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• How to convert 4:3 video to 16:9 without stretching the original in ffmpeg

  5 novembre 2016, par carvil

  I would like to convert some 4:3 videos that I took on an iPhone to 16:9, by adding black bars to both sides instead of stretching the video.

  I tried something like this without success :

  ffmpeg -y -i input.mov -aspect 1.7777777777777777 -s 640x360 output.mp4

  Even though the output has the correct size, the video is stretched, which is not what I want.

  How can I keep the proportion between the width and height of the original video, and add extra black bars to both sides to avoid stretching ?

  This would be similar to how YouTube does it when uploading a video from an iPhone directly to YouTube.

  Thanks !

• FFMPEG RTP Microphone Audio Stream Won't Work Over 4G/LTE

  11 juillet 2021, par Andrew Smith

  I am trying to RTP stream the Mic input of my USB soundcard over 4G to an iphone running VLC, the phone is on the Three UK mobile network. I cannot get any audio at all but it works with no problem if I route it via a VPN, my ffmpeg command is :-

  


  ffmpeg -f dshow -i audio="Microphone (C-Media USB Headphone Set  )" -c:a libmp3lame -f rtp rtp://xxx.xxx.xxx.xxx:1234

  


  I am streaming to the ip of the phone as shown by whatsmyip in a browser, then trying to play the stream on the iphone using rtp ://@:1234

  


  If I switch on my VPN and change the ffmpeg stream-to ip address to my 10.0.0.xxx ip then it works just fine.

  


  Something seems to be blocking RTP when not using the VPN, could it be the 4G network blocking it ?

  


• Creating Thumbnails From Ffmpeg Hangs Php

  30 octobre 2012, par Piyush Arora

  I have been working on a php webservice, which receives videos(uploaded) from iphone and upload them to Amazon cloudFront. After uploading videos, I need to generate thumbnails for video from the Amazon link generated. I am using ffmpeg with shell_exec command for it. Here is the code for the same :

  public function createThumbnail($userId,$fileUrl,$imageName){
  
      //$imageUrl = 'http://184.168.116.177:81/json_api/json/bin/';
  
      if(!is_dir("images/".$userId)){
  
          mkdir("images/".$userId);
  
      }
  
      // path of installed ffmpeg
  
      $ffmpeg = $_SERVER['DOCUMENT_ROOT'] .'bin/ffmpeg';
  
      $cmd = "$ffmpeg  -itsoffset -1 -i $fileUrl -vcodec mjpeg -vframes 1 -an -f rawvideo -s 320x240 images/".$userId."/".$imageName;
  
  
  
      shell_exec($cmd);
  
  
  
      return "images/".$userId."/".$imageName;
  
  }

  The above code generates the thumbnail, but script does not execute after shell_exec command. So, there is no response sent to iphone end about the thumbnail link. This function works well video is uploaded from web browser of pc. If I comment, shell_exec command, then response is sent to iphone end, but obviousely image is not created.

  Thanks in advance.