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• ffmpeg exact start and end times

  19 juin 2017, par Eng. M.Hamdy

  I’ve searched a lot but didn’t find what I nedd.
  I use this command :

  ffmpeg -ss <start> -i <srcfile> -t <duration> -c copy <dstfile>
  
  </dstfile></duration></srcfile></start>

  to copy a part of the video, but the output file start time and duration may differ than "start" and "duration" specified.
  I understand that ffmpeg seeks to the nearest Keyframe and that precise seeking to a timestamp is not possible unless re-encoding the video (I tried that but the output video losses quality !).
  It’s important to me to know the exact start and end timestamp that ffmpeg use to generate the output, because I use this info to adjust subtitle timing.
  Is there any way to make ffmpeg report start timestamp and end timestamp ?
  Or else : Is there any way to know the previous and next keyframes to specific Timestamp, so I can adjust the video cut markers in my project to fit nearest keyframes ?
  Thanks.

  Update :
   Is it possible to seek to the second keyframe, and to the keyframe before the last one ?
   what is the time interval between 2 keyframes ?

• Build : Run only the 'concat' task when src files change, to always get up-to-date source when reloading demo or test pages

  24 juin 2013, par jzaefferer

  Build : Run only the 'concat' task when src files change, to always get up-to-date source when reloading demo or test pages

• Download RTSP recording content between two dates and times, or from start seconds to end seconds

  23 septembre 2022, par holt2

  I need to download from an RTSP link the content recorded on an IP camera from a start and end date and time. It would also be valid to be able to download it from X seconds of start of the recording to seconds of end.

  


  With this ffmpeg command I download the recording content from the RTSP link only from the beginning of the recording content, with the duration in seconds passed by the -t parameter :

  


  ffmpeg -rtsp_transport tcp -i  -r 30 -t <seconds> -y -vf scale=800:-1 -c:v libx264 -crf 20 -preset fast -c:a aac -strict experimental -b:a 192k -ac 2 /path/to/video/filename.mp4&#xA;</seconds>

  


  I tried to download with ffmpeg the content using temporary media fragment URIs (https://www.w3.org/2008/WebVideo/Fragments/wiki/UA_Server_RTSP_Communication#.281.29_Temporal_Media_Fragment_URIs) but it doesn't do it correctly :

  


  ffmpeg -rtsp_transport tcp -i #t=10,20 -r 30 -y -vf scale=800:-1 -c:v libx264 -crf 20 -preset fast -c:a aac -strict experimental -b:a 192k -ac 2 -ss 19:09:13 -t 5 /path/to/video/filename.mp4


  


  I have also tried with ffmpeg to use the -ss parameter to try to extract the recording from a specific hour, minute and second (https://trac.ffmpeg.org/wiki/Seeking) but when running it gets stuck, it does not advance :

  


  ffmpeg -rtsp_transport tcp -i  -r 30 -y -vf scale=800:-1 -c:v libx264 -crf 20 -preset fast -c:a aac -strict experimental -b:a 192k -ac 2 -ss 19:09:13 -t <seconds> /path/to/video/filename.mp4&#xA;</seconds>

  


  In case it's helpful, to get the RTSP link, I'm using the ONVIF protocol with a NodeJS library (https://github.com/agsh/onvif). I have also reviewed the ONVIF documentation available but have not found a way to download recorded content between start and end dates and times.

  


  Do you know how to download from an RTSP link the content recorded on an IP camera from a start date and time and end date, or download it from X seconds of recording start to seconds of end ?

  


  I am also open to use other tools or commands that can do this.