[libcamera-devel] [RFC PATCH] android: Do not cap those minFrameDuration nearabout 30fps

[Umang Jain]

We have some stream resolution which can provide slightly better
frame duration than what we cap (i.e. 1/30 fps). The problem with
this is CTS complains if the camera goes faster during the test
than minFrameDuration reported for that stream. For instance,

1080p minFrameDuration:
	- Nautilus : 33282000
	- Soraka   : 33147000

Both are less than capped minFrameDuration (3333333).

This patch considers this situation and doesn't cap the
minFrameDuration if the hardware can provide frame durations slightly
better. The delta considered is 1% only from the cap.

Signed-off-by: Umang Jain <umang.jain at ideasonboard.com>
---
On LIMITED level - no regressions were found : 230/231 pass rate

On FULL level - this fixes the test:
android.hardware.camera2.cts.SurfaceViewPreviewTest#testPreviewFpsRange
---
 src/android/camera_capabilities.cpp | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/src/android/camera_capabilities.cpp b/src/android/camera_capabilities.cpp
index 3e566755..6421456a 100644
--- a/src/android/camera_capabilities.cpp
+++ b/src/android/camera_capabilities.cpp
@@ -810,8 +810,17 @@ int CameraCapabilities::initializeStreamConfigurations()
 			 * 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;
+			int64_t capMinFrameDuration = 1e9 / 30.0;
+			if (minFrameDuration < capMinFrameDuration) {
+				float delta = (capMinFrameDuration - minFrameDuration) * 100 / capMinFrameDuration;
+
+				/*
+				 * If the delta is less than 1%, do not cap the
+				 * frame duration.
+				 */
+				if (delta > 0.01)
+					minFrameDuration = capMinFrameDuration;
+			}
 
 			streamConfigurations_.push_back({
 				res, androidFormat, minFrameDuration, maxFrameDuration,
-- 
2.31.0