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Try to correct missing packets in image stream

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If a packet goes missing, use the data from previous row
to minimize distortion, or use some neutral dummy data.

http://lists.reactivated.net/pipermail/fprint/2009-December/001404.html
This commit is contained in:
Alexia Death 2009-12-24 21:42:01 +02:00 committed by Bastien Nocera
parent 4b518bd230
commit 8cd31f6ad8
1 changed files with 52 additions and 3 deletions
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55
libfprint/drivers/upeksonly.c
View file

@ -248,6 +248,7 @@ static void add_to_rowbuf(struct fp_img_dev *dev, unsigned char *data, int size)
sdev->rowbuf_offset += size;
if (sdev->rowbuf_offset >= IMG_WIDTH)
row_complete(dev);
}
static void start_new_row(struct sonly_dev *sdev, unsigned char *data, int size)
@ -282,11 +283,56 @@ static void handle_packet(struct fp_img_dev *dev, unsigned char *data)
int for_rowbuf;
int next_row_addr;
int diff;
unsigned char dummy_data[62];
/* Init dummy data to something neutral */
memset (dummy_data, 204, 62);
data += 2; /* skip sequence number */
if (seqnum != sdev->last_seqnum + 1) {
if (seqnum != 0 && sdev->last_seqnum != 16383)
fp_warn("lost some data");
if (seqnum != 0 && sdev->last_seqnum != 16383) {
int missing_data = seqnum - sdev->last_seqnum;
int i;
fp_warn("lost %d packets of data between %d and %d", missing_data, sdev->last_seqnum, seqnum );
/* Minimize distortions for readers that lose a lot of packets */
for (i =1; i < missing_data; i++) {
abs_base_addr = (sdev->last_seqnum + 1) * 62;
/* If possible take the replacement data from last row */
if (sdev->num_rows > 1) {
int row_left = IMG_WIDTH - sdev->rowbuf_offset;
unsigned char *last_row = g_slist_nth_data (sdev->rows, 0);
if (row_left >= 62) {
memcpy(dummy_data, last_row + sdev->rowbuf_offset, 62);
} else {
memcpy(dummy_data, last_row + sdev->rowbuf_offset, row_left);
memcpy(dummy_data + row_left, last_row , 62 - row_left);
}
}
fp_warn("adding dummy input for %d, i=%d", sdev->last_seqnum + i, i);
for_rowbuf = rowbuf_remaining(sdev);
if (for_rowbuf != -1) {
add_to_rowbuf(dev, dummy_data, for_rowbuf);
/* row boundary */
if (for_rowbuf < 62) {
start_new_row(sdev, dummy_data + for_rowbuf, 62 - for_rowbuf);
}
} else if (abs_base_addr % IMG_WIDTH == 0) {
start_new_row(sdev, dummy_data, 62);
} else {
/* does the data in the packet reside on a row boundary?
* if so capture it */
next_row_addr = ((abs_base_addr / IMG_WIDTH) + 1) * IMG_WIDTH;
diff = next_row_addr - abs_base_addr;
if (diff < 62)
start_new_row(sdev, dummy_data + diff, 62 - diff);
}
sdev->last_seqnum = sdev->last_seqnum + 1;
}
}
}
if (seqnum <= sdev->last_seqnum) {
fp_dbg("detected wraparound");
@ -302,7 +348,10 @@ static void handle_packet(struct fp_img_dev *dev, unsigned char *data)
for_rowbuf = rowbuf_remaining(sdev);
if (for_rowbuf != -1) {
add_to_rowbuf(dev, data, for_rowbuf);
/* FIXME: we drop a row here */
/*row boundary*/
if (for_rowbuf < 62) {
start_new_row(sdev, data + for_rowbuf, 62 - for_rowbuf);
}
return;
}