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• Timestamp information of MP4

  25 juillet 2016, par Zhenjie Zhao

  I want to ask for an easy way to get the timestamp information of a mp4 file. (Sorry that I am not familiar with codec.)

  I am reading the Tobii Pro Glasses SDK document that explains how to synchronize frame with eye tracking data, where they use a terminorlogy called VTS. Goolge cannot find the exact meaning, so I want to ask for what VTS really stands for and how to get it from a mp4 file. Thanks very much !

• Unable to get a continuous video of last N seconds using ffmpeg [duplicate]

  28 juin 2021, par trycatch22

  I am trying to create a dashcam from an RTSP streaming device using ffmpeg (in Python). I have it working, but I am losing a small bit of video between stopping a file and starting a new file.

  


  My pseudocode looks like this :

  


  Start recording in 5s increments
while True:
   now = get current time
   if now > split:
       stop recording
       start recording with new file name


  


  At any point when I send a trigger, I wait (up to 5s) for the current file to be written to disk, and then I stitch the required number of files to get a video of the desired length. The issue is that I am losing time between the stop and the start.

  


  I am starting a new file like so :

  


  process_cmd = "ffmpeg -y -loglevel panic -i rtsp://{}:{}@{} -vf scale={}:{} -t {} {}".format(self._rtsp_login, self._rtsp_pwd, self._rtsp_server, self._width, self._height,self._rtsp_video_duration,output_file)
self._process_handle = subprocess.Popen(process_cmd, shell=True)


  


  I am waiting for the video to be done recording by :

  


  self._process_handle.wait()


  


  What's a cleaner way to do this ? One option would be to write a longer file and then use ffmpeg to extract the desired N seconds from it.

  


  proc = subprocess.Popen("ffmpeg -y -i rtsp://admin:ambi1234@192.168.1.200 -profile:v high -pix_fmt nv12 -b:v 15M -acodec aac out.mp4", stdin=subprocess.PIPE,shell=True)


  


  This requires me to stop the recording first by sending 'q' to the process and then :

  


  subprocess.Popen("ffmpeg -y -sseof -00:00:3 -i out.mp4 -vcodec copy -acodec copy test.mp4", shell=True)


  


  But that source file (out.mp4) would have to be cleaned up every so often and if an event happens at that point, then I won't be able to capture the data.

  


• ffmpeg command does not work when run from .sh file

  19 novembre 2020, par Felipe Hurtado

  I am trying to run an ffmpeg command from a shell file but I am getting the following error :

  


  'NULL @ 0x343e9c0] Unable to find a suitable output format for '


  


   : Invalid argument

  


  Below the ffmpeg commnad

  


  ffmpeg -i "rtsp://admin:adminCTZSDS@192.168.0.5/1" -s 600x400 -framerate 20 -b:v 16k -preset slow -acodec libmp3lame -ar 11025 -crf 20 -f flv rtmp://localhost:1935/live/camara2 


  


  and this is the content of the shell file :

  


  #!/bin/bash
#script streaming
ffmpeg -i "rtsp://admin:adminCTZSDS@192.168.0.5/1" -s 600x400 -framerate 20 -b:v 16k -preset slow -acodec libmp3lame -ar 11025 -crf 20 -f flv rtmp://localhost:1935/live/camara2 
        


  


  the command works if I run it manually in a terminal