[libcamera-devel] [PATCH 9/9] android: Elevate min duration to 30 FPS if it's lower within 2%

[Laurent Pinchart]

Hi Han-Lin,

Thank you for the patch.

I'm CC'ing Jacopo and Umang as they've both spent a large amount of time
solving issues related to frame durations.

On Wed, Feb 09, 2022 at 03:19:17PM +0800, Han-Lin Chen wrote:
> It's notice that Chrome Camera App filters out the resolutions which cannot
> achieve 30 FPS. Elevate the minimum frame duration to 30 FPS if FPS is lower
> within 2%.

Unless I'm mistaken this patch doesn't depend on the rest of the series,
so we can review and merge it separately.

> Signed-off-by: Han-Lin Chen <hanlinchen at chromium.org>
> ---
>  src/android/camera_capabilities.cpp | 31 +++++++++++++++++++----------
>  1 file changed, 20 insertions(+), 11 deletions(-)
> 
> diff --git a/src/android/camera_capabilities.cpp b/src/android/camera_capabilities.cpp
> index 55d651f3..e10ab036 100644
> --- a/src/android/camera_capabilities.cpp
> +++ b/src/android/camera_capabilities.cpp
> @@ -655,7 +655,9 @@ int CameraCapabilities::initializeStreamConfigurations()
>  			int64_t maxFrameDuration = frameDurations->second.max().get<int64_t>() * 1000;
>  
>  			/*
> -			 * Cap min frame duration to 30 FPS with 1% tolerance.
> +			 * Cap min frame duration to 30 FPS with 1% tolerance,
> +			 * and elevate min frame duration to 30 FPS with 2%
> +			 * tolerance.
>  			 *
>  			 * 30 frames per second has been validated as the most
>  			 * opportune frame rate for quality tuning, and power
> @@ -675,17 +677,24 @@ int CameraCapabilities::initializeStreamConfigurations()
>  			 * to the in-development configuration API rework.
>  			 */
>  			int64_t minFrameDurationCap = 1e9 / 30.0;
> -			if (minFrameDuration < minFrameDurationCap) {
> -				float tolerance =
> -					(minFrameDurationCap - minFrameDuration) * 100.0 / minFrameDurationCap;
> +			float tolerance =
> +				(minFrameDurationCap - minFrameDuration) * 100.0 / minFrameDurationCap;
>  
> -				/*
> -				 * If the tolerance is less than 1%, do not cap
> -				 * the frame duration.
> -				 */
> -				if (tolerance > 1.0)
> -					minFrameDuration = minFrameDurationCap;
> -			}
> +			/*
> +			 * If the tolerance is less than 1%, do not cap
> +			 * the frame duration.
> +			 */
> +			if (tolerance > 1.0)
> +				minFrameDuration = minFrameDurationCap;
> +
> +			/*
> +			 * Some applications, ex: Chrome Camera App filters out
> +			 * the resolutions which cannot achieve 30 FPS. Elevate
> +			 * the minimum frame duration to 30 FPS if FPS is lower
> +			 * within 2%.
> +			 */
> +			if (tolerance < 0 && tolerance > -2.0)
> +				minFrameDuration = minFrameDurationCap;
>  
>  			streamConfigurations_.push_back({
>  				res, androidFormat, minFrameDuration, maxFrameDuration,

-- 
Regards,

Laurent Pinchart