Recherche avancée

Sur d’autres sites (11715)

• FireFox Video throws warning but video actually works ?

  21 février 2021, par SdBill
  

  • OS : Ubuntu 18.04

  


  • FF : 85.0.1

  


  • Error/warning : Cannot play media. No decoders for requested formats : video/mp4, video/mp4

  


  


  Same error for video/ogg

  


  Here are my questions : 1) The video still plays fine once loaded, and there is no error in Chrome or Chromium. Why does the video work fine after loading but throws the error on load ? 2) Is there anything that can be done without re-encoding over 2 gigs of video ?

  


  Context : this is an old no-profit site that used Flash for video and we really don't want to throw a lot of time at, but there are gigs of videos. I converted all .flv files and .mpg files to .mp4 using the most simple of ffmpeg commands, examples :

  


  ffmpeg -i video-source.flv video-source.mp4
ffmpeg -i video-source.mpg video-source.mp4
ffmpeg -i video-source.mpg video-source.ogg


  


  As I watched the ffmpeg output, it looked to me like the codec was H264 (at least, I think that is what I am seeing, not a video expert.)

  


  Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> theora (libtheora))
  Stream #0:1 -> #0:1 (aac (native) -> vorbis (libvorbis))


  


  Server response in a direct request to the mp4 files is

  


  Content-Type
    video/mp4


  


  I have seen the documentation and posts on fragmented mp4 and if re-encoding is the only option, we're probably going to abandon as it does play once loaded.

  


  Code is simplistic, using an html5 doctype :

  


    <video width="320" height="240" controls="controls">&#xA;   <source src="/images/video/mp4/video-source.mp4" type="video/mp4">&#xA;   <source src="/images/video/ogg/video-source.ogg" type="video/ogg">&#xA;   Your browser does not support the video tag.&#xA;  </source></source></video>&#xA;

  


  Is the only option here to pander to FireFox and re-encode everything since as mentioned, it plays fine once loaded and throws no error in Chrome ?

  


• Overlay video onto another video at multiple points in time

  22 décembre 2024, par kbcool

  I have a case where I want to have a background video and use a second video overlaying the first but at multiple points in time. The second video is shorter.

  



  So for example the main video is a minute long and the second video is 10 seconds. I want to overlay the second video once at 15seconds then again at 35 seconds and then again at 55 seconds (terminating when the main video does).

  



  I am able to get the second video to overlay successfully using overlay filter and between option but it only ever works for the first overlay. The second overlay seems to show the last or first frame of the video(??) but for the period I set in between. I am guessing it needs to be rewound and played somehow.

  



  Eg :

  



  ffmpeg  -i background.mp4 -i overlay.mov -filter_complex "[0][1]overlay=0:0:enable='between(t,0,2)'[out];[out][1]overlay=-200:200:enable='between(t,4,8)'[out]" -map "[out]" -t 00:00:10 -y output.mp4


  



  I have also tried specifying the overlay as an input twice eg :

  



  ffmpeg  -i background.mp4 -i overlay.mov -i overlay.mov -filter_complex "[0][1]overlay=0:0:enable='between(t,0,2)'[out];[out][2]overlay=-200:200:enable='between(t,4,8)'[out]" -map "[out]" -t 00:00:10 -y output.mp4


  



  The same thing happens.

  



  I'm sure the answer is simple and probably to do with how I'm using inputs but I'm not able to wrap my head around how to get the overlay video to play twice at different times on top of the original.

  



  I have also tried using the setpts filter to rewind the overlay but again the results are exactly the same.

  



  Eg :

  



  ffmpeg  -i background.mp4 -i overlay.mov -filter_complex "[0][1]overlay=0:0:enable='between(t,0,2)'[out];[1]setpts=PTS-STARTPTS,[out]overlay=-200:200:enable='between(t,4,8)'[out]" -map "[out]" -t 00:00:10 -y output.mp4


  



  There are a lot of similar questions involving overlaying multiple videos but I can't find anything about reusing the same video at multiple points in time.

  


• Text Watermarking on video without loss of audio and video quality

  8 janvier 2021, par Aditya Kumar

  I am using following command to add text watermark on a video file(for mp4, mpg,m4v,flv,mov etc..) :

  


  ffmpeg -i input.mp4 -vf "drawtext=text='Opentext':x=(w-text_w)/2:y=(h-text_h)/2:fontsize=24:fontcolor=white" TextOutput.mp4


  


  For some of the file transformation the property of video file changes. for example- When I tried to add text watermark on a mkv file I got this message :

  


  


  [matroska @ 0000001867d36ec0] Non-monotonous DTS in output stream 0:1 ;
previous : 2273, current : 1596 ; changing to 2273. This may result in
incorrect timestamps in the output file.

  


  


  This is one of the issues, i have mentioned here. There are others as well, such as :

  


  

  • video quality is reduced

  


  • video file size is changed(increses/decreases drastically)

  


  • Audio lagging occurs etc...

  


  


  So, I want to preserve the quality of video after adding the text watermark. How can I do that ?