On Tue, Feb 03, 2026 at 11:11:19PM +0200, Jarkko Sakkinen wrote: > On Tue, Feb 03, 2026 at 10:57:42PM +0200, Laurent Pinchart wrote: > > On Tue, Feb 03, 2026 at 03:36:59AM +0200, Jarkko Sakkinen wrote: > > > On Tue, Feb 03, 2026 at 02:10:15AM +0200, Jarkko Sakkinen wrote: > > > > On Tue, Feb 03, 2026 at 12:50:06AM +0200, Sakari Ailus wrote: > > > > > On Mon, Feb 02, 2026 at 10:44:21PM +0200, Jarkko Sakkinen wrote: > > > > > > Already a quick Google survey backs strongly that OOT drivers (e.g., > > > > > > v4l2loopback) are the defacto solution for streaming phone cameras > > > > > > in > > > > > > video conference calls, which puts confidential discussions at risk. > > > > > > > > > > As I think it was pointed out in review comments for v1, the reason > > > > > behind > > > > > using v4l2loopback is the use of a downstream driver, which itself is > > > > > a > > > > > source of a security risk. If I understand correctly, supporting this > > > > > (proprietary/downstream vendor drivers) would be the main use case > > > > > this > > > > > driver serves? Should this downstream driver be upstreamed to > > > > > alleviate the > > > > > security risks, the need for v4l2loopback or similar drivers > > > > > presumably > > > > > disappears. > > > > > > > > My goal is not to proactively support proprietary drivers, and I don't > > > > know how to measure such incentive or risk, when it comes to video > > > > drivers. > > > > > > > > And besides there is e.g. FUSE. > > > > > > > > > Another of the downsides of such proprietary/downstream solutions is > > > > > they > > > > > can never be properly integrated into the Linux ecosystem so > > > > > functionality > > > > > will remain spotty (limited to specific systems and specific releases > > > > > of > > > > > specific distributions) at best. > > > > > > > > > > In other words, this driver appears to be orthogonal to solving > > > > > either of > > > > > the above two problems the proprietary/downstream solutions have. > > > > > > > > > > From the Open Source libcamera based camera software stack point of > > > > > view > > > > > there doesn't seem to be a need for v4l2loopback or another similar > > > > > driver. > > > > > The two main reasons for this is that (1) there's no need for glueing > > > > > something separate together like this and (2) V4L2 isn't a great > > > > > application interface for cameras -- use libcamera or Pipewire > > > > > instead. > > > > > > > > While I get this argument isolated, it does not match the observed > > > > reality, and does not provide tools to address the core issue. I > > > > will be in my grave before I've fixed the world like you are > > > > suggesting :-) > > > > I really hope we'll provide a solution much faster than that :-) > > > > > > Like, first off, where would I use libcamera or Pipewire? There's > > > > no well-defined target other than kernel in this problem. > > > > PipeWire is becoming the de facto media server on desktop systems, for > > both audio and video. It has been shipped by distributions for a while > > for audio, and is the core component that allows screen capture (and > > therefore screen sharing in video conferencing) on Wayland-based > > systems. For video, PipeWire support has most notably been integrated in > > WebRTC, used by both Firefox and Chrome. The number of applications > > using PipeWire is growing, OBS has recently received support for > > PipeWire sources for instance. If you need to use it in an application > > that requires a V4L2 capture device, the pw-v4l2 script emulates the > > V4L2 API to provide a quick stopgap measure until applications get > > native PipeWire support. > > > > libcamera solves an orthogonal problem, which is control of raw camera > > sensors and ISPs typically found in mobile and embedded devices, and now > > increasingly in laptops as well (Intel IPU3, IPU4, IPU6 and IPU7). > > Applications typically don't use libcamera directly, but interface it > > with GStreamer (libcamerasrc element) or PipeWire (which has native > > libcamera support). > > > > While I understand that libcamera and PipeWire may be quite new for a > > large number of users, the ecosystem is moving in that direction, and > > both projects are very active. > > Thanks for the information and I take this into account when/if considering > any updates. The response is so informative that I need to purge this a > bit (thank you for that) :-) This does not disregard your response but > personally I'm not have huge a fan of LD_PRELOAD style compatibility > wrappers.
I'm not either as it can only provide best-effort compatibility, but it has proven to be useful. For instance, we successfully tested the libcamera LD_PRELOAD v4l2-compat.so with Firefox before support for PipeWire was ready in WebRTC, providing a way to use ISPs in video conferencing as a stopgap measure. It's all about helping the ecosystem with the transition, and not intended as a long-term solution. -- Regards, Laurent Pinchart
