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• 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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• Display formatted date and time over frames using ffmpeg

  28 août 2020, par marcman

  I've gone through a handful of questions on here (this, this, this, etc) concerning overlaying the date and time on videos using ffmpeg, but I haven't been able to figure out the solution.

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  I personally have found the ffmpeg documentation difficult to parse as well regarding drawing text that updates every (N) frame(s).

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  I have the exif data from a movie specifying when it was created. I'd like to be able to emblazen that over the movie (as though it were a home video from some old VHS tape). For example, let's say I have a video from January 2, 2012 at 10:33:53. I'd like to be able to show "Jan 2, 2012 10:33:53am" on the lower right in white text. The spatial positioning and color are clear to me, but just how to go from the timestamp information I have to the formatted expansion is proving to be quite difficult for me. I have succeeded in getting a clock starting from 00:00:00.00 and counting up (using timecode and timecode_rate), but unfortunately I can't get much more than that.

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  My question is : what is the proper datetext command that will allow me to both (a) provide the start time, and (b) format it with the proper expansion.

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  As a bonus, if you can also point me to how to do this using the wonderful ffmpeg-python library, it would be even better. That library is quite good, but it does not appear to be actively maintained anymore.

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