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• FFMPEG command capturing darker pics from webcam

  19 décembre 2018, par Pratul Yadav

  I am using ffmpeg in linux to capture pics from a webcam.

  Command Used : ffmpeg -y -f video4linux2 -ss 00:00:00.900 -t 1 -s 1280x720 -i /dev/v4l/by-id/usb-HD_Camera_Manufacturer_USB_2.0_Camera-video-index0 -vframes 1 -q:v 2 /tmp/test.jpg

  Query : The strange thing is the pics clicked using this command are darker (good) and brighter (good) alternately.
  Which means, 1st-time pic is darker, 2nd time its brighter, 3rd time its darker again and so on.

  Can anyone let me know why this is happening ? And how can I fix this issue to get all time brighter pics ?

  Please see sample pics.

  Brighter Pic
  

  Darker Pic
  

• vaapi_encode_h265 : Ensure that ref pics are always in the RPS

  25 janvier 2019, par Mark Thompson

  vaapi_encode_h265 : Ensure that ref pics are always in the RPS
  When making a new P-frame when B-frames are present the previous P-frame
  
  is normally in the DPB because it will be referred to by subsequent
  
  B-frames.  However, this is not true if there are no B-frames, or in edge
  
  cases where a GOP ends with two P-frames.  Fix this by adding the direct
  
  ref pics to the RPS explicitly.
  Fixes #7699.
  Tested-by : Ullysses A Eoff <ullysses.a.eoff@intel.com>
  

  • [DH] libavcodec/vaapi_encode_h265.c

• Shell script works fine from shell but doesn’t work as expected when executed via PHP “shell_exec” code

  9 décembre 2019, par Eric Feillant

  This record.sh script shell is here and works fine on command line to record an MP4 file from a local flv live stream :

  DATE=`date +"%d-%m-%Y-%T"`
  
  if [ -s NAMESTREAM ]
  
  then
  
  cat config.php | dos2unix | grep auth | grep username | \
  
  awk -F ' ' '{print $3}' | sed "s/'//g" | sed "s/;//g" | while read VAR
  
  do echo $VAR > RECSTREAM
  
  echo "Starting recording ..."
  
  ffmpeg -i "rtmp://localhost/hls/$VAR" -crf 19 videos/"$VAR"_"$DATE".mp4
  
  done
  
  else
  
  echo "Streaming is not started, please start it before"
  
  fi

  I send a shell_exec to call the last shell script in a php script like this :

  $old_path = getcwd();
  
  chdir('/usr/local/nginx/html/mydir');
  
  $output = shell_exec('nohup ./record.sh >/dev/null 2>/dev/null &');
  
  chdir($old_path);

  The MP4 video files are generated but unreadable with VLC, etc… It seems that the problem is due to my PHP script but I am not able to know why.

  When executing from the shell command line : PHP myphpscript.php works fine, MP4 video files are OK. But from the PHP web page, the MP4 video files are corrupted.

  Any ideas ? Any param to test in FFmpeg to have a good mp4 video file ?