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LPC: What's happening with webcamsLPC: What's happening with webcamsPosted Sep 26, 2008 15:18 UTC (Fri) by wingo (subscriber, #26929)Parent article: LPC: What's happening with webcams
The bits about a v4l daemon sound completely crazy. There is no sane use case that I know of that involves transparent access to the web cam from multiple applications.
We've seen this kind of user-space layering in innumerable sound servers, and it always proves to be a more difficult problem that the developers envision.
I say this as one who has worked a lot with v4l integration in gstreamer, both v1 and v2, and as a former hacker on Flumotion.
I might be wrong, but my instinct is that talk of v4l daemons indicates we have reached the point where entropy takes over from marginal returns.
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LPC: What's happening with webcams Posted Sep 26, 2008 18:01 UTC (Fri) by tmassey (guest, #52228) [Link]
They mentioned right in the article a case where this is necessary: Autofocus.
A userspace daemon is being used to focus the camera by analyzing the output from the webcam. I assume that you want some *other* application to have access to the stream *beside* the autofocus daemon?
They also mentioned another one: being able to use one program to take a snapshot of a video stream while another is displaying the feed. While you could expect every app that wants to have access to the video to make their own captures, why not just have a second application do it once and be done with it?
LPC: What's happening with webcams Posted Oct 2, 2008 17:50 UTC (Thu) by smurf (subscriber, #17840) [Link]
Yes there are usecases for simultaneous access.
Program A archives periodic cam snapshots.
Program B does motion analysis.
Program C provides a high-quality stream for the internal LAN.
Program D provides a low-quality stream for Internet access.
Program E does the aforementioned autofocus, auto-brightness, and/or whatever.
Program F monitors that the stream exists, and raises bloody hell if somebody disconnects the camera.
Program G ... you get the idea.
Requiring that all of this be packaged in one single application which does all of it perfectly is (a) unrealistic and (b) not The Unix Way.
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