Commit 9afb6700 authored by Paul Wilkins's avatar Paul Wilkins Committed by Gerrit Code Review

Adjust q range

Skip Q values between the q.0 mode and a real q of
2.0 as these are not valuable from an RD perspective.

Change-Id: I110c4858c57f97315953f4d88a2596d4764360df
parent 67266cb2
......@@ -15,7 +15,7 @@
static int16_t dc_qlookup[QINDEX_RANGE];
static int16_t ac_qlookup[QINDEX_RANGE];
#define ACDC_MIN 4
#define ACDC_MIN 8
// TODO(dkovalev) move to common and reuse
static double poly3(double a, double b, double c, double d, double x) {
......@@ -25,10 +25,19 @@ static double poly3(double a, double b, double c, double d, double x) {
void vp9_init_quant_tables() {
int i, val = 4;
for (i = 0; i < QINDEX_RANGE; i++) {
// A "real" q of 1.0 forces lossless mode.
// In practice non lossless Q's between 1.0 and 2.0 (represented here by
// integer values from 5-7 give poor rd results (lower psnr and often
// larger size than the lossless encode. To block out those "not very useful"
// values we increment the ac and dc q lookup values by 4 after position 0.
ac_qlookup[0] = val;
dc_qlookup[0] = val;
val += 4;
for (i = 1; i < QINDEX_RANGE; i++) {
const int ac_val = val;
val = (int)(val * 1.02);
val = (int)(val * 1.01975);
if (val == ac_val)
++val;
......
......@@ -161,6 +161,11 @@ static int calculate_minq_index(double maxq,
const double minqtarget = MIN(((x3 * maxq + x2) * maxq + x1) * maxq + c,
maxq);
// Special case handling to deal with the step from q2.0
// down to lossless mode represented by q 1.0.
if (minqtarget <= 2.0)
return 0;
for (i = 0; i < QINDEX_RANGE; i++) {
if (minqtarget <= vp9_convert_qindex_to_q(i))
return i;
......
......@@ -263,10 +263,6 @@ void vp9_set_quantizer(struct VP9_COMP *cpi, int Q) {
cm->base_qindex = Q;
// Set lossless mode
if (cm->base_qindex <= 4)
cm->base_qindex = 0;
// if any of the delta_q values are changing update flag will
// have to be set.
cm->y_dc_delta_q = 0;
......
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