Raspberry pi Video Capture freezes while writing to video - python-2.7

Question

I am trying to display the webcam stream as well as write the video to a file simultaneously.But while am writing, it freezes the live stream. The problem is that OpenCV uses a loop to record video,the program gets stuck in the OpenCV loop and the user is unable to continue.It doesn't listen for user response. How can i simultaneously record video and listen for user responses?
code iam using :
import wx
import vlc
import os
import user
import numpy as np
import time
import cv, cv2
class MainWindow(wx.Panel):
def __init__(self, parent,capture):
wx.Panel.__init__(self, parent)
mainSizer = wx.BoxSizer(wx.VERTICAL)
# video
videoWarper = wx.StaticBox(self,size=(640,480)
videoBoxSizer = wx.StaticBoxSizer(videoWarper, wx.VERTICAL)
videoFrame = wx.Panel(self, -1,size=(640,480))
capture = ShowCapture(videoFrame, capture)
videoBoxSizer.Add(videoFrame,0)
mainSizer.Add(videoBoxSizer,0)
parent.Centre()
self.Show()
self.SetSizerAndFit(mainSizer)
# Panels
# The first panel holds the video and it's all black
self.videopanel = wx.Panel(self, -1)
self.videopanel.SetBackgroundColour(wx.BLACK)
# The second panel holds controls
ctrlpanel = wx.Panel(self, -1 )
self.timeslider = wx.Slider(ctrlpanel, -1, 0, 0, 1000)
self.timeslider.SetRange(0, 1000)
record = wx.Button(ctrlpanel, label="Record")
end = wx.Button(ctrlpanel, label="End")
# Bind controls to events
self.Bind(wx.EVT_BUTTON, self.OnRecord, record)
self.Bind(wx.EVT_BUTTON, self.OnEnd, end)
# Give a pretty layout to the controls
ctrlbox = wx.BoxSizer(wx.VERTICAL)
box = wx.BoxSizer(wx.HORIZONTAL)
# box contains some buttons and the volume controls
box.Add(record)
box.Add(end)
# Merge box to the ctrlsizer
ctrlbox.Add(box, flag=wx.EXPAND, border=10)
ctrlpanel.SetSizer(ctrlbox)
# Put everything togheter
sizer = wx.BoxSizer(wx.VERTICAL)
sizer.Add(ctrlpanel, flag=wx.EXPAND | wx.BOTTOM | wx.TOP, border=10)
self.SetSizer(sizer)
self.SetMinSize((350, 300))
# VLC player controls
self.Instance = vlc.Instance()
self.player = self.Instance.media_player_new()
def OnRecord(self, evt):
fourcc = cv2.cv.CV_FOURCC('D', 'I', 'V', 'X')
out = cv2.VideoWriter('video.avi', fourcc, 8.0, (640, 480))
counter = 0
while counter < 1:
ret,frame = capture.read()
out.write(frame)
def OnEnd(self, evt):
out = cv2.VideoWriter('video.avi', fourcc, 8.0, (640, 480))
out.release()
cv2.destroyAllWindows()
class ShowCapture(wx.Panel):
def __init__(self, parent, capture, fps=8):
wx.Panel.__init__(self, parent, wx.ID_ANY, (0,0), (640,480))
self.capture = capture
ret, frame = capture.read()
height, width = frame.shape[:2]
parent.SetSize((width, height))
frame = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
self.bmp = wx.BitmapFromBuffer(width, height, frame)
self.timer = wx.Timer(self)
self.timer.Start(1000./fps)
self.Bind(wx.EVT_PAINT, self.OnPaint)
self.Bind(wx.EVT_TIMER, self.NextFrame)
def OnPaint(self, evt):
dc = wx.BufferedPaintDC(self)
dc.DrawBitmap(self.bmp, 0, 0)
def NextFrame(self, event):
ret, frame = self.capture.read()
if ret:
frame = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
self.bmp.CopyFromBuffer(frame)
self.Refresh()
capture = cv2.VideoCapture(-1)
app = wx.App(False)
frame = wx.Frame(None, title='CamGUI')
panel = MainWindow(frame, capture)
frame.Show()
app.MainLoop()
Does raspberry pi capable of Read/write the video parallely or it hurts the performance of pi?
Hope for experts advice :)

Answer 1

Add a timer, that will allow you to test for input and other changes during the execution of the application.
wx.timer