1/* 2 * MxPEG clip file demuxer 3 * Copyright (c) 2010 Anatoly Nenashev 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#include "libavutil/channel_layout.h" 23#include "libavutil/internal.h" 24#include "libavutil/intreadwrite.h" 25#include "libavcodec/mjpeg.h" 26#include "avformat.h" 27#include "internal.h" 28#include "avio.h" 29 30#define DEFAULT_PACKET_SIZE 1024 31#define OVERREAD_SIZE 3 32 33typedef struct MXGContext { 34 uint8_t *buffer; 35 uint8_t *buffer_ptr; 36 uint8_t *soi_ptr; 37 unsigned int buffer_size; 38 int64_t dts; 39 unsigned int cache_size; 40} MXGContext; 41 42static int mxg_read_header(AVFormatContext *s) 43{ 44 AVStream *video_st, *audio_st; 45 MXGContext *mxg = s->priv_data; 46 47 /* video parameters will be extracted from the compressed bitstream */ 48 video_st = avformat_new_stream(s, NULL); 49 if (!video_st) 50 return AVERROR(ENOMEM); 51 video_st->codec->codec_type = AVMEDIA_TYPE_VIDEO; 52 video_st->codec->codec_id = AV_CODEC_ID_MXPEG; 53 avpriv_set_pts_info(video_st, 64, 1, 1000000); 54 55 audio_st = avformat_new_stream(s, NULL); 56 if (!audio_st) 57 return AVERROR(ENOMEM); 58 audio_st->codec->codec_type = AVMEDIA_TYPE_AUDIO; 59 audio_st->codec->codec_id = AV_CODEC_ID_PCM_ALAW; 60 audio_st->codec->channels = 1; 61 audio_st->codec->channel_layout = AV_CH_LAYOUT_MONO; 62 audio_st->codec->sample_rate = 8000; 63 audio_st->codec->bits_per_coded_sample = 8; 64 audio_st->codec->block_align = 1; 65 avpriv_set_pts_info(audio_st, 64, 1, 1000000); 66 67 mxg->soi_ptr = mxg->buffer_ptr = mxg->buffer = 0; 68 mxg->buffer_size = 0; 69 mxg->dts = AV_NOPTS_VALUE; 70 mxg->cache_size = 0; 71 72 return 0; 73} 74 75static uint8_t* mxg_find_startmarker(uint8_t *p, uint8_t *end) 76{ 77 for (; p < end - 3; p += 4) { 78 uint32_t x = AV_RN32(p); 79 80 if (x & (~(x+0x01010101)) & 0x80808080) { 81 if (p[0] == 0xff) { 82 return p; 83 } else if (p[1] == 0xff) { 84 return p+1; 85 } else if (p[2] == 0xff) { 86 return p+2; 87 } else if (p[3] == 0xff) { 88 return p+3; 89 } 90 } 91 } 92 93 for (; p < end; ++p) { 94 if (*p == 0xff) return p; 95 } 96 97 return end; 98} 99 100static int mxg_update_cache(AVFormatContext *s, unsigned int cache_size) 101{ 102 MXGContext *mxg = s->priv_data; 103 unsigned int current_pos = mxg->buffer_ptr - mxg->buffer; 104 unsigned int soi_pos; 105 uint8_t *buffer; 106 int ret; 107 108 /* reallocate internal buffer */ 109 if (current_pos > current_pos + cache_size) 110 return AVERROR(ENOMEM); 111 soi_pos = mxg->soi_ptr - mxg->buffer; 112 buffer = av_fast_realloc(mxg->buffer, &mxg->buffer_size, 113 current_pos + cache_size + 114 FF_INPUT_BUFFER_PADDING_SIZE); 115 if (!buffer) 116 return AVERROR(ENOMEM); 117 mxg->buffer = buffer; 118 mxg->buffer_ptr = mxg->buffer + current_pos; 119 if (mxg->soi_ptr) mxg->soi_ptr = mxg->buffer + soi_pos; 120 121 /* get data */ 122 ret = avio_read(s->pb, mxg->buffer_ptr + mxg->cache_size, 123 cache_size - mxg->cache_size); 124 if (ret < 0) 125 return ret; 126 127 mxg->cache_size += ret; 128 129 return ret; 130} 131 132static int mxg_read_packet(AVFormatContext *s, AVPacket *pkt) 133{ 134 int ret; 135 unsigned int size; 136 uint8_t *startmarker_ptr, *end, *search_end, marker; 137 MXGContext *mxg = s->priv_data; 138 139 while (!url_feof(s->pb) && !s->pb->error){ 140 if (mxg->cache_size <= OVERREAD_SIZE) { 141 /* update internal buffer */ 142 ret = mxg_update_cache(s, DEFAULT_PACKET_SIZE + OVERREAD_SIZE); 143 if (ret < 0) 144 return ret; 145 } 146 end = mxg->buffer_ptr + mxg->cache_size; 147 148 /* find start marker - 0xff */ 149 if (mxg->cache_size > OVERREAD_SIZE) { 150 search_end = end - OVERREAD_SIZE; 151 startmarker_ptr = mxg_find_startmarker(mxg->buffer_ptr, search_end); 152 } else { 153 search_end = end; 154 startmarker_ptr = mxg_find_startmarker(mxg->buffer_ptr, search_end); 155 if (startmarker_ptr >= search_end - 1 || 156 *(startmarker_ptr + 1) != EOI) break; 157 } 158 159 if (startmarker_ptr != search_end) { /* start marker found */ 160 marker = *(startmarker_ptr + 1); 161 mxg->buffer_ptr = startmarker_ptr + 2; 162 mxg->cache_size = end - mxg->buffer_ptr; 163 164 if (marker == SOI) { 165 mxg->soi_ptr = startmarker_ptr; 166 } else if (marker == EOI) { 167 if (!mxg->soi_ptr) { 168 av_log(s, AV_LOG_WARNING, "Found EOI before SOI, skipping\n"); 169 continue; 170 } 171 172 pkt->pts = pkt->dts = mxg->dts; 173 pkt->stream_index = 0; 174#if FF_API_DESTRUCT_PACKET 175FF_DISABLE_DEPRECATION_WARNINGS 176 pkt->destruct = NULL; 177FF_ENABLE_DEPRECATION_WARNINGS 178#endif 179 pkt->buf = NULL; 180 pkt->size = mxg->buffer_ptr - mxg->soi_ptr; 181 pkt->data = mxg->soi_ptr; 182 183 if (mxg->soi_ptr - mxg->buffer > mxg->cache_size) { 184 if (mxg->cache_size > 0) { 185 memcpy(mxg->buffer, mxg->buffer_ptr, mxg->cache_size); 186 } 187 188 mxg->buffer_ptr = mxg->buffer; 189 } 190 mxg->soi_ptr = 0; 191 192 return pkt->size; 193 } else if ( (SOF0 <= marker && marker <= SOF15) || 194 (SOS <= marker && marker <= COM) ) { 195 /* all other markers that start marker segment also contain 196 length value (see specification for JPEG Annex B.1) */ 197 size = AV_RB16(mxg->buffer_ptr); 198 if (size < 2) 199 return AVERROR(EINVAL); 200 201 if (mxg->cache_size < size) { 202 ret = mxg_update_cache(s, size); 203 if (ret < 0) 204 return ret; 205 startmarker_ptr = mxg->buffer_ptr - 2; 206 mxg->cache_size = 0; 207 } else { 208 mxg->cache_size -= size; 209 } 210 211 mxg->buffer_ptr += size; 212 213 if (marker == APP13 && size >= 16) { /* audio data */ 214 /* time (GMT) of first sample in usec since 1970, little-endian */ 215 pkt->pts = pkt->dts = AV_RL64(startmarker_ptr + 8); 216 pkt->stream_index = 1; 217#if FF_API_DESTRUCT_PACKET 218FF_DISABLE_DEPRECATION_WARNINGS 219 pkt->destruct = NULL; 220FF_ENABLE_DEPRECATION_WARNINGS 221#endif 222 pkt->buf = NULL; 223 pkt->size = size - 14; 224 pkt->data = startmarker_ptr + 16; 225 226 if (startmarker_ptr - mxg->buffer > mxg->cache_size) { 227 if (mxg->cache_size > 0) { 228 memcpy(mxg->buffer, mxg->buffer_ptr, mxg->cache_size); 229 } 230 mxg->buffer_ptr = mxg->buffer; 231 } 232 233 return pkt->size; 234 } else if (marker == COM && size >= 18 && 235 !strncmp(startmarker_ptr + 4, "MXF", 3)) { 236 /* time (GMT) of video frame in usec since 1970, little-endian */ 237 mxg->dts = AV_RL64(startmarker_ptr + 12); 238 } 239 } 240 } else { 241 /* start marker not found */ 242 mxg->buffer_ptr = search_end; 243 mxg->cache_size = OVERREAD_SIZE; 244 } 245 } 246 247 return AVERROR_EOF; 248} 249 250static int mxg_close(struct AVFormatContext *s) 251{ 252 MXGContext *mxg = s->priv_data; 253 av_freep(&mxg->buffer); 254 return 0; 255} 256 257AVInputFormat ff_mxg_demuxer = { 258 .name = "mxg", 259 .long_name = NULL_IF_CONFIG_SMALL("MxPEG clip"), 260 .priv_data_size = sizeof(MXGContext), 261 .read_header = mxg_read_header, 262 .read_packet = mxg_read_packet, 263 .read_close = mxg_close, 264 .extensions = "mxg", 265}; 266