iq: Add ae-delay and ae-interval parameters

The ae-delay parameter selects the number of frames to skip at stream
startup before running the auto exposure algorithm. The ae-interval
selects the number of frames between AE runs. This can be used to delay
AE when the sensor needs one or more frames to apply exposure and/or
gain values.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

4 files changed, 27 insertions, 3 deletions

diff --git a/iq.c b/iq.c
index efc00c2..8230d09 100644
--- a/iq.c
+++ b/iq.c
@@ -61,8 +61,17 @@ void iq_aewb_process(struct iq_tuning *iq,
 
 	omap3_isp_preview_set_white_balance(iq->isp, gains);
 
-	/* Automatic Exposure */
-	if ((iq->frame_count++ % 2) == 0)
+	/* Automatic Exposure
+	 *
+	 * Skip ae_delay frames at stream startup, and only run AE every
+	 * ae_interval frames to take sensor exposure internal delays into
+	 * account.
+	 */
+	iq->frame_count++;
+	if (iq->frame_count <= iqp->ae_delay)
+		return;
+
+	if ((iq->frame_count - iqp->ae_delay - 1) % iqp->ae_interval)
 		return;
 
 	mean = stats->accum[0] + stats->accum[1]
@@ -97,6 +106,8 @@ void iq_params_init(struct iq_params *params)
 	params->window.top = 0.0;
 	params->window.width = 1.0;
 	params->window.height = 1.0;
+	params->ae_delay = 1;
+	params->ae_interval = 2;
 	params->mean_level = 0.15;
 	params->exposure = 1000;
 	params->exposure_min = 10;
@@ -137,7 +148,11 @@ int iq_params_parse(struct iq_params *params, const char *arg)
 	size = value - arg;
 	value++;
 
-	if (strncmp(arg, "exposure-def", size) == 0)
+	if (strncmp(arg, "ae-delay", size) == 0)
+		val_uint = &params->ae_delay;
+	else if (strncmp(arg, "ae-interval", size) == 0)
+		val_uint = &params->ae_interval;
+	else if (strncmp(arg, "exposure-def", size) == 0)
 		val_uint = &params->exposure;
 	else if (strncmp(arg, "exposure-min", size) == 0)
 		val_uint = &params->exposure_min;
diff --git a/iq.h b/iq.h
index a5c5028..74be0a2 100644
--- a/iq.h
+++ b/iq.h
@@ -30,6 +30,8 @@ struct omap3_isp_aewb_stats;
 /**
  * struct iq_params - Image quality tuning parameters
  * @window: Statistics computation window (fraction of the image size)
+ * @ae_delay: Number of frames to skip at stream start before enabling AE
+ * @ae_interval: Number of frames between AE algorithm runs
  * @mean_level: Target mean luminance level (fraction of the maximum)
  * @exposure: Initial exposure value (sensor-specific units)
  * @exposure_min: Minimum exposure value
@@ -47,6 +49,9 @@ struct iq_params {
 		float height;
 	} window;
 
+	unsigned int ae_delay;
+	unsigned int ae_interval;
+
 	float mean_level;
 
 	unsigned int exposure;
diff --git a/live.c b/live.c
index cc7d02d..75f62ba 100644
--- a/live.c
+++ b/live.c
@@ -327,6 +327,8 @@ static void usage(const char *argv0)
 	printf("-s, --skip n		Skip display of n frames out of n+1\n");
 	printf("    --aewb param=value	Set AEWB algorithm parameter 'param' to 'value'\n");
 	printf("\nSupported AEWB parameters are:\n");
+ 	printf("- ae-delay		Number of frames to skip at stream start before enabling AE\n");
+	printf("- ae-interval		Number of frames between AE algorithm runs (>= 1)\n");
 	printf("- exposure-def		Exposure time default value\n");
 	printf("- exposure-min		Exposure time minimum value\n");
 	printf("- exposure-max		Exposure time maximum value\n");
diff --git a/snapshot.c b/snapshot.c
index 76df91a..958307e 100644
--- a/snapshot.c
+++ b/snapshot.c
@@ -402,6 +402,8 @@ static void usage(const char *argv0)
 	printf("-v, --view		Enable viewfinder\n");
 	printf("    --aewb param=value	Set AEWB algorithm parameter 'param' to 'value'\n");
 	printf("\nSupported AEWB parameters are:\n");
+ 	printf("- ae-delay		Number of frames to skip at stream start before enabling AE\n");
+	printf("- ae-interval		Number of frames between AE algorithm runs (>= 1)\n");
 	printf("- exposure-def		Exposure time default value\n");
 	printf("- exposure-min		Exposure time minimum value\n");
 	printf("- exposure-max		Exposure time maximum value\n");