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• Save frame as image during video stream using ffmpeg, in C

  30 avril 2017, par George T.

  I’m using the Parrot SDK3 to retrieve the video stream from a Bebop2 drone. From it I need to "extract" a frame and save it as an image.

  The whole code can be found here, but I shall try to include the (what I understand as) important parts here.

  Where the video is sent to mplayer. I assume from this that the video format is h624.

  if (videoOut != NULL)
  
  {
  
      if (codec.type == ARCONTROLLER_STREAM_CODEC_TYPE_H264)
  
      {
  
          if (DISPLAY_WITH_MPLAYER)
  
          {
  
              fwrite(codec.parameters.h264parameters.spsBuffer, codec.parameters.h264parameters.spsSize, 1, videoOut);
  
              fwrite(codec.parameters.h264parameters.ppsBuffer, codec.parameters.h264parameters.ppsSize, 1, videoOut);
  
  
  
              fflush (videoOut);
  
          }
  
      }
  
  }

  Where the frame is received and written to videoOut, to be displayed

  eARCONTROLLER_ERROR didReceiveFrameCallback (ARCONTROLLER_Frame_t *frame, void *customData)
  
  {
  
      if (videoOut != NULL)
  
      {
  
          if (frame != NULL)
  
          {
  
              if (DISPLAY_WITH_MPLAYER)
  
              {
  
                  fwrite(frame->data, frame->used, 1, videoOut);
  
  
  
                  fflush (videoOut);
  
              }
  
          }
  
      }
  
      return ARCONTROLLER_OK;
  
  }

  The idea I had in mind is to fwrite(frame->data, frame->used, 1, videoOut); to a different file but that just creates a corrupted file, probably because of encoding. In what way can I get this frame and store it to a separate image ? The preferable image filetype .png, .jpg or .gif

  Any help will be greatly appreciated ! Thanks in advance !

• Slicing an AVI file

  7 novembre 2014, par Peter Lur

  I am trying to upload only a certain part of an AVI file on the server without having to upload the whole file first.

  If I set the slice to the beginning (byte : 0), I can read the resulting file no problem even if I slice it in any size. However if the slice start anywhere but not at byte 0, the file become unreadable. I guess this has something to do with the avi header/index being messed up. I was wondering maybe I could use ffmpeg to move the header or something ?

  HTML Source

      
  
          
  
          <code class="echappe-js">&lt;script type=&quot;text/javascript&quot;&gt;<br />
  
  <br />
  
              window.BlobBuilder = window.MozBlobBuilder || window.WebKitBlobBuilder || window.BlobBuilder;<br />
  
  <br />
  
              function sendRequest() {<br />
  
                  var blob = document.getElementById('fileToUpload').files[0];<br />
  
  <br />
  
  <br />
  
                  //Slicing parameters<br />
  
  <br />
  
  <br />
  
                  //#1: Starting at byte:0 = WORKING WELL<br />
  
                  var start = 0;<br />
  
                  var end = 1048576;  // 1MB chunk sizes.<br />
  
  <br />
  
  <br />
  
                  //#2: Slicing the video file somewhere else (FAIL)<br />
  
  <br />
  
                  /*<br />
  
                  var start = 1048576*3;<br />
  
                  var end = 1048576*4;<br />
  
                  */<br />
  
  <br />
  
  <br />
  
                  var chunk = blob.slice(start, end, 'video/avi');<br />
  
                  uploadFile(chunk);<br />
  
  <br />
  
              }<br />
  
  <br />
  
              function fileSelected() {<br />
  
                  var file = document.getElementById('fileToUpload').files[0];<br />
  
                  if (file) {<br />
  
                      var fileSize = 0;<br />
  
                      if (file.size &gt; 1024 * 1024)<br />
  
                          fileSize = (Math.round(file.size * 100 / (1024 * 1024)) / 100).toString() + 'MB';<br />
  
                      else<br />
  
                          fileSize = (Math.round(file.size * 100 / 1024) / 100).toString() + 'KB';<br />
  
  <br />
  
                      document.getElementById('fileName').innerHTML = 'Name: ' + file.name;<br />
  
                      document.getElementById('fileSize').innerHTML = 'Size: ' + fileSize;<br />
  
                      document.getElementById('fileType').innerHTML = 'Type: ' + file.type;<br />
  
                  }<br />
  
              }<br />
  
  <br />
  
              function uploadFile(blobFile) {<br />
  
                  //var file = document.getElementById('fileToUpload').files[0];  <br />
  
                  var fd = new FormData();<br />
  
                  fd.append(&quot;fileToUpload&quot;, blobFile);<br />
  
  <br />
  
                  var xhr = new XMLHttpRequest();<br />
  
                  xhr.upload.addEventListener(&quot;progress&quot;, uploadProgress, false);<br />
  
                  xhr.addEventListener(&quot;load&quot;, uploadComplete, false);<br />
  
                  xhr.addEventListener(&quot;error&quot;, uploadFailed, false);<br />
  
                  xhr.addEventListener(&quot;abort&quot;, uploadCanceled, false);<br />
  
                  xhr.open(&quot;POST&quot;, &quot;upload.php&quot;);<br />
  
                  xhr.onload = function(e) {<br />
  
                    //alert(&quot;loaded!&quot;);<br />
  
                    };<br />
  
  <br />
  
                  xhr.send(fd);<br />
  
                  //alert(&quot;oen over&quot;);<br />
  
              }<br />
  
  <br />
  
              function uploadProgress(evt) {<br />
  
                  if (evt.lengthComputable) {<br />
  
                      var percentComplete = Math.round(evt.loaded * 100 / evt.total);<br />
  
                      document.getElementById('progressNumber').innerHTML = percentComplete.toString() + '%';<br />
  
                  }<br />
  
                  else {<br />
  
                      document.getElementById('progressNumber').innerHTML = 'unable to compute';<br />
  
                  }<br />
  
              }<br />
  
  <br />
  
              function uploadComplete(evt) {<br />
  
                  /* This event is raised when the server send back a response */<br />
  
                  //alert(evt.target.responseText);<br />
  
              }<br />
  
  <br />
  
              function uploadFailed(evt) {<br />
  
                  alert(&quot;There was an error attempting to upload the file.&quot;);<br />
  
              }<br />
  
  <br />
  
              function uploadCanceled(evt) {<br />
  
                  xhr.abort();<br />
  
                  xhr = null;<br />
  
                  //alert(&quot;The upload has been canceled by the user or the browser dropped the connection.&quot;);<br />
  
              }<br />
  
          &lt;/script&gt;
  
              
  
                  Select a File to Upload
  
                  
                  
              
              
  
              
  
              
  
              
  
                  
              
              
  
          
  

  PHP Source (upload.php)

  <?php
  
  
  
  $tmp_name = $_FILES['fileToUpload']['tmp_name'];
  
  $size = $_FILES['fileToUpload']['size'];
  
  $name = $_FILES['fileToUpload']['name'];
  
  
  
  $target_file = basename($name);
  
  
  
  $complete = "complete.avi";
  
  $com = fopen($complete, "ab");
  
  
  
  // Open temp file
  
  $out = fopen($target_file, "wb");
  
  
  
  if ( $out ) {
  
      // Read binary input stream and append it to temp file
  
      $in = fopen($tmp_name, "rb");
  
      if ( $in ) {
  
          while ( $buff = fread( $in, 1048576 ) ) {
  
              fwrite($out, $buff);
  
              fwrite($com, $buff);
  
          }   
  
      }
  
      fclose($in);
  
      fclose($out);
  
  }
  
  fclose($com);
  
  
  
  ?>

• Sending 2 streams to FFmpeg from nodejs

  18 août 2019, par Sylens

  I am trying to send 2 ReadableStreams to FFmpeg from nodejs. I have tried using fluent-ffmpeg library to do this, but it only supports sending one stream for processing. Check here

  My problem is :
  I have 2 incoming mono audio streams, I want to send them to ffmpeg to create a stereo stream, which I will then send to google’s speech to text service, to generate a transcription.

  I am successfully receiving both the mono streams to the nodejs server.
  How to utilize FFmpeg to merge them in realtime is still unclear, I could spawn a FFmpeg child process, but I’m not sure how to give 2 ReadableStreams as inputs and get the output as another stream ? FFmpeg supports multiple input streams.

  I can merge the 2 mono streams if they are in two separate files with this code.

  const { spawn } = childProcess;
  
  const ffmpeg = spawn('ffmpeg', [
  
    '-i', this.phoneAudioFile,
  
    '-i', this.micAudioFile,
  
    '-filter_complex', '[0:a][1:a]amerge=inputs=2[a]',
  
    '-map', '[a]',
  
    this.outputLosslessFile,
  
  ]);

  How can I acheive the same using 2 streams instead of 2 files ?

  EDIT

  • The incoming streams both have PCM audio data.
  • This entire process runs on a linux Ubuntu server.
  • The final output must be a wav file.