Libav 0.7.1
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00001 /* 00002 * Apple MJPEG-B decoder 00003 * Copyright (c) 2002 Alex Beregszaszi 00004 * 00005 * This file is part of Libav. 00006 * 00007 * Libav 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 * Libav 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 Libav; 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 if (buf_end - buf_ptr >= 1 << 28) 00063 return AVERROR_INVALIDDATA; 00064 00065 init_get_bits(&hgb, buf_ptr, /*buf_size*/(buf_end - buf_ptr)*8); 00066 00067 skip_bits(&hgb, 32); /* reserved zeros */ 00068 00069 if (get_bits_long(&hgb, 32) != MKBETAG('m','j','p','g')) 00070 { 00071 av_log(avctx, AV_LOG_WARNING, "not mjpeg-b (bad fourcc)\n"); 00072 return AVERROR_INVALIDDATA; 00073 } 00074 00075 field_size = get_bits_long(&hgb, 32); /* field size */ 00076 av_log(avctx, AV_LOG_DEBUG, "field size: 0x%x\n", field_size); 00077 skip_bits(&hgb, 32); /* padded field size */ 00078 second_field_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "second_field_offs is %d and size is %d\n"); 00079 av_log(avctx, AV_LOG_DEBUG, "second field offs: 0x%x\n", second_field_offs); 00080 00081 dqt_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dqt is %d and size is %d\n"); 00082 av_log(avctx, AV_LOG_DEBUG, "dqt offs: 0x%x\n", dqt_offs); 00083 if (dqt_offs) 00084 { 00085 init_get_bits(&s->gb, buf_ptr+dqt_offs, (buf_end - (buf_ptr+dqt_offs))*8); 00086 s->start_code = DQT; 00087 ff_mjpeg_decode_dqt(s); 00088 } 00089 00090 dht_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dht is %d and size is %d\n"); 00091 av_log(avctx, AV_LOG_DEBUG, "dht offs: 0x%x\n", dht_offs); 00092 if (dht_offs) 00093 { 00094 init_get_bits(&s->gb, buf_ptr+dht_offs, (buf_end - (buf_ptr+dht_offs))*8); 00095 s->start_code = DHT; 00096 ff_mjpeg_decode_dht(s); 00097 } 00098 00099 sof_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n"); 00100 av_log(avctx, AV_LOG_DEBUG, "sof offs: 0x%x\n", sof_offs); 00101 if (sof_offs) 00102 { 00103 init_get_bits(&s->gb, buf_ptr+sof_offs, (buf_end - (buf_ptr+sof_offs))*8); 00104 s->start_code = SOF0; 00105 if (ff_mjpeg_decode_sof(s) < 0) 00106 return -1; 00107 } 00108 00109 sos_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sos is %d and size is %d\n"); 00110 av_log(avctx, AV_LOG_DEBUG, "sos offs: 0x%x\n", sos_offs); 00111 sod_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n"); 00112 av_log(avctx, AV_LOG_DEBUG, "sod offs: 0x%x\n", sod_offs); 00113 if (sos_offs) 00114 { 00115 init_get_bits(&s->gb, buf_ptr + sos_offs, 00116 8 * FFMIN(field_size, buf_end - buf_ptr - sos_offs)); 00117 s->mjpb_skiptosod = (sod_offs - sos_offs - show_bits(&s->gb, 16)); 00118 s->start_code = SOS; 00119 ff_mjpeg_decode_sos(s, NULL, NULL); 00120 } 00121 00122 if (s->interlaced) { 00123 s->bottom_field ^= 1; 00124 /* if not bottom field, do not output image yet */ 00125 if (s->bottom_field != s->interlace_polarity && second_field_offs) 00126 { 00127 buf_ptr = buf + second_field_offs; 00128 second_field_offs = 0; 00129 goto read_header; 00130 } 00131 } 00132 00133 //XXX FIXME factorize, this looks very similar to the EOI code 00134 00135 *picture= *s->picture_ptr; 00136 *data_size = sizeof(AVFrame); 00137 00138 if(!s->lossless){ 00139 picture->quality= FFMAX3(s->qscale[0], s->qscale[1], s->qscale[2]); 00140 picture->qstride= 0; 00141 picture->qscale_table= s->qscale_table; 00142 memset(picture->qscale_table, picture->quality, (s->width+15)/16); 00143 if(avctx->debug & FF_DEBUG_QP) 00144 av_log(avctx, AV_LOG_DEBUG, "QP: %d\n", picture->quality); 00145 picture->quality*= FF_QP2LAMBDA; 00146 } 00147 00148 return buf_size; 00149 } 00150 00151 AVCodec ff_mjpegb_decoder = { 00152 "mjpegb", 00153 AVMEDIA_TYPE_VIDEO, 00154 CODEC_ID_MJPEGB, 00155 sizeof(MJpegDecodeContext), 00156 ff_mjpeg_decode_init, 00157 NULL, 00158 ff_mjpeg_decode_end, 00159 mjpegb_decode_frame, 00160 CODEC_CAP_DR1, 00161 NULL, 00162 .max_lowres = 3, 00163 .long_name = NULL_IF_CONFIG_SMALL("Apple MJPEG-B"), 00164 };