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• Different results using qt-faststart and "ffmpeg -movflags +faststart"

  31 mars 2020, par Juan Ignacio Sánchez

  I have a set of videos generated by security cameras, which have the MOOV atom at the end of the file, like this :

  ftyp (32 bytes)
  
  free (8 bytes)
  
  mdat (29647845 bytes)
  
  moov (42054 bytes)

  I want to serve these files using progressive downloads (pseudo streaming) and it’s the only acceptable way to do it.

  Knowing that I tried to use tools like qt-faststart or directly ffmpeg with the corresponding flags (-movflags +faststart). Other detail is that I’m running this on a low profile machine, and FFmpeg takes like 6 8 seconds to finish (even using -c copy) and the other tool results to be much more efficient since it only moves some bytes, taking less than a second to finish. The thing here is that qt-faststart produces a video that can’t be pseudo streamed but ffmpeg does it. Here are some comparisons :

  ffmpeg :

  ftyp (32 bytes)
  
  moov (42422 bytes)
  
  free (8 bytes)
  
  mdat (29647845 bytes)

  qt-faststart :

  ftyp (32 bytes)
  
  moov (42054 bytes)
  
  free (8 bytes)
  
  mdat (29647845 bytes)

  As you can see, FFmpeg adds some extra bytes on the MOOV atom, can anyone point me in some research direction ? Thank you all.

• "Missing reference picture" error when saving rtsp stream with ffmpeg

  4 mars 2020, par Cédric Kamermans

  I want to record 10 seconds of video with an IP camera via ffmpeg. The output video looks fine but i get a bunch of "Missing reference picture" errors in the log. This only happens in the beginning of the process. I also get the warning "circular_buffer_size is not supported on this build".

  I started of with the following code :

  -y -i rtsp://username:password@IP:88/videoMain -t 10 ffmpeg_capture.mp4

  But this resulted in the output being corrupted in the beginning.
  I found the following code on a forum and this seems to fix that problem. The errors still remain though.

  -y -i rtsp://username:password@IP:88/videoMain -b 900k -vcodec copy -r 60 -t 10 ffmpeg_capture.mp4

  One thing to note is that currently we’re using a C2 V3 IP camera. This model is just for testing, we will upgrade to a better model when we get this working.

  I want to clarify that i’m just beginning to use ffmpeg, so I don’t quite understand it yet. It would be greatly appreciated if someone could provide an example code of how I can fix this problem.

  Thanks in advance !

• problem with "subprocess.Popen" AFTER make .exe file

  1er février 2020, par afcc0060

  im try to convert mp3 to mp4 with ffmpeg (command line)
  everything is well and program runs correctly.
  i have one progressbar and handle it from this function by reading ffmpeg command line output

  cls_wnd.pbar_step(line.lower())

  but after make (single) .exe file with pyinstaller program not run and did not convert anything

          def _cli(self ,cls_wnd ,cmd):
  
              errors = False
  
              cmd_output=""
  
  
  
              line=''
  
              try:
  
                      p = subprocess.Popen(cmd ,stdout=subprocess.PIPE ,
  
                                                stderr=subprocess.STDOUT ,
  
                                                universal_newlines=True ,
  
                                                shell=False ,
  
                                                creationflags = subprocess.CREATE_NO_WINDOW)
  
  
  
                      for line in p.stdout:
  
                              if cls_wnd.bt02.cget('text').lower()!="cancel":
  
                                      p.kill()
  
                                      return cmd_output, True ,'cancel'
  
                              cmd_output+=line
  
                              if line.lower().find('duration:')>-1 or line.lower().find('frame=')<1:
  
                                      cls_wnd.pbar_step(line.lower())
  
                              cls_wnd.root.update()
  
  
  
                      stdoutdata, stderrdata = p.communicate()
  
                      if p.wait() != 0:
  
                              p.kill()
  
                              return cmd_output, True ,line
  
                      p.kill()
  
                      return cmd_output, errors ,' '
  
              except OSError as e:
  
                      p.kill()
  
                      return cmd_output,True,' exit from except '
  
              return '',True,'exit from _cli end'

  cmd is somthnig like this

  cmd='ffmpeg -y -loop 1 -i 1.jpg -i 1.mp3 -c:a copy -c:v libx264 -shortest 1.mp4'

  make .exe file with this command

  pyinstaller -w --onefile  mp3tomp4.py --onefile

  if i dont use’-w’ every thing is well .. but that ugly black cmd-windows shown and i can not close or hide it