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• TCP or UDP ? Delays building up on production for video stream

  31 janvier 2020, par Ben Beri

  I am creating a video stream from a camera with FFMPEG and nodejs stream Duplex class.

  this.ffmpegProcess = spawn('"ffmpeg"', [
  
  
  
    '-i', '-',
  
    '-loglevel', 'info',
  
  
  
    /**
  
     * MJPEG Stream
  
     */
  
  
  
    '-map', '0:v',
  
    '-c:v', 'mjpeg',
  
    '-thread_type', 'frame', // suggested for performance on StackOverflow.
  
    '-q:v', '20', // force quality of image. 2-31 when 2=best, 31=worst
  
    '-r', '25', // force framerate
  
    '-f', 'mjpeg',
  
    `-`,
  
  
  
  ], {
  
    shell: true,
  
    detached: false,
  
  });

  On local network, we are testing it with a few computers and every thing works very stable with latency of maximum 2 seconds.

  However, we have imported the service to AWS production, when we connect the first computer we have a latency of around 2 seconds, but if another client connects to the stream, they both start delaying a lot, where the latency builds up to 10+ seconds, and in addition the video is very slow, as in the motion between frames.

  Now I asked about TCP or UDP is because we are using TCP for the stream, which means that every packet that is sent is implementing the TCP syn-ack-synack protocol and sequence.

  My question is, could TCP really be causing such an issue that the delays get up to 10 seconds with very slow motion ? because on local network it works very just fine.

• what is the best way to append a video file to multiple video files using batch file [on hold]

  5 avril 2017, par JAGGADAKU

  i am beginner with computer programming and i have knowledge of c/c++

  from [https://trac.ffmpeg.org/wiki/Concatenate][1] i have learned that how to merge video files using ffmpeg

  To list all video files containing in a folder

  (for %%i in (*.mp4) do @echo %%i) > mylist.txt

  to concatenate files

  ffmpeg -f concat -safe 0 -i mylist.txt -c copy output.mp4

  This merges all files of a list to one single file.
  but How do i append one video file(main.mp4) at the starting of all the video files listed in mylist.txt ?

  can someone help me ?

  Hello there

  i have tried following code i don’t know what’s wrong with it but it is not `

  @echo off
  
  (for %%i in (*.mp4) do @echo %%i) > mylist.txt
  
  
  
  for /F "tokens=*" %%A in (mylist.txt) do (
  
      echo %%A
  
      ffmpeg -i "concat:main.mp4|%%A" -c copy  %%Aoutput.mp4
  
  
  
  )
  
  `

• libffmpeg writes bad mp4 file if the RTSP stream loses packets

  5 avril 2017, par user92238

  I’m working with libffmpeg in iOS, using it to open an RTSP stream and save the data to a file.

  I’ve been able to successfully save video files in both .mp4 and .mov formats, but there is a problem.

  If the RTSP stream is perfect — that is, if there are no dropped packets — then the resulting file is fine. I can play it in a player, and I can even transcode it using an AVAssetExportSession.

  The problem is, I’m dealing with a wireless camera that sends data over UDP only, so there are often dropped packets. When a dropped packet occurs, the resulting file has a big glitch in it : even if it’s just one or two packets, the playback freezes for about 12 seconds. Also, I cannot use AVAssetExportSession with these files. It fails, reporting a decoding problem.

  I feel like there must be some way I can cause ffmpeg to write a valid mp4 file when packets are missing. I don’t care what happens, whether the missing packets are simply deleted from the file or if they are replaced with something, I just don’t want a 12 second freeze.

  For what it’s worth, if I take the file off of my iOS device and play it on my computer, it plays fine. There’s a small glitch where the frame was dropped, but it doesn’t freeze for 12 seconds or anything.

  Thanks.