Recherche avancée

Sur d’autres sites (6643)

• ffmpeg zoompan + crop

  24 février 2021, par andykais

  I need to pan across a video that is also being cropped by ffmpeg. How can I accomplish this in a single ffmpeg command ?

  


  So far I see two possible options :

  


  Option #1 : use crop variables pan across the video. This is choppy, but possibly fixed by upscaling the input.

  


  ffmpeg -i input.mp4 -vf 'crop=w=in_w/2:h=in_h:x=t*10' crop_panned_output.mp4


  


  Option #2 : create an alpha mask in the shape of the crop, and then apply it on top of the input video with a zoompan filter. ffmpeg is doing extra work in this case, because we have to pad the input, then zoom in on it, then pan across it, then apply the alpha mask. This is actually using the "zoompan" feature to "pan" though.

  


  magick -size 1920x1080 xc:none -fill black -draw "rectangle 480,0 1440,1080" rectangular-alpha-mask.png
ffmpeg -i input.mp4  -i rectangular-alpha-mask.png  -filter_complex "
  [0:v]pad=2112:1188,zoompan=z=1.1:px+0.5:d=1:fps=60:s=1920x1080[input_pan];
  [1:v]alphaextract[alf];
  [input_pan][alf]alphamerge[masked];
  color=s=1920x1080:color=red[base];
  [base][masked]overlay=shortest=1
"  mask_panned_output.mp4


  


  Are either of these the right way to do it or are they incredibly inefficient ? Is there another option ? Cropping & panning together feels like a fairly common workflow, but these solutions feel a bit hacky.

  


  Here is a visual description of what panning and cropping a video looks like :

  


  First start with a video. Here is a simple one.


  


  I want to crop the video to a certain width/height, and move from the left to the right across the video. The background is colored red for clarity


  


  The video moves from left to right across the original video, and keeps the same crop ratio.


  


• Revision a7355f3bbb : Merge changes Iaf7d6b0a,Iece0bf56 * changes : Use INLINE and include vpx_confi

  5 mai 2014, par Johann

  Merge changes Iaf7d6b0a,Iece0bf56

  * changes :
  Use INLINE and include vpx_config.h instead of plain ’inline’
  Use vreinterpret instead of casting neon vector types

• Swift : How can I generate Mp4 video from programmaticall output ? [closed]

  21 août 2020, par Mount Ain

  This question is specifically to Swift programming language for Linux & macOS platforms.To understanding the concept, I used Swift programming language. But not depend on Swift programming language. C or C++ is also good to me.

  


  I can generate JPEG image from NSView by using NSBitmapImageRep. But Linux I don't what I want to do. So, the first thing I need to know is the step to generate JPEG image by programmatically without using the NSView. I really don't know How hard it is. But I want to learn how it's work. I feel It's the way to fill the color into pixels one by one to combine a Image. But I don't know How to do in programming. I knew the same way is used in videos by packing the series of image with audio & subtitle & other meta info.

  


  If you ask about compression, I really want to know How Twitter & YouTube compressing uploaded videos without loss of quality.

  


  So what is the concept,

  


  

  1. To generate a JPEG image by programmatically without using NSView ?

  


  2. To generate MPEG-4 video by group of JPEG images ?

  


  


  Thanking in advance...