1/* 2 * MxPEG clip file demuxer 3 * Copyright (c) 2010 Anatoly Nenashev 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#include "libavutil/intreadwrite.h" 23#include "libavcodec/mjpeg.h" 24#include "avformat.h" 25#include "internal.h" 26#include "avio.h" 27 28#define DEFAULT_PACKET_SIZE 1024 29#define OVERREAD_SIZE 3 30 31typedef struct MXGContext { 32 uint8_t *buffer; 33 uint8_t *buffer_ptr; 34 uint8_t *soi_ptr; 35 unsigned int buffer_size; 36 int64_t dts; 37 unsigned int cache_size; 38} MXGContext; 39 40static int mxg_read_header(AVFormatContext *s, AVFormatParameters *ap) 41{ 42 AVStream *video_st, *audio_st; 43 MXGContext *mxg = s->priv_data; 44 45 /* video parameters will be extracted from the compressed bitstream */ 46 video_st = avformat_new_stream(s, NULL); 47 if (!video_st) 48 return AVERROR(ENOMEM); 49 video_st->codec->codec_type = AVMEDIA_TYPE_VIDEO; 50 video_st->codec->codec_id = CODEC_ID_MXPEG; 51 avpriv_set_pts_info(video_st, 64, 1, 1000000); 52 53 audio_st = avformat_new_stream(s, NULL); 54 if (!audio_st) 55 return AVERROR(ENOMEM); 56 audio_st->codec->codec_type = AVMEDIA_TYPE_AUDIO; 57 audio_st->codec->codec_id = CODEC_ID_PCM_ALAW; 58 audio_st->codec->channels = 1; 59 audio_st->codec->sample_rate = 8000; 60 audio_st->codec->bits_per_coded_sample = 8; 61 audio_st->codec->block_align = 1; 62 avpriv_set_pts_info(audio_st, 64, 1, 1000000); 63 64 mxg->soi_ptr = mxg->buffer_ptr = mxg->buffer = 0; 65 mxg->buffer_size = 0; 66 mxg->dts = AV_NOPTS_VALUE; 67 mxg->cache_size = 0; 68 69 return 0; 70} 71 72static uint8_t* mxg_find_startmarker(uint8_t *p, uint8_t *end) 73{ 74 for (; p < end - 3; p += 4) { 75 uint32_t x = *(uint32_t*)p; 76 77 if (x & (~(x+0x01010101)) & 0x80808080) { 78 if (p[0] == 0xff) { 79 return p; 80 } else if (p[1] == 0xff) { 81 return p+1; 82 } else if (p[2] == 0xff) { 83 return p+2; 84 } else if (p[3] == 0xff) { 85 return p+3; 86 } 87 } 88 } 89 90 for (; p < end; ++p) { 91 if (*p == 0xff) return p; 92 } 93 94 return end; 95} 96 97static int mxg_update_cache(AVFormatContext *s, unsigned int cache_size) 98{ 99 MXGContext *mxg = s->priv_data; 100 unsigned int current_pos = mxg->buffer_ptr - mxg->buffer; 101 unsigned int soi_pos; 102 int ret; 103 104 /* reallocate internal buffer */ 105 if (current_pos > current_pos + cache_size) 106 return AVERROR(ENOMEM); 107 if (mxg->soi_ptr) soi_pos = mxg->soi_ptr - mxg->buffer; 108 mxg->buffer = av_fast_realloc(mxg->buffer, &mxg->buffer_size, 109 current_pos + cache_size + 110 FF_INPUT_BUFFER_PADDING_SIZE); 111 if (!mxg->buffer) 112 return AVERROR(ENOMEM); 113 mxg->buffer_ptr = mxg->buffer + current_pos; 114 if (mxg->soi_ptr) mxg->soi_ptr = mxg->buffer + soi_pos; 115 116 /* get data */ 117 ret = avio_read(s->pb, mxg->buffer_ptr + mxg->cache_size, 118 cache_size - mxg->cache_size); 119 if (ret < 0) 120 return ret; 121 122 mxg->cache_size += ret; 123 124 return ret; 125} 126 127static int mxg_read_packet(AVFormatContext *s, AVPacket *pkt) 128{ 129 int ret; 130 unsigned int size; 131 uint8_t *startmarker_ptr, *end, *search_end, marker; 132 MXGContext *mxg = s->priv_data; 133 134 while (!s->pb->eof_reached && !s->pb->error){ 135 if (mxg->cache_size <= OVERREAD_SIZE) { 136 /* update internal buffer */ 137 ret = mxg_update_cache(s, DEFAULT_PACKET_SIZE + OVERREAD_SIZE); 138 if (ret < 0) 139 return ret; 140 } 141 end = mxg->buffer_ptr + mxg->cache_size; 142 143 /* find start marker - 0xff */ 144 if (mxg->cache_size > OVERREAD_SIZE) { 145 search_end = end - OVERREAD_SIZE; 146 startmarker_ptr = mxg_find_startmarker(mxg->buffer_ptr, search_end); 147 } else { 148 search_end = end; 149 startmarker_ptr = mxg_find_startmarker(mxg->buffer_ptr, search_end); 150 if (startmarker_ptr >= search_end - 1 || 151 *(startmarker_ptr + 1) != EOI) break; 152 } 153 154 if (startmarker_ptr != search_end) { /* start marker found */ 155 marker = *(startmarker_ptr + 1); 156 mxg->buffer_ptr = startmarker_ptr + 2; 157 mxg->cache_size = end - mxg->buffer_ptr; 158 159 if (marker == SOI) { 160 mxg->soi_ptr = startmarker_ptr; 161 } else if (marker == EOI) { 162 if (!mxg->soi_ptr) { 163 av_log(s, AV_LOG_WARNING, "Found EOI before SOI, skipping\n"); 164 continue; 165 } 166 167 pkt->pts = pkt->dts = mxg->dts; 168 pkt->stream_index = 0; 169 pkt->destruct = NULL; 170 pkt->size = mxg->buffer_ptr - mxg->soi_ptr; 171 pkt->data = mxg->soi_ptr; 172 173 if (mxg->soi_ptr - mxg->buffer > mxg->cache_size) { 174 if (mxg->cache_size > 0) { 175 memcpy(mxg->buffer, mxg->buffer_ptr, mxg->cache_size); 176 } 177 178 mxg->buffer_ptr = mxg->buffer; 179 } 180 mxg->soi_ptr = 0; 181 182 return pkt->size; 183 } else if ( (SOF0 <= marker && marker <= SOF15) || 184 (SOS <= marker && marker <= COM) ) { 185 /* all other markers that start marker segment also contain 186 length value (see specification for JPEG Annex B.1) */ 187 size = AV_RB16(mxg->buffer_ptr); 188 if (size < 2) 189 return AVERROR(EINVAL); 190 191 if (mxg->cache_size < size) { 192 ret = mxg_update_cache(s, size); 193 if (ret < 0) 194 return ret; 195 startmarker_ptr = mxg->buffer_ptr - 2; 196 mxg->cache_size = 0; 197 } else { 198 mxg->cache_size -= size; 199 } 200 201 mxg->buffer_ptr += size; 202 203 if (marker == APP13 && size >= 16) { /* audio data */ 204 /* time (GMT) of first sample in usec since 1970, little-endian */ 205 pkt->pts = pkt->dts = AV_RL64(startmarker_ptr + 8); 206 pkt->stream_index = 1; 207 pkt->destruct = NULL; 208 pkt->size = size - 14; 209 pkt->data = startmarker_ptr + 16; 210 211 if (startmarker_ptr - mxg->buffer > mxg->cache_size) { 212 if (mxg->cache_size > 0) { 213 memcpy(mxg->buffer, mxg->buffer_ptr, mxg->cache_size); 214 } 215 mxg->buffer_ptr = mxg->buffer; 216 } 217 218 return pkt->size; 219 } else if (marker == COM && size >= 18 && 220 !strncmp(startmarker_ptr + 4, "MXF", 3)) { 221 /* time (GMT) of video frame in usec since 1970, little-endian */ 222 mxg->dts = AV_RL64(startmarker_ptr + 12); 223 } 224 } 225 } else { 226 /* start marker not found */ 227 mxg->buffer_ptr = search_end; 228 mxg->cache_size = OVERREAD_SIZE; 229 } 230 } 231 232 return AVERROR_EOF; 233} 234 235static int mxg_close(struct AVFormatContext *s) 236{ 237 MXGContext *mxg = s->priv_data; 238 av_freep(&mxg->buffer); 239 return 0; 240} 241 242AVInputFormat ff_mxg_demuxer = { 243 .name = "mxg", 244 .long_name = NULL_IF_CONFIG_SMALL("MxPEG clip file format"), 245 .priv_data_size = sizeof(MXGContext), 246 .read_header = mxg_read_header, 247 .read_packet = mxg_read_packet, 248 .read_close = mxg_close, 249 .extensions = "mxg" 250}; 251