--- /dev/null
+/*
+ * Functions for auto gain.
+ *
+ * Copyright (C) 2010-2012 Hans de Goede <hdegoede@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+#include "gspca.h"
+
+/* auto gain and exposure algorithm based on the knee algorithm described here:
+ http://ytse.tricolour.net/docs/LowLightOptimization.html
+
+ Returns 0 if no changes were made, 1 if the gain and or exposure settings
+ where changed. */
+int gspca_expo_autogain(
+ struct gspca_dev *gspca_dev,
+ int avg_lum,
+ int desired_avg_lum,
+ int deadzone,
+ int gain_knee,
+ int exposure_knee)
+{
+ s32 gain, orig_gain, exposure, orig_exposure;
+ int i, steps, retval = 0;
+
+ if (v4l2_ctrl_g_ctrl(gspca_dev->autogain) == 0)
+ return 0;
+
+ orig_gain = gain = v4l2_ctrl_g_ctrl(gspca_dev->gain);
+ orig_exposure = exposure = v4l2_ctrl_g_ctrl(gspca_dev->exposure);
+
+ /* If we are of a multiple of deadzone, do multiple steps to reach the
+ desired lumination fast (with the risc of a slight overshoot) */
+ steps = abs(desired_avg_lum - avg_lum) / deadzone;
+
+ PDEBUG(D_FRAM, "autogain: lum: %d, desired: %d, steps: %d",
+ avg_lum, desired_avg_lum, steps);
+
+ for (i = 0; i < steps; i++) {
+ if (avg_lum > desired_avg_lum) {
+ if (gain > gain_knee)
+ gain--;
+ else if (exposure > exposure_knee)
+ exposure--;
+ else if (gain > gspca_dev->gain->default_value)
+ gain--;
+ else if (exposure > gspca_dev->exposure->minimum)
+ exposure--;
+ else if (gain > gspca_dev->gain->minimum)
+ gain--;
+ else
+ break;
+ } else {
+ if (gain < gspca_dev->gain->default_value)
+ gain++;
+ else if (exposure < exposure_knee)
+ exposure++;
+ else if (gain < gain_knee)
+ gain++;
+ else if (exposure < gspca_dev->exposure->maximum)
+ exposure++;
+ else if (gain < gspca_dev->gain->maximum)
+ gain++;
+ else
+ break;
+ }
+ }
+
+ if (gain != orig_gain) {
+ v4l2_ctrl_s_ctrl(gspca_dev->gain, gain);
+ retval = 1;
+ }
+ if (exposure != orig_exposure) {
+ v4l2_ctrl_s_ctrl(gspca_dev->exposure, exposure);
+ retval = 1;
+ }
+
+ if (retval)
+ PDEBUG(D_FRAM, "autogain: changed gain: %d, expo: %d",
+ gain, exposure);
+ return retval;
+}
+EXPORT_SYMBOL(gspca_expo_autogain);
+
+/* Autogain + exposure algorithm for cameras with a coarse exposure control
+ (usually this means we can only control the clockdiv to change exposure)
+ As changing the clockdiv so that the fps drops from 30 to 15 fps for
+ example, will lead to a huge exposure change (it effectively doubles),
+ this algorithm normally tries to only adjust the gain (between 40 and
+ 80 %) and if that does not help, only then changes exposure. This leads
+ to a much more stable image then using the knee algorithm which at
+ certain points of the knee graph will only try to adjust exposure,
+ which leads to oscilating as one exposure step is huge.
+
+ Returns 0 if no changes were made, 1 if the gain and or exposure settings
+ where changed. */
+int gspca_coarse_grained_expo_autogain(
+ struct gspca_dev *gspca_dev,
+ int avg_lum,
+ int desired_avg_lum,
+ int deadzone)
+{
+ s32 gain_low, gain_high, gain, orig_gain, exposure, orig_exposure;
+ int steps, retval = 0;
+
+ if (v4l2_ctrl_g_ctrl(gspca_dev->autogain) == 0)
+ return 0;
+
+ orig_gain = gain = v4l2_ctrl_g_ctrl(gspca_dev->gain);
+ orig_exposure = exposure = v4l2_ctrl_g_ctrl(gspca_dev->exposure);
+
+ gain_low = (gspca_dev->gain->maximum - gspca_dev->gain->minimum) /
+ 5 * 2 + gspca_dev->gain->minimum;
+ gain_high = (gspca_dev->gain->maximum - gspca_dev->gain->minimum) /
+ 5 * 4 + gspca_dev->gain->minimum;
+
+ /* If we are of a multiple of deadzone, do multiple steps to reach the
+ desired lumination fast (with the risc of a slight overshoot) */
+ steps = (desired_avg_lum - avg_lum) / deadzone;
+
+ PDEBUG(D_FRAM, "autogain: lum: %d, desired: %d, steps: %d",
+ avg_lum, desired_avg_lum, steps);
+
+ if ((gain + steps) > gain_high &&
+ exposure < gspca_dev->exposure->maximum) {
+ gain = gain_high;
+ gspca_dev->exp_too_low_cnt++;
+ gspca_dev->exp_too_high_cnt = 0;
+ } else if ((gain + steps) < gain_low &&
+ exposure > gspca_dev->exposure->minimum) {
+ gain = gain_low;
+ gspca_dev->exp_too_high_cnt++;
+ gspca_dev->exp_too_low_cnt = 0;
+ } else {
+ gain += steps;
+ if (gain > gspca_dev->gain->maximum)
+ gain = gspca_dev->gain->maximum;
+ else if (gain < gspca_dev->gain->minimum)
+ gain = gspca_dev->gain->minimum;
+ gspca_dev->exp_too_high_cnt = 0;
+ gspca_dev->exp_too_low_cnt = 0;
+ }
+
+ if (gspca_dev->exp_too_high_cnt > 3) {
+ exposure--;
+ gspca_dev->exp_too_high_cnt = 0;
+ } else if (gspca_dev->exp_too_low_cnt > 3) {
+ exposure++;
+ gspca_dev->exp_too_low_cnt = 0;
+ }
+
+ if (gain != orig_gain) {
+ v4l2_ctrl_s_ctrl(gspca_dev->gain, gain);
+ retval = 1;
+ }
+ if (exposure != orig_exposure) {
+ v4l2_ctrl_s_ctrl(gspca_dev->exposure, exposure);
+ retval = 1;
+ }
+
+ if (retval)
+ PDEBUG(D_FRAM, "autogain: changed gain: %d, expo: %d",
+ gain, exposure);
+ return retval;
+}
+EXPORT_SYMBOL(gspca_coarse_grained_expo_autogain);
#include <linux/usb.h>
#include <linux/videodev2.h>
#include <media/v4l2-common.h>
+#include <media/v4l2-ctrls.h>
#include <media/v4l2-device.h>
#include <linux/mutex.h>
unsigned ctrl_dis; /* disabled controls (bit map) */
unsigned ctrl_inac; /* inactive controls (bit map) */
+ /* autogain and exposure or gain control cluster, these are global as
+ the autogain/exposure functions in autogain_functions.c use them */
+ struct {
+ struct v4l2_ctrl *autogain;
+ struct v4l2_ctrl *exposure;
+ struct v4l2_ctrl *gain;
+ int exp_too_low_cnt, exp_too_high_cnt;
+ };
+
#define USB_BUF_SZ 64
__u8 *usb_buf; /* buffer for USB exchanges */
struct urb *urb[MAX_NURBS];
#endif
int gspca_auto_gain_n_exposure(struct gspca_dev *gspca_dev, int avg_lum,
int desired_avg_lum, int deadzone, int gain_knee, int exposure_knee);
+int gspca_expo_autogain(struct gspca_dev *gspca_dev, int avg_lum,
+ int desired_avg_lum, int deadzone, int gain_knee, int exposure_knee);
+int gspca_coarse_grained_expo_autogain(struct gspca_dev *gspca_dev,
+ int avg_lum, int desired_avg_lum, int deadzone);
+
#endif /* GSPCAV2_H */
projects / ~andy / linux / commitdiff