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• Using a Web-based installer to retrieve (not distribute) 3rd party GPL or non-free software

  25 août 2013, par user1493918

  I am developing a software product which is able to communicate over a command line interface with GPL-covered software (specifically, my software can feed commands to FFMpeg). I understand that a crucial aspect of the GPL license is whether or not you distribute GPL-covered applications. My goal is to allow my users to have a seamless experience installing both my software and 3rd party GPL software. But I am trying to do this without my software actually including the the 3rd party (GPL-covered) software. To do this I am considering Web-based installers. I could use a Web-based installer to allow the end-user the option to retrieve a GPL-covered or non-free software app from a totally different server, independent of my own and outside my control. The user would be the one to install the software simply by making a decision (i.e. pressing "Next" in my installer). If they chose to do so, then my software's Web-based installer would retrieve the 3rd-party software, decompress and install it, then move on to installing my own application. In this way, my installer doesn't ship any GPL-covered or non-free software, and yet from the user's perspective all they had to do is click Next... Next... Next... Done !

  I have read about the GPL allowing you to distribute GPL-covered apps as part of an "aggregate..."
  http://www.gnu.org/licenses/gpl-faq.html#MereAggregation

  ...but this scenario isn't that. It's allowing the user to retrieve applications or libraries at his own discretion, using his own bandwidth, downloading from a server that has nothing to do with me.

  I can't seem to find information anywhere about the GPL-related licensing implications of using a Web-based installer. My goal is simply to give the end user every high-quality transcoding option possible within FFMpeg without stepping on anybody's toes legally.

  Possible ? If so then I'm hoping someone might be able to point me to a software installer program that would facilitate this. Thank you in advance for any replies.

• Improve ffmpeg scene detection in particular scenario

  17 septembre 2021, par Nobody-Knows-I-am-a-Dog

  I have 50 hours of video where a speaker is in the lower right corner of the video and the by far larger part of the video consists of slides in the center. The speaker moves a bit, the slides transition into the video. I need to detect the time codes of the slide transitions. +- 1 second precision is fine. I am playing around with select filters in ffmpeg such as ffmpeg -i lecture.mp4  -filter:v "select='gt(scene,0.1)',showinfo"   -f null - but I have remaining problems where some help or hint would be highly appreciated.

  


  Problem 1 : Speaker movement occasionally triggers false positives. If there is some possibility to restrict frame comparison to a certain (spatial, cropped) area of the scene then I could focus on the slide area and this would greatly help.

  


  Problem 2 : Speed of slide transition is slow so I occasionally miss a transition since the change from frame(n) to frame(n+1) is too small. It would be great if I could compare, for example, frame(n) to frame(n+10) for threshold detection. ffmpeg scene detection : check only every nth frame ? does not help here, because it only checks every n-th frame but still compares a frame with its immediate neighbor.

  


  Of course, both problems can be solved by producing a cropped version with reduced framerate. However, I am looking for a solution where I can do this in a single pass with some complex filter expression ... and this is exactly the place where my own experience with ffmpeg fails me and where I would appreciate some help.

  


  Problem 3 : Occasionally a single slide transition triggers several times in a row throughout the transition. I have no idea how to solve this in ffmpeg.

  


• How to add suffix to duplicate filenames output by ffmpeg in Windows batch file ?

  27 septembre 2015, par Nick Hope

  I have written a script in Sony Vegas Pro that outputs an edit list of video files (E :\editlist.txt) of the following form, where the 2nd item is the start timecode and the 3rd item is the length :

  E:\folder\file1a.mp4 16.8835333 17.5175
  
  E:\folder\file2a.mp4 6.0393666 12.1454666
  
  E:\folder\file3a.mp4 0 3.5368667
  
  E:\folder\file3a.mp4 5.1344667 9.3033
  
  E:\folder\file3a.mp4 12.1224623 19.483756

  I have also cobbled together a Windows batch script that uses ffmpeg to trim those files and re-wrap them in a .mov container.

  for /F "tokens=1,2,3 delims= " %%F in (E:\editlist.txt) do ffmpeg.exe -ss "%%G" -i "%%F" -c copy -t "%%H" "%%~dF%%~pF%%~nF.mov"

  However because some files originate from the same source file (in this case, file3a.mp4), the trimmed files have duplicate names.

  I would like to create a script that detects duplicates and adds an incremental single-digit suffix to the output file names, before the file extension. In this case the 5 output files should be file1a.mov, file2a.mov, file3a.mov, file3a1.mov and file3a2.mov.

  I have had a go but I have no experience of writing Windows batch files, so the following effort fails and is probably very wrong, but hopefully it shows what I am trying to achieve (it was loosely based on an answer to this question) :

  for /F "tokens=1,2,3 delims= " %%F in (E:\editlist.txt)
  
      set counter=0
  
      if exist "%%~dF%%~pF%%~nF.mov" (
  
      set counter=%counter%+1
  
      do ffmpeg.exe -ss "%%G" -i "%%F" -c copy -t "%%H" "%%~dF%%~pF%%~nF%counter%.mov"
  
  ) else do ffmpeg.exe -ss "%%G" -i "%%F" -c copy -t "%%H" "%%~dF%%~pF%%~nF.mov"

  I would greatly appreciate it if someone could help me get this working. Thanks !