[gst-devel] live video latency

[Wim Taymans]

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..

Wim


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