Skip to content

Commit

Permalink
[media] gspca_sonixb: Rewrite start of frame detection
Browse files Browse the repository at this point in the history 
Our old start of frame detection code wrongly assumes that the sof
marker always lives at the beginning of the frame. At least for the
0c45:602a camera this is not the case. This patch also improves
the framerate from 28 fps to 30 fps with the 0c45:6005 and 0c45:6007

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
  • Loading branch information
Hans de Goede authored and Mauro Carvalho Chehab committed Dec 29, 2010
1 parent d6746d5 commit 2b3e284
Showing 1 changed file with 106 additions and 54 deletions.
160 changes: 106 additions & 54 deletions drivers/media/video/gspca/sonixb.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -56,6 +56,8 @@ struct sd {
int prev_avg_lum;
int exp_too_low_cnt;
int exp_too_high_cnt;
int header_read;
u8 header[12]; /* Header without sof marker */

unsigned short exposure;
unsigned char gain;
Expand Down Expand Up @@ -1177,13 +1179,10 @@ static void sd_stopN(struct gspca_dev *gspca_dev)
sd_init(gspca_dev);
}

static void sd_pkt_scan(struct gspca_dev *gspca_dev,
u8 *data, /* isoc packet */
int len) /* iso packet length */
static u8* find_sof(struct gspca_dev *gspca_dev, u8 *data, int len)
{
int i;
struct sd *sd = (struct sd *) gspca_dev;
struct cam *cam = &gspca_dev->cam;
int i, header_size = (sd->bridge == BRIDGE_103) ? 18 : 12;

/* frames start with:
* ff ff 00 c4 c4 96 synchro
Expand All @@ -1194,58 +1193,84 @@ static void sd_pkt_scan(struct gspca_dev *gspca_dev,
* ll mm brightness sum outside auto exposure
* (xx xx xx xx xx) audio values for snc103
*/
if (len > 6 && len < 24) {
for (i = 0; i < len - 6; i++) {
if (data[0 + i] == 0xff
&& data[1 + i] == 0xff
&& data[2 + i] == 0x00
&& data[3 + i] == 0xc4
&& data[4 + i] == 0xc4
&& data[5 + i] == 0x96) { /* start of frame */
int lum = -1;
int pkt_type = LAST_PACKET;
int fr_h_sz = (sd->bridge == BRIDGE_103) ?
18 : 12;

if (len - i < fr_h_sz) {
PDEBUG(D_STREAM, "packet too short to"
" get avg brightness");
} else if (sd->bridge == BRIDGE_103) {
lum = data[i + 9] +
(data[i + 10] << 8);
} else {
lum = data[i + 8] + (data[i + 9] << 8);
}
/* When exposure changes midway a frame we
get a lum of 0 in this case drop 2 frames
as the frames directly after an exposure
change have an unstable image. Sometimes lum
*really* is 0 (cam used in low light with
low exposure setting), so do not drop frames
if the previous lum was 0 too. */
if (lum == 0 && sd->prev_avg_lum != 0) {
lum = -1;
sd->frames_to_drop = 2;
sd->prev_avg_lum = 0;
} else
sd->prev_avg_lum = lum;
atomic_set(&sd->avg_lum, lum);

if (sd->frames_to_drop) {
sd->frames_to_drop--;
pkt_type = DISCARD_PACKET;
}

gspca_frame_add(gspca_dev, pkt_type,
NULL, 0);
data += i + fr_h_sz;
len -= i + fr_h_sz;
gspca_frame_add(gspca_dev, FIRST_PACKET,
data, len);
return;
for (i = 0; i < len; i++) {
switch (sd->header_read) {
case 0:
if (data[i] == 0xff)
sd->header_read++;
break;
case 1:
if (data[i] == 0xff)
sd->header_read++;
else
sd->header_read = 0;
break;
case 2:
if (data[i] == 0x00)
sd->header_read++;
else if (data[i] != 0xff)
sd->header_read = 0;
break;
case 3:
if (data[i] == 0xc4)
sd->header_read++;
else if (data[i] == 0xff)
sd->header_read = 1;
else
sd->header_read = 0;
break;
case 4:
if (data[i] == 0xc4)
sd->header_read++;
else if (data[i] == 0xff)
sd->header_read = 1;
else
sd->header_read = 0;
break;
case 5:
if (data[i] == 0x96)
sd->header_read++;
else if (data[i] == 0xff)
sd->header_read = 1;
else
sd->header_read = 0;
break;
default:
sd->header[sd->header_read - 6] = data[i];
sd->header_read++;
if (sd->header_read == header_size) {
sd->header_read = 0;
return data + i + 1;
}
}
}
return NULL;
}

static void sd_pkt_scan(struct gspca_dev *gspca_dev,
u8 *data, /* isoc packet */
int len) /* iso packet length */
{
int fr_h_sz = 0, lum_offset = 0, len_after_sof = 0;
struct sd *sd = (struct sd *) gspca_dev;
struct cam *cam = &gspca_dev->cam;
u8 *sof;

sof = find_sof(gspca_dev, data, len);
if (sof) {
if (sd->bridge == BRIDGE_103) {
fr_h_sz = 18;
lum_offset = 3;
} else {
fr_h_sz = 12;
lum_offset = 2;
}

len_after_sof = len - (sof - data);
len = (sof - data) - fr_h_sz;
if (len < 0)
len = 0;
}

if (cam->cam_mode[gspca_dev->curr_mode].priv & MODE_RAW) {
/* In raw mode we sometimes get some garbage after the frame
Expand All @@ -1259,6 +1284,33 @@ static void sd_pkt_scan(struct gspca_dev *gspca_dev,
}

gspca_frame_add(gspca_dev, INTER_PACKET, data, len);

if (sof) {
int lum = sd->header[lum_offset] +
(sd->header[lum_offset + 1] << 8);

/* When exposure changes midway a frame we
get a lum of 0 in this case drop 2 frames
as the frames directly after an exposure
change have an unstable image. Sometimes lum
*really* is 0 (cam used in low light with
low exposure setting), so do not drop frames
if the previous lum was 0 too. */
if (lum == 0 && sd->prev_avg_lum != 0) {
lum = -1;
sd->frames_to_drop = 2;
sd->prev_avg_lum = 0;
} else
sd->prev_avg_lum = lum;
atomic_set(&sd->avg_lum, lum);

if (sd->frames_to_drop)
sd->frames_to_drop--;
else
gspca_frame_add(gspca_dev, LAST_PACKET, NULL, 0);

gspca_frame_add(gspca_dev, FIRST_PACKET, sof, len_after_sof);
}
}

static int sd_setbrightness(struct gspca_dev *gspca_dev, __s32 val)
Expand Down

0 comments on commit 2b3e284

Please sign in to comment.