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 "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    init_get_bits(&hgb, buf_ptr, /*buf_size*/(buf_end - buf_ptr)*8);
63
64    skip_bits(&hgb, 32); /* reserved zeros */
65
66    if (get_bits_long(&hgb, 32) != MKBETAG('m','j','p','g'))
67    {
68        av_log(avctx, AV_LOG_WARNING, "not mjpeg-b (bad fourcc)\n");
69        return 0;
70    }
71
72    field_size = get_bits_long(&hgb, 32); /* field size */
73    av_log(avctx, AV_LOG_DEBUG, "field size: 0x%x\n", field_size);
74    skip_bits(&hgb, 32); /* padded field size */
75    second_field_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "second_field_offs is %d and size is %d\n");
76    av_log(avctx, AV_LOG_DEBUG, "second field offs: 0x%x\n", second_field_offs);
77
78    dqt_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dqt is %d and size is %d\n");
79    av_log(avctx, AV_LOG_DEBUG, "dqt offs: 0x%x\n", dqt_offs);
80    if (dqt_offs)
81    {
82        init_get_bits(&s->gb, buf_ptr+dqt_offs, (buf_end - (buf_ptr+dqt_offs))*8);
83        s->start_code = DQT;
84        ff_mjpeg_decode_dqt(s);
85    }
86
87    dht_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dht is %d and size is %d\n");
88    av_log(avctx, AV_LOG_DEBUG, "dht offs: 0x%x\n", dht_offs);
89    if (dht_offs)
90    {
91        init_get_bits(&s->gb, buf_ptr+dht_offs, (buf_end - (buf_ptr+dht_offs))*8);
92        s->start_code = DHT;
93        ff_mjpeg_decode_dht(s);
94    }
95
96    sof_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n");
97    av_log(avctx, AV_LOG_DEBUG, "sof offs: 0x%x\n", sof_offs);
98    if (sof_offs)
99    {
100        init_get_bits(&s->gb, buf_ptr+sof_offs, (buf_end - (buf_ptr+sof_offs))*8);
101        s->start_code = SOF0;
102        if (ff_mjpeg_decode_sof(s) < 0)
103            return -1;
104    }
105
106    sos_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sos is %d and size is %d\n");
107    av_log(avctx, AV_LOG_DEBUG, "sos offs: 0x%x\n", sos_offs);
108    sod_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n");
109    av_log(avctx, AV_LOG_DEBUG, "sod offs: 0x%x\n", sod_offs);
110    if (sos_offs)
111    {
112//        init_get_bits(&s->gb, buf+sos_offs, (buf_end - (buf+sos_offs))*8);
113        init_get_bits(&s->gb, buf_ptr+sos_offs, field_size*8);
114        s->mjpb_skiptosod = (sod_offs - sos_offs - show_bits(&s->gb, 16));
115        s->start_code = SOS;
116        ff_mjpeg_decode_sos(s);
117    }
118
119    if (s->interlaced) {
120        s->bottom_field ^= 1;
121        /* if not bottom field, do not output image yet */
122        if (s->bottom_field != s->interlace_polarity && second_field_offs)
123        {
124            buf_ptr = buf + second_field_offs;
125            second_field_offs = 0;
126            goto read_header;
127            }
128    }
129
130    //XXX FIXME factorize, this looks very similar to the EOI code
131
132    *picture= s->picture;
133    *data_size = sizeof(AVFrame);
134
135    if(!s->lossless){
136        picture->quality= FFMAX3(s->qscale[0], s->qscale[1], s->qscale[2]);
137        picture->qstride= 0;
138        picture->qscale_table= s->qscale_table;
139        memset(picture->qscale_table, picture->quality, (s->width+15)/16);
140        if(avctx->debug & FF_DEBUG_QP)
141            av_log(avctx, AV_LOG_DEBUG, "QP: %d\n", picture->quality);
142        picture->quality*= FF_QP2LAMBDA;
143    }
144
145    return buf_ptr - buf;
146}
147
148AVCodec mjpegb_decoder = {
149    "mjpegb",
150    AVMEDIA_TYPE_VIDEO,
151    CODEC_ID_MJPEGB,
152    sizeof(MJpegDecodeContext),
153    ff_mjpeg_decode_init,
154    NULL,
155    ff_mjpeg_decode_end,
156    mjpegb_decode_frame,
157    CODEC_CAP_DR1,
158    NULL,
159    .long_name = NULL_IF_CONFIG_SMALL("Apple MJPEG-B"),
160};
161