[libcamera-devel] [PATCH 14/16] android: capabilities: Cap frame rate to 30 FPS

[paul.elder at ideasonboard.com]

Hi Jacopo,

On Fri, Aug 27, 2021 at 02:07:55PM +0200, Jacopo Mondi wrote:
> Limit the reported minumum frame duration to 30 FPS.
> 
> The reason to do is to bring the libcamra HAL in par with the Intel
> HAL implementation on IPU3 platform, where 30FPS is the frame rate used
> to perform quality tuning in the closed-source IPA module and has been
> validated as the most efficient rate for the power/performace budget.
> 
> This change bring into the HAL a platform specific constraints, which
> might be opportune for most platforms but should rather be configurable
> by system integrators. Record that with a \todo entry.
> 
> Also record that, even if we report a lower frame rate, we currently
> do not limit what the camera actually produce.
> 
> Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>

It looks like this patch is reverted in the next patch...?


Paul

> ---
>  src/android/camera_capabilities.cpp | 23 +++++++++++++++++++++++
>  1 file changed, 23 insertions(+)
> 
> diff --git a/src/android/camera_capabilities.cpp b/src/android/camera_capabilities.cpp
> index 01cdbcf1395d..6890bfecab29 100644
> --- a/src/android/camera_capabilities.cpp
> +++ b/src/android/camera_capabilities.cpp
> @@ -632,6 +632,29 @@ int CameraCapabilities::initializeStreamConfigurations()
>  
>  			int64_t minFrameDuration = frameDurations->second.min().get<int64_t>() * 1000;
>  			int64_t maxFrameDuration = frameDurations->second.max().get<int64_t>() * 1000;
> +
> +			/*
> +			 * Cap min frame duration to 30 FPS.
> +			 *
> +			 * 30 frames per second has been validated as the most
> +			 * opportune frame rate for quality tuning, and power
> +			 * vs performances budget on Intel IPU3.
> +			 *
> +			 * \todo This is a platform-specific decision that needs
> +			 * to be abstracted and delegated to the configuration
> +			 * file.
> +			 *
> +			 * \todo libcamera only allows to control frame duration
> +			 * through the per-request controls::FrameDuration
> +			 * control. If we cap the durations here, we should be
> +			 * capable of configuring the camera to operate at such
> +			 * duration without requiring to have the FrameDuration
> +			 * control to be specified for each Request. Defer this
> +			 * to the in-development configuration API rework.
> +			 */
> +			if (minFrameDuration < 1e9 / 30.0)
> +				minFrameDuration = 1e9 / 30.0;
> +
>  			streamConfigurations_.push_back({
>  				res, androidFormat, minFrameDuration, maxFrameDuration,
>  			});
> -- 
> 2.32.0
>