• Main Page
  • Related Pages
  • Modules
  • Data Structures
  • Files
  • Examples
  • File List
  • Globals

libavcodec/mxpegdec.c

Go to the documentation of this file.
00001 /*
00002  * MxPEG decoder
00003  * Copyright (c) 2011 Anatoly Nenashev
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 
00022 
00028 #include "mjpeg.h"
00029 #include "mjpegdec.h"
00030 
00031 typedef struct MXpegDecodeContext {
00032     MJpegDecodeContext jpg;
00033     AVFrame picture[2]; /* pictures array */
00034     int picture_index; /* index of current picture */
00035     int got_sof_data; /* true if SOF data successfully parsed */
00036     int got_mxm_bitmask; /* true if MXM bitmask available */
00037     uint8_t *mxm_bitmask; /* bitmask buffer */
00038     unsigned bitmask_size; /* size of bitmask */
00039     int has_complete_frame; /* true if has complete frame */
00040     uint8_t *completion_bitmask; /* completion bitmask of macroblocks */
00041     unsigned mb_width, mb_height; /* size of picture in MB's from MXM header */
00042 } MXpegDecodeContext;
00043 
00044 static av_cold int mxpeg_decode_init(AVCodecContext *avctx)
00045 {
00046     MXpegDecodeContext *s = avctx->priv_data;
00047 
00048     s->picture[0].reference = s->picture[1].reference = 3;
00049     s->jpg.picture_ptr      = &s->picture[0];
00050     ff_mjpeg_decode_init(avctx);
00051 
00052     return 0;
00053 }
00054 
00055 static int mxpeg_decode_app(MXpegDecodeContext *s,
00056                             const uint8_t *buf_ptr, int buf_size)
00057 {
00058     int len;
00059     if (buf_size < 2)
00060         return 0;
00061     len = AV_RB16(buf_ptr);
00062     skip_bits(&s->jpg.gb, 8*FFMIN(len,buf_size));
00063 
00064     return 0;
00065 }
00066 
00067 static int mxpeg_decode_mxm(MXpegDecodeContext *s,
00068                             const uint8_t *buf_ptr, int buf_size)
00069 {
00070     unsigned bitmask_size, mb_count;
00071     int i;
00072 
00073     s->mb_width  = AV_RL16(buf_ptr+4);
00074     s->mb_height = AV_RL16(buf_ptr+6);
00075     mb_count = s->mb_width * s->mb_height;
00076 
00077     bitmask_size = (mb_count + 7) >> 3;
00078     if (bitmask_size > buf_size - 12) {
00079         av_log(s->jpg.avctx, AV_LOG_ERROR,
00080                "MXM bitmask is not complete\n");
00081         return AVERROR(EINVAL);
00082     }
00083 
00084     if (s->bitmask_size != bitmask_size) {
00085         s->bitmask_size = 0;
00086         av_freep(&s->mxm_bitmask);
00087         s->mxm_bitmask = av_malloc(bitmask_size);
00088         if (!s->mxm_bitmask) {
00089             av_log(s->jpg.avctx, AV_LOG_ERROR,
00090                    "MXM bitmask memory allocation error\n");
00091             return AVERROR(ENOMEM);
00092         }
00093 
00094         av_freep(&s->completion_bitmask);
00095         s->completion_bitmask = av_mallocz(bitmask_size);
00096         if (!s->completion_bitmask) {
00097             av_log(s->jpg.avctx, AV_LOG_ERROR,
00098                    "Completion bitmask memory allocation error\n");
00099             return AVERROR(ENOMEM);
00100         }
00101 
00102         s->bitmask_size = bitmask_size;
00103     }
00104 
00105     memcpy(s->mxm_bitmask, buf_ptr + 12, bitmask_size);
00106     s->got_mxm_bitmask = 1;
00107 
00108     if (!s->has_complete_frame) {
00109         uint8_t completion_check = 0xFF;
00110         for (i = 0; i < bitmask_size; ++i) {
00111             s->completion_bitmask[i] |= s->mxm_bitmask[i];
00112             completion_check &= s->completion_bitmask[i];
00113         }
00114         s->has_complete_frame = !(completion_check ^ 0xFF);
00115     }
00116 
00117     return 0;
00118 }
00119 
00120 static int mxpeg_decode_com(MXpegDecodeContext *s,
00121                             const uint8_t *buf_ptr, int buf_size)
00122 {
00123     int len, ret = 0;
00124     if (buf_size < 2)
00125         return 0;
00126     len = AV_RB16(buf_ptr);
00127     if (len > 14 && len <= buf_size && !strncmp(buf_ptr + 2, "MXM", 3)) {
00128         ret = mxpeg_decode_mxm(s, buf_ptr + 2, len - 2);
00129     }
00130     skip_bits(&s->jpg.gb, 8*FFMIN(len,buf_size));
00131 
00132     return ret;
00133 }
00134 
00135 static int mxpeg_check_dimensions(MXpegDecodeContext *s, MJpegDecodeContext *jpg,
00136                                   AVFrame *reference_ptr)
00137 {
00138     if ((jpg->width + 0x0F)>>4 != s->mb_width ||
00139         (jpg->height + 0x0F)>>4 != s->mb_height) {
00140         av_log(jpg->avctx, AV_LOG_ERROR,
00141                "Picture dimensions stored in SOF and MXM mismatch\n");
00142         return AVERROR(EINVAL);
00143     }
00144 
00145     if (reference_ptr->data[0]) {
00146         int i;
00147         for (i = 0; i < MAX_COMPONENTS; ++i) {
00148             if ( (!reference_ptr->data[i] ^ !jpg->picture_ptr->data[i]) ||
00149                  reference_ptr->linesize[i] != jpg->picture_ptr->linesize[i]) {
00150                 av_log(jpg->avctx, AV_LOG_ERROR,
00151                        "Dimensions of current and reference picture mismatch\n");
00152                 return AVERROR(EINVAL);
00153             }
00154         }
00155     }
00156 
00157     return 0;
00158 }
00159 
00160 static int mxpeg_decode_frame(AVCodecContext *avctx,
00161                           void *data, int *data_size,
00162                           AVPacket *avpkt)
00163 {
00164     const uint8_t *buf = avpkt->data;
00165     int buf_size = avpkt->size;
00166     MXpegDecodeContext *s = avctx->priv_data;
00167     MJpegDecodeContext *jpg = &s->jpg;
00168     const uint8_t *buf_end, *buf_ptr;
00169     const uint8_t *unescaped_buf_ptr;
00170     int unescaped_buf_size;
00171     int start_code;
00172     AVFrame *picture = data;
00173     int ret;
00174 
00175     buf_ptr = buf;
00176     buf_end = buf + buf_size;
00177     jpg->got_picture = 0;
00178     s->got_mxm_bitmask = 0;
00179     while (buf_ptr < buf_end) {
00180         start_code = ff_mjpeg_find_marker(jpg, &buf_ptr, buf_end,
00181                                           &unescaped_buf_ptr, &unescaped_buf_size);
00182         if (start_code < 0)
00183             goto the_end;
00184         {
00185             init_get_bits(&jpg->gb, unescaped_buf_ptr, unescaped_buf_size*8);
00186 
00187             if (start_code >= APP0 && start_code <= APP15) {
00188                 mxpeg_decode_app(s, unescaped_buf_ptr, unescaped_buf_size);
00189             }
00190 
00191             switch (start_code) {
00192             case SOI:
00193                 if (jpg->got_picture) //emulating EOI
00194                     goto the_end;
00195                 break;
00196             case EOI:
00197                 goto the_end;
00198             case DQT:
00199                 ret = ff_mjpeg_decode_dqt(jpg);
00200                 if (ret < 0) {
00201                     av_log(avctx, AV_LOG_ERROR,
00202                            "quantization table decode error\n");
00203                     return ret;
00204                 }
00205                 break;
00206             case DHT:
00207                 ret = ff_mjpeg_decode_dht(jpg);
00208                 if (ret < 0) {
00209                     av_log(avctx, AV_LOG_ERROR,
00210                            "huffman table decode error\n");
00211                     return ret;
00212                 }
00213                 break;
00214             case COM:
00215                 ret = mxpeg_decode_com(s, unescaped_buf_ptr,
00216                                        unescaped_buf_size);
00217                 if (ret < 0)
00218                     return ret;
00219                 break;
00220             case SOF0:
00221                 s->got_sof_data = 0;
00222                 ret = ff_mjpeg_decode_sof(jpg);
00223                 if (ret < 0) {
00224                     av_log(avctx, AV_LOG_ERROR,
00225                            "SOF data decode error\n");
00226                     return ret;
00227                 }
00228                 if (jpg->interlaced) {
00229                     av_log(avctx, AV_LOG_ERROR,
00230                            "Interlaced mode not supported in MxPEG\n");
00231                     return AVERROR(EINVAL);
00232                 }
00233                 s->got_sof_data = 1;
00234                 break;
00235             case SOS:
00236                 if (!s->got_sof_data) {
00237                     av_log(avctx, AV_LOG_WARNING,
00238                            "Can not process SOS without SOF data, skipping\n");
00239                     break;
00240                 }
00241                 if (!jpg->got_picture) {
00242                     if (jpg->first_picture) {
00243                         av_log(avctx, AV_LOG_WARNING,
00244                                "First picture has no SOF, skipping\n");
00245                         break;
00246                     }
00247                     if (!s->got_mxm_bitmask){
00248                         av_log(avctx, AV_LOG_WARNING,
00249                                "Non-key frame has no MXM, skipping\n");
00250                         break;
00251                     }
00252                     /* use stored SOF data to allocate current picture */
00253                     if (jpg->picture_ptr->data[0])
00254                         avctx->release_buffer(avctx, jpg->picture_ptr);
00255                     if (avctx->get_buffer(avctx, jpg->picture_ptr) < 0) {
00256                         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
00257                         return AVERROR(ENOMEM);
00258                     }
00259                     jpg->picture_ptr->pict_type = AV_PICTURE_TYPE_P;
00260                     jpg->picture_ptr->key_frame = 0;
00261                     jpg->got_picture = 1;
00262                 } else {
00263                     jpg->picture_ptr->pict_type = AV_PICTURE_TYPE_I;
00264                     jpg->picture_ptr->key_frame = 1;
00265                 }
00266 
00267                 if (s->got_mxm_bitmask) {
00268                     AVFrame *reference_ptr = &s->picture[s->picture_index ^ 1];
00269                     if (mxpeg_check_dimensions(s, jpg, reference_ptr) < 0)
00270                         break;
00271 
00272                     /* allocate dummy reference picture if needed */
00273                     if (!reference_ptr->data[0] &&
00274                         avctx->get_buffer(avctx, reference_ptr) < 0) {
00275                         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
00276                         return AVERROR(ENOMEM);
00277                     }
00278 
00279                     ff_mjpeg_decode_sos(jpg, s->mxm_bitmask, reference_ptr);
00280                 } else {
00281                     ff_mjpeg_decode_sos(jpg, NULL, NULL);
00282                 }
00283 
00284                 break;
00285             }
00286 
00287             buf_ptr += (get_bits_count(&jpg->gb)+7) >> 3;
00288         }
00289 
00290     }
00291 
00292 the_end:
00293     if (jpg->got_picture) {
00294         *data_size = sizeof(AVFrame);
00295         *picture = *jpg->picture_ptr;
00296         s->picture_index ^= 1;
00297         jpg->picture_ptr = &s->picture[s->picture_index];
00298 
00299         if (!s->has_complete_frame) {
00300             if (!s->got_mxm_bitmask)
00301                 s->has_complete_frame = 1;
00302             else
00303                 *data_size = 0;
00304         }
00305     }
00306 
00307     return buf_ptr - buf;
00308 }
00309 
00310 static av_cold int mxpeg_decode_end(AVCodecContext *avctx)
00311 {
00312     MXpegDecodeContext *s = avctx->priv_data;
00313     MJpegDecodeContext *jpg = &s->jpg;
00314     int i;
00315 
00316     jpg->picture_ptr = NULL;
00317     ff_mjpeg_decode_end(avctx);
00318 
00319     for (i = 0; i < 2; ++i) {
00320         if (s->picture[i].data[0])
00321             avctx->release_buffer(avctx, &s->picture[i]);
00322     }
00323 
00324     av_freep(&s->mxm_bitmask);
00325     av_freep(&s->completion_bitmask);
00326 
00327     return 0;
00328 }
00329 
00330 AVCodec ff_mxpeg_decoder = {
00331     .name           = "mxpeg",
00332     .long_name      = NULL_IF_CONFIG_SMALL("Mobotix MxPEG video"),
00333     .type           = AVMEDIA_TYPE_VIDEO,
00334     .id             = CODEC_ID_MXPEG,
00335     .priv_data_size = sizeof(MXpegDecodeContext),
00336     .init           = mxpeg_decode_init,
00337     .close          = mxpeg_decode_end,
00338     .decode         = mxpeg_decode_frame,
00339     .capabilities   = CODEC_CAP_DR1,
00340     .max_lowres     = 3
00341 };

Generated on Fri Feb 22 2013 07:24:28 for FFmpeg by  doxygen 1.7.1