1/*
2 * Apple MJPEG-B decoder
3 * Copyright (c) 2002 Alex Beregszaszi
4 *
5 * This file is part of Libav.
6 *
7 * Libav 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 * Libav 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 Libav; 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 "avcodec.h"
28#include "mjpeg.h"
29#include "mjpegdec.h"
30
31static uint32_t read_offs(AVCodecContext *avctx, GetBitContext *gb, uint32_t size, const char *err_msg){
32    uint32_t offs= get_bits_long(gb, 32);
33    if(offs >= size){
34        av_log(avctx, AV_LOG_WARNING, err_msg, offs, size);
35        return 0;
36    }
37    return offs;
38}
39
40static int mjpegb_decode_frame(AVCodecContext *avctx,
41                              void *data, int *data_size,
42                              AVPacket *avpkt)
43{
44    const uint8_t *buf = avpkt->data;
45    int buf_size = avpkt->size;
46    MJpegDecodeContext *s = avctx->priv_data;
47    const uint8_t *buf_end, *buf_ptr;
48    AVFrame *picture = data;
49    GetBitContext hgb; /* for the header */
50    uint32_t dqt_offs, dht_offs, sof_offs, sos_offs, second_field_offs;
51    uint32_t field_size, sod_offs;
52
53    buf_ptr = buf;
54    buf_end = buf + buf_size;
55
56read_header:
57    /* reset on every SOI */
58    s->restart_interval = 0;
59    s->restart_count = 0;
60    s->mjpb_skiptosod = 0;
61
62    if (buf_end - buf_ptr >= 1 << 28)
63        return AVERROR_INVALIDDATA;
64
65    init_get_bits(&hgb, buf_ptr, /*buf_size*/(buf_end - buf_ptr)*8);
66
67    skip_bits(&hgb, 32); /* reserved zeros */
68
69    if (get_bits_long(&hgb, 32) != MKBETAG('m','j','p','g'))
70    {
71        av_log(avctx, AV_LOG_WARNING, "not mjpeg-b (bad fourcc)\n");
72        return AVERROR_INVALIDDATA;
73    }
74
75    field_size = get_bits_long(&hgb, 32); /* field size */
76    av_log(avctx, AV_LOG_DEBUG, "field size: 0x%x\n", field_size);
77    skip_bits(&hgb, 32); /* padded field size */
78    second_field_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "second_field_offs is %d and size is %d\n");
79    av_log(avctx, AV_LOG_DEBUG, "second field offs: 0x%x\n", second_field_offs);
80
81    dqt_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dqt is %d and size is %d\n");
82    av_log(avctx, AV_LOG_DEBUG, "dqt offs: 0x%x\n", dqt_offs);
83    if (dqt_offs)
84    {
85        init_get_bits(&s->gb, buf_ptr+dqt_offs, (buf_end - (buf_ptr+dqt_offs))*8);
86        s->start_code = DQT;
87        if (ff_mjpeg_decode_dqt(s) < 0 &&
88            (avctx->err_recognition & AV_EF_EXPLODE))
89          return AVERROR_INVALIDDATA;
90    }
91
92    dht_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dht is %d and size is %d\n");
93    av_log(avctx, AV_LOG_DEBUG, "dht offs: 0x%x\n", dht_offs);
94    if (dht_offs)
95    {
96        init_get_bits(&s->gb, buf_ptr+dht_offs, (buf_end - (buf_ptr+dht_offs))*8);
97        s->start_code = DHT;
98        ff_mjpeg_decode_dht(s);
99    }
100
101    sof_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n");
102    av_log(avctx, AV_LOG_DEBUG, "sof offs: 0x%x\n", sof_offs);
103    if (sof_offs)
104    {
105        init_get_bits(&s->gb, buf_ptr+sof_offs, (buf_end - (buf_ptr+sof_offs))*8);
106        s->start_code = SOF0;
107        if (ff_mjpeg_decode_sof(s) < 0)
108            return -1;
109    }
110
111    sos_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sos is %d and size is %d\n");
112    av_log(avctx, AV_LOG_DEBUG, "sos offs: 0x%x\n", sos_offs);
113    sod_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n");
114    av_log(avctx, AV_LOG_DEBUG, "sod offs: 0x%x\n", sod_offs);
115    if (sos_offs)
116    {
117        init_get_bits(&s->gb, buf_ptr + sos_offs,
118                      8 * FFMIN(field_size, buf_end - buf_ptr - sos_offs));
119        s->mjpb_skiptosod = (sod_offs - sos_offs - show_bits(&s->gb, 16));
120        s->start_code = SOS;
121        if (ff_mjpeg_decode_sos(s, NULL, NULL) < 0 &&
122            (avctx->err_recognition & AV_EF_EXPLODE))
123          return AVERROR_INVALIDDATA;
124    }
125
126    if (s->interlaced) {
127        s->bottom_field ^= 1;
128        /* if not bottom field, do not output image yet */
129        if (s->bottom_field != s->interlace_polarity && second_field_offs)
130        {
131            buf_ptr = buf + second_field_offs;
132            second_field_offs = 0;
133            goto read_header;
134            }
135    }
136
137    //XXX FIXME factorize, this looks very similar to the EOI code
138
139    *picture= *s->picture_ptr;
140    *data_size = sizeof(AVFrame);
141
142    if(!s->lossless){
143        picture->quality= FFMAX3(s->qscale[0], s->qscale[1], s->qscale[2]);
144        picture->qstride= 0;
145        picture->qscale_table= s->qscale_table;
146        memset(picture->qscale_table, picture->quality, (s->width+15)/16);
147        if(avctx->debug & FF_DEBUG_QP)
148            av_log(avctx, AV_LOG_DEBUG, "QP: %d\n", picture->quality);
149        picture->quality*= FF_QP2LAMBDA;
150    }
151
152    return buf_size;
153}
154
155AVCodec ff_mjpegb_decoder = {
156    .name           = "mjpegb",
157    .type           = AVMEDIA_TYPE_VIDEO,
158    .id             = CODEC_ID_MJPEGB,
159    .priv_data_size = sizeof(MJpegDecodeContext),
160    .init           = ff_mjpeg_decode_init,
161    .close          = ff_mjpeg_decode_end,
162    .decode         = mjpegb_decode_frame,
163    .capabilities   = CODEC_CAP_DR1,
164    .max_lowres = 3,
165    .long_name = NULL_IF_CONFIG_SMALL("Apple MJPEG-B"),
166};
167