On Thu January 24 2013 16:59:36 forum::für::umläute wrote: > hi all, > > i'm currently maintainer of the "v4l2loopback" device [1], a virtual > video device that allows applications to share video-streams via the > v4l2 API (each device being V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_VIDEO_OUTPUT). > > now (unfortunately for someone maintaining a driver) i have not been > following development of the linux-kernel very closely (mainly using > debian unstable kernels myself), but some of my users do. > it seems that with newer kernel-versions the functionality for > video-output modules have been somehow removed from the kernel (3.7.1 > has been confirmed to make troubles, whereas 3.6.10 still works). > > i'd like to inquire, what happened in/to the mainstream kernel, and > what's the supposed way to proceed for a virtual video device like mine. > (i naively ask the question here, as i'm a bit afraid of kernel-dev > mailing list :-)) In 3.7 the vfl_dir field was added to struct video_device. For output devices this has to be set to VFL_DIR_TX. For devices that do both capture and output it has to be set to VFL_DIR_M2M (memory-to-memory). Otherwise the v4l2 core will assume that it is a capture device and disable any output support. > > what's more, if the v4l2-taskforce would be interested to take over a > kernel-module that - to my knowledge - is currently the only feasible > way on linux to exchange live video streams between applications, we > might talk about that :-) Personally I am all for that, but I know Mauro has (had?) reservations about it. Looking at the code it would also be a fair amount of work to get it ready for inclusion in the kernel. Frankly, I wonder if much of the functionality isn't already part of the mem2mem_testdev driver. Regards, Hans -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
