Python and webcam capture delay?
timr at probo.com
Mon Jul 6 02:36:11 CEST 2009
"jack catcher (nick)" <nomail at thank.you> wrote:
>I'm thinking of using Python for capturing and showing live webcam
>stream simultaneously between two computers via local area network.
>Operating system is Windows. I'm going to begin with VideoCapture
>extension, no ideas about other implementation yet. Do you have any
>suggestions on how short delay I should hope to achieve in showing the
>video? This would be part of a psychological experiment, so I would need
>to deliver the video stream with a reasonable delay (say, below 100ms).
You need to do the math on this. Remember that a full 640x480 RGB stream
at 30 frames per second runs 28 megabytes per second. That's more than
twice what a 100 megabit network can pump.
You can probably use Python to oversee this, but you might want to consider
using lower-level code to control the actual hardware. If you are
targeting Windows, for example, you could write a DirectShow graph to pump
into a renderer that transmits out to a network, then another graph to
receive from the network and display it.
You can manage the network latency by adding a delays in the local graph.
Tim Roberts, timr at probo.com
Providenza & Boekelheide, Inc.
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