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• How does one go about undoing an avformat_seek_file call in libavcodec ?

  2 juillet 2020, par John Allard

  I have an application written around libavcodec that sometimes attempts to seek ahead in a video while performing some work. The call to avformat_seek_file can only seek to a keyframe, so sometimes I end up in a situation where it ends up seek backwards from my current position in the decoding routine causing me to have to repeat work. For example, if I'm on frame 150 and I want to seek to frame 200, but the only key frames in the file are on frames 1 and 100, this call will have me seek back to frame 100, meaning I now have to decode 100 frames to get to 200 instead o 50 frames to get to 200 from my original decoding position of frame 150.

  


  Is there a way for me to tell avformat_seek_file to undo its last seek and reset me to my previous location ? Is there some other way for me to "save" my decoding state to undo this wrongful seek manually ?

  


  edit - it should be noted that my videos are always h264 encoded in an mp4 container.

  


• (no accepted answer) How to merge 2 overlapping videos into one video using ffmpeg or opencv ?

  3 janvier 2021, par Muhammad Umer

  Merging two videos is easy, been answered couple of times. What I have is multiple overlapping videos. A video might have overlaps with video before it. Meaning if video 1 covers 1-5 timeline then video 2 may overlap 1, and cover 3 to 8. Merging them as is would result in 1-5|3-8, when i need 1-8 only.

  



  Videos are alphabetically sorted.

  



  My general idea of solution is...

  



  

  • grab last frame of the video

  


  • if it's first video continue

  


  • if it's not first video, ie. 2nd, search for frame saved in previous steps frame by frame

  


  • if it reaches to last frame of current video then there is no overlap continue

  


  • if it founds a frame then clip 2nd video up to that frame inclusive and then go to next frame

  


  • once all videos have been analyzed, merge them into one video.

  


  



  I need to translate this to ffmpeg commands. Or opencv if that's a better tool.

  



  If there is better way of doing that, I'm interested in that too.

  


• Requirements for using ffmpeg to create mpeg4 files in SaaS solution

  25 août 2016, par Paul Fleming

  My requirement is :
   On upload of a supported video file, convert the file to common formats to maximize web compatibility.

  Essentially, I want to take a non-web-supported video file, and converted it to WEBM and MPEG4. This will take place on a Windows Server VM inside Microsoft Azure.

  ffmpeg seems to be the de facto standard for video conversion yet it introduces licensing hell, not only with GPL/LGPL but by not offering a commercial license, meaning I now have to worry about paying royalties to MPEG-LA.

  Can anyone advise on MPEG-LAs licensing model as it applies to SaaS ? I will not be distributing ffmpeg (runs server side) and the conversion takes place on Windows (Server) OS.