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• Concatenate mkv files keeping original timestmap with gaps

  13 août 2020, par Filip

  16 days ago I had this problem : Concatenating mka files but keeping timestamp which I fixed by using amix, a delay by using start_pts from ffprobe.

  


  Today I have a new challenge like this, but with video.

  


  So I have a bunch of mkv videos. Each time a person joins a chat, a mkv is recorded, but if the person refreshes the page a new mkv is created with start_pts and start_time to what it actually is. Also if the meeting started and a person joins after a minute, the start_time is set to 1 minute. I need to merge all those mkv and pad them with blank screen when there is no feed.

  


  Like in the above example, if a person joins after a minute, the first minute is a blank screen. Also if the participant leaves and re-joins after 10 seconds, those 10 seconds are blank again.

  


  Any ideas on how to do that with ffmpeg ?

  


  Concrete example of files :

  


  0PA84c5c3f412769b311d44b159941b2d22.mkv - start_pts: 742 start_time: 0.742000
2PA73d94e8cb0f41c3002fadd6c04b4a88f.mkv - start_pts: 30761 start_time: 30.761000
3PAcd35e470325618fa8a3fb8bb5a41403e.mkv - start_pts: 50940 start_time: 50.940000
4PAddccde7b8847ecc43d5e8643b7903dba.mkv - start_pts: 69243 start_time: 69.243000


  


  The end file would result in a file with length 69.243000, first 0.742 seconds are blank and also the gaps between should also be blank.

  


  So far i've tried :

  


  ffmpeg -i 0PA84c5c3f412769b311d44b159941b2d22.mkv -i 2PA73d94e8cb0f41c3002fadd6c04b4a88f.mkv -i 3PAcd35e470325618fa8a3fb8bb5a41403e.mkv -i 4PAddccde7b8847ecc43d5e8643b7903dba.mkv -filter_complex "[0:v] [1:v] [2:v] [3:v] concat=n=4:v=1 [v]" -map "[v]" test.mkv

  


  This works but without those gaps i mentioned.

  


• Python - ffmpeg-like media seeking with requests

  8 janvier 2017, par Will

  Using ffmpeg, times in HTTP media resources, such as videos, can be seeked to very quickly with a command like ffmpeg -ss 00:01:00 -i https://example.com/video.mp4, presumably by downloading the video headers to look for the right byte offset. This means that it is very fast to run operations on a section of video, even if it is hours in.

  What I want to be able to do is to do the same thing but piping into ffmpeg with the requests module with something like (in partial pseudo-code) :

  stream = requests.get(url, stream=True)
  
  start_byte = get_byte_offset(stream, time=60)
  
  stream.seek_to(start_byte)
  
  
  
  process = subprocess.Popen(["ffmpeg", "-i" "pipe:" "out.mp4"], stdin=subprocess.PIPE)
  
  
  
  for chunk in stream.iter_content(chunk_size=64 * 2 ** 10):
  
      process.stdin.write(chunk)
  
  process.stdin.close()

  This would allow me to implement extra checks into the stream that I would normally need to parse ffmpeg for, such as if the stream returns a bad status code such as 404 or 403.

  How might I be able to implement this using the requests, and presumably other, modules ? I suppose the first part is using a tool to parse the video headers.

• Return a JSON response for DELETE requests.

  14 décembre 2013, par blueimp

  Return a JSON response for DELETE requests.