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| | 1 | /* |
| | 2 | * Copyright (c) 2020 John Stebbins <jstebbins.hb@gmail.com> |
| | 3 | * |
| | 4 | * This file is part of FFmpeg. |
| | 5 | * |
| | 6 | * FFmpeg is free software; you can redistribute it and/or |
| | 7 | * modify it under the terms of the GNU Lesser General Public |
| | 8 | * License as published by the Free Software Foundation; either |
| | 9 | * version 2.1 of the License, or (at your option) any later version. |
| | 10 | * |
| | 11 | * FFmpeg is distributed in the hope that it will be useful, |
| | 12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| | 13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| | 14 | * Lesser General Public License for more details. |
| | 15 | * |
| | 16 | * You should have received a copy of the GNU Lesser General Public |
| | 17 | * License along with FFmpeg; if not, write to the Free Software |
| | 18 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| | 19 | */ |
| | 20 | |
| | 21 | /** |
| | 22 | * @file |
| | 23 | * This bitstream filter merges PGS subtitle packets containing incomplete |
| | 24 | * set of segments into a single packet |
| | 25 | * |
| | 26 | * Packets already containing a complete set of segments will be passed through |
| | 27 | * unchanged. |
| | 28 | */ |
| | 29 | |
| | 30 | #include "libavutil/attributes.h" |
| | 31 | #include "libavutil/intreadwrite.h" |
| | 32 | #include "libavutil/log.h" |
| | 33 | #include "bsf.h" |
| | 34 | #include "bsf_internal.h" |
| | 35 | |
| | 36 | enum PGSSegmentType { |
| | 37 | PALETTE_SEGMENT = 0x14, |
| | 38 | OBJECT_SEGMENT = 0x15, |
| | 39 | PRESENTATION_SEGMENT = 0x16, |
| | 40 | WINDOW_SEGMENT = 0x17, |
| | 41 | END_DISPLAY_SET_SEGMENT = 0x80, |
| | 42 | }; |
| | 43 | |
| | 44 | typedef struct PGSMergeContext { |
| | 45 | AVPacket *buffer_pkt, *in; |
| | 46 | int presentation_found; |
| | 47 | int pkt_flags; |
| | 48 | } PGSMergeContext; |
| | 49 | |
| | 50 | static av_cold void frame_merge_flush(AVBSFContext *bsf) |
| | 51 | { |
| | 52 | PGSMergeContext *ctx = bsf->priv_data; |
| | 53 | |
| | 54 | ctx->presentation_found = ctx->pkt_flags = 0; |
| | 55 | av_packet_unref(ctx->in); |
| | 56 | av_packet_unref(ctx->buffer_pkt); |
| | 57 | } |
| | 58 | |
| | 59 | static int frame_merge_output(PGSMergeContext *ctx, AVPacket *dst, AVPacket *src) |
| | 60 | { |
| | 61 | if (!ctx->presentation_found) |
| | 62 | ctx->pkt_flags |= AV_PKT_FLAG_CORRUPT; |
| | 63 | ctx->presentation_found = 0; |
| | 64 | src->flags |= ctx->pkt_flags; |
| | 65 | ctx->pkt_flags = 0; |
| | 66 | av_packet_move_ref(dst, src); |
| | 67 | return 0; |
| | 68 | } |
| | 69 | |
| | 70 | static int frame_merge_filter(AVBSFContext *bsf, AVPacket *out) |
| | 71 | { |
| | 72 | PGSMergeContext *ctx = bsf->priv_data; |
| | 73 | AVPacket *in = ctx->in, *pkt = ctx->buffer_pkt; |
| | 74 | int ret, size, pos, display = 0, presentation = 0; |
| | 75 | unsigned int i; |
| | 76 | |
| | 77 | if (!in->data) { |
| | 78 | ret = ff_bsf_get_packet_ref(bsf, in); |
| | 79 | if (ret == AVERROR_EOF && pkt->data) { |
| | 80 | // Output remaining data |
| | 81 | ctx->pkt_flags |= AV_PKT_FLAG_CORRUPT; |
| | 82 | return frame_merge_output(ctx, out, pkt); |
| | 83 | } |
| | 84 | if (ret < 0) |
| | 85 | return ret; |
| | 86 | } |
| | 87 | if (!in->size) { |
| | 88 | av_packet_unref(in); |
| | 89 | return AVERROR(EAGAIN); |
| | 90 | } |
| | 91 | in->flags &= ~AV_PKT_FLAG_KEY; // Will be detected in the stream |
| | 92 | |
| | 93 | // Validate packet data and find display_end segment |
| | 94 | size = in->size; |
| | 95 | i = 0; |
| | 96 | while (i + 3 <= in->size) { |
| | 97 | uint8_t segment_type = in->data[i]; |
| | 98 | int segment_len = AV_RB16(in->data + i + 1) + 3; |
| | 99 | |
| | 100 | if (i + segment_len > in->size) |
| | 101 | break; // Invalid, segments can't span packets |
| | 102 | if (segment_type == PRESENTATION_SEGMENT && ctx->presentation_found) |
| | 103 | break; // Invalid, there can be only one |
| | 104 | if (segment_type == PRESENTATION_SEGMENT) { |
| | 105 | uint8_t state; |
| | 106 | if (segment_len < 11) |
| | 107 | break; // Invalid presentation segment length |
| | 108 | ctx->presentation_found = presentation = 1; |
| | 109 | state = in->data[i + 10] & 0xc0; |
| | 110 | if (state) |
| | 111 | ctx->pkt_flags |= AV_PKT_FLAG_KEY; |
| | 112 | else |
| | 113 | ctx->pkt_flags &= ~AV_PKT_FLAG_KEY; |
| | 114 | } |
| | 115 | i += segment_len; |
| | 116 | if (segment_type == END_DISPLAY_SET_SEGMENT) { |
| | 117 | size = i; |
| | 118 | display = 1; |
| | 119 | break; |
| | 120 | } |
| | 121 | } |
| | 122 | if (display && pkt->size == 0 && size == in->size) // passthrough |
| | 123 | return frame_merge_output(ctx, out, in); |
| | 124 | if (!display && i != in->size) { |
| | 125 | av_log(bsf, AV_LOG_WARNING, "Failed to parse PGS segments.\n"); |
| | 126 | // force output what we have |
| | 127 | size = in->size; |
| | 128 | display = 1; |
| | 129 | ctx->pkt_flags |= AV_PKT_FLAG_CORRUPT; |
| | 130 | } |
| | 131 | |
| | 132 | if (presentation) { |
| | 133 | ret = av_packet_copy_props(pkt, in); |
| | 134 | if (ret < 0) |
| | 135 | goto fail; |
| | 136 | } |
| | 137 | pos = pkt->size; |
| | 138 | ret = av_grow_packet(pkt, size); |
| | 139 | if (ret < 0) |
| | 140 | goto fail; |
| | 141 | memcpy(pkt->data + pos, in->data, size); |
| | 142 | |
| | 143 | if (size == in->size) |
| | 144 | av_packet_unref(in); |
| | 145 | else { |
| | 146 | in->data += size; |
| | 147 | in->size -= size; |
| | 148 | } |
| | 149 | |
| | 150 | if (display) |
| | 151 | return frame_merge_output(ctx, out, pkt); |
| | 152 | return AVERROR(EAGAIN); |
| | 153 | |
| | 154 | fail: |
| | 155 | frame_merge_flush(bsf); |
| | 156 | return ret; |
| | 157 | } |
| | 158 | |
| | 159 | static av_cold int frame_merge_init(AVBSFContext *bsf) |
| | 160 | { |
| | 161 | PGSMergeContext *ctx = bsf->priv_data; |
| | 162 | |
| | 163 | ctx->in = av_packet_alloc(); |
| | 164 | ctx->buffer_pkt = av_packet_alloc(); |
| | 165 | if (!ctx->in || !ctx->buffer_pkt) |
| | 166 | return AVERROR(ENOMEM); |
| | 167 | |
| | 168 | return 0; |
| | 169 | } |
| | 170 | |
| | 171 | static av_cold void frame_merge_close(AVBSFContext *bsf) |
| | 172 | { |
| | 173 | PGSMergeContext *ctx = bsf->priv_data; |
| | 174 | |
| | 175 | av_packet_free(&ctx->in); |
| | 176 | av_packet_free(&ctx->buffer_pkt); |
| | 177 | } |
| | 178 | |
| | 179 | static const enum AVCodecID frame_merge_codec_ids[] = { |
| | 180 | AV_CODEC_ID_HDMV_PGS_SUBTITLE, AV_CODEC_ID_NONE, |
| | 181 | }; |
| | 182 | |
| | 183 | const FFBitStreamFilter ff_pgs_frame_merge_bsf = { |
| | 184 | .p.name = "pgs_frame_merge", |
| | 185 | .p.codec_ids = frame_merge_codec_ids, |
| | 186 | .priv_data_size = sizeof(PGSMergeContext), |
| | 187 | .init = frame_merge_init, |
| | 188 | .flush = frame_merge_flush, |
| | 189 | .close = frame_merge_close, |
| | 190 | .filter = frame_merge_filter, |
| | 191 | }; |