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• FPS from RTSP stream info does not match actual framerate

  17 mai 2021, par Krapow

  I have a 25FPS RTSP stream coming from an IP-camera. I can successfully display the video stream. But when analyzing the stream with ffmpeg (ffprobe actually), I observe fewer frames per second rate :

  


  $ ffprobe -rtsp_transport tcp -i rtsp://camera_ip:554/stream -select_streams v:0 -show_frames -show_entries frame=coded_picture_number,pkt_pts_time -of csv=p=0
Stream #0:0: Video: h264 (Main), yuvj420p(pc, bt709, progressive), 640x480, 25 fps, 25 tbr, 90k tbn, 50 tbc
0.400000,0
0.080000,1
0.120000,2
0.200000,3
0.240000,4
0.320000,5
0.360000,6
0.440000,7
0.480000,8
0.560000,9
0.600000,10
0.680000,11
0.720000,12
0.800000,13
0.840000,14
0.920000,15
0.960000,16
1.040000,17
1.080000,18
1.160000,19
1.200000,20
1.280000,21
1.320000,22
1.400000,23
1.440000,24
1.520000,25
1.560000,26
1.640000,27
1.680000,28
1.760000,29
1.800000,30
1.880000,31
1.920000,32
2.000000,33


  


  We can clearly see the 80ms gap between some of the frames, resulting in a 16fps stream.

  


  I have observed the same framerate issue with GStreamer (printing information in the rtpjitterbuffer indicates the frame gap is sometimes 80ms and sometimes 40ms). But the weird thing is, I encountered the same issue with an HDMI-RJ45 decoder, and I doubt the same issue comes from 2 different devices.
I didn't get much more informations using -loglevel debug or trace.
Does anybody have an idea about what is going wrong in the stream ?

  


  (I used ffprobe 4.2.3 and the last "2021-05-09-git-8649f5dca6-full_build-www.gyan.dev" with the same results, and GStreamer 1.16.2 with a pipeline like "urisourcebin ! h264depay ! h264parse ! fakesink")

  


  EDIT : The camera skipping of frames was caused by the activation of a third stream in the options. I find it really weird that it skips exactly the same frames every seconds. However, I still haven't found the cause of the downrate on my RTSP encoder.
Anyway, this was actually hardware related and not software related.

  


• JAVE (Java Audio Video Encoder) library exception only on Linux (CentOS 7)

  13 octobre 2017, par Linu Radu

  I’m using JAVE (Java Audio Video Encoder) library and the developed application is on windows.
  On windows the conversion of an .mp3 file is working fine but when I deployed on linux (CentOS 7) an exception is thrown.

  As I understand JAVE has also a wrapper around an ffmpeg executable.

  Here is my code :

  try {
  
          File source = new File(sourceFile);
  
          File target = new File(targetFile);
  
  
  
          final AudioAttributes audio = new AudioAttributes();
  
          audio.setCodec("libmp3lame");
  
          audio.setBitRate(88000);
  
          audio.setChannels(2);
  
          audio.setSamplingRate(44100);   
  
  
  
          EncodingAttributes attrs = new EncodingAttributes();
  
          attrs.setFormat("mp3");
  
          attrs.setAudioAttributes(audio);
  
  
  
          Encoder encoder = new Encoder();
  
          encoder.encode(source, target, attrs);
  
  } catch (EncoderException ex) {
  
      throw ex;
  
  }

  Exception :

  ...
  
  
  
  Caused by: it.sauronsoftware.jave.EncoderException: Error while opening codec for output stream #0.0 - maybe incorrect parameters such as bit_rate, rate, width or height
  
      at it.sauronsoftware.jave.Encoder.encode(Encoder.java:926)
  
      at it.sauronsoftware.jave.Encoder.encode(Encoder.java:713)
  
      at com.hft2.ejb.util.Mp3JaveEncoder.encode(Mp3JaveEncoder.java:36)
  
      ... 206 more

  Update

  Here is the official page : http://www.sauronsoftware.it/projects/jave/

  Full exception log : https://jpst.it/1678l

  Does anyone have any idea ?

• Cannot suppress ffmpeg output from ruby

  3 avril 2014, par Danny

  I have ruby on rails app that allows users to upload videos. When a video is added, I have a before_save filter that uses ffmpeg to generate a series of thumbnails. The problem is that ffmpeg is producing tons of console output when I'm saving a video item in the rails console, and when I run my tests.

  My environment :

  • Host Machine : OS X 10.9.2
  • Vagrant Box : Ubuntu 10.04.4
  • ffmpeg version : SVN-r0.5.9-4:0.5.9-0ubuntu0.10.04.3
  • ruby version : 1.9.3-p194

  Command I'm running :

  `ffmpeg -v 0 -ss #{timestamp} -i #{video_file.path} -y -f image2 -vcodec mjpeg -vframes 1 -s 640*360 #{thumbnail_path}/thumbnail#{i}.jpg`

  This version of ffmpeg on my VM doesn't seem to care about the "-v 0" option. I've also tried "-loglevel quiet" which causes ffmpeg to error, indicating that the option isn't recognized (both loglevel and v work on my host machine's ffmpeg).

  Tried using both exec() and system(), which both caused execution to hang. Tried to redirecting output to a file by doing :

  `ffmpeg -v 0 -ss #{timestamp} -i #{video_file.path} -y -f image2 -vcodec mjpeg -vframes 1 -s 640*360 #{thumbnail_path}/thumbnail#{i}.jpg > #{thumbnail_path}/output.txt`

  Still see output. Next I tried :

  `ffmpeg -v 0 -ss #{timestamp} -i #{video_file.path} -y -f image2 -vcodec mjpeg -vframes 1 -s 640*360 #{thumbnail_path}/thumbnail#{i}.jpg &> dev/null`

  Still seeing output ! Finally I tried :

  $stdout.reopen("#{thumbnail_path}/output.txt", "w")
  
  $stderr.reopen("#{thumbnail_path}/error.txt", "w")
  
  `ffmpeg -v 0 -ss #{timestamp} -i #{video_file.path} -y -f image2 -vcodec mjpeg -vframes 1 -s 640*360 #{thumbnail_path}/thumbnail#{i}.jpg`
  
  $stdout = STDOUT
  
  $stderr = STDERR

  Holy cow, that worked ! Well, sort of. No more verbose output when running tests, BUT somehow anytime this runs I get kicked out of the rails console.

  Does anyone have a more elegant solution ?