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• ImagickPixelIterator is not read-only after all..

  9 juin 2010, par Mikko Koppanen — Imagick, PHP stuff

  A few days ago I got a help request from a user : "How do you change pixel color during the iteration with ImagickPixelIterator". My initial response was that ImagickPixelIterator is read-only. Well, I have to admit I was wrong. After searching trough ImageMagick docs I stumbled across an (...)

• "Undefined reference to `avcodec_alloc_frame" Error when compile and install Opencv on linux

  7 avril 2016, par Kathy Lee

  I am compiling and installing OpenCV using the steps in http://docs.opencv.org/2.4/doc/tutorials/introduction/linux_install/linux_install.html

  But during "making" it, it has error when it reaches 45%. The error message is

  ...
  
  [ 43%] Built target pch_Generate_opencv_video
  
  [ 44%] Built target opencv_video
  
  [ 44%] Built target opencv_perf_video_pch_dephelp
  
  [ 45%] Built target pch_Generate_opencv_perf_video  
  
  Linking CXX executable ../../bin/opencv_perf_video
  
  ../../lib/libopencv_videoio.so.3.1.0: undefined reference to `avcodec_alloc_frame'
  
  ../../lib/libopencv_videoio.so.3.1.0: undefined reference to `avcodec_encode_video'
  
  collect2: error: ld returned 1 exit status
  
  make[2]: *** [bin/opencv_perf_video] Error 1
  
  make[1]: *** [modules/video/CMakeFiles/opencv_perf_video.dir/all] Error 2
  
  make: *** [all] Error 2

  I downloaded and installed the latest version of ffmpeg from https://www.ffmpeg.org/.

  Anyone knows how can I fix the errors ?

  Thank you.

• FFmpeg takes too much time for generating m3u8 files from a mp4 file (166MB)

  3 août 2021, par Angele

  I am using ffmpeg in nodejs to generate 4 different resolutions (360p, 480p, 720p, 1080p).
I use a AWS lambda for each resolution and the last two take too much time.
I convert a mp4 file which has a size of 166MB into .ts files (with all segments associated)
It takes more than 900 seconds, and that's above the limit for a lambda timeout.

  


  Also my goal is to encode mp4 videos of a maximum size of 4go... and it would be to encode within 900 seconds maximum for each resolution.

  


  I used this website to find some parameters : https://docs.peer5.com/guides/production-ready-hls-vod/

  


  These are my parameters given to ffmpeg :

  


  "ffmpegParams": [
    "-vf",
    "scale=-2:1920",
    "-c:a",
    "aac",
    "-ar",
    "48000",
    "-c:v",
    "h264",
    "-profile:v",
    "main",
    "-crf",
    "20",
    "-sc_threshold",
    "0",
    "-g",
    "48",
    "-keyint_min",
    "48",
    "-hls_time",
    "4",
    "-hls_playlist_type",
    "vod",
    "-b:v",
    "5000k",
    "-maxrate",
    "5350k",
    "-bufsize",
    "7500k",
    "-b:a",
    "192k",
    "-hls_segment_filename",
    "/tmp/1080p_%03d.ts",
    "/tmp/1080p.m3u8"
]


  


  Also I tried with these parameters '-vcodec', 'libx264', '-preset', 'ultrafast' and it made it faster but it is not enough...

  


  Maybe there's something wrong with my command. If someone could maybe enlighten me ? :)

  


  Edit : I ended up using an EC Fargate, perfect for this kind of need.