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• ffmpeg is dropping frames of second video in concat

  17 juin 2018, par bugwheels94

  I did a screen share and when sharing the screen I minimized the sharing window so the video that I am sharing has some thing weird going on. Seeking does not work on mplayer but works on VLC. However, when doing the concat

  ffmpeg -i test.webm -f lavfi -i color=c=blue:s=1366x768:d=71 \
  
  -filter_complex "[0]scale=w='min(1366\, iw)':h='min(768\, ih)':force_original_aspect_ratio=decrease,\
  
  pad=width=1366:height=768:x=(ow-iw)/2:y=(oh-ih)/2,setsar=1/1[v1];\
  
  [1][v1]concat=n=2[v]" -map [v] -qscale 7 result.mp4

  The webm video of length 155 seconds is not showing complete. Ideally the result should be 71 + 156 = 227 but I am getting 155 seconds and the webm video of concat being cropped.

  If I reverse the concat order to [v1][1]concat=n=2[v] then everything is perfect at 227 seconds

  Download test.webm

  May you please tell me about what might be wrong here ? Thanks

• Code must find all MP4 files within subdirectory to compress using ffmpeg

  22 juin 2019, par ellipsical

  I have a drive with a lot of MP4 files which are tough to go through folder by folder and compress.

  I’m trying to make a script that runs in terminal that will open a designated folder, find all .mp4 files in the subfolder, and compress the files using specs I designate with ffmpeg. Obviously, the output files should be much lower in size if done right. I’m drafting a code which I have an idea about below but I’m not too good with BASH and/or PERL.

  for f in $(find ../ -iname '*.avi'); do 
  
    n=$(echo $f|sed -e 's/.avi/_cbr.mp4/i'); 
  
    echo "ffmpeg [options] -i $f $n"; 
  
  done

  output :

  ffmpeg [options] -i ../1hourjob/videncode/sound10s.avi ../1hourjob/videncode/sound10s_cbr.mp4
  
  ffmpeg [options] -i ../1hourjob/videncode/t003.avi ../1hourjob/videncode/t003_cbr.mp4
  
  ffmpeg [options] -i ../ffmpeg/Masha.avi ../ffmpeg/Masha_cbr.mp4
  
  ffmpeg [options] -i ../ffmpeg/window.avi ../ffmpeg/window_cbr.mp4

  I’m wondering if I can even make some sort of GUI for this too. I feel a bit lost.

• FFmpeg - Low/unstable encoding speed

  12 février 2023, par Erwan

  Trying to transcode two streams into one gives me poor/unstable encoding speeds from x0.400 to x0.988, sometimes above x1.

  


  fmpeg \
   -thread_queue_size 15 -rtbufsize 100M -i "https://.../stream.m3u8" \
   -thread_queue_size 15 -rtbufsize 100M -i "http://.../video.mjpg" \
   -filter_complex \
   "[0:v]setpts=PTS-STARTPTS [bg]; \
    [1:v]scale=200:-1,setpts=PTS-STARTPTS [fg]; \
    [bg][fg]overlay=W-w-10:10" \
   -c:v mpeg1video \
   -b:v 1000k \
    -r 25 \
   -threads 1 \
   -f mjpeg udp://127.0.0.1:1235?pkt_size=1316


  


  Hardware specs :

  


  

  • CPU is Intel Core 2 Duo

  


  • Mechanical hard drive

  


  


  I choose the mpeg1video encoder because of the low CPU usage. It seems that my Core 2 Duo can't keep up with libx264 .

  


  I played with output bitrates, fps and threads, -re but nothing seems to improve and stabilize encoding speed to x1. Which parameters do I need to change/add/remove to achieve a reliable x1 encoding speed ?

  


  Input streams are not reliable, download internet connection is slow and unreliable.