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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 "mjpeg.h" | |
31 | #include "mjpegdec.h" | |
32 | ||
33 | static uint32_t read_offs(AVCodecContext *avctx, GetBitContext *gb, uint32_t size, const char *err_msg){ | |
34 | uint32_t offs= get_bits_long(gb, 32); | |
35 | if(offs >= size){ | |
36 | av_log(avctx, AV_LOG_WARNING, err_msg, offs, size); | |
37 | return 0; | |
38 | } | |
39 | return offs; | |
40 | } | |
41 | ||
42 | static int mjpegb_decode_frame(AVCodecContext *avctx, | |
43 | void *data, int *got_frame, | |
44 | AVPacket *avpkt) | |
45 | { | |
46 | const uint8_t *buf = avpkt->data; | |
47 | int buf_size = avpkt->size; | |
48 | 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 | buf_ptr = buf; | |
56 | buf_end = buf + buf_size; | |
57 | s->got_picture = 0; | |
58 | ||
59 | read_header: | |
60 | /* reset on every SOI */ | |
61 | s->restart_interval = 0; | |
62 | s->restart_count = 0; | |
63 | s->mjpb_skiptosod = 0; | |
64 | ||
65 | if (buf_end - buf_ptr >= 1 << 28) | |
66 | return AVERROR_INVALIDDATA; | |
67 | ||
68 | init_get_bits(&hgb, buf_ptr, /*buf_size*/(buf_end - buf_ptr)*8); | |
69 | ||
70 | skip_bits(&hgb, 32); /* reserved zeros */ | |
71 | ||
72 | if (get_bits_long(&hgb, 32) != MKBETAG('m','j','p','g')) | |
73 | { | |
74 | av_log(avctx, AV_LOG_WARNING, "not mjpeg-b (bad fourcc)\n"); | |
75 | return AVERROR_INVALIDDATA; | |
76 | } | |
77 | ||
78 | field_size = get_bits_long(&hgb, 32); /* field size */ | |
79 | av_log(avctx, AV_LOG_DEBUG, "field size: 0x%"PRIx32"\n", field_size); | |
80 | skip_bits(&hgb, 32); /* padded field size */ | |
81 | second_field_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "second_field_offs is %d and size is %d\n"); | |
82 | av_log(avctx, AV_LOG_DEBUG, "second field offs: 0x%"PRIx32"\n", | |
83 | second_field_offs); | |
84 | ||
85 | dqt_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dqt is %d and size is %d\n"); | |
86 | av_log(avctx, AV_LOG_DEBUG, "dqt offs: 0x%"PRIx32"\n", dqt_offs); | |
87 | if (dqt_offs) | |
88 | { | |
89 | init_get_bits(&s->gb, buf_ptr+dqt_offs, (buf_end - (buf_ptr+dqt_offs))*8); | |
90 | s->start_code = DQT; | |
91 | if (ff_mjpeg_decode_dqt(s) < 0 && | |
92 | (avctx->err_recognition & AV_EF_EXPLODE)) | |
93 | return AVERROR_INVALIDDATA; | |
94 | } | |
95 | ||
96 | dht_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dht is %d and size is %d\n"); | |
97 | av_log(avctx, AV_LOG_DEBUG, "dht offs: 0x%"PRIx32"\n", dht_offs); | |
98 | if (dht_offs) | |
99 | { | |
100 | init_get_bits(&s->gb, buf_ptr+dht_offs, (buf_end - (buf_ptr+dht_offs))*8); | |
101 | s->start_code = DHT; | |
102 | ff_mjpeg_decode_dht(s); | |
103 | } | |
104 | ||
105 | sof_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n"); | |
106 | av_log(avctx, AV_LOG_DEBUG, "sof offs: 0x%"PRIx32"\n", sof_offs); | |
107 | if (sof_offs) | |
108 | { | |
109 | init_get_bits(&s->gb, buf_ptr+sof_offs, (buf_end - (buf_ptr+sof_offs))*8); | |
110 | s->start_code = SOF0; | |
111 | if (ff_mjpeg_decode_sof(s) < 0) | |
112 | return -1; | |
113 | } | |
114 | ||
115 | sos_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sos is %d and size is %d\n"); | |
116 | av_log(avctx, AV_LOG_DEBUG, "sos offs: 0x%"PRIx32"\n", sos_offs); | |
117 | sod_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n"); | |
118 | av_log(avctx, AV_LOG_DEBUG, "sod offs: 0x%"PRIx32"\n", sod_offs); | |
119 | if (sos_offs) | |
120 | { | |
121 | init_get_bits(&s->gb, buf_ptr + sos_offs, | |
122 | 8 * FFMIN(field_size, buf_end - buf_ptr - sos_offs)); | |
123 | s->mjpb_skiptosod = (sod_offs - sos_offs - show_bits(&s->gb, 16)); | |
124 | s->start_code = SOS; | |
125 | if (ff_mjpeg_decode_sos(s, NULL, 0, NULL) < 0 && | |
126 | (avctx->err_recognition & AV_EF_EXPLODE)) | |
127 | return AVERROR_INVALIDDATA; | |
128 | } | |
129 | ||
130 | if (s->interlaced) { | |
131 | s->bottom_field ^= 1; | |
132 | /* if not bottom field, do not output image yet */ | |
133 | if (s->bottom_field != s->interlace_polarity && second_field_offs) | |
134 | { | |
135 | buf_ptr = buf + second_field_offs; | |
136 | goto read_header; | |
137 | } | |
138 | } | |
139 | ||
140 | //XXX FIXME factorize, this looks very similar to the EOI code | |
141 | ||
142 | if(!s->got_picture) { | |
143 | av_log(avctx, AV_LOG_WARNING, "no picture\n"); | |
144 | return buf_size; | |
145 | } | |
146 | ||
147 | if ((ret = av_frame_ref(data, s->picture_ptr)) < 0) | |
148 | return ret; | |
149 | *got_frame = 1; | |
150 | ||
151 | if (!s->lossless && avctx->debug & FF_DEBUG_QP) { | |
152 | av_log(avctx, AV_LOG_DEBUG, "QP: %d\n", | |
153 | FFMAX3(s->qscale[0], s->qscale[1], s->qscale[2])); | |
154 | } | |
155 | ||
156 | return buf_size; | |
157 | } | |
158 | ||
159 | AVCodec ff_mjpegb_decoder = { | |
160 | .name = "mjpegb", | |
161 | .long_name = NULL_IF_CONFIG_SMALL("Apple MJPEG-B"), | |
162 | .type = AVMEDIA_TYPE_VIDEO, | |
163 | .id = AV_CODEC_ID_MJPEGB, | |
164 | .priv_data_size = sizeof(MJpegDecodeContext), | |
165 | .init = ff_mjpeg_decode_init, | |
166 | .close = ff_mjpeg_decode_end, | |
167 | .decode = mjpegb_decode_frame, | |
168 | .capabilities = CODEC_CAP_DR1, | |
169 | .max_lowres = 3, | |
170 | }; |