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• Open avi file with OpenCV : ffmpeg ?

  28 juin 2012, par CTZStef

  This question is related to a previous question I asked here.

  I read on the Willow Garage website dedicated to OpenCV that we do not have to take care of ffmpeg while installing OpenCV since version 1.2.x. Here it is.

  However, some questions asked here on Stackoverflow suggest the contrary.

  So, what should I do ? Do I have to recompile OpenCV and do some special operation related to ffmpeg to get it to, finally, open avi file on my Linux system ?

• How to fix a segmentaion fault in a C program ? [closed]

  13 janvier 2012, par ipegasus

  Possible Duplicate :
  Segmentation fault

  Currently I am upgrading an open source program used for HTTP streaming. It needs to support the latest FFMPEG.
  The code compiles fine with no warnings although I am getting a segmentation fault error.
  I would like to know how to fix the issue ? and / or the best way to debug ? Please find attached a portion of the code due to size. I will try to add the project to github :) Thanks in advance !

  Sample Usage

  # segmenter --i out.ts --l 10 --o stream.m3u8 --d segments --f stream

  Makefile

  FFLIBS=`pkg-config --libs libavformat libavcodec libavutil`
  
  FFFLAGS=`pkg-config --cflags libavformat libavcodec libavutil`
  
  
  
  all:
  
      gcc -Wall -g segmenter.c -o segmenter ${FFFLAGS} ${FFLIBS}

  segmenter.c

  /*
  
   * Copyright (c) 2009 Chase Douglas
  
   *
  
   * This program is free software; you can redistribute it and/or
  
   * modify it under the terms of the GNU General Public License version 2
  
   * as published by the Free Software Foundation.
  
   *
  
   * This program is distributed in the hope that it will be useful,
  
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
  
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  
   * GNU General Public License for more details.
  
   *
  
   * You should have received a copy of the GNU General Public License
  
   * along with this program; if not, write to the Free Software
  
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  
   */
  
  #include 
  
  #include 
  
  #include 
  
  #include 
  
  #include 
  
  #include "libavformat/avformat.h"
  
  
  
  #include "libavformat/avio.h"
  
  
  
  #include <sys></sys>stat.h>
  
  
  
  #include "segmenter.h"
  
  #include "libavformat/avformat.h"
  
  
  
  #define IMAGE_ID3_SIZE 9171
  
  
  
  void printUsage() {
  
      fprintf(stderr, "\nExample: segmenter --i infile --d baseDir --f baseFileName --o playListFile.m3u8 --l 10 \n");
  
      fprintf(stderr, "\nOptions: \n");
  
      fprintf(stderr, "--i <infile>.\n");
  
      fprintf(stderr, "--o <outfile>.\n");
  
      fprintf(stderr, "--d basedir, the base directory for files.\n");
  
      fprintf(stderr, "--f baseFileName, output files will be baseFileName-#.\n");
  
      fprintf(stderr, "--l segment length, the length of each segment.\n");
  
      fprintf(stderr, "--a,  audio only decode for &lt; 64k streams.\n");
  
      fprintf(stderr, "--v,  video only decode for &lt; 64k streams.\n");
  
      fprintf(stderr, "--version, print version details and exit.\n");
  
      fprintf(stderr, "\n\n");
  
  }
  
  
  
  void ffmpeg_version() {
  
      // output build and version numbers
  
      fprintf(stderr, "  libavutil version:   %s\n", AV_STRINGIFY(LIBAVUTIL_VERSION));
  
      fprintf(stderr, "  libavutil build:     %d\n", LIBAVUTIL_BUILD);
  
      fprintf(stderr, "  libavcodec version:  %s\n", AV_STRINGIFY(LIBAVCODEC_VERSION));
  
      fprintf(stdout, "  libavcodec build:    %d\n", LIBAVCODEC_BUILD);
  
      fprintf(stderr, "  libavformat version: %s\n", AV_STRINGIFY(LIBAVFORMAT_VERSION));
  
      fprintf(stderr, "  libavformat build:   %d\n", LIBAVFORMAT_BUILD);
  
      fprintf(stderr, "  built on " __DATE__ " " __TIME__);
  
  #ifdef __GNUC__
  
      fprintf(stderr, ", gcc: " __VERSION__ "\n");
  
  #else
  
      fprintf(stderr, ", using a non-gcc compiler\n");
  
  #endif
  
  }
  
  
  
  
  
  static AVStream *add_output_stream(AVFormatContext *output_format_context, AVStream *input_stream) {
  
      AVCodecContext *input_codec_context;
  
      AVCodecContext *output_codec_context;
  
      AVStream *output_stream;
  
  
  
      output_stream = avformat_new_stream(output_format_context, 0);
  
      if (!output_stream) {
  
          fprintf(stderr, "Segmenter error: Could not allocate stream\n");
  
          exit(1);
  
      }
  
  
  
      input_codec_context = input_stream->codec;
  
      output_codec_context = output_stream->codec;
  
  
  
      output_codec_context->codec_id = input_codec_context->codec_id;
  
      output_codec_context->codec_type = input_codec_context->codec_type;
  
      output_codec_context->codec_tag = input_codec_context->codec_tag;
  
      output_codec_context->bit_rate = input_codec_context->bit_rate;
  
      output_codec_context->extradata = input_codec_context->extradata;
  
      output_codec_context->extradata_size = input_codec_context->extradata_size;
  
  
  
      if (av_q2d(input_codec_context->time_base) * input_codec_context->ticks_per_frame > av_q2d(input_stream->time_base) &amp;&amp; av_q2d(input_stream->time_base) &lt; 1.0 / 1000) {
  
          output_codec_context->time_base = input_codec_context->time_base;
  
          output_codec_context->time_base.num *= input_codec_context->ticks_per_frame;
  
      } else {
  
          output_codec_context->time_base = input_stream->time_base;
  
      }
  
  
  
      switch (input_codec_context->codec_type) {
  
  #ifdef USE_OLD_FFMPEG
  
          case CODEC_TYPE_AUDIO:
  
  #else
  
          case AVMEDIA_TYPE_AUDIO:
  
  #endif
  
              output_codec_context->channel_layout = input_codec_context->channel_layout;
  
              output_codec_context->sample_rate = input_codec_context->sample_rate;
  
              output_codec_context->channels = input_codec_context->channels;
  
              output_codec_context->frame_size = input_codec_context->frame_size;
  
              if ((input_codec_context->block_align == 1 &amp;&amp; input_codec_context->codec_id == CODEC_ID_MP3) || input_codec_context->codec_id == CODEC_ID_AC3) {
  
                  output_codec_context->block_align = 0;
  
              } else {
  
                  output_codec_context->block_align = input_codec_context->block_align;
  
              }
  
              break;
  
  #ifdef USE_OLD_FFMPEG
  
          case CODEC_TYPE_VIDEO:
  
  #else
  
          case AVMEDIA_TYPE_VIDEO:
  
  #endif
  
              output_codec_context->pix_fmt = input_codec_context->pix_fmt;
  
              output_codec_context->width = input_codec_context->width;
  
              output_codec_context->height = input_codec_context->height;
  
              output_codec_context->has_b_frames = input_codec_context->has_b_frames;
  
  
  
              if (output_format_context->oformat->flags &amp; AVFMT_GLOBALHEADER) {
  
                  output_codec_context->flags |= CODEC_FLAG_GLOBAL_HEADER;
  
              }
  
              break;
  
          default:
  
              break;
  
      }
  
  
  
      return output_stream;
  
  }
  
  
  
  int write_index_file(const char index[], const char tmp_index[], const unsigned int planned_segment_duration, const unsigned int actual_segment_duration[],
  
          const char output_directory[], const char output_prefix[], const char output_file_extension[],
  
          const unsigned int first_segment, const unsigned int last_segment) {
  
      FILE *index_fp;
  
      char *write_buf;
  
      unsigned int i;
  
  
  
      index_fp = fopen(tmp_index, "w");
  
      if (!index_fp) {
  
          fprintf(stderr, "Could not open temporary m3u8 index file (%s), no index file will be created\n", tmp_index);
  
          return -1;
  
      }
  
  
  
      write_buf = malloc(sizeof (char) * 1024);
  
      if (!write_buf) {
  
          fprintf(stderr, "Could not allocate write buffer for index file, index file will be invalid\n");
  
          fclose(index_fp);
  
          return -1;
  
      }
  
  
  
      unsigned int maxDuration = planned_segment_duration;
  
  
  
      for (i = first_segment; i &lt;= last_segment; i++)
  
          if (actual_segment_duration[i] > maxDuration)
  
              maxDuration = actual_segment_duration[i];
  
  
  
  
  
  
  
      snprintf(write_buf, 1024, "#EXTM3U\n#EXT-X-TARGETDURATION:%u\n", maxDuration);
  
  
  
      if (fwrite(write_buf, strlen(write_buf), 1, index_fp) != 1) {
  
          fprintf(stderr, "Could not write to m3u8 index file, will not continue writing to index file\n");
  
          free(write_buf);
  
          fclose(index_fp);
  
          return -1;
  
      }
  
  
  
      for (i = first_segment; i &lt;= last_segment; i++) {
  
          snprintf(write_buf, 1024, "#EXTINF:%u,\n%s-%u%s\n", actual_segment_duration[i], output_prefix, i, output_file_extension);
  
          if (fwrite(write_buf, strlen(write_buf), 1, index_fp) != 1) {
  
              fprintf(stderr, "Could not write to m3u8 index file, will not continue writing to index file\n");
  
              free(write_buf);
  
              fclose(index_fp);
  
              return -1;
  
          }
  
      }
  
  
  
      snprintf(write_buf, 1024, "#EXT-X-ENDLIST\n");
  
      if (fwrite(write_buf, strlen(write_buf), 1, index_fp) != 1) {
  
          fprintf(stderr, "Could not write last file and endlist tag to m3u8 index file\n");
  
          free(write_buf);
  
          fclose(index_fp);
  
          return -1;
  
      }
  
  
  
      free(write_buf);
  
      fclose(index_fp);
  
  
  
      return rename(tmp_index, index);
  
  }
  
  
  
  int main(int argc, const char *argv[]) {
  
      //input parameters
  
      char inputFilename[MAX_FILENAME_LENGTH], playlistFilename[MAX_FILENAME_LENGTH], baseDirName[MAX_FILENAME_LENGTH], baseFileName[MAX_FILENAME_LENGTH];
  
      char baseFileExtension[5]; //either "ts", "aac" or "mp3"
  
      int segmentLength, outputStreams, verbosity, version;
  
  
  
  
  
  
  
      char currentOutputFileName[MAX_FILENAME_LENGTH];
  
      char tempPlaylistName[MAX_FILENAME_LENGTH];
  
  
  
  
  
      //these are used to determine the exact length of the current segment
  
      double prev_segment_time = 0;
  
      double segment_time;
  
      unsigned int actual_segment_durations[2048];
  
      double packet_time = 0;
  
  
  
      //new variables to keep track of output size
  
      double output_bytes = 0;
  
  
  
      unsigned int output_index = 1;
  
      AVOutputFormat *ofmt;
  
      AVFormatContext *ic = NULL;
  
      AVFormatContext *oc;
  
      AVStream *video_st = NULL;
  
      AVStream *audio_st = NULL;
  
      AVCodec *codec;
  
      int video_index;
  
      int audio_index;
  
      unsigned int first_segment = 1;
  
      unsigned int last_segment = 0;
  
      int write_index = 1;
  
      int decode_done;
  
      int ret;
  
      int i;
  
  
  
      unsigned char id3_tag[128];
  
      unsigned char * image_id3_tag;
  
  
  
      size_t id3_tag_size = 73;
  
      int newFile = 1; //a boolean value to flag when a new file needs id3 tag info in it
  
  
  
      if (parseCommandLine(inputFilename, playlistFilename, baseDirName, baseFileName, baseFileExtension, &amp;outputStreams, &amp;segmentLength, &amp;verbosity, &amp;version, argc, argv) != 0)
  
          return 0;
  
  
  
      if (version) {
  
          ffmpeg_version();
  
          return 0;
  
      }
  
  
  
  
  
      fprintf(stderr, "%s %s\n", playlistFilename, tempPlaylistName);
  
  
  
  
  
      image_id3_tag = malloc(IMAGE_ID3_SIZE);
  
      if (outputStreams == OUTPUT_STREAM_AUDIO)
  
          build_image_id3_tag(image_id3_tag);
  
      build_id3_tag((char *) id3_tag, id3_tag_size);
  
  
  
      snprintf(tempPlaylistName, strlen(playlistFilename) + strlen(baseDirName) + 1, "%s%s", baseDirName, playlistFilename);
  
      strncpy(playlistFilename, tempPlaylistName, strlen(tempPlaylistName));
  
      strncpy(tempPlaylistName, playlistFilename, MAX_FILENAME_LENGTH);
  
      strncat(tempPlaylistName, ".", 1);
  
  
  
      //decide if this is an aac file or a mpegts file.
  
      //postpone deciding format until later
  
      /*  ifmt = av_find_input_format("mpegts");
  
      if (!ifmt) 
  
      {
  
      fprintf(stderr, "Could not find MPEG-TS demuxer.\n");
  
      exit(1);
  
      } */
  
  
  
      av_log_set_level(AV_LOG_DEBUG);
  
  
  
      av_register_all();
  
      ret = avformat_open_input(&amp;ic, inputFilename, NULL, NULL);
  
      if (ret != 0) {
  
          fprintf(stderr, "Could not open input file %s. Error %d.\n", inputFilename, ret);
  
          exit(1);
  
      }
  
  
  
      if (avformat_find_stream_info(ic, NULL) &lt; 0) {
  
          fprintf(stderr, "Could not read stream information.\n");
  
          exit(1);
  
      }
  
  
  
      oc = avformat_alloc_context();
  
      if (!oc) {
  
          fprintf(stderr, "Could not allocate output context.");
  
          exit(1);
  
      }
  
  
  
      video_index = -1;
  
      audio_index = -1;
  
  
  
      for (i = 0; i &lt; ic->nb_streams &amp;&amp; (video_index &lt; 0 || audio_index &lt; 0); i++) {
  
          switch (ic->streams[i]->codec->codec_type) {
  
  
  
  #ifdef USE_OLD_FFMPEG
  
              case CODEC_TYPE_VIDEO:
  
  #else
  
              case AVMEDIA_TYPE_VIDEO:
  
  #endif
  
                  video_index = i;
  
                  ic->streams[i]->discard = AVDISCARD_NONE;
  
                  if (outputStreams &amp; OUTPUT_STREAM_VIDEO)
  
                      video_st = add_output_stream(oc, ic->streams[i]);
  
                  break;
  
  #ifdef USE_OLD_FFMPEG
  
              case CODEC_TYPE_AUDIO:
  
  #else
  
              case AVMEDIA_TYPE_AUDIO:
  
  #endif
  
                  audio_index = i;
  
                  ic->streams[i]->discard = AVDISCARD_NONE;
  
                  if (outputStreams &amp; OUTPUT_STREAM_AUDIO)
  
                      audio_st = add_output_stream(oc, ic->streams[i]);
  
                  break;
  
              default:
  
                  ic->streams[i]->discard = AVDISCARD_ALL;
  
                  break;
  
          }
  
      }
  
  
  
      if (video_index == -1) {
  
          fprintf(stderr, "Stream must have video component.\n");
  
          exit(1);
  
      }
  
  
  
      //now that we know the audio and video output streams
  
      //we can decide on an output format.
  
      if (outputStreams == OUTPUT_STREAM_AUDIO) {
  
          //the audio output format should be the same as the audio input format
  
          switch (ic->streams[audio_index]->codec->codec_id) {
  
              case CODEC_ID_MP3:
  
                  fprintf(stderr, "Setting output audio to mp3.");
  
                  strncpy(baseFileExtension, ".mp3", strlen(".mp3"));
  
                  ofmt = av_guess_format("mp3", NULL, NULL);
  
                  break;
  
              case CODEC_ID_AAC:
  
                  fprintf(stderr, "Setting output audio to aac.");
  
                  ofmt = av_guess_format("adts", NULL, NULL);
  
                  break;
  
              default:
  
                  fprintf(stderr, "Codec id %d not supported.\n", ic->streams[audio_index]->id);
  
          }
  
          if (!ofmt) {
  
              fprintf(stderr, "Could not find audio muxer.\n");
  
              exit(1);
  
          }
  
      } else {
  
          ofmt = av_guess_format("mpegts", NULL, NULL);
  
          if (!ofmt) {
  
              fprintf(stderr, "Could not find MPEG-TS muxer.\n");
  
              exit(1);
  
          }
  
      }
  
      oc->oformat = ofmt;
  
  
  
      if (outputStreams &amp; OUTPUT_STREAM_VIDEO &amp;&amp; oc->oformat->flags &amp; AVFMT_GLOBALHEADER) {
  
          oc->flags |= CODEC_FLAG_GLOBAL_HEADER;
  
      }
  
  
  
  
  
      /*  Deprecated: pass the options to avformat_write_header directly. 
  
          if (av_set_parameters(oc, NULL) &lt; 0) {
  
              fprintf(stderr, "Invalid output format parameters.\n");
  
              exit(1);
  
          }
  
       */
  
  
  
      av_dump_format(oc, 0, baseFileName, 1);
  
  
  
  
  
      //open the video codec only if there is video data
  
      if (video_index != -1) {
  
          if (outputStreams &amp; OUTPUT_STREAM_VIDEO)
  
              codec = avcodec_find_decoder(video_st->codec->codec_id);
  
          else
  
              codec = avcodec_find_decoder(ic->streams[video_index]->codec->codec_id);
  
          if (!codec) {
  
              fprintf(stderr, "Could not find video decoder, key frames will not be honored.\n");
  
          }
  
  
  
          if (outputStreams &amp; OUTPUT_STREAM_VIDEO)
  
              ret = avcodec_open2(video_st->codec, codec, NULL);
  
          else
  
              avcodec_open2(ic->streams[video_index]->codec, codec, NULL);
  
          if (ret &lt; 0) {
  
              fprintf(stderr, "Could not open video decoder, key frames will not be honored.\n");
  
          }
  
      }
  
  
  
      snprintf(currentOutputFileName, strlen(baseDirName) + strlen(baseFileName) + strlen(baseFileExtension) + 10, "%s%s-%u%s", baseDirName, baseFileName, output_index++, baseFileExtension);
  
  
  
      if (avio_open(&amp;oc->pb, currentOutputFileName, URL_WRONLY) &lt; 0) {
  
          fprintf(stderr, "Could not open &#39;%s&#39;.\n", currentOutputFileName);
  
          exit(1);
  
      }
  
      newFile = 1;
  
  
  
      int r = avformat_write_header(oc,NULL);
  
      if (r) {
  
          fprintf(stderr, "Could not write mpegts header to first output file.\n");
  
          debugReturnCode(r);
  
          exit(1);
  
      }
  
  
  
      //no segment info is written here. This just creates the shell of the playlist file
  
      write_index = !write_index_file(playlistFilename, tempPlaylistName, segmentLength, actual_segment_durations, baseDirName, baseFileName, baseFileExtension, first_segment, last_segment);
  
  
  
      do {
  
          AVPacket packet;
  
  
  
          decode_done = av_read_frame(ic, &amp;packet);
  
  
  
          if (decode_done &lt; 0) {
  
              break;
  
          }
  
  
  
          if (av_dup_packet(&amp;packet) &lt; 0) {
  
              fprintf(stderr, "Could not duplicate packet.");
  
              av_free_packet(&amp;packet);
  
              break;
  
          }
  
  
  
          //this time is used to check for a break in the segments
  
          //  if (packet.stream_index == video_index &amp;&amp; (packet.flags &amp; PKT_FLAG_KEY)) 
  
          //  {
  
          //    segment_time = (double)video_st->pts.val * video_st->time_base.num / video_st->time_base.den;         
  
          //  }
  
  #if USE_OLD_FFMPEG
  
          if (packet.stream_index == video_index &amp;&amp; (packet.flags &amp; PKT_FLAG_KEY))
  
  #else
  
          if (packet.stream_index == video_index &amp;&amp; (packet.flags &amp; AV_PKT_FLAG_KEY))
  
  #endif
  
          {
  
              segment_time = (double) packet.pts * ic->streams[video_index]->time_base.num / ic->streams[video_index]->time_base.den;
  
          }
  
          //  else if (video_index &lt; 0) 
  
          //  {
  
          //      segment_time = (double)audio_st->pts.val * audio_st->time_base.num / audio_st->time_base.den;
  
          //  }
  
  
  
          //get the most recent packet time
  
          //this time is used when the time for the final segment is printed. It may not be on the edge of
  
          //of a keyframe!
  
          if (packet.stream_index == video_index)
  
              packet_time = (double) packet.pts * ic->streams[video_index]->time_base.num / ic->streams[video_index]->time_base.den; //(double)video_st->pts.val * video_st->time_base.num / video_st->time_base.den;
  
          else if (outputStreams &amp; OUTPUT_STREAM_AUDIO)
  
              packet_time = (double) audio_st->pts.val * audio_st->time_base.num / audio_st->time_base.den;
  
          else
  
              continue;
  
          //start looking for segment splits for videos one half second before segment duration expires. This is because the 
  
          //segments are split on key frames so we cannot expect all segments to be split exactly equally. 
  
          if (segment_time - prev_segment_time >= segmentLength - 0.5) {
  
              fprintf(stderr, "looking to print index file at time %lf\n", segment_time);
  
              avio_flush(oc->pb);
  
              avio_close(oc->pb);
  
  
  
              if (write_index) {
  
                  actual_segment_durations[++last_segment] = (unsigned int) rint(segment_time - prev_segment_time);
  
                  write_index = !write_index_file(playlistFilename, tempPlaylistName, segmentLength, actual_segment_durations, baseDirName, baseFileName, baseFileExtension, first_segment, last_segment);
  
                  fprintf(stderr, "Writing index file at time %lf\n", packet_time);
  
              }
  
  
  
              struct stat st;
  
              stat(currentOutputFileName, &amp;st);
  
              output_bytes += st.st_size;
  
  
  
              snprintf(currentOutputFileName, strlen(baseDirName) + strlen(baseFileName) + strlen(baseFileExtension) + 10, "%s%s-%u%s", baseDirName, baseFileName, output_index++, baseFileExtension);
  
              if (avio_open(&amp;oc->pb, currentOutputFileName, URL_WRONLY) &lt; 0) {
  
                  fprintf(stderr, "Could not open &#39;%s&#39;\n", currentOutputFileName);
  
                  break;
  
              }
  
  
  
              newFile = 1;
  
              prev_segment_time = segment_time;
  
          }
  
  
  
          if (outputStreams == OUTPUT_STREAM_AUDIO &amp;&amp; packet.stream_index == audio_index) {
  
              if (newFile &amp;&amp; outputStreams == OUTPUT_STREAM_AUDIO) {
  
                  //add id3 tag info
  
                  //fprintf(stderr, "adding id3tag to file %s\n", currentOutputFileName);
  
                  //printf("%lf %lld %lld %lld %lld %lld %lf\n", segment_time, audio_st->pts.val, audio_st->cur_dts, audio_st->cur_pkt.pts, packet.pts, packet.dts, packet.dts * av_q2d(ic->streams[audio_index]->time_base) );
  
                  fill_id3_tag((char*) id3_tag, id3_tag_size, packet.dts);
  
                  avio_write(oc->pb, id3_tag, id3_tag_size);
  
                  avio_write(oc->pb, image_id3_tag, IMAGE_ID3_SIZE);
  
                  avio_flush(oc->pb);
  
                  newFile = 0;
  
              }
  
  
  
              packet.stream_index = 0; //only one stream in audio only segments
  
              ret = av_interleaved_write_frame(oc, &amp;packet);
  
          } else if (outputStreams &amp; OUTPUT_STREAM_VIDEO) {
  
              if (newFile) {
  
                  //fprintf(stderr, "New File: %lld %lld %lld\n", packet.pts, video_st->pts.val, audio_st->pts.val);
  
                  //printf("%lf %lld %lld %lld %lld %lld %lf\n", segment_time, audio_st->pts.val, audio_st->cur_dts, audio_st->cur_pkt.pts, packet.pts, packet.dts, packet.dts * av_q2d(ic->streams[audio_index]->time_base) );
  
                  newFile = 0;
  
              }
  
              if (outputStreams == OUTPUT_STREAM_VIDEO)
  
                  ret = av_write_frame(oc, &amp;packet);
  
              else
  
                  ret = av_interleaved_write_frame(oc, &amp;packet);
  
          }
  
  
  
          if (ret &lt; 0) {
  
              fprintf(stderr, "Warning: Could not write frame of stream.\n");
  
          } else if (ret > 0) {
  
              fprintf(stderr, "End of stream requested.\n");
  
              av_free_packet(&amp;packet);
  
              break;
  
          }
  
  
  
          av_free_packet(&amp;packet);
  
      } while (!decode_done);
  
  
  
      //make sure all packets are written and then close the last file. 
  
      avio_flush(oc->pb);
  
      av_write_trailer(oc);
  
  
  
      if (video_st &amp;&amp; video_st->codec)
  
          avcodec_close(video_st->codec);
  
  
  
      if (audio_st &amp;&amp; audio_st->codec)
  
          avcodec_close(audio_st->codec);
  
  
  
      for (i = 0; i &lt; oc->nb_streams; i++) {
  
          av_freep(&amp;oc->streams[i]->codec);
  
          av_freep(&amp;oc->streams[i]);
  
      }
  
  
  
      avio_close(oc->pb);
  
      av_free(oc);
  
  
  
      struct stat st;
  
      stat(currentOutputFileName, &amp;st);
  
      output_bytes += st.st_size;
  
  
  
  
  
      if (write_index) {
  
          actual_segment_durations[++last_segment] = (unsigned int) rint(packet_time - prev_segment_time);
  
  
  
          //make sure that the last segment length is not zero
  
          if (actual_segment_durations[last_segment] == 0)
  
              actual_segment_durations[last_segment] = 1;
  
  
  
          write_index_file(playlistFilename, tempPlaylistName, segmentLength, actual_segment_durations, baseDirName, baseFileName, baseFileExtension, first_segment, last_segment);
  
  
  
      }
  
  
  
      write_stream_size_file(baseDirName, baseFileName, output_bytes * 8 / segment_time);
  
  
  
      return 0;
  
  }
  
  </outfile></infile>

• Texai Remote Presence System Using VP8 Video

  19 novembre 2010, par noreply@blogger.com (John Luther)

  Guest blogger Josh Tyler is a member of the Texai team at Willow Garage.

  Willow Garage is busy building the next version of its Texai remote presence platform with VP8, the video codec used in WebM.

  In short, Texai is a two-way videoconferencing app on a tele-operated robotic platform (for more details, see the piece about Texai in the New York Times). Video and audio quality are critical to providing the best user experience on Texai. We’ve evaluated several video codecs and found VP8’s image quality, low latency and tolerance to packet loss far better than anything else we tested.

  The video below shows VP8 running on one of our systems.

  (If you have a WebM-enabled browser and are enrolled in the YouTube HTML5 beta the video will play in WebM HTML5, otherwise it will play in Flash Player.)

  We’re also looking for help ! If you’re interested in helping us create an incredible, high-fidelity user experience, either by joining our team, partnering on development, or by being added to our early customer interest list, please email us at texai-info@willowgarage.com.