Recherche avancée

Sur d’autres sites (4857)

• Ways to output video using C ?

  18 mars 2015, par Frank Harris

  I do a lot of physical modeling in C, and for a long time I’ve been using a roundabout way of animating these models ; grid the system to an array of chars and write to a numerically ordered PPM file, then use convert *.ppm video.gif and wait. The output is fine, the time it takes to run ? Not so much. It can take a handful of minutes to produce a video from a simulation that takes a second to run.

  I’m convinced that there must be a more efficient way. The first thing I tried was SDL ; I was able to produce video with it, but I’m doing this on a remote server, and SDL’s performance over SSH is beyond abysmal. Maybe 0.7 FPS.

  I’ve tried using ffmpeg as well, but I haven’t had luck with getting it to work ; not sure why. If there’s no better solution I’ll renew efforts in solving the ffmpeg problem.

  Ideally, I’d like a simple way to avoid outputting all those intermediate files in the first place. Are there any C libraries that would allow me to sequentially combine pixel arrays into frames of an animation ? Preferably relatively simple ?

• ffmpeg and libx264 videos do not play on video player

  24 décembre 2019, par Tobi

  for a few months now I encountered a problem using FFmpeg in combination with the video code h264. The video generation works fine and without any errors. I am using the following script since 2015 to build my videos from single pictures :

  #!/bin/bash                                                                     
  
  # ------------------------------------------------------------------------------
  
  #                                                                               
  
  # Video generator                                                               
  
  # Tobias Holzmann                                                               
  
  # Date: 18.03.15                                                                
  
  # Update: 24.12.2019                                                            
  
  # Switch back to ffmpeg from avconv                                             
  
  #                                                                               
  
  # ------------------------------------------------------------------------------
  
  
  
  frameRate=30                                                                    
  
  vcodec="h264"                                                                   
  
  crf=18              # Between 0-51; 23 is default. 0 = lossless                 
  
  
  
  
  
  # ------------------------------------------------------------------------------
  
  
  
  ffmpeg \                                                                        
  
      -f image2 \                                                                 
  
      -r $frameRate \                                                             
  
      -i animation.%4d.png \                                                      
  
      -r $frameRate \                                                             
  
      -crf $crf \                                                                 
  
      -vcodec $vcodec \                                                           
  
      AVideo.flv                                                                  
  
  
  
  
  
  # ------------------------------------------------------------------------------

  Today I made it a bit more fancy and easier to use. However, the problem is, that all videos I generate with h264 do not play at all using the vlc player or the common Ubuntu video player. I get errors such as :

  shorty@animation: vlc AVideo.flv 
  
  VLC media player 3.0.8 Vetinari (revision 3.0.8-0-gf350b6b5a7)
  
  [000055c0e70af420] main libvlc: Running vlc with the default interface. Use 'cvlc' to use vlc without interface.
  
  [NULL @ 0x7fe318c2c2a0] Invalid NAL unit size (30490 > 15039).
  
  [NULL @ 0x7fe318c2c2a0] missing picture in access unit with size 15733
  
  [h264 @ 0x7fe318c2c2a0] Invalid NAL unit size (30490 > 15039).
  
  [h264 @ 0x7fe318c2c2a0] Error splitting the input into NAL units.
  
  [00007fe324c1c420] avcodec decoder: Using NVIDIA VDPAU Driver Shared Library  430.50  Thu Sep  5 22:38:52 CDT 2019 for hardware decoding
  
  [h264 @ 0x7fe325428ac0] hardware accelerator failed to decode picture
  
  [h264 @ 0x7fe324c1fb00] hardware accelerator failed to decode picture
  
  [h264 @ 0x7fe324eb9d80] hardware accelerator failed to decode picture
  
  [h264 @ 0x7fe324ed6080] hardware accelerator failed to decode picture
  
  [h264 @ 0x7fe324ef2400] hardware accelerator failed to decode picture
  
  [h264 @ 0x7fe324f0e780] hardware accelerator failed to decode picture
  
  [h264 @ 0x7fe325428ac0] hardware accelerator failed to decode picture
  
  [h264 @ 0x7fe324c1fb00] hardware accelerator failed to decode picture
  
  [h264 @ 0x7fe324eb9d80] hardware accelerator failed to decode picture
  
  [h264 @ 0x7fe324ed6080] hardware accelerator failed to decode picture
  
  [h264 @ 0x7fe324ef2400] hardware accelerator failed to decode picture
  
  [00007fe324c1c420] main decoder error: buffer deadlock prevented
  
  [h264 @ 0x7fe324f0e780] hardware accelerator failed to decode picture
  
  ...
  
  ...

  I am wondering if someone does know where the problem is located. Any hint or feedback is appreciated. Thank you in advance and kind regards, Tobi.

• How to turn-off Anti-aliasing when convert video into gif file with ffmpeg

  4 novembre 2023, par NewPal

  I want to know how can i turn off Anti-aliasing when i convert video into gif file with ffmpeg, Actually i want ouput in 100% pure aliased gif animation. like this sample image

  


  Here i try this but i did not get the results as i expected.

  


  ffmpeg -i video.mp4 -t 5 out.gif

  


  Any help will be appreciated.