flags &= ~AV_PKT_FLAG_KEY; // Will be detected in the stream |
| |
| // Validate packet data and find display_end segment |
| size = in->size; |
| i = 0; |
| while (i + 3 <= in->size) { |
| uint8_t segment_type = in->data[i]; |
| int segment_len = AV_RB16(in->data + i + 1) + 3; |
| |
| if (i + segment_len > in->size) |
| break; // Invalid, segments can't span packets |
| if (segment_type == PRESENTATION_SEGMENT && ctx->presentation_found) |
| break; // Invalid, there can be only one |
| if (segment_type == PRESENTATION_SEGMENT) { |
| uint8_t state; |
| if (segment_len < 11) |
| break; // Invalid presentation segment length |
| ctx->presentation_found = presentation = 1; |
| state = in->data[i + 10] & 0xc0; |
| if (state) |
| ctx->pkt_flags |= AV_PKT_FLAG_KEY; |
| else |
| ctx->pkt_flags &= ~AV_PKT_FLAG_KEY; |
| } |
| i += segment_len; |
| if (segment_type == END_DISPLAY_SET_SEGMENT) { |
| size = i; |
| display = 1; |
| break; |
| } |
| } |
| if (display && pkt->size == 0 && size == in->size) // passthrough |
| return frame_merge_output(ctx, out, in); |
| if (!display && i != in->size) { |
| av_log(bsf, AV_LOG_WARNING, "Failed to parse PGS segments.\n"); |
| // force output what we have |
| size = in->size; |
| display = 1; |
| ctx->pkt_flags |= AV_PKT_FLAG_CORRUPT; |
| } |
| |
| if (presentation) { |
| ret = av_packet_copy_props(pkt, in); |
| if (ret < 0) |
| goto fail; |
| } |
| 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) |
| return frame_merge_output(ctx, out, pkt); |
| return AVERROR(EAGAIN); |
| |
| fail: |
| frame_merge_flush(bsf); |
| return ret; |
| } |
| |
| static av_cold 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 av_cold 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 FFBitStreamFilter ff_pgs_frame_merge_bsf = { |
| .p.name = "pgs_frame_merge", |
| .p.codec_ids = frame_merge_codec_ids, |
| .priv_data_size = sizeof(PGSMergeContext), |
| .init = frame_merge_init, |
| .flush = frame_merge_flush, |
| .close = frame_merge_close, |
| .filter = frame_merge_filter, |
| }; |