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• lavfi/vf_libplacebo : determine PTS of next frame from any input

  15 juin 2023, par Niklas Haas

  lavfi/vf_libplacebo : determine PTS of next frame from any input
  When combining multiple inputs with different PTS and durations, in
  
  input-timed mode, we emit one output frame for every input frame PTS,
  
  from *any* input. So when combining a low FPS stream with a high FPS
  
  stream, the output framerate would match the higher FPS, independent of
  
  which order they are specified in.
  

  • [DH] libavfilter/vf_libplacebo.c

• Determine timestamp in mpg video of KLV streams

  22 février 2024, par Joshua Levoy

  I'm currently working with MISP compliant klv data containing mpg videos. I'm able to find the streams containing this data with ffmpeg using the following command

  


  `ffmpeg -v 0 -ss 0 -i "Day Flight.mpg" -map 0:1 -f framecrc  -`


  


  By varying the -ss argument I am able to select for different klv streams by excluding parts of the video, which leads me to believe that ffmpeg is capable of determining how far into the video these klv streams are. I'd very much be interested in finding these timestams of the KLV streams, such that I can create a process by which a misp compliant mpg video can be clipped into smaller segments, for which its relevant MISP-compliant klv data will be preserved.

  


  Is there a way to get ffmpeg to show me the timestamps where these KLV streams begin, and if not, does anyone know of any better approach to determining the position within the video of these klv streams ?

  


  you can obtain the mpg video file containing mpg data that I am using here https://samples.ffmpeg.org/MPEG2/mpegts-klv/Day%20Flight.mpg

  


  Currently I have run the line laid out above and receive the following output :

  


     #software: Lavf58.29.100 #tb 0: 1/90000 #media_type 0: data #codec_id 0: klv 0,          0,          0,        0,      163, 0xc7572adf, S=1,        1, 0x00bd00bd 0,          0,          0,        0,      163, 0xeddd2774, S=1,        1, 0x00bd00bd 0,          0,          0,        0,      163, 0x5c8d29b0, S=1,        1, 0x00bd00bd 0,          0,          0,        0,      163, 0xb7c428f5, S=1,        1, 0x00bd00bd 0,          0,          0,        0,      163, 0x3c3d28a5, S=1,        1, 0x00bd00bd 0,          0,          0,        0,      162, 0x5cdd2898, S=1,        1, 0x00bd00bd

  


  which is useful for determining there are KLV packets within the video but provides me very little in the way of the timestamp where they are relevant. I have other methods of extracting and decoding these KLV values at these locations, but what I'm interested in specifically, is knowing as close as possible the exact timestamps that the KLV streams are referring to within the 3 minute and 20 second video.

  


• How can I determine video rotation/orientation in PHP/FFMPEG/PhoneGap ?

  15 août 2024, par SomethingOn

  Once I upload videos to my server I'm creating a screencap using FFMPEG. Problem is, if the user takes a video in portrait mode the screencap is rotated 90º. The ridiculous things is that PhoneGap and FFMEG-php and FFMPEG don't seem to offer a mechanism for reading the video rotation/orientation value.

  



  I found another library called mediainfo that will provide the info, but not in an easy to read/digest manner and I'm trying to avoid having to use another library.

  



  Am I wrong about PhoneGap/FFMPEG ? Is there a direct way to determine video orienation ?

  



  ---

  



  Here's my solution as a PHP function :

  



  function get_video_orientation($video_path) {
    $cmd = FFMPEG_PATH . "ffprobe " . $video_path . " -show_streams 2>/dev/null";
    $result = shell_exec($cmd);

    $orientation = 0;
    if(strpos($result, 'TAG:rotate') !== FALSE) {
        $result = explode("\n", $result);
        foreach($result as $line) {
            if(strpos($line, 'TAG:rotate') !== FALSE) {
                $stream_info = explode("=", $line);
                $orientation = $stream_info[1];
            }
        }
    }

    return $orientation;
}