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• How to add or generate a missing keyframe at the beginning of converted video in FFMPEG ?

  21 décembre 2022, par Jindrich Vavruska

  There is a MP4 file representing a downloaded stream transmission from which I want to extract a program that starts after the beginning and ends before end of this MP4 file. I cut the unwanted parts off by two simple ffmpeg 'conversions'. In the first step, I cut off the tail :

  


  ffmpeg -i stream_record.mp4 -c copy -t 1:26:33.15 cut_record.mp4


  


  The second step is to cut off the unwanted beginning, but here I run into problems. E.g. after

  


  ffmpeg -i cut_record.mp4 -c copy -ss 02:36 final_record.mp4


  


  I quite often get a file with no video in the beginning (up to 6 seconds), only audio is playing. This is because after skipping the time specified in -ss option there is no keyframe in the video stream and it takes up to those 6 seconds to find the first one. Unfortunately, my desired part of the downloaded stream quite seldom starts with a keyframe, and I must keep some part of the video preceding my program to maintain video integrity in the beginning of the file.

  


  Is there a method in FFMPEG to add something (e.g. black rectangle) as the first keyframe right at the start of the copied video stream ? I mean, other than completely recoding the video stream (I would like to keep the -c copy parameter in the process) ?

  


  I could probably achieve the desired result using Openshot Editor - but it recodes the video and audio, takes relatively long time and consumes much CPU and memory resources.

  


• How to install FFMpeg in WampServer 2.0 (Windows XP) [closed]

  16 décembre 2012, par Richard Knop

  I need to install the ffmpeg PHP extension on my localhost so I can test few of my scripts but I am having troubles figuring out how to do that.

  I have WampServer 2.0 with PHP 5.2.9-2, my OS is Windows XP. Please somebody give me step by step instructions.

  I have found some Windows builds here : http://sourceforge.net/projects/ffmpeg-php/files/

  But I don't know which one to download and what to do with files.

  EDITED :

  What I have done so far :

  1. Download ffmpeg_new
  2. Copy php_ffmpeg.dll from the php5 folder to the C :\wamp\bin\php\php5.2.9-2\ext
  3. Copy files from common to the windows/system32 folder
  4. Add extension=php_ffmpeg.dll to php.ini file
  5. Restarted all services (Apache, PHP...)

  I am gettings an error after using this code :

              $extension = 'ffmpeg';
  
              $extension_soname = 'php_ffmpeg.dll';
  
              $extension_fullname = PHP_EXTENSION_DIR . "/" . $extension_soname;
  
  
  
              // load extension
  
              if(false === extension_loaded($extension)) {
  
                  if (false === dl($extension_soname))
  
                      throw new Exception("Can't load extension $extension_fullname\n");
  
              }

  The error :

  Warning: dl() [function.dl]: Not supported in multithreaded Web servers - use extension=ffmpeg.dll in your php.ini in C:\wamp\www\hunnyhive\application\modules\default\controllers\MyAccountController.php on line 314

  Plus I also get the exception from above.

• FFMPEG merge two .mp4 videos - resolution distorted

  9 juin 2016, par Misha Moryachok

  I am trying to merge two .mp4 videos, and in some cases the seconds video part is distorted in the output video. Providing an example below :
  https://www.youtube.com/watch?v=wWMNTBWJ37A

  The real video is : https://www.youtube.com/watch?v=ASio-j-Epi8

  As you can see, we added intro before the real content, however, the real content is stretched.
  In my opinion it happens because first video is 1280x720 and the second is 460x720.

  Providing commands for merging videos :

  *1st step (convert the videos from .mp4 to .ts)

   ffmpeg -i videoPathMP4 -c copy -bsf:v h264_mp4toannexb -f mpegts videoPathTS

  *2nd step (merge videos)

  ffmpeg -i "concat:$video1 | $video2" -c copy -bsf:a aac_adtstoasc $meagePathMP4

  Video output is like you saw in provided videolink on youtube.
  I also tried to change the first video resolution to be like the second video :

  ffmpeg -i inputVideo.mp4 -s 460x720 outputVideo.mp4

  However it doesn’t helped.
  Is anyone know how to solve this ?
  Thanks