[libcamera-devel] [PATCH 0/1] Fake Pipeline Handler

[Cheng-Hao Yang]

On Wed, Oct 12, 2022 at 5:56 PM Kieran Bingham <
kieran.bingham at ideasonboard.com> wrote:

> Quoting Cheng-Hao Yang (2022-10-12 10:42:32)
> > Thanks Kieran for your thoughts!
> >
> > On Wed, Oct 12, 2022 at 5:10 PM Kieran Bingham <
> > kieran.bingham at ideasonboard.com> wrote:
> >
> > > Quoting Harvey Yang via libcamera-devel (2022-10-12 08:59:24)
> > > > This is a POC PATCH of the fake pipeline handler, which should be
> used
> > > > for tests and validating Android adaptor can pass CTS limited mode.
> > > >
> > >
> > > Aha, this is interesting. I've wondered if we should have a
> virtual/fake
> > > camera too, perhaps with our own internal pattern generator.
> > >
> > >
> > This fake pipeline handler actually came from a design in ChromeOS
> > that tried to do some tests (CTS for example) without involving the real
> > cameras, like green frames or providing frames from a prepared video
> file.
> >
> > We also wonder how the fake pipeline handler could help libcamera scale
> > and launch on more real devices.
>
> Is there a reason you couldn't use the VIMC camera?
>  (modprobe vimc is perhaps required)
>
> Though I think I've already seen situations where it would be helpful to
> have a fake camera that produces a test pattern, without requiring
> kernel drivers...
>
>
That's exactly the point. ChromeOS models have different kernel versions.
Tomasz
told me that vimc only works after a specific linux kernel version (5.10?).

It'd be preferred if the fake pipeline handler can be used on all ChromeOS
models.


>
> > > There's lots that could be mocked up, perhaps even as far down as a
> Fake
> > > CameraSensor, and an IPA to support testing of controls too (or perhaps
> > > without an IPA as it could all be internal to the pipeline handler,
> with
> > > no particular imagery).
> > >
> > >
> > Yeah there's a TODO to read a prepared configuration file, which defines
> > the
> > fake cameras and maybe a prepared video file as well. True that I was not
> > sure
> > why an IPA is needed. Maybe some controls can be applied on the output
> > frames
> > (from the video)?
>
> If there's an internal test pattern generator yes. But I don't think we
> should introduce any kind of 'video' decoder.
>
> > There's a lot of commented code in there from the IPU3, so I suspect
> > > that was the source.
> > >
> > > There's https://git.libcamera.org/libcamera/vivid.git/log/ which might
> > > be a 'smaller' pipeline handler to consider as a fake pipeline handler
> > > starting point, or even UVC might be simpler comparable starting point.
> > >
> > >
> > Thanks! Will take a look and update on my next patch.
> >
> >
> > > --
> > > Kieran
> > >
> > >
> > >
> > > > Signed-off-by: Harvey Yang <chenghaoyang at chromium.org>
> > > >
> > > > Harvey Yang (1):
> > > >   Add fake pipeline handler
> > > >
> > > >  meson_options.txt                       |   2 +-
> > > >  src/android/camera_capabilities.cpp     |   1 +
> > > >  src/libcamera/pipeline/fake/fake.cpp    | 518
> ++++++++++++++++++++++++
> > > >  src/libcamera/pipeline/fake/meson.build |   3 +
> > > >  src/libcamera/pipeline_handler.cpp      |   2 +-
> > > >  test/camera/camera_reconfigure.cpp      |   2 +-
> > > >  6 files changed, 525 insertions(+), 3 deletions(-)
> > > >  create mode 100644 src/libcamera/pipeline/fake/fake.cpp
> > > >  create mode 100644 src/libcamera/pipeline/fake/meson.build
> > > >
> > > > --
> > > > 2.38.0.rc1.362.ged0d419d3c-goog
> > > >
> > >
>
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