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