[SciPy-User] ANN: imageio v1.1

Almar Klein almar.klein at gmail.com
Sat Feb 7 11:20:17 EST 2015


> At least on linux it is definitively possible to set the fps via ffmpeg.
> The following command works fine on my computer:
> hkt at HP-Z200:~/.imageio/ffmpeg$ ./ffmpeg.linux64 -f v4l2 *-framerate 25*
> -video_size 640x480 -i /dev/video0 output.mkv

Great! Do you feel like submitting a pull request for this? Should be a 
relatively easy one. The code should be somewhere in 
imageio/plugins/ffmpeg.py.

Otherwise I can do it up when I have a chance.

- Almar

>
> I found the information at https://trac.ffmpeg.org/wiki/Capture/Webcam.
> It looks like it should work on windows too. But, I'm less certain about
> OS X.
>
> Best regards,
> Hjalmar
>
>
> On Thu, Feb 5, 2015 at 6:33 PM, Almar Klein <almar.klein at gmail.com
> <mailto:almar.klein at gmail.com>> wrote:
>
>     Hi Hjalmar,
>
>     Currently, there is no way to set fps for the webcam directly. You can
>     set the size though, which is likely to affect the fps (smaller size ->
>     higher fps. Just add e.g. ``size='768x576'`` to the arguments. Similarly
>     you can set the pixelformat. See
>     http://imageio.readthedocs.org/en/latest/format_ffmpeg.html
>
>     I am not sure if setting fps directly is possible via ffmepg. You could
>     look into it. I welcome a PR :)
>
>     - Almar
>
>
>     On 05-02-15 17:54, Hjalmar Turesson wrote:
>     > Hi,
>     >
>     > It looks and works beautifully.
>     > But... is there a way of setting the frame rate for webcams? I see that
>     > one can set fps for a writer, but I cannot find a way to set fps for a
>     > reader. And when using a webcam it makes sense to be able to control the
>     > fps.
>     >
>     > Thanks a lot!
>     > Hjalmar
>     >
>     > On Thu, Feb 5, 2015 at 6:40 AM, Christophe Bal <projetmbc at gmail.com <mailto:projetmbc at gmail.com>
>     > <mailto:projetmbc at gmail.com <mailto:projetmbc at gmail.com>>> wrote:
>     >
>     >     That's a very good point so I will play with your library which has
>     >     a so easy to use interface (I really like the way to walk through
>     >     the frames of video).
>     >
>     >     Thanks a lot for your answers !
>     >
>     >
>     >     *Christophe BAL*
>     >     *Enseignant de mathématiques en Lycée **et développeur Python amateur*
>     >     *---*
>     >     *French math teacher in a "Lycée" **and **Python **amateur developer*
>     >
>     >     2015-02-05 10:37 GMT+01:00 Almar Klein <almar.klein at gmail.com <mailto:almar.klein at gmail.com>
>      >     <mailto:almar.klein at gmail.com <mailto:almar.klein at gmail.com>>>:
>     >
>     >         > Working with pictures can be slow with Python so I would like to know if
>     >         > imageio is a fast, or a slow package, or a medium one ?
>     >
>     >         Imageio only reads and writes images. It does that pretty fast. E.g.
>     >         png/jpg and other common formats are handled via the FreeImage
>     >         library.
>     >         Video via ffmpeg.
>     >
>     >         When reading an image it yields a numpy array. For processing
>     >         the data,
>     >         you need to use other tools, e.g. scikit-image.
>     >
>     >         - Almar
>     >
>     >
>     >
>     >         >
>     >         > *Christophe BAL*
>     >         > *Enseignant de mathématiques en Lycée **et développeur Python amateur*
>     >         > *---*
>     >         > *French math teacher in a "Lycée" **and **Python **amateur developer*
>     >         >
>     >         > 2015-02-05 10:29 GMT+01:00 Almar Klein <almar.klein at gmail.com <mailto:almar.klein at gmail.com>
>     <mailto:almar.klein at gmail.com <mailto:almar.klein at gmail.com>>
>      >          > <mailto:almar.klein at gmail.com
>     <mailto:almar.klein at gmail.com> <mailto:almar.klein at gmail.com
>     <mailto:almar.klein at gmail.com>>>>:
>     >         >
>     >         >
>     >         >     > This looks nice. Is there some perfomance issue ?
>     >         >
>     >         >     How do you mean?
>     >         >
>     >         >     - Almar
>     >         >
>     >         >
>     >         >      >
>     >         >      >
>     >         >      > *Christophe BAL*
>     >         >      > *Enseignant de mathématiques en Lycée **et développeur Python
>     >         >     amateur*
>     >         >      > *---*
>     >         >      > *French math teacher in a "Lycée" **and **Python **amateur developer*
>     >         >     >
>     >         >     > 2015-02-05 9:34 GMT+01:00 Philipp A. <flying-sheep at web.de <mailto:flying-sheep at web.de>
>     <mailto:flying-sheep at web.de <mailto:flying-sheep at web.de>>
>     >         <mailto:flying-sheep at web.de <mailto:flying-sheep at web.de>
>     <mailto:flying-sheep at web.de <mailto:flying-sheep at web.de>>>
>     >          >      > <mailto:flying-sheep at web.de <mailto:flying-sheep at web.de>
>     >         <mailto:flying-sheep at web.de <mailto:flying-sheep at web.de>>
>     <mailto:flying-sheep at web.de <mailto:flying-sheep at web.de>
>     >         <mailto:flying-sheep at web.de <mailto:flying-sheep at web.de>>>>>:
>     >         >     >
>     >         >     >     this really fills a niche well. good job!
>     >         >     >
>     >         >      >     Almar Klein <almar.klein at gmail.com <mailto:almar.klein at gmail.com>
>     <mailto:almar.klein at gmail.com <mailto:almar.klein at gmail.com>>
>     >          >     <mailto:almar.klein at gmail.com <mailto:almar.klein at gmail.com>
>      >         <mailto:almar.klein at gmail.com
>     <mailto:almar.klein at gmail.com>>> <mailto:almar.klein at gmail.com
>     <mailto:almar.klein at gmail.com>
>      >         <mailto:almar.klein at gmail.com <mailto:almar.klein at gmail.com>>
>      >         >     <mailto:almar.klein at gmail.com
>     <mailto:almar.klein at gmail.com> <mailto:almar.klein at gmail.com
>     <mailto:almar.klein at gmail.com>>>>>
>      >         >     >     schrieb am Wed Feb 04 2015 at 15:43:47:
>      >         >     >
>      >         >     >         Imageio is a Python library that provides
>     an easy interface to
>      >         >     >         read and
>      >         >     >         write a wide range of image data,
>     including animated images. video,
>      >         >     >         volumetric data, and scientific formats.
>     It is cross-platform,
>      >         >     >         runs on
>      >         >     >         Python 2.x and 3.x, and is easy to install.
>      >         >     >
>      >         >     >         More information:http://imageio.github.io/
>      >         >     >         Release notes:
>      >         >
>      >http://imageio.readthedocs.__org/en/latest/releasenotes.__html
>      >         >      >
>       <http://imageio.readthedocs.org/en/latest/releasenotes.html>
>      >         >      >
>      >         >      >         Regards,
>      >         >      >             Almar
>      >         >      >
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