gstreamer

[Otto Fajardo]

Hi Tony,

thanks very much for your reply! I solved the problem and found a couple of
things that can be useful for other users:

1- I am using Windows XP.

2- I didn't manage to property install gstreamer. I fail to import critical
modules. No idea why.

3- Opencv works! The interesting thing is that it needs pygtk module to be
installed.

   In the past I already tried opencv for this purpose and failed. While
trying to install gstreamer I install pygtk, and now it works
fine, both using scikits and opencv itself!!!
   Windows binaries for both opencv and pygtk can be obtained from
Christoph Gohlke webpage, so it's quite easy to install.
   I think you could mention this in your webpage, could be useful for
future users.

4- I found something I think is a but, and I have a suggestion:

   * Bug: the method duration is not working well, it gives strange results
to me. The problem is in video.py line 107. I replace this line by
     return cv.GetCaptureProperty(self.capture,
cv.CV_CAP_PROP_FRAME_COUNT)/cv.GetCaptureProperty(self.capture,
cv.CV_CAP_PROP_FPS)
     and now works fine.

  * Suggestion: implement a method to directly obtain fps from the video.
It's quite easy, will be 2 minutes:
    I added two funtions in video.py, one in classs CvVideo:
    def fps(self):

    return cv.GetCaptureProperty(self.capture, cv.CV_CAP_PROP_FPS)

    and another in class Video:

    def fps(self):

    return self.video.fps()



   I think this is useful.



Cheers!




2012/7/12 Tony Yu <tsyu80 at gmail.com>

> Hi Otto,
>
> See response below.
>
>  On Wed, Jul 11, 2012 at 5:14 AM, Otto <otto.fajardob at gmail.com> wrote:
>
>> Hi,
>> I would like to try the Video function in skimage.io. I installed
>> gstreamer, toghether with gstreamer sdk providing the python bindings.
>> So, when I say import pygst from python console, it does not complain.
>> However, trying to use the Video function like this:
>>
>> myvideo = skio.Video(source=source,backend='gstreamer')
>>
>> gives this error message:
>>
>>
> <snip>
>
>
>>     raise ImportError("GStreamer Python bindings 0.10+ required")
>> ImportError: GStreamer Python bindings 0.10+ required
>>
>> So: how to install properly these python bindings for gstreamer???
>>
>
> What system are you running and how did you install GStreamer?
>
> I don't actually have GStreamer installed, so my usefulness here is
> limited. Looking at the code though, I'm not sure it's actually failing on
> the version check (which I think raises an Assertion error, but the caught
> exception is an ImportError).
>
> Could you try running the following imports:
>
> import gst
> import gobject
> from gst.extend.discoverer import Discoverer
>
>
>
>>
>> By the way: Is this module appropiate to open a video file, let's say
>> an avi file, that is compressed using for example with XViD, and then
>> retrieve single frames as numpy arrays?
>>
>> thanks!
>
>
> If GStreamer can read it, then the video plugin should be able to as well.
> Yes, you can access a frame with the video's `get` method (which returns a
> numpy array).
>
> You can also use the video functionality by using OpenCV as a backend (but
> that could be difficult to install, depending on your system).
>
> Cheers,
> -Tony
>
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