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• FFMpeg crashes on decoding MJpeg

  22 octobre 2012, par Lior Ohana

  I'm working with FFMpeg for decoding Mjpeg streams.
  Recently I've bumped into access violation exceptions from FFMpeg, after investigating, I found that due to network packet drops, I'm passing to the FFMpeg a frame that might have "gaps" in it.
  The FFMpeg probably crash since it jumps to a marker payload which doesn't exist in the frame's memory.

  Any idea where I can find a mjpeg structure validator ?
  Is there any way to configure FFMpeg to perform such validations by itself ?

  Thanks.

• _docElement is always false

  8 octobre 2013, par jgabios

  _docElement is always false
  I looked for documentation on _docElement, but there is none.
  
  I guess it was meant doc.documentElement to get to the HTML root element, but otherwise going from body directly to the first DIV seems reasonable enough.
  

• How to run a video on chromium/lubuntu smoothly on a low-end machine ?

  29 juillet 2020, par Altuğ Ceylan

  the cpu of the machine is Atom X5-Z8350 with a ram size of 4 GB. It does not have an external gpu.
The problem is that when it runs a video on chromium such as a youtube video, it stutters and fps drop happens. I found out that the cpu supports h264 and vp8, and chromium only supports vp-8 and vp-9. Therefore, I used ffmpeg to transcode a video I downloaded from youtube to see if it was going to help.
I used the following script from my github repository which also contains driver update scripts etc

  


  
#$1 input filename
#$2 good realtime best
#$3 --cpu-used for best and good deadline valid values are from 0 to 5 for realtime 0 to 15
#$4 tile columns allow multi threading use powers of 2 eg 2=4
#$5 no threads to use
#$6 minrate around 2k is good for 1080p60
#$7 out filename
# -b:v bitrate 512k maybe too low for 720p30 try 1500k to 2000k 
#for fast/quality use realtime 6-7 
#for very good quality use good 2
start=$(date +%s.%N)
ffmpeg -i $1 -r 30 -g 90 -s 1280x720 -aspect 16:9 -c:v libvpx -deadline $2 -row-mt 1 -b:v 2500k -threads $5 -tile-columns $4 -cpu-used $3 -minrate $6 -bufsize 3000k -maxrate 3000k -crf 30 -frame-parallel 1 $7.webm
duration=$(echo "$(date +%s.%N) - $start" | bc)
execution_time=`printf "%.2f seconds" $duration`
echo "Script Execution Time: $execution_time"



  


  I changed crf to 5, -r to 120 -s to 1920x1080 and passed $2 as realtime, $3 as 7, $4 as 2 , $5 as 4, $6 as 2000k, I used the following video https://www.youtube.com/watch?v=jZKvJY6gDfg. It was a lot better than before, the chromium was having hard time running 720p30 but now it actually ran the 1080p120 video with minor tear and fps drops. How can I prevent the tears and the fps drops from happening ?