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• PHP readfile on a file which is increasing in size

  13 février 2013, par Sathiya Sundaram

  Is it possible to use PHP readfile function on a remote file whose size is unknown and is increasing in size ? Here is the scenario :

  I'm developing a script which downloads a video from a third party website and simultaneously trans-codes the video into MP3 format. This MP3 is then transferred to the user via readfile.

  The query used for the above process is like this :

  wget -q -O- "VideoURLHere" | ffmpeg -i - "Output.mp3" > /dev/null 2>&1 &

  So the file is fetched and encoded at the same time.
  Now when the above process is in progress I begin sending the output mp3 to the user via readfile. The problem is that the encoding process takes some time and therefore depending on the users download speed readfile reaches an assumed EoF before the whole file is encoded, resulting in the user receiving partial content/incomplete files.

  My first attempt to fix this was to apply a speed limit on the users download, but this is not foolproof as the encoding time and speed vary with load and this still led to partial downloads.

  So is there a way to implement this system in such a way that I can serve the downloads simultaneously along with the encoding and also guarantee sending the complete file to the end user ?

  Any help is appreciated.

  EDIT :
  In response to Peter, I'm actually using fread(read readfile_chunked) :

   <?php
  
   function readfile_chunked($filename,$retbytes=true) {
  
              $chunksize = 1*(1024*1024); // how many bytes per chunk
  
              $totChunk = 0;
  
              $buffer = '';
  
              $cnt =0;
  
              $handle = fopen($filename, 'rb');
  
              if ($handle === false) {
  
                  return false;
  
              }
  
              while (!feof($handle)) {
  
                  //usleep(120000); //Used to impose an artificial speed limit
  
                  $buffer = fread($handle, $chunksize);
  
                  echo $buffer;
  
                  ob_flush();
  
                  flush();
  
                  if ($retbytes) {
  
                      $cnt += strlen($buffer);
  
                  }
  
              }
  
                  $status = fclose($handle);
  
              if ($retbytes && $status) {
  
                  return $cnt;        // return num. bytes delivered like readfile() does.
  
              }
  
              return $status;
  
          }
  
          readfile_chunked($linkToMp3);
  
      ?>

  This still does not guarantee complete downloads as depending on the users download speed and the encoding speed, the EOF() may be reached prematurely.

  Also in response to theJeztah's comment, I'm trying to achieve this without having to make the user wait..so that's not an option.

• How to record playable video files in gstreamer even if recording is interrupted unexpectedly (e.g. power disconnects) ?

  16 septembre 2021, par Otter_warrior

  I have been recording video streams on my Jetson Xavier NX using a simple gstreamer pipeline such as this

  


  gst-launch-1.0 -v \
nvarguscamerasrc sensor-id=0 ! \
'video/x-raw(memory:NVMM), width=(int)1920, height=(int)1080, format=(string)NV12, framerate=(fraction)30/1' ! \
nvv4l2h265enc ! 'video/x-h265, stream-format=(string)byte-stream' ! \
h265parse ! qtmux ! filesink location=video.mp4 -e


  


  All is working if the recording is interrupted by keyboard interrupt Ctrl + C, but if the recording is interrupted unexpectedly (e.g. power gets disconnected) the resulting file has no playable stream, even if the file size is correct.

  


  I know that mp4 recording needs to be stopped properly otherwise it won't have the necessary information at the end of the file, but I was wondering if there was any other gstreamer pipelines or final file formats that would allow for an H265 encoded video file to be playable even if the recording is ended unexpectedly.

  


  It would be good even if the recorded file needed to be converted before being playable (e.g. with ffmpeg), as long as the information can be recovered without having to go through non-free mp4 recovery tools.

  


• ffmpeg : adding an audio file to a video at specified delays

  15 juillet 2020, par JarsOfJam-Scheduler

  I have an array that may contain multiple occurrences of these terms : 'video, forest'. An audio file is added to the video file when the current element of this array I iterate is 'forest'. Otherwise, not. 'video and forest' elements will increment (of 5 seconds) the delay at which an audio file will be added. Example : the array contains "video, video, forest, video, forest". The first audio file will be added at delay=15000ms. The last one, at 25000ms. Computation details : 0 (initialization) + 5000 (video) + 5000 (video) + 5000 (forest) + 5000 (video) + 5000 (forest). 5000 + 5000 + 5000 = 15000. 5000*5 = 25000.

  


  I use ffmpeg to implement this program. The problem is that only one audio file is added, at the beginning of my video file. So the delays are not actually taken into account I think.

  


  Note that the video file also contains a music. The audio files that I try to add must be present in the video file in addition to this music. The first line of the following code adds the music to the video. The next lines try to add the audio files at good delays.

  


  subprocess.call(
    ['C:/Users/XYZ/Downloads/ffmpeg/bin/ffmpeg.exe', '-i', 'XYZ/my_XYZ_video.webm', '-stream_loop', '-1', '-i', 'tmp_music/original_music.wav',
     '-c:v', 'copy', '-shortest', '-fflags', '+shortest', '-max_interleave_delta', '100M',
     'XYZ/my_XYZ_video_with_music.webm']
    , cwd='C:/Users/XYZ/Desktop/XYZ/')

chosen_songs = ['video', 'forest', 'forest', 'video']

time_for_ffmpeg = 0
for chosen_song in chosen_songs:
    if chosen_song == 'video':
        print('video')
        print(time_for_ffmpeg)
        time_for_ffmpeg += 2000    

    elif chosen_song == 'forest':
        print('forest')
        print(time_for_ffmpeg)
        subprocess.call(
            ['C:/Users/XYZ/Downloads/ffmpeg/bin/ffmpeg.exe', '-i', 'XYZ/my_XYZ_video_with_music.webm', '-i', 'tmp_music/forest.mp3',
             '-filter_complex',
             '[1]adelay=' + str(time_for_ffmpeg) + '|' + str(time_for_ffmpeg) + '[a1];[0][a1]amix', '-c:v', 'copy',
             'XYZ/my_XYZ_video_with_music_with_songs.webm']
            , cwd='C:/Users/XYZ/Desktop/XYZ/')
        time_for_ffmpeg += 5000
    


  


  My question

  


  Why can't I add the audio files corresponding to the forest the specified delays (implemented by the variable time_for_ffmpeg`) ? How could I fix my code ?