00001 /* 00002 * Apple MJPEG-B decoder 00003 * Copyright (c) 2002 Alex Beregszaszi 00004 * 00005 * This file is part of FFmpeg. 00006 * 00007 * FFmpeg is free software; you can redistribute it and/or 00008 * modify it under the terms of the GNU Lesser General Public 00009 * License as published by the Free Software Foundation; either 00010 * version 2.1 of the License, or (at your option) any later version. 00011 * 00012 * FFmpeg is distributed in the hope that it will be useful, 00013 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00014 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 00015 * Lesser General Public License for more details. 00016 * 00017 * You should have received a copy of the GNU Lesser General Public 00018 * License along with FFmpeg; if not, write to the Free Software 00019 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 00020 */ 00021 00027 #include "avcodec.h" 00028 #include "mjpeg.h" 00029 #include "mjpegdec.h" 00030 00031 static uint32_t read_offs(AVCodecContext *avctx, GetBitContext *gb, uint32_t size, const char *err_msg){ 00032 uint32_t offs= get_bits_long(gb, 32); 00033 if(offs >= size){ 00034 av_log(avctx, AV_LOG_WARNING, err_msg, offs, size); 00035 return 0; 00036 } 00037 return offs; 00038 } 00039 00040 static int mjpegb_decode_frame(AVCodecContext *avctx, 00041 void *data, int *data_size, 00042 AVPacket *avpkt) 00043 { 00044 const uint8_t *buf = avpkt->data; 00045 int buf_size = avpkt->size; 00046 MJpegDecodeContext *s = avctx->priv_data; 00047 const uint8_t *buf_end, *buf_ptr; 00048 AVFrame *picture = data; 00049 GetBitContext hgb; /* for the header */ 00050 uint32_t dqt_offs, dht_offs, sof_offs, sos_offs, second_field_offs; 00051 uint32_t field_size, sod_offs; 00052 00053 buf_ptr = buf; 00054 buf_end = buf + buf_size; 00055 00056 read_header: 00057 /* reset on every SOI */ 00058 s->restart_interval = 0; 00059 s->restart_count = 0; 00060 s->mjpb_skiptosod = 0; 00061 00062 init_get_bits(&hgb, buf_ptr, /*buf_size*/(buf_end - buf_ptr)*8); 00063 00064 skip_bits(&hgb, 32); /* reserved zeros */ 00065 00066 if (get_bits_long(&hgb, 32) != MKBETAG('m','j','p','g')) 00067 { 00068 av_log(avctx, AV_LOG_WARNING, "not mjpeg-b (bad fourcc)\n"); 00069 return 0; 00070 } 00071 00072 field_size = get_bits_long(&hgb, 32); /* field size */ 00073 av_log(avctx, AV_LOG_DEBUG, "field size: 0x%x\n", field_size); 00074 skip_bits(&hgb, 32); /* padded field size */ 00075 second_field_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "second_field_offs is %d and size is %d\n"); 00076 av_log(avctx, AV_LOG_DEBUG, "second field offs: 0x%x\n", second_field_offs); 00077 00078 dqt_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dqt is %d and size is %d\n"); 00079 av_log(avctx, AV_LOG_DEBUG, "dqt offs: 0x%x\n", dqt_offs); 00080 if (dqt_offs) 00081 { 00082 init_get_bits(&s->gb, buf_ptr+dqt_offs, (buf_end - (buf_ptr+dqt_offs))*8); 00083 s->start_code = DQT; 00084 if (ff_mjpeg_decode_dqt(s) < 0 && 00085 (avctx->err_recognition & AV_EF_EXPLODE)) 00086 return AVERROR_INVALIDDATA; 00087 } 00088 00089 dht_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dht is %d and size is %d\n"); 00090 av_log(avctx, AV_LOG_DEBUG, "dht offs: 0x%x\n", dht_offs); 00091 if (dht_offs) 00092 { 00093 init_get_bits(&s->gb, buf_ptr+dht_offs, (buf_end - (buf_ptr+dht_offs))*8); 00094 s->start_code = DHT; 00095 ff_mjpeg_decode_dht(s); 00096 } 00097 00098 sof_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n"); 00099 av_log(avctx, AV_LOG_DEBUG, "sof offs: 0x%x\n", sof_offs); 00100 if (sof_offs) 00101 { 00102 init_get_bits(&s->gb, buf_ptr+sof_offs, (buf_end - (buf_ptr+sof_offs))*8); 00103 s->start_code = SOF0; 00104 if (ff_mjpeg_decode_sof(s) < 0) 00105 return -1; 00106 } 00107 00108 sos_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sos is %d and size is %d\n"); 00109 av_log(avctx, AV_LOG_DEBUG, "sos offs: 0x%x\n", sos_offs); 00110 sod_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n"); 00111 av_log(avctx, AV_LOG_DEBUG, "sod offs: 0x%x\n", sod_offs); 00112 if (sos_offs) 00113 { 00114 // init_get_bits(&s->gb, buf+sos_offs, (buf_end - (buf+sos_offs))*8); 00115 init_get_bits(&s->gb, buf_ptr+sos_offs, field_size*8); 00116 s->mjpb_skiptosod = (sod_offs - sos_offs - show_bits(&s->gb, 16)); 00117 s->start_code = SOS; 00118 if (ff_mjpeg_decode_sos(s, NULL, NULL) < 0 && 00119 (avctx->err_recognition & AV_EF_EXPLODE)) 00120 return AVERROR_INVALIDDATA; 00121 } 00122 00123 if (s->interlaced) { 00124 s->bottom_field ^= 1; 00125 /* if not bottom field, do not output image yet */ 00126 if (s->bottom_field != s->interlace_polarity && second_field_offs) 00127 { 00128 buf_ptr = buf + second_field_offs; 00129 second_field_offs = 0; 00130 goto read_header; 00131 } 00132 } 00133 00134 //XXX FIXME factorize, this looks very similar to the EOI code 00135 00136 *picture= *s->picture_ptr; 00137 *data_size = sizeof(AVFrame); 00138 00139 if(!s->lossless){ 00140 picture->quality= FFMAX3(s->qscale[0], s->qscale[1], s->qscale[2]); 00141 picture->qstride= 0; 00142 picture->qscale_table= s->qscale_table; 00143 memset(picture->qscale_table, picture->quality, (s->width+15)/16); 00144 if(avctx->debug & FF_DEBUG_QP) 00145 av_log(avctx, AV_LOG_DEBUG, "QP: %d\n", picture->quality); 00146 picture->quality*= FF_QP2LAMBDA; 00147 } 00148 00149 return buf_ptr - buf; 00150 } 00151 00152 AVCodec ff_mjpegb_decoder = { 00153 .name = "mjpegb", 00154 .type = AVMEDIA_TYPE_VIDEO, 00155 .id = CODEC_ID_MJPEGB, 00156 .priv_data_size = sizeof(MJpegDecodeContext), 00157 .init = ff_mjpeg_decode_init, 00158 .close = ff_mjpeg_decode_end, 00159 .decode = mjpegb_decode_frame, 00160 .capabilities = CODEC_CAP_DR1, 00161 .max_lowres = 3, 00162 .long_name = NULL_IF_CONFIG_SMALL("Apple MJPEG-B"), 00163 };