Recherche avancée

Sur d’autres sites (9433)

• ffmpeg cache whole video stream and save

  19 juillet 2016, par Luiz

  I have a security DVR that can stream a video recording using the RTSP protocol. I can record the playback using ffmpeg and save it to a file, but for a 20 min video, I have to watch the video to save or wait the whole playback time.
  I’m using :

  ffmpeg -i "rtsp://mystream" -r 15 -acodec copy -vcodec copy myvideo.mp4

  to do this

  Is there any way to buffer the whole stream and just save it to a file using ffmpeg, without the need to watch or wait the whole 20 minutes playback ? I don’t need to reencode anything since the stream video format is good enough for me.

  Thanks in advance

• SDL save screenshot on iOS

  12 avril 2018, par Law Gimenez

  I am trying to save a screen or frame from the SDL’s "window" into a PNG file and so I’m using SDL_image library. My code is below

  IMG_Init(Int32(IMG_INIT_PNG.rawValue))
  
  let screenShot = SDL_CreateRGBSurface(0, 640, 480, 32, 0, 0, 0, 0)
  
  SDL_SetRenderTarget(renderer, texture)
  
  SDL_RenderReadPixels(renderer, nil, Uint32(SDL_PIXELFORMAT_ARGB8888), screenShot?.pointee.pixels, (screenShot?.pointee.pitch)!)
  
  let documentsPath = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0] as String
  
  IMG_SavePNG(screenShot, "\(documentsPath)/image.png")
  
  SDL_FreeSurface(screenShot)

  But the image.png was not saved. If anyone can lead or help me. Thank you !

  Additional code, the image saved is just black

  IMG_Init(Int32(IMG_INIT_PNG.rawValue))
  
  let screenShot = SDL_CreateRGBSurface(Uint32(SDL_SWSURFACE), 640, 480, 32, 0, 0, 0, 0)
  
  // SDL_SetRenderTarget(renderer, texture)
  
  SDL_RenderReadPixels(renderer, nil, Uint32(SDL_PIXELFORMAT_ARGB8888), screenShot?.pointee.pixels, (screenShot?.pointee.pitch)!)
  
  // Save to documents directory
  
  let fileManager = FileManager.default
  
  do {
  
      let documentDirectory = try fileManager.url(for: .documentDirectory, in: .userDomainMask, appropriateFor: nil, create: true)
  
      let fileUrl = documentDirectory.appendingPathComponent("imageLOL.png")
  
      if !fileManager.fileExists(atPath: fileUrl.path) {
  
          print("File NO exists")
  
          // Create file at path
  
          let data = Data()
  
          let createFile = fileManager.createFile(atPath: fileUrl.path, contents: data, attributes: nil)
  
          if createFile {
  
              print("Create file success")
  
          } else {
  
              print("Create file failed")
  
          }
  
      } else {
  
          print("File exists")
  
  
  
      }
  
      let result = IMG_SavePNG(screenShot, fileUrl.path)
  
      print("result = \(result)")
  
      // After saving screenshot
  
      let image = UIImage(contentsOfFile: fileUrl.path)
  
      let imageData = UIImagePNGRepresentation(image!)
  
      print("image length = \(String(describing: imageData?.count))")
  
      UIImageWriteToSavedPhotosAlbum(image!, nil, nil, nil)
  
      SDL_FreeSurface(screenShot)
  
  } catch {
  
      print("Error docs = \(error)")
  
  }

• Matplotlib use Ffmpeg to save plot to be mp4 not include full step

  21 décembre 2020, par 昌翰余

  I use ffmpeg to store the dynamic graph drawn on matplotlib, but the output file is only 2 seconds
but It should have been 30 seconds.
I set a graph to run three curves, a total of 30 seconds of data,
the graph that ran on the py file is normal,
but the output is only the first two seconds of the output.
May I ask if I missed something

  


  Below is my code

  


  import matplotlib.pyplot as plt
from matplotlib import animation
from numpy import random 
import pandas as pd
from matplotlib.animation import FFMpegWriter

FFwriter=animation.FFMpegWriter(fps=30, extra_args=['-vcodec', 'libx264'])
data = pd.read_csv('apple1.csv', delimiter = ',', dtype = None)
data = data.values
AccX1=[]
AccY1=[]
AccZ1=[]
AccX2=[]
AccY2=[]
AccZ2=[]

time = []

for i in range(600):
        AccX1.append(data[i][8])
        AccY1.append(data[i][9])
        AccZ1.append(data[i][10])
        AccX2.append(data[i][24])
        AccY2.append(data[i][25])
        AccZ2.append(data[i][26])
        
        time.append(data[i][0])
        
fig = plt.figure()
ax1 = plt.axes(xlim=(0,3000), ylim=(6,-6))
line, = ax1.plot([], [], lw=2)
plt.xlabel('ACC')
plt.ylabel('Time')

plotlays, plotcols = [3], ["r","g","b"]
lines = []
for index in range(3):
    lobj = ax1.plot([],[],lw=2,color=plotcols[index])[0]
    lines.append(lobj)


def init():
    for line in lines:
        line.set_data([],[])
    return lines

x1,y1 = [],[]
x2,y2 = [],[]
x3,y3 = [],[]



i=0

def animate(frame):
    global i
    
    i+=1
    x = i
    y = AccX1[i]

    x1.append(x)
    y1.append(y)

    x = i
    y = AccY1[i]
    x2.append(x)
    y2.append(y)

    x = i
    y = AccZ1[i]
    x3.append(x)
    y3.append(y)
    

    xlist = [x1, x2,x3]
    ylist = [y1, y2,y3]


    for lnum,line in enumerate(lines):
        line.set_data(xlist[lnum], ylist[lnum]) 


    return lines


anim = animation.FuncAnimation(fig, animate,
                    init_func=init, blit=True,interval=10)
anim.save('test.mp4',writer=FFwriter)
plt.show()


  


  The dynamic picture ran out using plt.show is correct.
And I don't think I have set the length of storage. Did I add something ?