Recherche avancée

Sur d’autres sites (12126)

• Revision b0c146eea9 : [svc] 1. Add two pass RC options in vp9_spatial_scalable_encoder. 2. Add r

  28 février 2014, par Minghai Shang

  Changed Paths :
   Modify /examples.mk

  
   Modify /examples/vp9_spatial_scalable_encoder.c

  
   Modify /vpx/exports_enc

  
   Modify /vpx/src/svc_encodeframe.c

  
   Modify /vpx/svc_context.h

  
  
  [svc] 1. Add two pass RC options in vp9_spatial_scalable_encoder.
  2. Add read/write for RC stats file
  The two pass RC for svc does not work yet. This is just the first
  step. We need further development to make it working.
  Change-Id : I8ef0e177dff0b5ed3c97a916beea5123717cc6f2

• ffmpeg convert white color to alpha

  11 janvier 2021, par tony

  Hello i took a picture with my camera :a drawing of a square frame on a white paper ; i'm trying to convert the white to transparent and keep the black color frame.

  


  So i started making 1 palette with only 2 colors to make the colors uniform and 1 palette to add the transparency

  


  ffmpeg -f lavfi -i "color=color=white:100x100" -f lavfi -i "color=color=black:100x100" -filter_complex "[0][1]hstack" -frames:v 1 blackwhite.png`
ffmpeg -i blackwhite.png -filter_complex "[0]split[a][b];[a]palettegen[pal1];[b]palettegen=reserve_transparent=on:transparency_color=white[pal2]" -map [pal1] palette1.png -map [pal2] palette2.png


  


  then i mapped the image png of the frame to convert the white to transparent and overlayed the result to a red background

  


  ffmpeg -i image.png -i palette1.png -i palette2.png -i background.png -filter_complex "[0:v][1:v]paletteuse=dither=bayer[a],[a]split[a1][a2];[a1][2:v]paletteuse=alpha_threshold=128[c];[3:v][c]overlay[d]" -map [a2] -c:v png out.png -map [d] -c:v png out1.png


  


  the png mapped to the first palette (as a test) comes as it should be, pure black and white,the second comes with no transparency at all and covers the background
what am i doing wrong ?

  


• How do I connect two GIFs to play one after another in Python ?

  9 novembre 2022, par Andrew

  If I have two GIFs, GIF 1 being 10 seconds long and GIF 2 being 5 seconds long, is there a way to connect them so the final GIF is a total of 15 seconds long ?

  


  Would I have to loop through each frame of both the GIFs with imageio.mimread() and output, once all the frames are read in memory ?

  


  Or is there another way by knowing the start and end times and shifting it ?

  


  Edit :
The solution presented by FirefoxMetzger is extremely Pythonic, ideal if you do not wish to install other software / packages like gifsicle.

  


  import imageio.v3 as iio
import numpy as np

frames = np.vstack([
    iio.imread("imageio1.gif"),
    iio.imread("imageio2.gif"),
])

# get duration each frame is displayed
iio.imwrite("imageio_combined.gif", frames)


  


  This completes in 15.6 seconds for two GIFs, each containing 100 frames.

  


  However, if runtime is important, I recommend gifsicle :

  


  gifsicle(
    sources=["imageio1.gif", "imageio2.gif"], # or just omit it and will use the first source provided.
    destination="imageio3.gif",
    options=["--optimize=2", "--threads=2", "--no-conserve-memory"]
)


  


  This completes in 4.8 seconds, which is three times as fast.