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• ffmpeg encoding outputs a file with incorrect metadata

  20 juillet 2013, par user2554615

  I use ffmpeg to convert a flv file to an mp3 file like so in bash :

  ffmpeg -i path/to/file.flv path/to/output.mp3

  say the flv is 5 minutes long, the output file is supposedly say, 3 minutes long. however when played back it will reach the 3 minute mark and keep playing (as it should) the full length. when i try to skip to a portion of the song it only skips by fractions of the time it should, take for example if the video is labeled as 3 minutes long and i skip to the end, it will actually be playing the area that is about 30 seconds in. why is it doing this and how do i fix it ? is there any other utility that i can use that will effectively convert .flv and .mp4 files to .mp3 or .wav in a loss-less fashion while maintaining the correct metadata, preferably for windows ? perhaps an API i can use in java or c++ ?

  PS : i ask here because it relates to a command line utility and i assume that the the solution will relate to the options used in the command.

  PPS : i am using the ffmpeg that comes with puppy linux (precise) 5.4

• ffmpeg not splitting into EXACT same length chunks

  4 octobre 2018, par jupiar

  I am trying to use ffmpeg to split a long video into exactly 20second long clips, and accomplishing that by :
  inside docker as a python sub-process

  subprocess.run(["/usr/sbin/ffmpeg",
  
          "-i", video_loc,
  
          "-async", "1",
  
          "-map", "0",
  
          "-segment_time", "20",
  
          "-f", "segment", 
  
          "-reset_timestamps", "1",
  
          "n-%05d.mp4"], cwd=r'/clips')

  My problem is that each are roughly 20seconds, some are as low as 10seconds, some as high as 27 seconds, i would say most are around 16-23. Is there something else that I can do to ensure the split of exactly 20 seconds ? I am open to any technique possible, aside from anything manual...

• FFMPEG - How to reduce frame rate without slow motion effect ? [closed]

  4 avril 2024, par crater33

  I have an MP4 video that's 21 minutes long, that was shot on a GoPro Hero 9 Black at 2.7k and 240 frames per second using HEVC.

  


  I would like to use FFMPEG to reduce the frame rate, with the output being a video that is also 21 minutes long and 2.7k ... but with a frame rate of 120 frames per second. But when I use the command "ffmpeg -i input.mp4 -filter:v fps=120 output.mp4 I get a video that is 42 minutes long.

  


  I would like to tell FFMPEG to simply delete every other frame of the input video, while keeping the total length of the video the same. What command would I use to do that ?

  


  Also, how would I modify this command if I wanted the output to be encoded in AVC ?

  


  Thank you.