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• avformat/matroskadec : Fix demuxing ProRes

  28 septembre 2019, par Andreas Rheinhardt

  avformat/matroskadec : Fix demuxing ProRes
  The structure of a ProRes frame in mov/mp4 is that of a typical atom :
  
  First a 32 bit BE size field, then a tag detailling the content. Said
  
  size field includes the eight bytes of the atom header.
  This header is actually redundant, as the size of the atom is already
  
  known from the containing atom. It is therefore stripped away when muxed
  
  into Matroska and so the Matroska demuxer has to recreate upon demuxing.
  
  But it did not account for the fact that the size field includes the
  
  size of the header and this can lead to problems when a decoder uses the
  
  in-band size field.
  Fixes ticket #8210.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
  
  Signed-off-by : James Almer <jamrial@gmail.com>
  

  • [DH] libavformat/matroskadec.c

• How to force FFMPEG to ignore KeyboardInterrupts ?

  3 mars 2023, par Straxan

  In my Python script I intercept KeyboardInterrupts to ensure that the script can finish what its doing before shutting down. However I've found that FFMPEG, which I'm using by triggering commandline commands, immediately ends its current prosessing, before then leading into my script's shutdown processes.

  


  The code below shows my KeyboardInterrupt handling system.

  


  prepareToStop = 0
while prepareToStop == 0:
    t = threading.Thread(target=main_loop, args=[instanceID])
    try:
        t.start()
        t.join() # wait for the threading task to end
    except KeyboardInterrupt:
        prepareToStop = 1


  


  And the code below creates and runs the FFMPEG commands :

  


  command = "\"" + ffmpeg + "\" -y -i " + "uploaded/" + videofile_name + " -c:v " + codec + " " + commandDimensions + " " + commandCompression + " -c:a copy" + commandAspect + " "+str(outputFilePath) #bash command to proccess file
print("Running command: " + command) 
res = os.system(command) #run command 


  


  What I'm looking for is a way to ensure that FFMPEG ignores KeyboardInterrupts, so that the system can handle shutdown process after it has completed.

  


  Edit :

  


  I've identified that this is an issue with FFMPEG. I need it to ignore external commands while processing. I've seen examples suggesting that using '-nostdin' can do this, however it appeared to have no effect when I added it to the command. I intended on posting about this as a seperate question, but my account is apparently restricted.

  


• How to keep highest value of ffmpeg crop detect

  13 décembre 2020, par Vincent Duprez

  Case :

  



  I'm converting an old archive of 18000 commercials 
I'd like to automate this reconversion from DV to some lighter and uptodate h264 mp4

  



  The whole process is ready but I'm stuck at the first part : cropping the black bars...

  



  Tools used :

  



  The thing is : all videos are different, I cannot use one static value, thus I use the wonderful cropdetect tool by ffmpeg which outputs me this kind of lines in the cli :

  



  [Parsed_cropdetect_0 @ 0xbe5e960] x1:22 x2:697 y1:93 y2:483 w:672 h:384 x:24 y:98 pts:63 t:2.520000 crop=672:384:24:98
[Parsed_cropdetect_0 @ 0xbe5e960] x1:22 x2:697 y1:93 y2:483 w:672 h:384 x:24 y:98 pts:64 t:2.560000 crop=672:384:24:98
[Parsed_cropdetect_0 @ 0xbe5e960] x1:22 x2:697 y1:93 y2:484 w:672 h:384 x:24 y:98 pts:65 t:2.600000 crop=672:384:24:98
[Parsed_cropdetect_0 @ 0xbe5e960] x1:22 x2:697 y1:93 y2:496 w:672 h:400 x:24 y:96 pts:66 t:2.640000 crop=672:400:24:96
[Parsed_cropdetect_0 @ 0xbe5e960] x1:2 x2:717 y1:80 y2:496 w:704 h:416 x:8 y:80 pts:67 t:2.680000 crop=704:416:8:80
[Parsed_cropdetect_0 @ 0xbe5e960] x1:1 x2:718 y1:80 y2:496 w:704 h:416 x:8 y:80 pts:68 t:2.720000 crop=704:416:8:80
[Parsed_cropdetect_0 @ 0xbe5e960] x1:1 x2:718 y1:80 y2:496 w:704 h:416 x:8 y:80 pts:69 t:2.760000 crop=704:416:8:80
[Parsed_cropdetect_0 @ 0xbe5e960] x1:1 x2:718 y1:80 y2:496 w:704 h:416 x:8 y:80 pts:70 t:2.800000 crop=704:416:8:80
[Parsed_cropdetect_0 @ 0xbe5e960] x1:1 x2:718 y1:80 y2:496 w:704 h:416 x:8 y:80 pts:71 t:2.840000 crop=704:416:8:80


  



  So the last part : crop= gives the result of the remaining frame (width, hight, starting x point starting y point. to crop the video..

  



  But these values are not always the same inside one video how can I extract 'the biggest values' out of these hundreds of lines ?

  



  In this case, just keep crop=704:416:8:80

  



  Edit

  



  Actually, the result should take in account the lowest x1, highest x2, lowest y1 and highest y2, then create a rectangle multiple of 16 inside it...