[libcamera-devel] [PATCH v4 2/6] pipeline: raspberrypi: Set the ISP Output1 to 1/4 resolution if unused

[Naushir Patuck]

Hi Laurent,



On Tue, 26 Jan 2021 at 22:53, Laurent Pinchart <
laurent.pinchart at ideasonboard.com> wrote:

> Hi Naush,
>
> Thank you for the patch.
>
> On Tue, Jan 26, 2021 at 04:24:08PM +0000, Naushir Patuck wrote:
> > In preparation for fast colour denoise, set the low resolution ISP
> > output stream (Output1) to a 1/4 resolution of the application requested
> > stream (Output0). This only happens if the application has not requested
> > an additional YUV or RGB stream.
> >
> > We also constrain this 1/4 resolution to at most 1200 pixels in the
> > largest dimension to avoid being too taxing on memory usage and system
> > bandwidth.
> >
> > Also switch the default StreamRole::VideoRecording to YUV420 to allow
> > fast colour denoise to run.
>
> Could you explain why all this is needed ? What happens if an
> application requests the second output with a higher resolution that
> this, will fast colour denoise still work correctly ?
>

Fast colour denoise essentially works by doing some analysis at a 1:4 or
1:1 resolution image when compared with the output image resolution.  It
then applies correction on the output image directly based on this
analysis.  If the application were to require a second output stream that
is not 1:4 or 1:1 in resolution ratio, the colour denoise will silently be
bypassed.  There is another constraint that this analysis image must be in
YUV420 format.  Unfortunately, this is a limitation with our
implementation that we currently have.

Regards,
Naush


>
> > Signed-off-by: Naushir Patuck <naush at raspberrypi.com>
> > Reviewed-by: David Plowman <david.plowman at raspberrypi.com>
> > Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
> > ---
> >  .../pipeline/raspberrypi/raspberrypi.cpp      | 35 ++++++++++++++++++-
> >  1 file changed, 34 insertions(+), 1 deletion(-)
> >
> > diff --git a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > index d9895c779725..fe4c75f09925 100644
> > --- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > +++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > @@ -496,7 +496,7 @@ CameraConfiguration
> *PipelineHandlerRPi::generateConfiguration(Camera *camera,
> >
> >               case StreamRole::VideoRecording:
> >                       fmts = data->isp_[Isp::Output0].dev()->formats();
> > -                     pixelFormat = formats::NV12;
> > +                     pixelFormat = formats::YUV420;
> >                       size = { 1920, 1080 };
> >                       bufferCount = 4;
> >                       outCount++;
> > @@ -608,6 +608,7 @@ int PipelineHandlerRPi::configure(Camera *camera,
> CameraConfiguration *config)
> >        * StreamConfiguration appropriately.
> >        */
> >       V4L2DeviceFormat format;
> > +     bool output1Set = false;
> >       for (unsigned i = 0; i < config->size(); i++) {
> >               StreamConfiguration &cfg = config->at(i);
> >
> > @@ -632,6 +633,9 @@ int PipelineHandlerRPi::configure(Camera *camera,
> CameraConfiguration *config)
> >               format.size = cfg.size;
> >               format.fourcc = fourcc;
> >
> > +             LOG(RPI, Info) << "Setting " << stream->name() << " to a
> resolution of "
> > +                            << format.toString();
> > +
> >               ret = stream->dev()->setFormat(&format);
> >               if (ret)
> >                       return -EINVAL;
> > @@ -645,6 +649,35 @@ int PipelineHandlerRPi::configure(Camera *camera,
> CameraConfiguration *config)
> >
> >               cfg.setStream(stream);
> >               stream->setExternal(true);
> > +
> > +             if (i != maxIndex)
> > +                     output1Set = true;
> > +     }
> > +
> > +     /*
> > +      * If ISP::Output1 stream has not been requested by the
> application, we
> > +      * set it up for internal use now. This second stream will be used
> for
> > +      * fast colour denoise, and must be a quarter resolution of the
> ISP::Output0
> > +      * stream. However, also limit the maximum size to 1200 pixels in
> the
> > +      * larger dimension, just to avoid being wasteful with buffer
> allocations
> > +      * and memory bandwidth.
> > +      */
> > +     if (!output1Set) {
> > +             V4L2DeviceFormat output1Format = format;
> > +             constexpr unsigned int maxDimensions = 1200;
> > +             const Size limit = Size(maxDimensions,
> maxDimensions).boundedToAspectRatio(format.size);
> > +
> > +             output1Format.size = (format.size /
> 2).boundedTo(limit).alignedDownTo(2, 2);
> > +
> > +             LOG(RPI, Info) << "Setting ISP Output1 (internal) to a
> resolution of "
> > +                            << output1Format.toString();
> > +
> > +             ret =
> data->isp_[Isp::Output1].dev()->setFormat(&output1Format);
> > +             if (ret) {
> > +                     LOG(RPI, Error) << "Failed to set format on ISP
> Output1: "
> > +                                     << ret;
> > +                     return -EINVAL;
> > +             }
> >       }
> >
> >       /* ISP statistics output format. */
>
> --
> Regards,
>
> Laurent Pinchart
>
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