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