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• Reading a File while it is being written by FFMPEG

  29 mai 2014, par Haris Tasawar

  As the title suggests, i am in the process of creating a client/server application where the server(PHP) reads a file which is being written on by ffmpeg and then outputs it to the client(JAVA). I have succeeded in writing the server script in php which initiates the ffmpeg and then after a while starts to read the file and concurrently sends it to the JAVA client, the problem is that after a while the client stops to receive any sort of data and then just quits, For example if i have a 5MB file, it would read only 12KB and then it quits. Could someone tell what can be the issue here ? Is it on the server side or on the client side.
  For References i am attaching both the reading of file code in php and the client side code.

  Code For Reading the file while FFMPEG converts the file(PHP) :

  $file = 'D:\\'.$destination;
  
  $fp = @fopen($file, 'r');
  
  //ob_end_clean();  
  
  header('Content-Description: File Transfer');
  
  header('Content-Type: application/octet-stream'); 
  
  header("Cache-control: private");
  
  header('Pragma: private');
  
  header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");
  
  header('Content-Length: ' . filesize($file));
  
  
  
  $buffer = 4096;
  
  while(!feof($fp)) {
  
  
  
  usleep(300000);
  
  echo fread($fp, $buffer);
  
  ob_flush();
  
  flush();
  
  
  
  
  
  }
  
  fclose($fp);
  
  exit();

  Code For reading the File transferred by PHP (JAVA) :

  URL u = new URL(streamURL);
  
  
  
                  clientSocket = (HttpURLConnection) u.openConnection();
  
  
  
                  if( clientSocket.getResponseCode() == HttpURLConnection.HTTP_OK ){
  
                  //clientSocket.setReadTimeout(0);
  
                  inRemoteStream = clientSocket.getInputStream();
  
  
  
  
  
                  while (((count = inRemoteStream.read(buf)) != -1)) {
  
                      offset += count;
  
                      System.out.println(offset);
  
                      fileOutputStream.write(buf, 0, count);
  
                      setVideoOffset(offset, contentLength);
  
                  }

  I`ll be very happy if someone can solve this problem for me :) .

• Capturing PCM audio data stream into file, and playing stream via ffmpeg, how ?

  11 avril 2015, par icarus74

  Would like to do following four things (separately), and need a bit of help understanding how to approach this,

  1. Dump audio data (from a serial-over-USB port), encoded as PCM, 16-bit, 8kHz, little-endian, into a file (plain binary data dump, not into any container format). Can this approach be used :

     $ cat /dev/ttyUSB0 > somefile.dat

  Can I do a ^C to close the file writing, while the dumping is in progress, as per the above command ?

  2. Stream audio data (same as above described kind), directly into ffmpeg for it to play out ? Like this :

     $ cat /dev/ttyUSB0 | ffmpeg

  or, do I have to specify the device port as a "-source" ? If so, I couldn’t figure out the format.

  Note that, I’ve tried this,

  $ cat /dev/urandom | aplay

  which works as expected, by playing out white-noise..., but trying the following doesn’t help :

  $ cat /dev/ttyUSB1 | aplay -f S16_LE

  Even though, opening /dev/ttyUSB1 using picocom @ 115200bps, 8-bit, no parity, I do see gibbrish, indicating presence of audio data, exactly when I expect.

  3. Use the audio data dumped into the file, use as a source in ffmpeg ? If so how, because so far I get the impression that ffmpeg can read a file in standard containers.

  4. Use pre-recorded audio captured in any format (perhaps .mp3 or .wav) to be streamed by ffmpeg, into /dev/ttyUSB0 device. Should I be using this as a "-sink" parameter, or pipe into it or redirect into it ? Also, is it possible that in 2 terminal windows, I use ffmpeg to capture and transmit audio data from/into same device /dev/ttyUSB0, simultaneously ?

  My knowledge of digital audio recording/processing formats, codecs is somewhat limited, so not sure if what I am trying to do qualifies as working with ’raw’ audio or not ?

  If ffmpeg is unable to do what I am hoping to achieve, could gstreamer be the solution ?

  PS> If anyone thinks that the answer could be improved, please feel free to suggest specific points. Would be happy to add any detail requested, provided I have the information.

• mp4 Vj Animation video lagging hi res video

  21 février 2020, par Ryan Stone

  I am trying to get a video to play inside a video tag at the top left hand corner of my page, it loads ok, the resolution is good and it seems to be looping but it is lagging very much, definatly not achieving 60fps it is in mp4 format and the resolution on the original mp4 is 1920x1080 it is a hi resolution vj free loop called GlassVein, you can see it if you search on youtube. On right clicking properties it comes up with the following inforamtion ;

  Bitrate:127kbs
  Data rate:11270kbps
  Total bitrate:11398kbs
  Audio sample rate is : 44khz
  filetype is:VLC media file(.mp4)
  (but i do not want or need the audio)

  & it also says 30fps, but I’m not sure i believe this as it runs smooth as butter on vlc media player no lagging, just smooth loop animation

  I have searched on :https://trac.ffmpeg.org/wiki/Encode/AAC for encoding information but it is complete gobbldygook to me, I don’t understand a word its saying

  My code is so far as follows ;

      <video src="GlassVeinColorful.mp4" autoplay="1" preload="auto" class="Vid" width="640" height="360" loop="1" viewport="" faststart="faststart" mpeg4="mpeg4" 320x240="320x240" 1080="1080" 128k="128k">  
  
      </video>

  Does anyone know why this is lagging so much, or what I could do about it.
  it is a quality animation and I don’t really want to loose an of its resolution or crispness.. the -s section was originally set to 1920x1080 as this is what the original file is but i have changed it to try and render it quicker...

  Any helpful sites, articles or answers would be great..

  2020 Update

  The Solution to this problem was to convert the Video to WebM, then use Javascript & a Html5 Canvas Element to render the Video to the page instead of using the video tag to embed the video.

  Html

  <section>
  
          <video src="Imgs/Vid/PurpGlassVein.webm" type="video/webm" width="684" height="auto" muted="muted" loop="loop" autoplay="autoplay">
  
                 <source>
  
                 <source>
  
                 <source>
  
          </source></source></source></video>
  
          <canvas style="filter:opacity(0);"></canvas>
  
  </section>

  Css

  video{
  
     display:none !important;
  
     visibility:hidden;
  
  }

  Javascript

      const Canv = document.querySelector("canvas");
  
      const Video = document.querySelector("video");
  
      const Ctx = Canv.getContext("2d");
  
  
  
      Video.addEventListener('play',()=>{
  
        function step() {
  
          Ctx.drawImage(Video, 0, 0, Canv.width, Canv.height)
  
          requestAnimationFrame(step)
  
        }
  
        requestAnimationFrame(step);
  
      })
  
  
  
      Canv.animate({
  
          filter: ['opacity(0) blur(5.28px)','opacity(1) blur(8.20px)']
  
      },{
  
          duration: 7288,
  
          fill: 'forwards',
  
          easing: 'ease-in',
  
          iterations: 1,
  
          delay: 728
  
      })

  I’ve Also Used the Vanilla Javascript .animate() API to fade the element into the page when the page loads. But one Caveat is that both the Canvas and the off-screen Video Tag must match the original videos resolution otherwise it starts to lag again, however you can use Css to scale it down via transform:scale(0.5) ; which doesn’t seem to effect performance at all.

  runs smooth as butter, and doesn’t loose any of the high resolution image.
  Added a slight blur 0.34px onto it aswell to smooth it even more.

  Possibly could of still used ffmpeg to get a better[Smaller File Size] WebM Output file but thats something I’ll have to look into at a later date.