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• How to stop perl buffering ffmpeg output

  4 février 2017, par Sebastian King

  I am trying to have a Perl program process the output of an ffmpeg encode, however my test program only seems to receive the output of ffmpeg in periodic chunks, thus I am assuming there is some sort of buffering going on. How can I make it process it in real-time ?

  My test program (the tr command is there because I thought maybe ffmpeg’s carriage returns were causing perl to see one big long line or something) :

  #!/usr/bin/perl
  
  
  
  $i = "test.mkv"; # big file, long encode time
  
  $o = "test.mp4";
  
  
  
  open(F, "-|", "ffmpeg -y -i '$i' '$o' 2>&1 | tr '\r' '\n'")
  
          or die "oh no";
  
  
  
  while(<f>) {
  
          print "A12345: $_"; # some random text so i know the output was processed in perl
  
  }
  
  </f>

  Everything works fine when I replace the ffmpeg command with this script :

  #!/bin/bash
  
  
  
  echo "hello";
  
  
  
  for i in `seq 1 10`; do
  
          sleep 1;
  
          echo "hello $i";
  
  done
  
  
  
  echo "bye";

  When using the above script I see the output each second as it happens. With ffmpeg it is some 5-10 seconds or so until it outputs and will output sometimes 100 lines each output.

  I have tried using the program unbuffer ahead of ffmpeg in the command call but it seems to have no effect. Is it perhaps the 2>&1 that might be buffering ?
  Any help is much appreciated.

  If you are unfamiliar with ffmpeg’s output, it outputs a bunch of file information and stuff to STDOUT and then during encoding it outputs lines like

  frame=  332 fps= 93 q=28.0 size=     528kB time=00:00:13.33 bitrate= 324.2kbits/s speed=3.75x

  which begin with carriage returns instead of new lines (hence tr) on STDERR (hence 2>&1).

• How do I use ffmpeg to deliver the video

  19 juin 2014, par user3750991

  Our destination :

  We want to install camera on our device of arm architecture with capture real-time video and send them to ffserver, then we can watch this video from h ttp ://172.16.51.29:8090/stat.html on the other computer in the same time.

  Device IP address : 172.16.51.29
  computer IP address : 172.16.51.26

  1 I start the server on device

  ffserver -f /etc/ffserver.conf

  2 Camera start to capture video on device

  ffmpeg -s 320x240 -f video4linux2 -i /dev/video0 h ttp ://127.0.0.1:8090/cam1.ffm

  3 I got the messages

  Error while opening encoder for output stream #0.0 - maybe incorrect
  parameters such as bit_rate, rate, width or height

  4 Test

  ffmpeg -s 320x240 -f video4linux2 -i /dev/video0 cam1.asf

  Command above is perfect to produce video named cam1.asf

  5 Fix incorrect parameters such as bit_rate, rate, width or height

  ffmpeg -s 320x240 -f video4linux2 -i /dev/video0 -b 100k h ttp ://127.0.0.1:8090/cam1.ffm

  But use the command above produce the message presented below

  Input #0, video4linux2, from ’/dev/video0’ :
  Duration : N/A, start : 24300.069612, bitrate : 36864 kb/s
  Stream #0.0 : Video : rawvideo, yuyv422, 320x240, 36864 kb/s, 30 tbr, 1000k tbn, 30 tbc
  Sat Jan 1 07:09:07 2000 127.0.0.1 - - [GET] "/cam1.ffm HTTP/1.1" 200 4149
  [buffer @ 0x2f1a0] w:320 h:240 pixfmt:yuyv422
  [avsink @ 0x2f7e0] auto-inserting filter ’auto-inserted scaler 0’ between the filter ’src’ and the filter ’out’
  [scale @ 0x2ea60] w:320 h:240 fmt:yuyv422 -> w:320 h:240 fmt:yuv420p flags:0x4
  Sat Jan 1 07:09:07 2000 127.0.0.1 - - [POST] "/cam1.ffm HTTP/1.1" 200 0
  Segmentation fault

  What should I do to fix this issue ? Thanks.

• Ignore Connection Error on Multiple Rtsp Stream in FFmpeg

  17 décembre 2022, par Onur Külekci

  Sorry for my bad English. My problem is ;
ffmpeg command closes completely when one of the streams cannot be reached while multicasting. when it can't reach a single rtsp address, how can it ignore it and continue broadcasting from the others ?

  


  Example ;

  


  ffmpeg -i rtsp://5.63.151.4:443/atv/atv2 -map 0 c:\atv.flv -i rtsp://live.sabah.com.tr:443/ahaber/ahaber3 -map 1 c:\ahaber.flv


  


  if it can't reach the 2nd link, keep playing the first one

  


  Thank you !