CQ Mode
The merge includes hooks to for CQ mode and other code
changes merged from the test branch.
CQ mode attempts to maintain a more stable quantizer within a clip
whilst also trying to adhere to a guidline maximum bitrate.
The existing target data rate parameter is used to specify the
guideline maximum bitrate.
A new parameter allows the user to specify a target CQ level.
For normal (non kf/gf/arf) frames, the quantizer will not drop BELOW the
user specified value (0-63). However, in some cases the encoder may
choose to impose a target CQ that is above that specified by the user,
if it estimates that consistent use of the target value is not compatible
with guideline maximum bitrate.
Change-Id: I2221f9eecae8cc3c431d36caf83503941b25e4c1
diff --git a/vp8/encoder/firstpass.c b/vp8/encoder/firstpass.c
index ce273b9..0c79ade 100644
--- a/vp8/encoder/firstpass.c
+++ b/vp8/encoder/firstpass.c
@@ -58,6 +58,7 @@
#define KF_MB_INTRA_MIN 300
#define GF_MB_INTRA_MIN 200
+
#define DOUBLE_DIVIDE_CHECK(X) ((X)<0?(X)-.000001:(X)+.000001)
#define POW1 (double)cpi->oxcf.two_pass_vbrbias/100.0
@@ -66,6 +67,19 @@
static int vscale_lookup[7] = {0, 1, 1, 2, 2, 3, 3};
static int hscale_lookup[7] = {0, 0, 1, 1, 2, 2, 3};
+
+const int cq_level[QINDEX_RANGE] =
+{
+ 0,0,1,1,2,3,3,4,4,5,6,6,7,8,8,9,
+ 9,10,11,11,12,13,13,14,15,15,16,17,17,18,19,20,
+ 20,21,22,22,23,24,24,25,26,27,27,28,29,30,30,31,
+ 32,33,33,34,35,36,36,37,38,39,39,40,41,42,42,43,
+ 44,45,46,46,47,48,49,50,50,51,52,53,54,55,55,56,
+ 57,58,59,60,60,61,62,63,64,65,66,67,67,68,69,70,
+ 71,72,73,74,75,75,76,77,78,79,80,81,82,83,84,85,
+ 86,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100
+};
+
void vp8_find_next_key_frame(VP8_COMP *cpi, FIRSTPASS_STATS *this_frame);
int vp8_input_stats(VP8_COMP *cpi, FIRSTPASS_STATS *fps);
@@ -889,7 +903,7 @@
}
extern const int vp8_bits_per_mb[2][QINDEX_RANGE];
-#define BASE_ERRPERMB 150
+#define BASE_ERRPERMB 100
static int estimate_max_q(VP8_COMP *cpi, double section_err, int section_target_bandwitdh, int Height, int Width)
{
int Q;
@@ -945,7 +959,7 @@
corr_high = (corr_high < 0.05)
? 0.05 : (corr_high > 5.0) ? 5.0 : corr_high;
- // Try and pick a Q that should be high enough to encode the
+ // Try and pick a max Q that will be high enough to encode the
// content at the given rate.
for (Q = cpi->maxq_min_limit; Q < cpi->maxq_max_limit; Q++)
{
@@ -966,6 +980,15 @@
break;
}
+ // Restriction on active max q for constrained quality mode.
+ if ( (cpi->oxcf.end_usage == USAGE_CONSTRAINED_QUALITY) &&
+ (Q < cpi->cq_target_quality) )
+ //(Q < cpi->oxcf.cq_target_quality) )
+ {
+ Q = cpi->cq_target_quality;
+ //Q = cpi->oxcf.cq_target_quality;
+ }
+
return Q;
}
static int estimate_q(VP8_COMP *cpi, double section_err, int section_target_bandwitdh, int Height, int Width)
@@ -1114,6 +1137,79 @@
return Q;
}
+
+// For cq mode estimate a cq level that matches the observed
+// complexity and data rate.
+static int estimate_cq(VP8_COMP *cpi, double section_err,
+ int section_target_bandwitdh, int Height, int Width)
+{
+ int Q;
+ int num_mbs = ((Height * Width) / (16 * 16));
+ int target_norm_bits_per_mb;
+
+ double err_per_mb = section_err / num_mbs;
+ double correction_factor;
+ double corr_high;
+ double speed_correction = 1.0;
+ double pow_highq = 0.90;
+ double pow_lowq = 0.40;
+ double clip_iiratio;
+ double clip_iifactor;
+
+ target_norm_bits_per_mb = (section_target_bandwitdh < (1 << 20))
+ ? (512 * section_target_bandwitdh) / num_mbs
+ : 512 * (section_target_bandwitdh / num_mbs);
+
+ // Corrections for higher compression speed settings
+ // (reduced compression expected)
+ if ((cpi->compressor_speed == 3) || (cpi->compressor_speed == 1))
+ {
+ if (cpi->oxcf.cpu_used <= 5)
+ speed_correction = 1.04 + (cpi->oxcf.cpu_used * 0.04);
+ else
+ speed_correction = 1.25;
+ }
+ // II ratio correction factor for clip as a whole
+ clip_iiratio = cpi->total_stats->intra_error /
+ DOUBLE_DIVIDE_CHECK(cpi->total_stats->coded_error);
+ clip_iifactor = 1.0 - ((clip_iiratio - 10.0) * 0.025);
+ if (clip_iifactor < 0.80)
+ clip_iifactor = 0.80;
+
+ // Correction factor used for Q values >= 20
+ corr_high = pow(err_per_mb / BASE_ERRPERMB, pow_highq);
+ corr_high = (corr_high < 0.05) ? 0.05 : (corr_high > 5.0) ? 5.0 : corr_high;
+
+ // Try and pick a Q that can encode the content at the given rate.
+ for (Q = 0; Q < MAXQ; Q++)
+ {
+ int bits_per_mb_at_this_q;
+
+ if (Q < 50)
+ {
+ correction_factor =
+ pow( err_per_mb / BASE_ERRPERMB, (pow_lowq + Q * 0.01));
+
+ correction_factor = (correction_factor < 0.05) ? 0.05
+ : (correction_factor > 5.0) ? 5.0
+ : correction_factor;
+ }
+ else
+ correction_factor = corr_high;
+
+ bits_per_mb_at_this_q =
+ (int)( .5 + correction_factor *
+ speed_correction *
+ clip_iifactor *
+ (double)vp8_bits_per_mb[INTER_FRAME][Q] / 1.0);
+
+ if (bits_per_mb_at_this_q <= target_norm_bits_per_mb)
+ break;
+ }
+
+ return cq_level[Q];
+}
+
extern void vp8_new_frame_rate(VP8_COMP *cpi, double framerate);
void vp8_init_second_pass(VP8_COMP *cpi)
@@ -1767,7 +1863,9 @@
vp8_avg_stats(§ionstats);
- cpi->section_intra_rating = sectionstats.intra_error / DOUBLE_DIVIDE_CHECK(sectionstats.coded_error);
+ cpi->section_intra_rating =
+ sectionstats.intra_error /
+ DOUBLE_DIVIDE_CHECK(sectionstats.coded_error);
Ratio = sectionstats.intra_error / DOUBLE_DIVIDE_CHECK(sectionstats.coded_error);
//if( (Ratio > 11) ) //&& (sectionstats.pcnt_second_ref < .20) )
@@ -1994,9 +2092,26 @@
if (cpi->common.current_video_frame == 0)
{
- // guess at 2nd pass max q
cpi->est_max_qcorrection_factor = 1.0;
+ // Experimental code to try and set a cq_level in constrained
+ // quality mode.
+ if ( cpi->oxcf.end_usage == USAGE_CONSTRAINED_QUALITY )
+ {
+ int est_cq;
+
+ est_cq =
+ estimate_cq( cpi,
+ (cpi->total_coded_error_left / frames_left),
+ (int)(cpi->bits_left / frames_left),
+ cpi->common.Height, cpi->common.Width);
+
+ cpi->cq_target_quality = cpi->oxcf.cq_level;
+ if ( est_cq > cpi->cq_target_quality )
+ cpi->cq_target_quality = est_cq;
+ }
+
+ // guess at maxq needed in 2nd pass
cpi->maxq_max_limit = cpi->worst_quality;
cpi->maxq_min_limit = cpi->best_quality;
tmp_q = estimate_max_q( cpi,
@@ -2005,7 +2120,7 @@
cpi->common.Height,
cpi->common.Width);
- // Limit the maxq value retuned subsequently.
+ // Limit the maxq value returned subsequently.
// This increases the risk of overspend if the initial
// estimate for the clip is bad, but helps prevent excessive
// variation in Q, especially near the end of a clip
@@ -2018,6 +2133,7 @@
cpi->active_worst_quality = tmp_q;
cpi->ni_av_qi = tmp_q;
}
+
// The last few frames of a clip almost always have to few or too many
// bits and for the sake of over exact rate control we dont want to make
// radical adjustments to the allowed quantizer range just to use up a
