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
33static 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
42static 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
59read_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
159AVCodec 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};
171