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• How to select a rectangle of the screen to capture by dragging mouse on transparent background with wxPython ?

  4 août 2019, par makrottk

  I’m working on building an application to capture screen with ffmpeg and would like to determine the portion of the screen to capture by dragging the mouse, drawing a rectangle and passing the arguments to the ffmpeg call.

  I’m using wxPython to build a simple GUI for the application. I’ve gotten to the point where I can draw the rectangle and get the coordinates that I want : offset and size of the selected area.

  import wx
  
  
  
  global selectionOffset, selectionSize
  
  
  
  selectionOffset = ""
  
  selectionSize = ""
  
  
  
  class SelectableFrame(wx.Frame):
  
  
  
      c1 = None
  
      c2 = None
  
  
  
      def __init__(self, parent=None, id=wx.ID_ANY, title=""):
  
          wx.Frame.__init__(self, parent, id, title, size=wx.DisplaySize(), style=wx.TRANSPARENT_WINDOW)
  
  
  
          self.Bind(wx.EVT_MOTION, self.OnMouseMove)
  
          self.Bind(wx.EVT_LEFT_DOWN, self.OnMouseDown)
  
          self.Bind(wx.EVT_LEFT_UP, self.OnMouseUp)
  
          self.Bind(wx.EVT_PAINT, self.OnPaint)
  
  
  
          self.SetCursor(wx.Cursor(wx.CURSOR_CROSS))
  
  
  
      def OnMouseMove(self, event):
  
          if event.Dragging() and event.LeftIsDown():
  
              self.c2 = event.GetPosition()
  
              self.Refresh()
  
  
  
      def OnMouseDown(self, event):
  
          self.c1 = event.GetPosition()
  
  
  
      def OnMouseUp(self, event):
  
          self.SetCursor(wx.Cursor(wx.CURSOR_ARROW))
  
          self.Destroy()
  
  
  
      def OnPaint(self, event):
  
          global selectionOffset, selectionSize
  
          if self.c1 is None or self.c2 is None: return
  
  
  
          dc = wx.PaintDC(self)
  
          dc.SetPen(wx.Pen('red', 1))
  
          dc.SetBrush(wx.Brush(wx.Colour(0, 0, 0), wx.TRANSPARENT))
  
  
  
          dc.DrawRectangle(self.c1.x, self.c1.y, self.c2.x - self.c1.x, self.c2.y - self.c1.y)
  
          selectionOffset = str(self.c1.x) + "x" + str(self.c1.y)
  
          selectionSize = str(abs(self.c2.x - self.c1.x)) + "x" + str(abs(self.c2.y - self.c1.y))
  
      def PrintPosition(self, pos):
  
          return str(pos.x) + "x" + str(pos.y)
  
  
  
  
  
  class MyApp(wx.App):
  
  
  
      def OnInit(self):
  
          frame = SelectableFrame()
  
          frame.Show(True)
  
          self.SetTopWindow(frame)
  
  
  
          return True
  
  
  
  
  
  app = MyApp(redirect=False)
  
  app.MainLoop()
  
  print("offset: " + selectionOffset + ". Screen selection size: " + selectionSize)

  The problem is I can’t get the "background" to be transparent so I can see which portion of the screen I’m really grabbing. How can I do that with wxPython ? If there’s an easier way with another GUI tool or python module I’m open to suggestions. Thanks !

• Xamarin.Android.FFmpeg not compressing video from Nugat 7.1

  16 juillet 2018, par Mr Shoubs

  We have been using Xamarin.Android.FFmpeg successfully for some time to compress videos, it works up to Nougat 7.0 (API level 24), but it doesn’t seem to support the latest Android versions :

  • Oreo | 8.1.0 | API level 27
  • Oreo | 8.0.0 | API level 26
  • Nougat | 7.1 | API level 25

  Package Name : Xamarin.Android.FFmpeg v1.0.32

  We use the following options :

  string[] cmds = new string[] {
  
    "-y",
  
    "-i",
  
    inputFilepath,
  
    "-strict", "experimental",
  
    "-vcodec", "libx264",
  
    "-preset", "ultrafast",
  
    "-crf","30", "-acodec","aac", "-ar", "44100" ,
  
    "-q:v", "20",
  
    "-vf",
  
    "mp=eq2=1:1.68:0.3:1.25:1:0.96:1",
  
    ouputFile,
  
  };
  
  
  
  string cmdParams = string.Join(" ", cmds);
  
  
  
  FFMpeg.Xamarin.FFMpegLibrary.Run(Xamarin.Forms.Forms.Context, cmdParams, loggerAction);

  We’ve searched for alternatives, but nothing seems obvious. Does anyone know how to resolve this issue or suggest an alternative library/approach (even a paid for one) ?

  EDIT :

  We note a message on the read me read me which states :

  For Android 6.0 onwards, use Xamarin.Android.MP4Transcoder Android 6.0
  onwards, text relocations are strictly prohibited, many source files
  used in ffmpeg use text relocations so ffmpeg will never run on future
  android builds unless they rewrite large library and replace them with
  alternative of text relocations. For this, only alternative is to use
  Android’s native Mp4 transcoder.

  However, we’ve tried using :

   Xamarin.MP4Transcoder.Transcoder.For720pFormat().ConvertAsync
  
   Xamarin.MP4Transcoder.Transcoder.For960x540Format().ConvertAsync

  but this doesn’t solve our requirements for compression.

• avformat/mov : set correct error code in mov_read_custom

  27 novembre 2017, par Pan Bian

  avformat/mov : set correct error code in mov_read_custom
  In function mov_read_custom(), it returns 0 on the path that av_malloc()
  
  returns a NULL pointer. 0 indicates success. An error code should be
  
  assigned to ret.
  Signed-off-by : Pan Bian <bianpan2016@163.com>
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavformat/mov.c