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 <inttypes.h> 28 29#include "avcodec.h" 30#include "mjpeg.h" 31#include "mjpegdec.h" 32 33static uint32_t read_offs(AVCodecContext *avctx, GetBitContext *gb, uint32_t size, const char *err_msg){ 34 uint32_t offs= get_bits_long(gb, 32); 35 if(offs >= size){ 36 av_log(avctx, AV_LOG_WARNING, err_msg, offs, size); 37 return 0; 38 } 39 return offs; 40} 41 42static int mjpegb_decode_frame(AVCodecContext *avctx, 43 void *data, int *got_frame, 44 AVPacket *avpkt) 45{ 46 const uint8_t *buf = avpkt->data; 47 int buf_size = avpkt->size; 48 MJpegDecodeContext *s = avctx->priv_data; 49 const uint8_t *buf_end, *buf_ptr; 50 GetBitContext hgb; /* for the header */ 51 uint32_t dqt_offs, dht_offs, sof_offs, sos_offs, second_field_offs; 52 uint32_t field_size, sod_offs; 53 int ret; 54 55 buf_ptr = buf; 56 buf_end = buf + buf_size; 57 s->got_picture = 0; 58 59read_header: 60 /* reset on every SOI */ 61 s->restart_interval = 0; 62 s->restart_count = 0; 63 s->mjpb_skiptosod = 0; 64 65 if (buf_end - buf_ptr >= 1 << 28) 66 return AVERROR_INVALIDDATA; 67 68 init_get_bits(&hgb, buf_ptr, /*buf_size*/(buf_end - buf_ptr)*8); 69 70 skip_bits(&hgb, 32); /* reserved zeros */ 71 72 if (get_bits_long(&hgb, 32) != MKBETAG('m','j','p','g')) 73 { 74 av_log(avctx, AV_LOG_WARNING, "not mjpeg-b (bad fourcc)\n"); 75 return AVERROR_INVALIDDATA; 76 } 77 78 field_size = get_bits_long(&hgb, 32); /* field size */ 79 av_log(avctx, AV_LOG_DEBUG, "field size: 0x%"PRIx32"\n", field_size); 80 skip_bits(&hgb, 32); /* padded field size */ 81 second_field_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "second_field_offs is %d and size is %d\n"); 82 av_log(avctx, AV_LOG_DEBUG, "second field offs: 0x%"PRIx32"\n", 83 second_field_offs); 84 85 dqt_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dqt is %d and size is %d\n"); 86 av_log(avctx, AV_LOG_DEBUG, "dqt offs: 0x%"PRIx32"\n", dqt_offs); 87 if (dqt_offs) 88 { 89 init_get_bits(&s->gb, buf_ptr+dqt_offs, (buf_end - (buf_ptr+dqt_offs))*8); 90 s->start_code = DQT; 91 if (ff_mjpeg_decode_dqt(s) < 0 && 92 (avctx->err_recognition & AV_EF_EXPLODE)) 93 return AVERROR_INVALIDDATA; 94 } 95 96 dht_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dht is %d and size is %d\n"); 97 av_log(avctx, AV_LOG_DEBUG, "dht offs: 0x%"PRIx32"\n", dht_offs); 98 if (dht_offs) 99 { 100 init_get_bits(&s->gb, buf_ptr+dht_offs, (buf_end - (buf_ptr+dht_offs))*8); 101 s->start_code = DHT; 102 ff_mjpeg_decode_dht(s); 103 } 104 105 sof_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n"); 106 av_log(avctx, AV_LOG_DEBUG, "sof offs: 0x%"PRIx32"\n", sof_offs); 107 if (sof_offs) 108 { 109 init_get_bits(&s->gb, buf_ptr+sof_offs, (buf_end - (buf_ptr+sof_offs))*8); 110 s->start_code = SOF0; 111 if (ff_mjpeg_decode_sof(s) < 0) 112 return -1; 113 } 114 115 sos_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sos is %d and size is %d\n"); 116 av_log(avctx, AV_LOG_DEBUG, "sos offs: 0x%"PRIx32"\n", sos_offs); 117 sod_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n"); 118 av_log(avctx, AV_LOG_DEBUG, "sod offs: 0x%"PRIx32"\n", sod_offs); 119 if (sos_offs) 120 { 121 init_get_bits(&s->gb, buf_ptr + sos_offs, 122 8 * FFMIN(field_size, buf_end - buf_ptr - sos_offs)); 123 s->mjpb_skiptosod = (sod_offs - sos_offs - show_bits(&s->gb, 16)); 124 s->start_code = SOS; 125 if (ff_mjpeg_decode_sos(s, NULL, 0, NULL) < 0 && 126 (avctx->err_recognition & AV_EF_EXPLODE)) 127 return AVERROR_INVALIDDATA; 128 } 129 130 if (s->interlaced) { 131 s->bottom_field ^= 1; 132 /* if not bottom field, do not output image yet */ 133 if (s->bottom_field != s->interlace_polarity && second_field_offs) 134 { 135 buf_ptr = buf + second_field_offs; 136 goto read_header; 137 } 138 } 139 140 //XXX FIXME factorize, this looks very similar to the EOI code 141 142 if(!s->got_picture) { 143 av_log(avctx, AV_LOG_WARNING, "no picture\n"); 144 return buf_size; 145 } 146 147 if ((ret = av_frame_ref(data, s->picture_ptr)) < 0) 148 return ret; 149 *got_frame = 1; 150 151 if (!s->lossless && avctx->debug & FF_DEBUG_QP) { 152 av_log(avctx, AV_LOG_DEBUG, "QP: %d\n", 153 FFMAX3(s->qscale[0], s->qscale[1], s->qscale[2])); 154 } 155 156 return buf_size; 157} 158 159AVCodec ff_mjpegb_decoder = { 160 .name = "mjpegb", 161 .long_name = NULL_IF_CONFIG_SMALL("Apple MJPEG-B"), 162 .type = AVMEDIA_TYPE_VIDEO, 163 .id = AV_CODEC_ID_MJPEGB, 164 .priv_data_size = sizeof(MJpegDecodeContext), 165 .init = ff_mjpeg_decode_init, 166 .close = ff_mjpeg_decode_end, 167 .decode = mjpegb_decode_frame, 168 .capabilities = CODEC_CAP_DR1, 169 .max_lowres = 3, 170}; 171