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.
32 static int mjpegb_decode_frame(AVCodecContext *avctx,
33 void *data, int *data_size,
34 uint8_t *buf, int buf_size)
36 MJpegDecodeContext *s = avctx->priv_data;
37 uint8_t *buf_end, *buf_ptr;
38 AVFrame *picture = data;
39 GetBitContext hgb; /* for the header */
40 uint32_t dqt_offs, dht_offs, sof_offs, sos_offs, second_field_offs;
41 uint32_t field_size, sod_offs;
44 buf_end = buf + buf_size;
47 /* reset on every SOI */
48 s->restart_interval = 0;
50 s->mjpb_skiptosod = 0;
52 init_get_bits(&hgb, buf_ptr, /*buf_size*/(buf_end - buf_ptr)*8);
54 skip_bits(&hgb, 32); /* reserved zeros */
56 if (get_bits_long(&hgb, 32) != MKBETAG('m','j','p','g'))
58 av_log(avctx, AV_LOG_WARNING, "not mjpeg-b (bad fourcc)\n");
62 field_size = get_bits_long(&hgb, 32); /* field size */
63 av_log(avctx, AV_LOG_DEBUG, "field size: 0x%x\n", field_size);
64 skip_bits(&hgb, 32); /* padded field size */
65 second_field_offs = get_bits_long(&hgb, 32);
66 av_log(avctx, AV_LOG_DEBUG, "second field offs: 0x%x\n", second_field_offs);
68 dqt_offs = get_bits_long(&hgb, 32);
69 av_log(avctx, AV_LOG_DEBUG, "dqt offs: 0x%x\n", dqt_offs);
72 init_get_bits(&s->gb, buf+dqt_offs, (buf_end - (buf+dqt_offs))*8);
74 ff_mjpeg_decode_dqt(s);
77 dht_offs = get_bits_long(&hgb, 32);
78 av_log(avctx, AV_LOG_DEBUG, "dht offs: 0x%x\n", dht_offs);
81 init_get_bits(&s->gb, buf+dht_offs, (buf_end - (buf+dht_offs))*8);
83 ff_mjpeg_decode_dht(s);
86 sof_offs = get_bits_long(&hgb, 32);
87 av_log(avctx, AV_LOG_DEBUG, "sof offs: 0x%x\n", sof_offs);
90 init_get_bits(&s->gb, buf+sof_offs, (buf_end - (buf+sof_offs))*8);
92 if (ff_mjpeg_decode_sof(s) < 0)
96 sos_offs = get_bits_long(&hgb, 32);
97 av_log(avctx, AV_LOG_DEBUG, "sos offs: 0x%x\n", sos_offs);
98 sod_offs = get_bits_long(&hgb, 32);
99 av_log(avctx, AV_LOG_DEBUG, "sod offs: 0x%x\n", sod_offs);
102 // init_get_bits(&s->gb, buf+sos_offs, (buf_end - (buf+sos_offs))*8);
103 init_get_bits(&s->gb, buf+sos_offs, field_size*8);
104 s->mjpb_skiptosod = (sod_offs - sos_offs - show_bits(&s->gb, 16));
106 ff_mjpeg_decode_sos(s);
110 s->bottom_field ^= 1;
111 /* if not bottom field, do not output image yet */
112 if (s->bottom_field && second_field_offs)
114 buf_ptr = buf + second_field_offs;
115 second_field_offs = 0;
120 //XXX FIXME factorize, this looks very similar to the EOI code
122 *picture= s->picture;
123 *data_size = sizeof(AVFrame);
126 picture->quality= FFMAX(FFMAX(s->qscale[0], s->qscale[1]), s->qscale[2]);
128 picture->qscale_table= s->qscale_table;
129 memset(picture->qscale_table, picture->quality, (s->width+15)/16);
130 if(avctx->debug & FF_DEBUG_QP)
131 av_log(avctx, AV_LOG_DEBUG, "QP: %d\n", picture->quality);
132 picture->quality*= FF_QP2LAMBDA;
135 return buf_ptr - buf;
138 AVCodec mjpegb_decoder = {
142 sizeof(MJpegDecodeContext),
143 ff_mjpeg_decode_init,