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• Is there risk of shell/command injection when using FFmpeg or when there's no user input ?

  10 mai 2021, par Tris

  I am new when it comes to thinking about the security of my web applications. I have done research on shell injections and most of the time they say to just avoid using shell/command calls in the web applications. However, my alternative seems to limit which browsers clients can use. So I would prefer executing a shell command in my nodejs server. I am using FFmpeg and calling it through system command in nodejs child processes.

  


  I have a FFmpeg bash script like so :

  


  VIDSOURCE="rtsp:cameraurl"
AUDIO_OPTS="-c:a aac -b:a 160000 -ac 2"
VIDEO_OPTS="-s 854x480 -c:v libx264 -b:v 800000"
OUTPUT_HLS="-hls_time 10 -hls_list_size 10 -start_number 1 -hls_wrap 10"
ffmpeg -i "$VIDSOURCE" -y $AUDIO_OPTS $VIDEO_OPTS $OUTPUT_HLS mystream.m3u8


  


  I am wondering if I should worry about shell injection risk and if I should try another approach. I don't think there is any user input in this besides my own hard coded inputs. Therefore, I think it should be safe to use this script in a web browser... I just want to be safe and be sure. Thank you !

  


• How to close a stream opened by FFmpeg ?

  31 mars 2016, par Daneo

  I’m currently playing around with FFmpeg, and based myself on this github project.

  I’d like the ability to close the stream when I want it to close.

  How could I achieve this ?
  If I just extract the part in the dealloc method and call that when needed it crashes.

  I’ve read about an interrupt callback that needs to be called, but I have no idea how to do so. (C-code isn’t in my current skillset, so understanding it is a bit hard).

  Callback I referred to, but have no idea how to use :

  pFormatCtx->interrupt_callback.opaque;
  
  pFormatCtx->interrupt_callback.callback;

  Is there a certain order I need to respect, things I need to do upfront or in the other methods ?

  Thanks !

  Current :

  -(void) stopCapturing {
  
      if (pFrame) av_free(&pFrame);
  
      if (pCodecCtx) avcodec_close(pCodecCtx);
  
  
  
      if (img_convert_ctx) sws_freeContext(img_convert_ctx);
  
      avpicture_free(&picture);
  
      if (pFormatCtx) avformat_close_input(&pFormatCtx);
  
  }

• Revision f5209d7e01 : Remove rate component adjustment for AQ1 In AQ1 a rate adjustment was applied f

  21 novembre 2014, par Paul Wilkins

  Changed Paths :
   Modify /vp9/encoder/vp9_encodeframe.c

  
  
  Remove rate component adjustment for AQ1

  In AQ1 a rate adjustment was applied for blocks coded with a
  deltaq. This tends to skew the partition selection and cause
  rate overshoot.

  For example, consider a 64x64 super block where some but not all
  sub blocks are in a low q segment and some are in a high q segment.
  The choice of Q when considering large partition and transform sizes
  is defined by the lowest sub block segment id (currently this implies the
  lowest Q). If some parts of the larger partition are very hard this will
  cause a high rate component.

  The correct behavior here is for the rd code to discard the large partition
  choice and break down to sub blocks where some have low and some
  have high Q. However the rate correction factor above mask the high
  cost of coding at a larger partition size.

  Change-Id : Ie077edd0b1b43c094898f481df772ea280b35960