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• imagemagick gradient mask file creation

  6 avril 2016, par lang2

  I’m playing with this creative script here : http://www.fmwconcepts.com/imagemagick/transitions/. The plan is to mimic what happens with the script with ffmpeg and generate video with transition effects between pictures. My current understanding is this :

  1. I have two pictures A and B.
  2. I need in between a couple of pictures (say 15) that are partially A and partially B.
  3. To do that I use the composite -compose src-over A.jpg B.jpg mask-n.jpg out.jpg command.
  4. During the process, the mask-n.jpg gets generated automatically that gradually change from all black to all white.
  5. Depends on the mathematically equations, the way the transition effect looks is different.

  In one of the example, Fred the author gave this :

  convert -size 128x128 gradient: maskfile.jpg

  This will generate a image like this :
  

  This is partially black and partially white. For the transition to work, I’ll need an all white one and an all black one and a couple of others in between. What’s the magical command to do that ?

• Creating a video from data of server-side script

  8 mars 2016, par Peter Leupold

  My plan is to display the data that a server-side script generates in a video displayable on my web page. So far my approach is the following :

  1. A three dimensional integer array in a C script is use to accumulate the image data. Dimensions are width, breadth and color (R, G and B).
  2. The array is written to a ppm-file.
  3. The next picture is accumulated and written and so on.
  4. With ffmpeg a script merges the ppm-files to a mp4-video.

  Basically this works, but of course faster would be nicer. I would appreciate proposals for fundamentally different approaches as well as help on the following details :

  • Is there a file format simple as ppm that uses the HEX code for colors instead of triplets ? This would reduce the size of my array as well a the number of write operations.
  • Do I loose much time if I print every single value to the file with an fprintf operation instead of accumulating lines into a string ? Or do compilers optimize this kind of sequences of writes ?

• Live streaming to YouTube over HLS with FFMPEG [closed]

  19 septembre 2022, par Ash Raj

  When I stream my FaceTime camera to YouTube over HLS, my video freezes every couple seconds. Which settings do I have wrong, or am missing ?

  


  ffmpeg \
-f avfoundation \
-framerate 30 \
-video_size 1920x1080 \
-pixel_format yuyv422 \
-probesize 10M \
-i "0:0" \
-c:v hevc_videotoolbox \
-b:v 4500K \
-tag:v hvc1 \
-c:a aac \
-method POST \
-f hls \
"https://a.upload.youtube.com/http_upload_hls?cid=STREAM_KEY&copy=0&file=index.m3u8"


  


  I'm troubleshooting this with my FaceTime camera right now, but I plan on using a capture card with a 4K studio camera after I get this working