FFmpeg coverage

Directory: ../../../ffmpeg/
File: src/libavcodec/bsf/pgs_frame_merge.c
Date: 2025-11-10 11:20:04
Exec Total Coverage
Lines: 64 89 71.9%
Functions: 4 5 80.0%
Branches: 38 52 73.1%
Line Branch Exec Source
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 6 static int frame_merge_output(PGSMergeContext *ctx, AVPacket *dst, AVPacket *src)
60 {
61
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 6 if (!ctx->presentation_found)
62 ✗ ctx->pkt_flags |= AV_PKT_FLAG_CORRUPT;
63 6 ctx->presentation_found = 0;
64 6 src->flags |= ctx->pkt_flags;
65 6 ctx->pkt_flags = 0;
66 6 av_packet_move_ref(dst, src);
67 6 return 0;
68 }
69
70 31 static int frame_merge_filter(AVBSFContext *bsf, AVPacket *out)
71 {
72 31 PGSMergeContext *ctx = bsf->priv_data;
73 31 AVPacket *in = ctx->in, *pkt = ctx->buffer_pkt;
74 31 int ret, size, pos, display = 0, presentation = 0;
75 unsigned int i;
76
77
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 31 if (!in->data) {
78 31 ret = ff_bsf_get_packet_ref(bsf, in);
79
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 31 if (ret == AVERROR_EOF && pkt->data) {
80 // Output remaining data
81 3 ctx->pkt_flags |= AV_PKT_FLAG_CORRUPT;
82 3 return frame_merge_output(ctx, out, pkt);
83 }
84
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 28 if (ret < 0)
85 6 return ret;
86 }
87
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 22 if (!in->size) {
88 ✗ av_packet_unref(in);
89 ✗ return AVERROR(EAGAIN);
90 }
91 22 in->flags &= ~AV_PKT_FLAG_KEY; // Will be detected in the stream
92
93 // Validate packet data and find display_end segment
94 22 size = in->size;
95 22 i = 0;
96
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 49 while (i + 3 <= in->size) {
97 30 uint8_t segment_type = in->data[i];
98 30 int segment_len = AV_RB16(in->data + i + 1) + 3;
99
100
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 30 if (i + segment_len > in->size)
101 ✗ break; // Invalid, segments can't span packets
102
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 30 if (segment_type == PRESENTATION_SEGMENT && ctx->presentation_found)
103 ✗ break; // Invalid, there can be only one
104
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 30 if (segment_type == PRESENTATION_SEGMENT) {
105 uint8_t state;
106
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 6 if (segment_len < 11)
107 ✗ break; // Invalid presentation segment length
108 6 ctx->presentation_found = presentation = 1;
109 6 state = in->data[i + 10] & 0xc0;
110
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 6 if (state)
111 6 ctx->pkt_flags |= AV_PKT_FLAG_KEY;
112 else
113 ✗ ctx->pkt_flags &= ~AV_PKT_FLAG_KEY;
114 }
115 30 i += segment_len;
116
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 30 if (segment_type == END_DISPLAY_SET_SEGMENT) {
117 3 size = i;
118 3 display = 1;
119 3 break;
120 }
121 }
122
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 22 if (display && pkt->size == 0 && size == in->size) // passthrough
123 1 return frame_merge_output(ctx, out, in);
124
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 21 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
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 21 if (presentation) {
133 5 ret = av_packet_copy_props(pkt, in);
134
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 5 if (ret < 0)
135 ✗ goto fail;
136 }
137 21 pos = pkt->size;
138 21 ret = av_grow_packet(pkt, size);
139
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 21 if (ret < 0)
140 ✗ goto fail;
141 21 memcpy(pkt->data + pos, in->data, size);
142
143
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 21 if (size == in->size)
144 21 av_packet_unref(in);
145 else {
146 ✗ in->data += size;
147 ✗ in->size -= size;
148 }
149
150
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 21 if (display)
151 2 return frame_merge_output(ctx, out, pkt);
152 19 return AVERROR(EAGAIN);
153
154 ✗ fail:
155 ✗ frame_merge_flush(bsf);
156 ✗ return ret;
157 }
158
159 3 static av_cold int frame_merge_init(AVBSFContext *bsf)
160 {
161 3 PGSMergeContext *ctx = bsf->priv_data;
162
163 3 ctx->in = av_packet_alloc();
164 3 ctx->buffer_pkt = av_packet_alloc();
165
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 3 if (!ctx->in || !ctx->buffer_pkt)
166 ✗ return AVERROR(ENOMEM);
167
168 3 return 0;
169 }
170
171 3 static av_cold void frame_merge_close(AVBSFContext *bsf)
172 {
173 3 PGSMergeContext *ctx = bsf->priv_data;
174
175 3 av_packet_free(&ctx->in);
176 3 av_packet_free(&ctx->buffer_pkt);
177 3 }
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 };
192