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• How to get time stamp of closet k-frame before a given timestamp with ffmpeg ?

  20 février 2013, par jAckOdE

  I want a ffmpeg seeking command that fast and accurate. I found this

  The solution is that we apply -ss for both input (fast seeking) and output (accurate seeking). The question is that if the input seeking is not accurate how can we be sure that the seeking position is accurate.

  For example : as the example used in the link, if we want to seek to 00:03:00, the command is something likes

  ffmpeg -ss 00:02:30 -i ... -ss 00:00:30
  As said, the first seeking will seek to somewhere else not 00:02:30, say 00:02:31. and after applying second seek, the final result would be 00:03:01- NOT what we want. Is that correct ?

  Where does fist seeking seek to ? Does it seek to k-frame that closet to 00:02:30 ?

  If so, here is my thought, correct me if i'm wrong : after first seeking, we get the timestamp of the result (in this example : 00:02:31), then we apply second seeking with appropriate time, in this case 00:00:29.

  Question is how do we get time stamp of first seeking's result ?

• Stream copy given start and end time in ffmpeg

  10 mai 2013, par praks411

  I'm trying a small program which cuts clip from video file given start and end time. For this I'm doing a simple stream copy of both audio and video stream. I just copied the pts and dts from input packet to output with proper re-scaling. However the output which I'm getting is blank for some duration and then only for last few seconds it is displayed. I thought this could to problem of incorrent pts and dts. So I just manually set pts and dts using counter for each stream. Though I'm able to get the clip but video is very fast and audio goes fine. Please someone explain me how to set current pts and dts for both audio and video stream, when doing stream copy.

  Thanks
  Pradeep

• Real time livestreaming - RPI

  24 avril 2022, par Victor

  I work at a telehealth company and we are using connected medical devices in order to provide the doctor with real time information from these equipements, the equipements are used by a trained health Professional.

  


  Those devices work with video and audio. Right now, we are using them with peerjs (so peer to peer connection) but we are trying to move away from that and have a RPI with his only job to stream data (so streaming audio and video).

  


  Because the equipements are supposed to be used with instructions from a doctor we need the doctor to receive the data in real time.

  


  But we also need the trained health professional to see what he is doing (so we need a local feed from the equipement)

  


  How do we capture audio and video

  


  We are using ffmpeg with a go client that is in charge of managing the ffmpeg clients and stream them to a SRS server.
This works but we are having a 2-3 sec delay when streaming the data. (rtmp from ffmpeg and flv on the front end)

  


  ffmpeg settings :

  


  ("ffmpeg", "-f", "v4l2", `-i`, "*/video0", "-f", "flv", "-vcodec", "libx264", "-x264opts", "keyint=15", "-preset", "ultrafast", "-tune", "zerolatency", "-fflags", "nobuffer", "-b:a", "160k", "-threads", "0", "-g", "0", "rtmp://srs-url")


  


  My questions

  


  

  • Is there a way for this set up to achieve low latency (<1 sec) (for the nurse and for the doctor) ?

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  • Is the way I want to achieve this good ? Is there a batter way ?

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  Flow schema

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  Data exchange and use case flow

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