[libcamera-devel] [PATCH v5 2/6] pipeline: raspberrypi: Set the ISP Output1 to 1/4 resolution if unused

[Laurent Pinchart]

Hi Naush,

Thank you for the patch.

On Fri, Jan 29, 2021 at 03:11:50PM +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.
> 
> 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;

Does this mean that the colour denoise can only run when outputting
YUV420 ? Will it be silently disabled otherwise ? You set below the same
pixel format for outputs 0 and 1, if colour denoise can only run when
the format is YUV420, should we skip enabling output 1 if a different
pixel format has been selected, as that would waste resources ?

Actually, now that I think about it, and unless I'm mistaken, the
pipeline handler doesn't allocate and queue buffers for output 1 when
only output 0 is used by the application, so maybe it doesn't waste
resources and it's fine as is ?

>  			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();

Should this be a debug message ? I'd also write

		LOG(RPI, Debug) << "Setting " << stream->name() << " to "
				<< format.toString();

as format.toString() will output both the resolution and pixel format.

> +
>  		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);

You could also write

		constexpr Size maxDimensions(1200, 1200);
		const Size limit = maxDimensions.boundedToAspectRatio(format.size);

Up to you.

> +
> +		output1Format.size = (format.size / 2).boundedTo(limit).alignedDownTo(2, 2);
> +
> +		LOG(RPI, Info) << "Setting ISP Output1 (internal) to a resolution of "
> +			       << output1Format.toString();

Same comment as above.

> +
> +		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