FFmpeg coverage

Directory: ../../../ffmpeg/
File: src/libavcodec/mjpegbdec.c
Date: 2026-04-24 19:58:39
Exec Total Coverage
Lines: 63 77 81.8%
Functions: 2 2 100.0%
Branches: 20 40 50.0%
Line Branch Exec Source
1 /*
2 * Apple MJPEG-B decoder
3 * Copyright (c) 2002 Alex Beregszaszi
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 /**
23 * @file
24 * Apple MJPEG-B decoder.
25 */
26
27 #include <inttypes.h>
28
29 #include "avcodec.h"
30 #include "codec_internal.h"
31 #include "mjpeg.h"
32 #include "mjpegdec.h"
33
34 192 static uint32_t read_offs(AVCodecContext *avctx, GetBitContext *gb, uint32_t size, const char *err_msg){
35 192 uint32_t offs= get_bits_long(gb, 32);
36
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 192 if(offs >= size){
37 ✗ av_log(avctx, AV_LOG_WARNING, err_msg, offs, size);
38 ✗ return 0;
39 }
40 192 return offs;
41 }
42
43 16 static int mjpegb_decode_frame(AVCodecContext *avctx, AVFrame *rframe,
44 int *got_frame, AVPacket *avpkt)
45 {
46 16 const uint8_t *buf = avpkt->data;
47 16 int buf_size = avpkt->size;
48 16 MJpegDecodeContext *s = avctx->priv_data;
49 const uint8_t *buf_end, *buf_ptr;
50 GetBitContext hgb; /* for the header */
51 uint32_t dqt_offs, dht_offs, sof_offs, sos_offs, second_field_offs;
52 uint32_t field_size, sod_offs;
53 int ret;
54
55 16 buf_ptr = buf;
56 16 buf_end = buf + buf_size;
57 16 s->got_picture = 0;
58 16 s->adobe_transform = -1;
59 16 s->buf_size = buf_size;
60
61 32 read_header:
62 /* reset on every SOI */
63 32 s->restart_interval = 0;
64 32 s->mjpb_skiptosod = 0;
65
66
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 32 if ((ret = init_get_bits8(&hgb, buf_ptr, /*buf_size*/(buf_end - buf_ptr))) < 0)
67 ✗ return ret;
68
69 32 skip_bits(&hgb, 32); /* reserved zeros */
70
71
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 32 if (get_bits_long(&hgb, 32) != MKBETAG('m','j','p','g')) {
72 ✗ av_log(avctx, AV_LOG_WARNING, "not mjpeg-b (bad fourcc)\n");
73 ✗ return AVERROR_INVALIDDATA;
74 }
75
76 32 field_size = get_bits_long(&hgb, 32); /* field size */
77 32 av_log(avctx, AV_LOG_DEBUG, "field size: 0x%"PRIx32"\n", field_size);
78 32 skip_bits(&hgb, 32); /* padded field size */
79 32 second_field_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "second_field_offs is %d and size is %d\n");
80 32 av_log(avctx, AV_LOG_DEBUG, "second field offs: 0x%"PRIx32"\n",
81 second_field_offs);
82
83 32 dqt_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dqt is %d and size is %d\n");
84 32 av_log(avctx, AV_LOG_DEBUG, "dqt offs: 0x%"PRIx32"\n", dqt_offs);
85
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 32 if (dqt_offs) {
86 32 bytestream2_init(&s->gB, buf_ptr+dqt_offs, buf_end - (buf_ptr+dqt_offs));
87 32 ret = ff_mjpeg_decode_dqt(s);
88
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 32 if (ret < 0 && (avctx->err_recognition & AV_EF_EXPLODE))
89 ✗ return ret;
90 }
91
92 32 dht_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dht is %d and size is %d\n");
93 32 av_log(avctx, AV_LOG_DEBUG, "dht offs: 0x%"PRIx32"\n", dht_offs);
94
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 32 if (dht_offs) {
95 22 bytestream2_init(&s->gB, buf_ptr+dht_offs, buf_end - (buf_ptr+dht_offs));
96 22 ff_mjpeg_decode_dht(s);
97 }
98
99 32 sof_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n");
100 32 av_log(avctx, AV_LOG_DEBUG, "sof offs: 0x%"PRIx32"\n", sof_offs);
101
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 32 if (sof_offs) {
102 32 bytestream2_init(&s->gB, buf_ptr+sof_offs, buf_end - (buf_ptr+sof_offs));
103
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 32 if ((ret = ff_mjpeg_decode_sof(s)) < 0)
104 ✗ return ret;
105 }
106
107 32 sos_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sos is %d and size is %d\n");
108 32 av_log(avctx, AV_LOG_DEBUG, "sos offs: 0x%"PRIx32"\n", sos_offs);
109 32 sod_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n");
110 32 av_log(avctx, AV_LOG_DEBUG, "sod offs: 0x%"PRIx32"\n", sod_offs);
111
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 32 if (sos_offs) {
112 32 bytestream2_init(&s->gB, buf_ptr+sos_offs,
113 32 FFMIN(field_size, buf_end - buf_ptr - sos_offs));
114 32 s->mjpb_skiptosod = (sod_offs - sos_offs - bytestream2_peek_be16(&s->gB));
115
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 32 if (avctx->skip_frame == AVDISCARD_ALL) {
116 ✗ bytestream2_skipu(&s->gB, bytestream2_get_bytes_left(&s->gB));
117 } else {
118 32 ret = ff_mjpeg_decode_sos(s);
119
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 32 if (ret < 0 && (avctx->err_recognition & AV_EF_EXPLODE))
120 ✗ return ret;
121 }
122 }
123
124
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 32 if (s->interlaced) {
125 32 s->bottom_field ^= 1;
126 /* if not bottom field, do not output image yet */
127
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 32 if (s->bottom_field != s->interlace_polarity && second_field_offs) {
128 16 buf_ptr = buf + second_field_offs;
129 16 goto read_header;
130 }
131 }
132
133 //XXX FIXME factorize, this looks very similar to the EOI code
134
135
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 16 if(!s->got_picture) {
136 ✗ av_log(avctx, AV_LOG_WARNING, "no picture\n");
137 ✗ return buf_size;
138 }
139 16 av_frame_move_ref(rframe, s->picture_ptr);
140 16 s->got_picture = 0;
141
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 16 if (avctx->skip_frame == AVDISCARD_ALL)
142 ✗ return buf_size;
143 16 *got_frame = 1;
144
145
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 16 if (!s->lossless && avctx->debug & FF_DEBUG_QP) {
146 ✗ av_log(avctx, AV_LOG_DEBUG, "QP: %d\n",
147 ✗ FFMAX3(s->qscale[0], s->qscale[1], s->qscale[2]));
148 }
149
150 16 return buf_size;
151 }
152
153 const FFCodec ff_mjpegb_decoder = {
154 .p.name = "mjpegb",
155 CODEC_LONG_NAME("Apple MJPEG-B"),
156 .p.type = AVMEDIA_TYPE_VIDEO,
157 .p.id = AV_CODEC_ID_MJPEGB,
158 .priv_data_size = sizeof(MJpegDecodeContext),
159 .init = ff_mjpeg_decode_init,
160 .close = ff_mjpeg_decode_end,
161 FF_CODEC_DECODE_CB(mjpegb_decode_frame),
162 .p.capabilities = AV_CODEC_CAP_DR1,
163 .p.max_lowres = 3,
164 .caps_internal = FF_CODEC_CAP_INIT_CLEANUP,
165 };
166
167 const FFCodec ff_media100_decoder = {
168 .p.name = "media100",
169 CODEC_LONG_NAME("Media 100"),
170 .p.type = AVMEDIA_TYPE_VIDEO,
171 .p.id = AV_CODEC_ID_MEDIA100,
172 .priv_data_size = sizeof(MJpegDecodeContext),
173 .init = ff_mjpeg_decode_init,
174 .close = ff_mjpeg_decode_end,
175 FF_CODEC_DECODE_CB(mjpegb_decode_frame),
176 .p.capabilities = AV_CODEC_CAP_DR1,
177 .p.max_lowres = 3,
178 .caps_internal = FF_CODEC_CAP_INIT_CLEANUP,
179 .bsfs = "media100_to_mjpegb",
180 };
181