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• Transcode video with php ffmpeg library

  27 juin 2019, par dev

  I need to upload video in 3 formate/resolution as 360p, 480p, 720p.

  After some research i got to know that some paid service are there like Amazone Elastic Transcoder . But i want to do with open source so i found FFMPEG.

  Also i want to upload video on Amazon s3 after transcode and video are in big size like video may contain 1GB size.

  I got php library for FFMPEG Library Link

  I have installed ffmpeg and it successfully generate new video. But i cannot figure out that how can i generate different formate/resolution as 360p, 480p, 720p.

  My sample Code is

          error_reporting(E_ALL);
  
          ini_set('display_errors', 1);
  
  
  
          require 'vendor/autoload.php';
  
  
  
          //$ffmpeg = FFMpeg\FFMpeg::create();
  
          $video = $ffmpeg->open('assets/small.mp4');
  
          $video
  
              ->filters()
  
              ->resize(new FFMpeg\Coordinate\Dimension(320, 240))
  
              ->synchronize();
  
          $video
  
              ->frame(FFMpeg\Coordinate\TimeCode::fromSeconds(2))
  
              ->save('assets/frame.jpg');
  
  
  
          $format = new FFMpeg\Format\Video\X264();
  
          $format->setAudioCodec("libmp3lame");
  
  
  
          $video->save($format, 'assets/new.mp4');

  Can anyone suggest me any way that how can i achieve this ??

• Can you think of a reason why windows might not enable audio if noone is logged in ?

  3 juillet 2017, par Caius Jard

  I’m having a bizarre problem with some virtual servers created to record podcasts. They run on amazon AWS as windows server 2012 instances and a small c# app tells FFMPEG to do the heavy lifting of capturing from the virtual screen and reading from the virtual sound card (Virtual Audio Cable : https://en.wikipedia.org/wiki/Virtual_Audio_Cable) via DirectShow filters

  The problem I have is if I leave the machine to do its stuff unattended, the recordings are sometimes silent. If I log in via VNC and watch it doing its stuff the audio is recorded just fine. All other aspects of the test op are the same, and the virtual machine is shut down between successive recordings so each one should theoretically be a clean slate. The app runs under a logged in session (hence the use of VNC rather than RDP)

  I’m now wondering if there is some optimisation of the windows sound engine whereby it doesn’t bother playing audio if it thinks noone is listening. The confusing thing to me is that not every virtual machine suffers these problems ; some of them record fine (and they’re all created from the same seed virtual hard disk image) in unattended mode

  I’m asking this question with the aim of getting together a list of things I can check/look into/debug.. I don’t have much knowledge of how MME/DirectSound/WASAPI work internally...

• create max quality Frame with FFMPEG from ProRes Clip

  5 août 2021, par Josef Zugarov

  I want to extract a frame from a ProRes Clip, recorded with a Blackmagic URSA Mini Pro 4.6K Gen 2 camera with ffmpeg.
I noticed the following : When I import the ProRes Clip into Davinci I can recover some highlights, which are out of the displayed range by lowering the gain paramater.
As you can see in the waveform the thrid peak has information in all channels.

  


  After I extracted the frame with ffmpeg, I couldn't recover the highlights anymore.
Waveform : Values are clipped till the fifth peak.

  


  I used the following command :
ffmpeg  -ss 00:00:01 -i 0volt.mov -vf zscale=t=input,zscale=c=input -frames:v 1  TIFFs\0volt.tiff -v verbose

  


  Here is the output of the ffmpeg command line : https://pastebin.com/a36ML3tL

  


  Do you have any hint, how the original quality and dynanmic range by extracting a TIFF-Frame with ffmpeg can be retained ?

  


  Thank you !