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• Ffmpeg mixing audio only for n number of videos using offset and altered duraion

  26 août 2022, par Turgut

  I want to mix audio stream of n amount of video files with ffmpeg, with certain parameters such as :

  


  

  • Duration : I want to specify how long each audio is going to play for each output. For example if I specify ffmpeg -i -d:5 first.mp4 -i second.mp4 it should play the audio from first.mp4 for 5 seconds (I don't know if -d:5 is a real tag it's just an example I've made ).

  


  • Starting point : I want to specify when a given file is going start on the output, I probably need to use -itsoffset 5 but I don't know if it's the right one in terms of interacting with other commands, in on itself it works fine. For example : ffmpeg -i -isoffset 5 first.mp -i second.mp4 causes the second.mp4 to start immediately, and first.mp4 to start after 5 seconds.

  


  • Segmentation : This is the tricky one, I want to specify at which point the input's audio should start. It's like the -ss flag but the problem is it's not working together with -itsoffset. For example when I say ffmpeg -i -ss 5 first.mp4 -i second.mp4 both files should start immediately on the output, but first.mp4 should start on it's 5 seconds. So the 5th second of first.mp4 is heard at the 1st second of the output.

  


  


  This is what I'm trying to achieve, my problem is that I don't know how to implement 'duration' and -ss is not working together with -itsoffset.

  


  At the end I should have something similar to this :

  


  ffmpeg -y -d 5 -itsoffset 3.5 -i first.mp4 -d 10 -ss 10 -itsoffset 5.3 -i 3 -vn -copyts -async 1 -filter_complex amix=inputs=2 out.mp


  


  Which should result in an audio that sounds like this : The first 3.5 seconds are empty, no audio is heard. Then first.mp4 is heard from it's beginning for 5 seconds. When the outputs timestamp reaches 5.3, the 10th seconds of second.mp4 is heard (while first.mp4 is still playing, it's supposed to play until 8.5, so I should hear both files at the same time.) for 10 seconds.

  


  I can't find an example of this and some sources are out-of date.

  


• Real time livestreaming - RPI FFmpeg and H5 Player

  29 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) ?

  &#xA;

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

  &#xA;

  &#xA;

  Flow schema

  &#xA;

  Data exchange and use case flow :

  &#xA;

  

  &#xA;

  &#xA;

  Note : The nurse and doctor use HTTP-FLV to play the live stream, for low latency.

  &#xA;

  &#xA;

• 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.

  &#xA;

  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).

  &#xA;

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

  &#xA;

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

  &#xA;

  How do we capture audio and video

  &#xA;

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

  &#xA;

  ffmpeg settings :

  &#xA;

  ("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")


  &#xA;

  My questions

  &#xA;

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

  &#xA;

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

  &#xA;

  &#xA;

  Flow schema

  &#xA;

  Data exchange and use case flow

  &#xA;