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Improve QTRLE encoding performance, no change to output file size/content.

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Avoid searching for the lowest bulk cost for each pixel that isn't a repeat/skip. Instead store the lowest cost as we go along each pixel, and use it as needed.

Signed-off-by: Malcolm Bechard <malcolm.bechard@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Malcolm Bechard 2013-02-20 15:50:34 -05:00 committed by Michael Niedermayer
parent 2c21d34ea4
commit 239b88c284
1 changed files with 61 additions and 21 deletions
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82
libavcodec/qtrleenc.c
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@ -121,8 +121,6 @@ static void qtrle_encode_line(QtrleEncContext *s, const AVFrame *p, int line, ui
int i;
signed char rlecode;
/* We will use it to compute the best bulk copy sequence */
unsigned int av_uninit(bulkcount);
/* This will be the number of pixels equal to the preivous frame one's
* starting from the ith pixel */
unsigned int skipcount;
@ -131,12 +129,14 @@ static void qtrle_encode_line(QtrleEncContext *s, const AVFrame *p, int line, ui
unsigned int av_uninit(repeatcount);
/* The cost of the three different possibilities */
int total_bulk_cost;
int total_skip_cost;
int total_repeat_cost;
int temp_cost;
int j;
int base_bulk_cost;
int lowest_bulk_cost;
int lowest_bulk_cost_index;
int sec_lowest_bulk_cost;
int sec_lowest_bulk_cost_index;
uint8_t *this_line = p-> data[0] + line*p-> linesize[0] +
(width - 1)*s->pixel_size;
@ -146,8 +146,57 @@ static void qtrle_encode_line(QtrleEncContext *s, const AVFrame *p, int line, ui
s->length_table[width] = 0;
skipcount = 0;
/* Initial values */
lowest_bulk_cost = INT_MAX / 2;
lowest_bulk_cost_index = width;
sec_lowest_bulk_cost = INT_MAX / 2;
sec_lowest_bulk_cost_index = width;
base_bulk_cost = 1 + s->pixel_size;
for (i = width - 1; i >= 0; i--) {
int prev_bulk_cost;
/* If our lowest bulk cost index is too far away, replace it
* with the next lowest bulk cost */
if (FFMIN(width, i + MAX_RLE_BULK) < lowest_bulk_cost_index) {
lowest_bulk_cost = sec_lowest_bulk_cost;
lowest_bulk_cost_index = sec_lowest_bulk_cost_index;
sec_lowest_bulk_cost = INT_MAX / 2;
sec_lowest_bulk_cost_index = width;
}
/* Deal with the first pixel's bulk cost */
if (!i) {
base_bulk_cost++;
lowest_bulk_cost++;
sec_lowest_bulk_cost++;
}
/* Look at the bulk cost of the previous loop and see if it is
* a new lower bulk cost */
prev_bulk_cost = s->length_table[i + 1] + base_bulk_cost;
if (prev_bulk_cost <= sec_lowest_bulk_cost) {
/* If it's lower than the 2nd lowest, then it may be lower
* than the lowest */
if (prev_bulk_cost <= lowest_bulk_cost) {
/* If we have found a new lowest bulk cost,
* then the 2nd lowest bulk cost is now farther than the
* lowest bulk cost, and will never be used */
sec_lowest_bulk_cost = INT_MAX / 2;
lowest_bulk_cost = prev_bulk_cost;
lowest_bulk_cost_index = i + 1;
} else {
/* Then it must be the 2nd lowest bulk cost */
sec_lowest_bulk_cost = prev_bulk_cost;
sec_lowest_bulk_cost_index = i + 1;
}
}
if (!s->frame.key_frame && !memcmp(this_line, prev_line, s->pixel_size))
skipcount = FFMIN(skipcount + 1, MAX_RLE_SKIP);
else
@ -183,26 +232,17 @@ static void qtrle_encode_line(QtrleEncContext *s, const AVFrame *p, int line, ui
}
else {
/* We cannot do neither skip nor repeat
* thus we search for the best bulk copy to do */
* thus we use the best bulk copy */
int limit = FFMIN(width - i, MAX_RLE_BULK);
s->length_table[i] = lowest_bulk_cost;
s->rlecode_table[i] = lowest_bulk_cost_index - i;
temp_cost = 1 + s->pixel_size + !i;
total_bulk_cost = INT_MAX;
for (j = 1; j <= limit; j++) {
if (s->length_table[i + j] + temp_cost < total_bulk_cost) {
/* We have found a better bulk copy ... */
total_bulk_cost = s->length_table[i + j] + temp_cost;
bulkcount = j;
}
temp_cost += s->pixel_size;
}
s->length_table[i] = total_bulk_cost;
s->rlecode_table[i] = bulkcount;
}
/* These bulk costs increase every iteration */
lowest_bulk_cost += s->pixel_size;
sec_lowest_bulk_cost += s->pixel_size;
this_line -= s->pixel_size;
prev_line -= s->pixel_size;
}