Commit 0e1068a4 authored by Paul Wilkins's avatar Paul Wilkins
Browse files

Improve two pass VBR accuracy.

Adjustments to the GF interval choice and minimum boost.
Adjustment to the calculation of 2 pass worst q.
Compared to 09/29 head there is metrics hit on derf of
(-0.123%,-0.191%)

Compared to the September 29 head and a baseline on
September 18 baseline the accuracy of the VBR rate control
measured on the derf set is as follows:-

Mean error %  / Mean abs(error %)
Sept 18 baseline (-7.0% / 14.76%)
Sept 29 head (-15.7%, 19.8%)
This check in (-1.5% / 14.4%)

The mean undershoot is reduced slightly but the
worst case overshoot on e.g. harbour/highway is
increased. This will be addressed in a later patch.

Change-Id: Iffd9b0ab7432a131c98fbaaa82d1e5b40be72b58
parent d3bbd87d
......@@ -1758,7 +1758,7 @@ static void rd_use_partition(VP9_COMP *cpi,
// We must have chosen a partitioning and encoding or we'll fail later on.
// No other opportunities for success.
if ( bsize == BLOCK_64X64)
if (bsize == BLOCK_64X64)
assert(chosen_rate < INT_MAX && chosen_dist < INT64_MAX);
if (do_recon) {
......
......@@ -39,9 +39,9 @@
#define ARF_STATS_OUTPUT 0
#define BOOST_FACTOR 12.5
#define ERR_DIVISOR 100.0
#define FACTOR_PT_LOW 0.5
#define FACTOR_PT_HIGH 0.9
#define ERR_DIVISOR 125.0
#define FACTOR_PT_LOW 0.70
#define FACTOR_PT_HIGH 0.90
#define FIRST_PASS_Q 10.0
#define GF_MAX_BOOST 96.0
#define INTRA_MODE_PENALTY 1024
......@@ -1057,7 +1057,7 @@ static double calc_correction_factor(double err_per_mb,
// Adjustment based on actual quantizer to power term.
const double power_term =
MIN(vp9_convert_qindex_to_q(q, bit_depth) * 0.0125 + pt_low, pt_high);
MIN(vp9_convert_qindex_to_q(q, bit_depth) * 0.01 + pt_low, pt_high);
// Calculate correction factor.
if (power_term < 1.0)
......@@ -1066,6 +1066,11 @@ static double calc_correction_factor(double err_per_mb,
return fclamp(pow(error_term, power_term), 0.05, 5.0);
}
// Larger image formats are expected to be a little harder to code relatively
// given the same prediction error score. This in part at least relates to the
// increased size and hence coding cost of motion vectors.
#define EDIV_SIZE_FACTOR 800
static int get_twopass_worst_quality(const VP9_COMP *cpi,
const FIRSTPASS_STATS *stats,
int section_target_bandwidth) {
......@@ -1079,8 +1084,10 @@ static int get_twopass_worst_quality(const VP9_COMP *cpi,
const double section_err = stats->coded_error / stats->count;
const double err_per_mb = section_err / num_mbs;
const double speed_term = 1.0 + 0.04 * oxcf->speed;
const double ediv_size_correction = num_mbs / EDIV_SIZE_FACTOR;
const int target_norm_bits_per_mb = ((uint64_t)section_target_bandwidth <<
BPER_MB_NORMBITS) / num_mbs;
int q;
int is_svc_upper_layer = 0;
if (is_two_pass_svc(cpi) && cpi->svc.spatial_layer_id > 0)
......@@ -1090,7 +1097,7 @@ static int get_twopass_worst_quality(const VP9_COMP *cpi,
// content at the given rate.
for (q = rc->best_quality; q < rc->worst_quality; ++q) {
const double factor =
calc_correction_factor(err_per_mb, ERR_DIVISOR,
calc_correction_factor(err_per_mb, ERR_DIVISOR - ediv_size_correction,
is_svc_upper_layer ? SVC_FACTOR_PT_LOW :
FACTOR_PT_LOW, FACTOR_PT_HIGH, q,
cpi->common.bit_depth);
......@@ -1735,7 +1742,7 @@ static void define_gf_group(VP9_COMP *cpi, FIRSTPASS_STATS *this_frame) {
// bits to spare and are better with a smaller interval and smaller boost.
// At high Q when there are few bits to spare we are better with a longer
// interval to spread the cost of the GF.
active_max_gf_interval = 12 + MIN(4, (int_max_q / 32));
active_max_gf_interval = 12 + MIN(4, (int_max_q / 24));
if (active_max_gf_interval > rc->max_gf_interval)
active_max_gf_interval = rc->max_gf_interval;
}
......
......@@ -177,6 +177,9 @@ int vp9_rc_bits_per_mb(FRAME_TYPE frame_type, int qindex,
const double q = vp9_convert_qindex_to_q(qindex, bit_depth);
int enumerator = frame_type == KEY_FRAME ? 2700000 : 1800000;
assert(correction_factor <= MAX_BPB_FACTOR &&
correction_factor >= MIN_BPB_FACTOR);
// q based adjustment to baseline enumerator
enumerator += (int)(enumerator * q) >> 12;
return (int)(enumerator * correction_factor / q);
......@@ -187,7 +190,8 @@ static int estimate_bits_at_q(FRAME_TYPE frame_type, int q, int mbs,
vpx_bit_depth_t bit_depth) {
const int bpm = (int)(vp9_rc_bits_per_mb(frame_type, q, correction_factor,
bit_depth));
return ((uint64_t)bpm * mbs) >> BPER_MB_NORMBITS;
return MAX(FRAME_OVERHEAD_BITS,
(int)((uint64_t)bpm * mbs) >> BPER_MB_NORMBITS);
}
int vp9_rc_clamp_pframe_target_size(const VP9_COMP *const cpi, int target) {
......@@ -410,7 +414,7 @@ void vp9_rc_update_rate_correction_factors(VP9_COMP *cpi, int damp_var) {
rate_correction_factor,
cm->bit_depth);
// Work out a size correction factor.
if (projected_size_based_on_q > 0)
if (projected_size_based_on_q > FRAME_OVERHEAD_BITS)
correction_factor = (100 * cpi->rc.projected_frame_size) /
projected_size_based_on_q;
......
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