2 * Apple MJPEG-B decoder
3 * Copyright (c) 2002 Alex Beregszaszi
5 * This file is part of FFmpeg.
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.
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.
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
24 * Apple MJPEG-B decoder.
31 static uint32_t read_offs(AVCodecContext *avctx, GetBitContext *gb, uint32_t size, const char *err_msg){
32 uint32_t offs= get_bits_long(gb, 32);
34 av_log(avctx, AV_LOG_WARNING, err_msg, offs, size);
40 static int mjpegb_decode_frame(AVCodecContext *avctx,
41 void *data, int *data_size,
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;
54 buf_end = buf + buf_size;
57 /* reset on every SOI */
58 s->restart_interval = 0;
60 s->mjpb_skiptosod = 0;
62 init_get_bits(&hgb, buf_ptr, /*buf_size*/(buf_end - buf_ptr)*8);
64 skip_bits(&hgb, 32); /* reserved zeros */
66 if (get_bits_long(&hgb, 32) != MKBETAG('m','j','p','g'))
68 av_log(avctx, AV_LOG_WARNING, "not mjpeg-b (bad fourcc)\n");
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);
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);
82 init_get_bits(&s->gb, buf_ptr+dqt_offs, (buf_end - (buf_ptr+dqt_offs))*8);
84 ff_mjpeg_decode_dqt(s);
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);
91 init_get_bits(&s->gb, buf_ptr+dht_offs, (buf_end - (buf_ptr+dht_offs))*8);
93 ff_mjpeg_decode_dht(s);
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);
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)
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);
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));
116 ff_mjpeg_decode_sos(s);
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)
124 buf_ptr = buf + second_field_offs;
125 second_field_offs = 0;
130 //XXX FIXME factorize, this looks very similar to the EOI code
132 *picture= s->picture;
133 *data_size = sizeof(AVFrame);
136 picture->quality= FFMAX3(s->qscale[0], s->qscale[1], s->qscale[2]);
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;
145 return buf_ptr - buf;
148 AVCodec ff_mjpegb_decoder = {
152 sizeof(MJpegDecodeContext),
153 ff_mjpeg_decode_init,
160 .long_name = NULL_IF_CONFIG_SMALL("Apple MJPEG-B"),