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path: root/libavcodec/mjpegbdec.c (plain)
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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 "internal.h"
31#include "mjpeg.h"
32#include "mjpegdec.h"
33
34static uint32_t read_offs(AVCodecContext *avctx, GetBitContext *gb, uint32_t size, const char *err_msg){
35 uint32_t offs= get_bits_long(gb, 32);
36 if(offs >= size){
37 av_log(avctx, AV_LOG_WARNING, err_msg, offs, size);
38 return 0;
39 }
40 return offs;
41}
42
43static int mjpegb_decode_frame(AVCodecContext *avctx,
44 void *data, int *got_frame,
45 AVPacket *avpkt)
46{
47 const uint8_t *buf = avpkt->data;
48 int buf_size = avpkt->size;
49 MJpegDecodeContext *s = avctx->priv_data;
50 const uint8_t *buf_end, *buf_ptr;
51 GetBitContext hgb; /* for the header */
52 uint32_t dqt_offs, dht_offs, sof_offs, sos_offs, second_field_offs;
53 uint32_t field_size, sod_offs;
54 int ret;
55
56 buf_ptr = buf;
57 buf_end = buf + buf_size;
58 s->got_picture = 0;
59
60read_header:
61 /* reset on every SOI */
62 s->restart_interval = 0;
63 s->restart_count = 0;
64 s->mjpb_skiptosod = 0;
65
66 if (buf_end - buf_ptr >= 1 << 28)
67 return AVERROR_INVALIDDATA;
68
69 init_get_bits(&hgb, buf_ptr, /*buf_size*/(buf_end - buf_ptr)*8);
70
71 skip_bits(&hgb, 32); /* reserved zeros */
72
73 if (get_bits_long(&hgb, 32) != MKBETAG('m','j','p','g'))
74 {
75 av_log(avctx, AV_LOG_WARNING, "not mjpeg-b (bad fourcc)\n");
76 return AVERROR_INVALIDDATA;
77 }
78
79 field_size = get_bits_long(&hgb, 32); /* field size */
80 av_log(avctx, AV_LOG_DEBUG, "field size: 0x%"PRIx32"\n", field_size);
81 skip_bits(&hgb, 32); /* padded field size */
82 second_field_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "second_field_offs is %d and size is %d\n");
83 av_log(avctx, AV_LOG_DEBUG, "second field offs: 0x%"PRIx32"\n",
84 second_field_offs);
85
86 dqt_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dqt is %d and size is %d\n");
87 av_log(avctx, AV_LOG_DEBUG, "dqt offs: 0x%"PRIx32"\n", dqt_offs);
88 if (dqt_offs)
89 {
90 init_get_bits(&s->gb, buf_ptr+dqt_offs, (buf_end - (buf_ptr+dqt_offs))*8);
91 s->start_code = DQT;
92 if (ff_mjpeg_decode_dqt(s) < 0 &&
93 (avctx->err_recognition & AV_EF_EXPLODE))
94 return AVERROR_INVALIDDATA;
95 }
96
97 dht_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dht is %d and size is %d\n");
98 av_log(avctx, AV_LOG_DEBUG, "dht offs: 0x%"PRIx32"\n", dht_offs);
99 if (dht_offs)
100 {
101 init_get_bits(&s->gb, buf_ptr+dht_offs, (buf_end - (buf_ptr+dht_offs))*8);
102 s->start_code = DHT;
103 ff_mjpeg_decode_dht(s);
104 }
105
106 sof_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n");
107 av_log(avctx, AV_LOG_DEBUG, "sof offs: 0x%"PRIx32"\n", sof_offs);
108 if (sof_offs)
109 {
110 init_get_bits(&s->gb, buf_ptr+sof_offs, (buf_end - (buf_ptr+sof_offs))*8);
111 s->start_code = SOF0;
112 if (ff_mjpeg_decode_sof(s) < 0)
113 return -1;
114 }
115
116 sos_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sos is %d and size is %d\n");
117 av_log(avctx, AV_LOG_DEBUG, "sos offs: 0x%"PRIx32"\n", sos_offs);
118 sod_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n");
119 av_log(avctx, AV_LOG_DEBUG, "sod offs: 0x%"PRIx32"\n", sod_offs);
120 if (sos_offs)
121 {
122 init_get_bits(&s->gb, buf_ptr + sos_offs,
123 8 * FFMIN(field_size, buf_end - buf_ptr - sos_offs));
124 s->mjpb_skiptosod = (sod_offs - sos_offs - show_bits(&s->gb, 16));
125 s->start_code = SOS;
126 if (ff_mjpeg_decode_sos(s, NULL, 0, NULL) < 0 &&
127 (avctx->err_recognition & AV_EF_EXPLODE))
128 return AVERROR_INVALIDDATA;
129 }
130
131 if (s->interlaced) {
132 s->bottom_field ^= 1;
133 /* if not bottom field, do not output image yet */
134 if (s->bottom_field != s->interlace_polarity && second_field_offs)
135 {
136 buf_ptr = buf + second_field_offs;
137 goto read_header;
138 }
139 }
140
141 //XXX FIXME factorize, this looks very similar to the EOI code
142
143 if(!s->got_picture) {
144 av_log(avctx, AV_LOG_WARNING, "no picture\n");
145 return buf_size;
146 }
147
148 if ((ret = av_frame_ref(data, s->picture_ptr)) < 0)
149 return ret;
150 *got_frame = 1;
151
152 if (!s->lossless && avctx->debug & FF_DEBUG_QP) {
153 av_log(avctx, AV_LOG_DEBUG, "QP: %d\n",
154 FFMAX3(s->qscale[0], s->qscale[1], s->qscale[2]));
155 }
156
157 return buf_size;
158}
159
160AVCodec ff_mjpegb_decoder = {
161 .name = "mjpegb",
162 .long_name = NULL_IF_CONFIG_SMALL("Apple MJPEG-B"),
163 .type = AVMEDIA_TYPE_VIDEO,
164 .id = AV_CODEC_ID_MJPEGB,
165 .priv_data_size = sizeof(MJpegDecodeContext),
166 .init = ff_mjpeg_decode_init,
167 .close = ff_mjpeg_decode_end,
168 .decode = mjpegb_decode_frame,
169 .capabilities = AV_CODEC_CAP_DR1,
170 .max_lowres = 3,
171 .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
172};
173
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