[gst-devel] live video latency

[ensonic]

hi,

On 12:48:27 pm 23/01/2007 Wim Taymans <wim at fluendo.com> wrote:
> On Mon, 2007-01-22 at 13:40 +1100, Anthony Baxter wrote:
> >  For an upcoming play, I'm taking a live webcam feed, flipping it
> >  and adding an overlay to the image. I've got this working with the
> >  following pipeline:
> >  gst-launch "filesrc location=overlay.png ! pngdec
> >  ! alphacolor  ! videomixer name=mix ! ffmpegcolorspace
> >  ! videoflip method=horizontal-flip ! xvimagesink
> >  v4l2src! ffmpegcolorspace ! mix."
> >
> >  The only problem with this is that there's about a half-second or
> >  so of latency between the live action and what comes out the end
> >  of the pipeline. A much simpler pipeline also exhibits this. Are
> >  there any obvious tricks for reducing the latency?
>
> Set xvimagesink sync=false so that the sink runs ASAP. The rate is
> controlled by v4l2src.
>
> The only element that adds latency in this pipeline is v4l2src. It
> probably uses N internal buffers. There does not seem to be a property
> to reduce N on v4l2src..

v4l2src uses 2 buffers by default. CVS version has a property "queue-size"
to control this.

Stefan

>
> Wim
>
>
> >
> >  Thanks,
> >  Anthony
> >
> --
> Wim Taymans <wim at fluendo.com>
>
>
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