FFmpeg coverage

Directory: ../../../ffmpeg/
File: src/libavcodec/mpeg4video_parser.c
Date: 2025-11-29 19:14:23
Exec Total Coverage
Lines: 67 69 97.1%
Functions: 4 4 100.0%
Branches: 40 46 87.0%
Line Branch Exec Source
1 /*
2 * MPEG-4 video frame extraction
3 * Copyright (c) 2003 Fabrice Bellard
4 * Copyright (c) 2003 Michael Niedermayer
5 *
6 * This file is part of FFmpeg.
7 *
8 * FFmpeg is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
12 *
13 * FFmpeg is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
17 *
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with FFmpeg; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 */
22
23 #define UNCHECKED_BITSTREAM_READER 1
24
25 #include "decode.h"
26 #include "parser.h"
27 #include "mpegvideo.h"
28 #include "mpeg4videodec.h"
29 #include "mpeg4videodefs.h"
30 #include "parser_internal.h"
31
32 struct Mp4vParseContext {
33 ParseContext pc;
34 Mpeg4DecContext dec_ctx;
35 int first_picture;
36 };
37
38 /**
39 * Find the end of the current frame in the bitstream.
40 * @return the position of the first byte of the next frame, or -1
41 */
42 8488 static int mpeg4_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size)
43 {
44 int vop_found, i;
45 uint32_t state;
46
47 8488 vop_found = pc->frame_start_found;
48 8488 state = pc->state;
49
50 8488 i = 0;
51
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 8488 if (!vop_found) {
52
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 8483 for (i = 0; i < buf_size; i++) {
53 8481 state = (state << 8) | buf[i];
54
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 8481 if (state == VOP_STARTCODE) {
55 1086 i++;
56 1086 vop_found = 1;
57 1086 break;
58 }
59 }
60 }
61
62
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 8488 if (vop_found) {
63 /* EOF considered as end of frame */
64
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 8486 if (buf_size == 0)
65 26 return 0;
66
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 8769521 for (; i < buf_size; i++) {
67 8762134 state = (state << 8) | buf[i];
68
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 8762134 if ((state & 0xFFFFFF00) == 0x100) {
69
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 1103 if (state == SLICE_STARTCODE || state == EXT_STARTCODE)
70 30 continue;
71 1073 pc->frame_start_found = 0;
72 1073 pc->state = -1;
73 1073 return i - 3;
74 }
75 }
76 }
77 7389 pc->frame_start_found = vop_found;
78 7389 pc->state = state;
79 7389 return END_NOT_FOUND;
80 }
81
82 /* XXX: make it use less memory */
83 3601 static int mpeg4_decode_header(AVCodecParserContext *s1, AVCodecContext *avctx,
84 const uint8_t *buf, int buf_size)
85 {
86 3601 struct Mp4vParseContext *pc = s1->priv_data;
87 3601 Mpeg4DecContext *dec_ctx = &pc->dec_ctx;
88 3601 MPVContext *const s = &dec_ctx->h.c;
89 3601 GetBitContext gb1, *gb = &gb1;
90 int ret;
91
92 3601 s->avctx = avctx;
93
94
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 3601 if (avctx->extradata_size && pc->first_picture) {
95 241 init_get_bits(gb, avctx->extradata, avctx->extradata_size * 8);
96 241 ret = ff_mpeg4_parse_picture_header(dec_ctx, gb, 1, 1);
97
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 241 if (ret < 0)
98 ✗ av_log(avctx, AV_LOG_WARNING, "Failed to parse extradata\n");
99 }
100
101 3601 init_get_bits(gb, buf, 8 * buf_size);
102 3601 ret = ff_mpeg4_parse_picture_header(dec_ctx, gb, 0, 1);
103 3601 avctx->has_b_frames = !s->low_delay;
104
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 3601 if (s->width && (!avctx->width || !avctx->height ||
105
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 3536 !avctx->coded_width || !avctx->coded_height)) {
106 82 ret = ff_set_dimensions(avctx, s->width, s->height);
107
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 82 if (ret < 0)
108 ✗ return ret;
109 }
110
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 3601 if((s1->flags & PARSER_FLAG_USE_CODEC_TS) && s->avctx->framerate.num>0 && ret>=0){
111 av_assert1(s1->pts == AV_NOPTS_VALUE);
112 av_assert1(s1->dts == AV_NOPTS_VALUE);
113
114 875 s1->pts = av_rescale_q(s->time, (AVRational){1, s->avctx->framerate.num}, (AVRational){1, 1200000});
115 }
116
117 3601 s1->pict_type = s->pict_type;
118 3601 pc->first_picture = 0;
119 3601 return ret;
120 }
121
122 337 static av_cold int mpeg4video_parse_init(AVCodecParserContext *s)
123 {
124 337 struct Mp4vParseContext *pc = s->priv_data;
125
126 337 pc->first_picture = 1;
127 337 pc->dec_ctx.quant_precision = 5;
128 337 pc->dec_ctx.h.c.slice_context_count = 1;
129 337 pc->dec_ctx.showed_packed_warning = 1;
130 337 return 0;
131 }
132
133 10990 static int mpeg4video_parse(AVCodecParserContext *s,
134 AVCodecContext *avctx,
135 const uint8_t **poutbuf, int *poutbuf_size,
136 const uint8_t *buf, int buf_size)
137 {
138 10990 ParseContext *pc = s->priv_data;
139 int next;
140
141
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 10990 if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
142 2502 next = buf_size;
143 } else {
144 8488 next = mpeg4_find_frame_end(pc, buf, buf_size);
145
146
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 8488 if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
147 7389 *poutbuf = NULL;
148 7389 *poutbuf_size = 0;
149 7389 return buf_size;
150 }
151 }
152 3601 mpeg4_decode_header(s, avctx, buf, buf_size);
153
154 3601 *poutbuf = buf;
155 3601 *poutbuf_size = buf_size;
156 3601 return next;
157 }
158
159 const FFCodecParser ff_mpeg4video_parser = {
160 PARSER_CODEC_LIST(AV_CODEC_ID_MPEG4),
161 .priv_data_size = sizeof(struct Mp4vParseContext),
162 .init = mpeg4video_parse_init,
163 .parse = mpeg4video_parse,
164 .close = ff_parse_close,
165 };
166