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• ffmpeg randomly hangs and takes huge cpu usage when recording audio streams

  7 décembre 2017, par Maximax40

  I am trying to record 54 radio station using ffmpeg for Windows. I get those audio from different URL and separate instances of ffmpeg record and encode them to .wav format. It works great, it does it’s job with a very low cpu and memory usage and I get the results I want. However, sometimes a random ffmpeg process seems to hang and start using 25% cpu usage on it’s own and stop recording.

  It happens several times a day, and everytime I need to restart the process. If I’m not paying attention to the processes when one is stall, others will start to hang as well. If 4 of them hangs, I get 100% cpu usage and more than half of the recordings stops working, probably because of overload or something.

  When a process stall, I don’t get any error in the cmd window, it just freezes. It really seems to be random, because 2 computers are doing the same thing and record the exact same streams, but when a process stall on a computer, the same process works fine on the other, so I don’t think it’s related to the stream input.

  Here is an example of the command I use to launch a ffmpeg process :

  ffmpeg -y -i "http://icecast-cftx.rncm.ca/cftx.mp3" -ab 3200 -ar 16000 -ac 1 -f segment -segment_time 600 -strftime 1 "audios/CBFFMTR %%Y-%%m-%%d %%H-%%M-%%S.wav"

  Can anyone help me on this issue ? It’s really sad that I can’t rely on this software because of this.

  Thank you

  EDIT : After another check, I realise that when a recording crash on one of the computers, the same one crash on the other.

• How can I parse ffprobe output and run ffmpeg depending on the result ?

  14 septembre 2019, par Eli Greenberg

  I have had incredible trouble building a binary of ffmpeg for Mac that works correctly for all of my needs. I have an older build that works great remuxing h264 video without problems but lacks a library I need, namely libspeex. I built a newer build based on ffmpeg’s git that includes libspeex but crashes when trying to remux h264 from .flv files with bad timecodes (live dumps from rtmpdump). So I have two ffmpeg binaries that each do half of what I need. This is what I have as my current .command file :

  for f in ~/Desktop/Uploads/*.flv
  
  do
  
  /usr/local/bin/ffmpeg -i "$f" -vcodec copy -acodec libfaac -ab 128k -ar 48000 -async 1 "${f%.*}".mp4 && rmtrash "$f" || rmtrash "${f%.*}".mp4
  
  done

  This ffmpeg binary has libspeex included so it can decode speex audio in the .flv input files. What I’m looking to do is something like this pseudocode :

  for f in ~/Desktop/Uploads/*.flv
  
  do
  
  ffprobe input.flv
  
      if Stream #0:1 contains speex
  
          ffmpeg-speex -i input.flv -acodec copy -async 1 output.m4a
  
      fi
  
  ffmpeg-h264 -i input.flv -vcodec copy output.mp4
  
  MP4Box -add output.mp4 -add output.m4a finaloutput.mp4
  
  done

  Is something like this possible ? Are there any alternatives ?

• pyav / ffmpeg / libav receiving too many keyframe

  26 mai 2021, par user1315621

  I am streaming from an rtsp source. It looks like half of the frames received are key frames. Is there a way to reduce this percentage and have an higher number of P-frames and B-frames ? If possible, I would like to increase the number of P-frames (not the one of B-frames).
I am using pyav which is a Python wrapper for libav (ffmpeg)

  


  Code :

  


  container = av.open(
    url, 'r',
    options={
        'rtsp_transport': 'tcp',
        'stimeout': '5000000',
        'max_delay': '5000000',
    }
)
stream = container.streams.video[0]
codec_context = stream.codec_context
codec_context.export_mvs = True
codec_context.gop_size = 25  

for packet in self.container.demux(video=0):
    for video_frame in packet.decode():
        print(video_frame.is_key_frame)


  


  Output :

  


  True
False
True
False
...


  


  Note 1 : I can't edit the source. I can just edit the code used to stream the video.

  


  Note 2 : same solution should apply to pyav, libavi and ffmpeg.

  


  Edit : it seems that B-frames are disabled : codec_context.has_b_frames is False