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Autogain algorithm is very simple, if average luminance is low - increase gain, if it's high - decrease gain. Gain granularity is low enough for this algo to stabilize quickly. Signed-off-by: Vasily Khoruzhick <anarsoul@gmail.com> Signed-off-by: Hans de Goede <hdegoede@redhat.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
64 lines
1.8 KiB
C
64 lines
1.8 KiB
C
/*
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* SN9C2028 common functions
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*
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* Copyright (C) 2009 Theodore Kilgore <kilgota@auburn,edu>
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*
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* Based closely upon the file gspca/pac_common.h
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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*/
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static const unsigned char sn9c2028_sof_marker[] = {
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0xff, 0xff, 0x00, 0xc4, 0xc4, 0x96,
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0x00,
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0x00, /* seq */
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0x00,
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0x00,
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0x00, /* avg luminance lower 8 bit */
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0x00, /* avg luminance higher 8 bit */
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};
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static unsigned char *sn9c2028_find_sof(struct gspca_dev *gspca_dev,
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unsigned char *m, int len)
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{
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struct sd *sd = (struct sd *) gspca_dev;
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int i;
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/* Search for the SOF marker (fixed part) in the header */
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for (i = 0; i < len; i++) {
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if ((m[i] == sn9c2028_sof_marker[sd->sof_read]) ||
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(sd->sof_read > 5)) {
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sd->sof_read++;
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if (sd->sof_read == 11)
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sd->avg_lum_l = m[i];
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if (sd->sof_read == 12)
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sd->avg_lum = (m[i] << 8) + sd->avg_lum_l;
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if (sd->sof_read == sizeof(sn9c2028_sof_marker)) {
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PDEBUG(D_FRAM,
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"SOF found, bytes to analyze: %u."
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" Frame starts at byte #%u",
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len, i + 1);
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sd->sof_read = 0;
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return m + i + 1;
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}
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} else {
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sd->sof_read = 0;
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}
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}
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return NULL;
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}
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