libavformat/mxg.c

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