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• FFmpeg : Add alpha channel to a video using a PNG mask

  7 avril 2016, par Rodrigo Polo

  I saw that FFmpeg can merge/blend two videos with alpha channel and can encode video with alpha channel using the qtrle codec, but, It is possible to apply a PNG file mask, either a black and white or a PNG with an alpha channel to a video in order to have a video with the alpha channel of the PNG applied ?

  Here is the concept in images

  Original video :
  

  PNG file with alpha channel, the "mask" :
  

  And the result :
  

  Or even a black and white image as a mask for alpha channel :
  

  Any help would be appreciated, thank you !

• Clip long video segment quickly

  30 janvier 2020, par PRMan

  Let’s say I have a video called Concert.mp4. I want to extract a performance from it quickly with minimal reencoding. I want to do the equivalent of this, but faster :

  ffmpeg -i "Concert.mp4" -ss 00:11:45 -to 00:18:15  -preset veryfast -y artist.mp4

  This takes 17 seconds, which is way too long for our needs.

  Now, it turns out that 11:45 and 18:15 don’t fall on iframes, so if you try this you will get a 3 second delay at the beginning before the video shows :

  ffmpeg -i "Concert.mp4" -ss 00:11:45 -to 00:18:15 -c copy -y artist.mp4

  Running this command, we can see where we need to cut :

  ffprobe -read_intervals "11:00%19:00" -v error -skip_frame nokey -show_entries frame=pkt_pts_time -select_streams v -of csv=p=0 "Concert.mp4" > frames.txt

  So what we need to do is encode the first 3.708 seconds, copy the middle, and then encode the last 5.912 seconds.

  I can get the 3 segments to all look perfect (by themselves) like this :

  ffmpeg -ss 698.698 -i "Concert.mp4" -ss 6.302 -t 3.708 -c:v libx264 -c:a copy -c:s copy -y clipbegin.mp4
  
  
  
  ffmpeg -ss 708.708 -to 1089.088 -i "Concert.mp4" -c copy -y clipmiddle.mp4
  
  
  
  ffmpeg -ss 1089.088 -i "Concert.mp4" -t 5.912 -c:v libx264 -c:a copy -c:s copy -y clipend.mp4
  
  
  
  ffmpeg -f concat -i segments.txt -c copy -y artist.mp4

  segments.txt of course contains the following :

  file 'clipbegin.mkv'
  
  file 'clipmiddle.mkv'
  
  file 'clipend.mkv'

  I saw this solution presented here, but no amount of tweaking gets it to work for me :

  https://superuser.com/a/1039134/73272

  As far as I can tell, this method doesn’t work at all. It crashes VLC pretty hard no matter what I try.

  The combined video keeps glitching after the 3 seconds, probably because the PTS times are different or something (using some options, I have seen warning messages to this effect). Is there anything I can add to the commands above to get this to work ? The only requirement is that the middle command must not re-encode the video, but must do a fast copy.

  Thanks in advance.

• PHP - Upload video convert mp4 and upload to Amazon S3

  31 octobre 2019, par Kadir Geçit

  I’m using amazon s3 as video storage for my website. I’m having problems for some videos. black screen or sound problems etc.

  I want to convert the video to mp4 format after uploading the video to my server and then upload it to amazon. Is it possible with FFMPEG ?

  I’m using this code for uploading files now :

  $file1 = $_FILES['file']['name'];
  
  $videoFileType = strtolower(pathinfo($file1,PATHINFO_EXTENSION));
  
  $file_name = sprintf('%s_%s', uniqid(),uniqid().".".$videoFileType);
  
  $temp_file_location = $_FILES["file"]["tmp_name"];
  
  
  
  require 'application/libraries/Amazon/aws-autoloader.php';
  
          $s3 = new Aws\S3\S3Client([
  
              'region'  => $amazon_region,
  
              'version' => 'latest',
  
              'credentials' => [
  
              'key'    => $amazon_key,
  
              'secret' => $amazon_secret,
  
              ]
  
          ]);     
  
  
  
          $result = $s3->putObject([
  
              'Bucket' => $amazon_bucket,
  
              'Key'    => $file_name,
  
              'SourceFile' => $temp_file_location,
  
              'ACL'    => 'public-read',
  
              'CacheControl' => 'max-age=3153600',
  
          ]);
  
              $filepath = $result['ObjectURL'] . PHP_EOL;
  
  
  
              echo json_encode([
  
                  'status' => 'ok',
  
                  'path' => $filepath
  
  
  
              ]);