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mjpegbdec.c
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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 
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 
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;
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 
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),
166  .close = ff_mjpeg_decode_end,
168  .capabilities = CODEC_CAP_DR1,
169  .max_lowres = 3,
170 };