Recherche avancée

Sur d’autres sites (4518)

• How to add text with zoom out effection on video in FFMpeg ?

  29 septembre 2018, par Alexia1990

  I am developing android app with ffmpeg.
  I`d like to add text on video and set the zoom out animation on it.
  I can marquee the text from bottom to top and from left to right.
  If someone has experiences on zoom out animation of text with FFMpeg, please give me the tip.
  Here is my code.

  ffmpeg -i input.mp4 -vf "drawtext=fontfile=/path/to/font.ttf : text =’Test Line’:fontcolor=red:fontsize=65:x=100 : y=if(lt(t\,8)\,30*t\,240)" output.mp4

• Is there a way to apply a curve bend in ffmpeg ?

  25 mars 2020, par stevendesu

  I have four cameras each feeding me a different portion of a basketball court. Due to the slight offset of the cameras physical locations and lens distortion around the edges of the camera, I cannot simply stitch the videos together without some kind of correction.

  I’ve looked into ffmpeg’s perspective filter, as well as the lenscorrection filter. In the former case it was only able to create a trapezoid, not the curved image I want. In the latter case using negative values to k1 and k2 seemed to be heading in the right direction, but it either disorted the top and bottom of the image to the point of being nonsensical noise, or it zoomed in to the image so much that I lost important details.

  For the sample picture below, ultimately I want the midcourt line (the blue vertical line on the right side) to be vertical, and I want the mess of wires on the white desk at the bottom to remain visible and identifiable.

  Given a video which looks like the following :

  

  I wish to produce something like the following :

  

  This image was made using the "Curve Bend" filter in GIMP, but I just eye-balled it - so it’s not perfect. Ideally once I get the exact parameters the midcourt line will be perfectly vertical

  When using the lenscorrection filter, no values for k1 and k2 seemed to get the effect I want :

  Negative k1, negative k2 :

  

  Negative k1, positive k2 :

  

  Positive k1, negative k2 :

  

  Positive k1, positive k2 :

  

  In general :

  • negative / negative distorted the image beyond recognition
  • negative / positive looked alright, but the midcourt line was off the screen and it wasn’t clear if any distortion had been applied
  • positive / negative looked the best, but while the top and bottom curved in the middle of the left and right actually bulged out, leaving the midcourt line distorted
  • positive / positive was the opposite of the desired effect

• Concatenating with ffmpeg - audio out of sync after 2 or 3 files

  1er août 2015, par eCronik

  I have recorded some hour long .flv files I want to glue together. For that, I am using the concat script from https://trac.ffmpeg.org/wiki/Concatenate

  (on the page, at the bottom) with the following tweaks :

  EXTRA_OPTIONS='-c:v libx264 -preset slow -profile:v main -b:v 2175k -minrate 2175k -maxrate 2175k -bufsize 2175k -g 80 -c:a aac -strict -2 -b:a 192k'

  and at the bottom :

  ffmpeg -f u16le -acodec pcm_s16le -ac 2 -ar 44100 -re -i $TMP/mcs_a_all \
  
     -f yuv4mpegpipe -vcodec rawvideo -re -i $TMP/mcs_v_all -loop 1 -i /path/to/overlay.png \
  
     -filter_complex "[1:v][2:v]overlay=shortest=1[v]" -map "[v]" -map 0:a $EXTRA_OPTIONS \
  
     -f flv $last

  The first file, when started, is always 100% sync’ed. Files are randomized, so it’s not always the same one. When it reaches the second or third file, the audio (or video ?) gets more and more out of sync. I’ve tried

  '-vsync 0' as well as '-vsync 0 -copyts'

  but nothing helped so far. The files are all recorded with a sample rate of 44.1kHz - audio bitrate and video bitrate might vary a bit between them, but were always constant. To record them, I have used the following :

  -c:v libx264 -preset slow -profile:v main -b:v 2175k -minrate 2175k -maxrate 2175k -bufsize 2175k -r 40 -g 80 -keyint_min 40 -x264opts "keyint=80:min-keyint=80:no-scenecut" -c:a aac -strict -2 -b:a 192k -f flv rtmp://address \-c copy -f flv rtmp://address;

  The ’-keyint_min 40 -x264opts "keyint=80:min-keyint=80:no-scenecut"’ was added at a later point - so some files are recorded with it, some others were without.

  Does anybody has an idea what else I could try to fix it ? As the first file is always sync’ed, I guess the problem is not that the files were recorded wrong.

  Thanks a bunch,
  eC