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Modified Handling of min and max vbr rates.

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In two pass encodes bits are allocated to each frame
according to a modified error score for the frame as a
fraction of the modified error score for the clip or section.

Previously a minimum rate per frame was reserved and
subtracted from the bits allocatable by the two pass code.
The vbr max section rate was enforced by clipping the
actual number of bits allocated.

In this patch the min and max vbr rates are enforced
instead by clipping the modified error scores for each frame
rather than the number of bits allocated.

Small gains for all test sets (psnr and SSIM) ranging from
~ +0.05 for YT psnr up to ~ +0.25 for Std-hd SSIM.

Change-Id: Iae27d70bdd3944e3f0cceaf225bad2e8802833de
This commit is contained in:
Paul Wilkins
2014-01-02 15:45:06 +00:00
parent 3bcece9578
commit 65ede3da45
2 changed files with 20 additions and 21 deletions
Download Patch File Download Diff File Expand all files Collapse all files

39
vp9/encoder/vp9_firstpass.c
View File

@@ -271,8 +271,17 @@ static double calculate_modified_err(VP9_COMP *cpi,
const FIRSTPASS_STATS *const stats = &cpi->twopass.total_stats;
const double av_err = stats->ssim_weighted_pred_err / stats->count;
const double this_err = this_frame->ssim_weighted_pred_err;
return av_err * pow(this_err / DOUBLE_DIVIDE_CHECK(av_err),
this_err > av_err ? POW1 : POW2);
double modified_error;
modified_error = av_err * pow(this_err / DOUBLE_DIVIDE_CHECK(av_err),
this_err > av_err ? POW1 : POW2);
if (modified_error < cpi->twopass.modified_error_min)
modified_error = cpi->twopass.modified_error_min;
else if (modified_error > cpi->twopass.modified_error_max)
modified_error = cpi->twopass.modified_error_max;
return modified_error;
}
static const double weight_table[256] = {
@@ -1077,13 +1086,6 @@ void vp9_init_second_pass(VP9_COMP *cpi) {
FIRSTPASS_STATS this_frame;
FIRSTPASS_STATS *start_pos;
double lower_bounds_min_rate = FRAME_OVERHEAD_BITS * cpi->oxcf.framerate;
double two_pass_min_rate = (double)(cpi->oxcf.target_bandwidth *
cpi->oxcf.two_pass_vbrmin_section / 100);
if (two_pass_min_rate < lower_bounds_min_rate)
two_pass_min_rate = lower_bounds_min_rate;
zero_stats(&cpi->twopass.total_stats);
zero_stats(&cpi->twopass.total_left_stats);
@@ -1104,8 +1106,6 @@ void vp9_init_second_pass(VP9_COMP *cpi) {
cpi->output_framerate = cpi->oxcf.framerate;
cpi->twopass.bits_left = (int64_t)(cpi->twopass.total_stats.duration *
cpi->oxcf.target_bandwidth / 10000000.0);
cpi->twopass.bits_left -= (int64_t)(cpi->twopass.total_stats.duration *
two_pass_min_rate / 10000000.0);
// Calculate a minimum intra value to be used in determining the IIratio
// scores used in the second pass. We have this minimum to make sure
@@ -1142,9 +1142,16 @@ void vp9_init_second_pass(VP9_COMP *cpi) {
// Scan the first pass file and calculate a modified total error based upon
// the bias/power function used to allocate bits.
{
double av_error = cpi->twopass.total_stats.ssim_weighted_pred_err /
DOUBLE_DIVIDE_CHECK(cpi->twopass.total_stats.count);
start_pos = cpi->twopass.stats_in; // Note starting "file" position
cpi->twopass.modified_error_total = 0.0;
cpi->twopass.modified_error_min =
(av_error * cpi->oxcf.two_pass_vbrmin_section) / 100;
cpi->twopass.modified_error_max =
(av_error * cpi->oxcf.two_pass_vbrmax_section) / 100;
while (input_stats(cpi, &this_frame) != EOF) {
cpi->twopass.modified_error_total +=
@@ -2635,14 +2642,4 @@ void vp9_twopass_postencode_update(VP9_COMP *cpi, uint64_t bytes_used) {
#else
cpi->twopass.bits_left -= 8 * bytes_used;
#endif
if (!cpi->refresh_alt_ref_frame) {
double lower_bounds_min_rate = FRAME_OVERHEAD_BITS * cpi->oxcf.framerate;
double two_pass_min_rate = (double)(cpi->oxcf.target_bandwidth *
cpi->oxcf.two_pass_vbrmin_section
/ 100);
if (two_pass_min_rate < lower_bounds_min_rate)
two_pass_min_rate = lower_bounds_min_rate;
cpi->twopass.bits_left += (int64_t)(two_pass_min_rate /
cpi->oxcf.framerate);
}
}