uvch264src: Only broken examples

Mark Scudder mark at markscudder.com
Sat Feb 22 20:28:33 PST 2014

Hello. New gstreamer user. Latest version compiled from source on a new Linux Mint 16 install. 

All I'm trying to do at the moment is save video and audio to disk from a Logitech c920. Nothing fancy, just what the bundled Windows app would do. I'll get fancy with it later. However, I can only find examples that don't work. 

Here's one, for instance, in fact the only reasonably close documentation I can find on how to even get started: http://oz9aec.net/index.php/gstreamer/487-using-the-logitech-c920-webcam-with-gstreamer-12

I have a c920, I'm using gstreamer 1.2, so far so good. I paste the first example into a terminal. It says I should get two windows on screen, the low res viewfinder and a high quality 720p image as well. 

When I run this pipeline only the small window appears, showing me one frozen frame, but no video. A bunch of stuff comes up in the terminal window, but no errors. 

When I try to run the second example the same thing happens. 

The v4l2src example works, but if I change xvimagesink to filesink (ignoring for the moment that I don't have a viewfinder), the recorded video plays back at double speed. 

I guess I have two questions; first, somebody has to have made this work with the uvch264src plugin, otherwise why write it? And secondly, if the syntax of gstreamer has to be so complex, why have I not found more than a few examples out there of pipelines that actually work? Where's the definitive, rock-solid, working solution to saving the h264 stream from the c920 to disk? I feel like the driver should do it without me having to learn the magic words. If the driver is designed to take h264 video off a camera and send it to an imagesink or filesink, shouldn't it do that by default?

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