96 lines
2.5 KiB
Python
96 lines
2.5 KiB
Python
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# Live video input class.
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# Note that importing this module attempts to initialize video.
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# Check if video is available.
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# There are three reasons for failure here:
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# (1) this version of Python may not have the sv or imageop modules;
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# (2) this machine may not have a video board;
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# (3) initializing the video board may fail for another reason.
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# The global variable have_video is set to true iff we reall do have video.
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try:
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import sv
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import SV
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import imageop
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try:
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v = sv.OpenVideo()
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have_video = 1
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except sv.error:
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have_video = 0
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except ImportError:
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have_video = 0
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# The live video input class.
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# Only instantiate this if have_video is true!
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class LiveVideoIn:
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# Initialize an instance.
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# Parameters:
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# - vw, vh specify the size of the video window.
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# This initializes continuous capture.
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def init(self, pktmax, vw, vh):
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if not have_video:
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raise RuntimeError, 'no video available'
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realvw = vh*SV.PAL_XMAX/SV.PAL_YMAX
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if realvw < vw:
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print 'Funny, image too narrow...'
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self.realwidth, self.realheight = v.QuerySize(realvw, vh)
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##print 'Recording video in size', \
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## self.realwidth, self.realheight
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self.width = vw
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self.height = vh
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self.x0 = (self.realwidth-self.width)/2
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self.x1 = self.x0 + self.width - 1
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self.y0 = (self.realheight-self.height)/2
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self.y1 = self.y0 + self.height - 1
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# Compute # full lines per packet
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self.lpp = pktmax / self.width
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self.pktsize = self.lpp*self.width
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##print 'lpp =', self.lpp, '; pktsize =', self.pktsize
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# Initialize capture
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v.SetSize(self.realwidth, self.realheight)
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dummy = v.InitContinuousCapture(SV.RGB8_FRAMES, \
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self.realwidth, self.realheight, 2, 5)
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self.data = None
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self.lpos = 0
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return self
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# Remove an instance.
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# This turns off continuous capture.
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def close(self):
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v.EndContinuousCapture()
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# Get the next video packet.
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# This returns (lpos, data) where:
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# - lpos is the line position
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# - data is a piece of data
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# The dimensions of data are:
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# - pixel depth = 1 byte
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# - scan line width = self.width (the vw argument to init())
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# - number of scan lines = self.lpp (PKTMAX / vw)
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def getnextpacket(self):
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if not self.data:
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try:
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cd, id = v.GetCaptureData()
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except sv.error:
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return None
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data = cd.InterleaveFields(1)
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cd.UnlockCaptureData()
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self.data = imageop.crop(data, 1, \
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self.realwidth, \
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self.realheight, \
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self.x0, self.y0, \
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self.x1, self.y1)
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self.lpos = 0
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data = self.data[:self.pktsize]
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self.data = self.data[self.pktsize:]
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lpos = self.lpos
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self.lpos = self.lpos + self.lpp
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return lpos, data
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