[Interest] QProcess performance issues

[Pau Garcia i Quiles]

Hello,

Is OpenCV an option?

http://docs.opencv.org/doc/tutorials/highgui/video-write/video-write.html



On Tue, May 12, 2015 at 8:21 PM, Matthew Woehlke <
mw_triad at users.sourceforge.net> wrote:

> I have an application that generates a series of images (QImage) and
> writes them to disk as a video. I am encoding the video using an
> external FFmpeg process, which I start and communicate with via
> QProcess. I feed this the images via its stdin, using QImage::save to
> write them to the QProcess in BMP format (FFmpeg options '-f image2pipe
> -c:v bmp -i -').
>
> This works fine on Linux. On Windows, it is APPALLINGLY slow; on the
> order of seconds per frame. Also, on Windows, it takes a very long time
> (minutes) before even the initial output from FFmpeg appears. (I'm using
> QProcess::ForwardedChannels, although switching to default and just
> letting the output buffer doesn't seem to make a difference.)
>
> The problem *seems* to be with QProcess; running FFmpeg in a shell seems
> to have reasonable performance. It's almost as if running the process
> through QProcess is causing it to execute extremely slowly.
>
> Has anyone else encountered anything like this, or have any idea what
> might be going wrong?
>
> (Note: This is with Qt 4. Upgrading to Qt 5 is not an option at this time.)
>
> --
> Matthew
>
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>



-- 
Pau Garcia i Quiles
http://www.elpauer.org
(Due to my workload, I may need 10 days to answer)
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