ref: 085f76e535a4376042d8eeadb1e4c5f246d74802
parent: 447c6433b9a3d1c8dfa9f42e924ebd2f605ca250
author: Paul Wilkins <paulwilkins@google.com>
date: Mon Apr 14 14:06:52 EDT 2014
Add experimental VBR adaptation method. Add code to monitor over and under spend and apply limited correction to the data rate of subsequent frames. To prevent the problem of starvation or overspend on individual frames (especially near the end of a clip) the maximum adjustment on a single frame is limited to a % of its un-modified allocation. Change-Id: I6e1ca035ab8afb0c98eac4392115d0752d9cbd7f
--- a/vp9/encoder/vp9_firstpass.c
+++ b/vp9/encoder/vp9_firstpass.c
@@ -61,7 +61,7 @@
#define MIN_GF_INTERVAL 4
#endif
-#define DISABLE_RC_LONG_TERM_MEM
+#define LONG_TERM_VBR_CORRECTION
static void swap_yv12(YV12_BUFFER_CONFIG *a, YV12_BUFFER_CONFIG *b) {YV12_BUFFER_CONFIG temp = *a;
@@ -1033,6 +1033,9 @@
reset_fpf_position(twopass, start_pos);
}
+
+ // Reset the vbr bits off target counter
+ cpi->rc.vbr_bits_off_target = 0;
}
// This function gives an estimate of how badly we believe the prediction
@@ -2192,6 +2195,23 @@
cpi->rc.frames_to_key = INT_MAX;
}
+// For VBR...adjustment to the frame target based on error from previous frames
+void vbr_rate_correction(int * this_frame_target,
+ const int64_t vbr_bits_off_target) {+ int max_delta = *this_frame_target / 10;
+
+ // vbr_bits_off_target > 0 means we have extra bits to spend
+ if (vbr_bits_off_target > 0) {+ *this_frame_target +=
+ (vbr_bits_off_target > max_delta) ? max_delta
+ : (int)vbr_bits_off_target;
+ } else {+ *this_frame_target -=
+ (vbr_bits_off_target < -max_delta) ? max_delta
+ : (int)-vbr_bits_off_target;
+ }
+}
+
void vp9_rc_get_second_pass_params(VP9_COMP *cpi) {VP9_COMMON *const cm = &cpi->common;
RATE_CONTROL *const rc = &cpi->rc;
@@ -2219,8 +2239,15 @@
return;
if (cpi->refresh_alt_ref_frame) {+ int modified_target = twopass->gf_bits;
+ rc->base_frame_target = twopass->gf_bits;
cm->frame_type = INTER_FRAME;
- vp9_rc_set_frame_target(cpi, twopass->gf_bits);
+#ifdef LONG_TERM_VBR_CORRECTION
+ // Correction to rate target based on prior over or under shoot.
+ if (cpi->oxcf.end_usage == USAGE_LOCAL_FILE_PLAYBACK)
+ vbr_rate_correction(&modified_target, rc->vbr_bits_off_target);
+#endif
+ vp9_rc_set_frame_target(cpi, modified_target);
return;
}
@@ -2315,6 +2342,13 @@
target = vp9_rc_clamp_iframe_target_size(cpi, rc->this_frame_target);
else
target = vp9_rc_clamp_pframe_target_size(cpi, rc->this_frame_target);
+
+ rc->base_frame_target = target;
+#ifdef LONG_TERM_VBR_CORRECTION
+ // Correction to rate target based on prior over or under shoot.
+ if (cpi->oxcf.end_usage == USAGE_LOCAL_FILE_PLAYBACK)
+ vbr_rate_correction(&target, rc->vbr_bits_off_target);
+#endif
vp9_rc_set_frame_target(cpi, target);
// Update the total stats remaining structure.
@@ -2322,20 +2356,38 @@
}
void vp9_twopass_postencode_update(VP9_COMP *cpi) {-#ifdef DISABLE_RC_LONG_TERM_MEM
- const uint64_t bits_used = cpi->rc.this_frame_target;
+ RATE_CONTROL *const rc = &cpi->rc;
+#ifdef LONG_TERM_VBR_CORRECTION
+ // In this experimental mode, the VBR correction is done exclusively through
+ // rc->vbr_bits_off_target. Based on the sign of this value, a limited %
+ // adjustment is made to the target rate of subsequent frames, to try and
+ // push it back towards 0. This mode is less likely to suffer from
+ // extreme behaviour at the end of a clip or group of frames.
+ const int bits_used = rc->base_frame_target;
+ rc->vbr_bits_off_target += rc->base_frame_target - rc->projected_frame_size;
#else
- const uint64_t bits_used = cpi->rc.projected_frame_size;
+ // In this mode, VBR correction is acheived by altering bits_left,
+ // kf_group_bits & gf_group_bits to reflect any deviation from the target
+ // rate in this frame. This alters the allocation of bits to the
+ // remaning frames in the group / clip.
+ // This method can give rise to unstable behaviour near the end of a clip
+ // or kf/gf group of frames where any accumulated error is corrected over an
+ // ever decreasing number of frames.
+ const int bits_used = rc->projected_frame_size;
#endif
+
cpi->twopass.bits_left -= bits_used;
cpi->twopass.bits_left = MAX(cpi->twopass.bits_left, 0);
- // Update bits left to the kf and gf groups to account for overshoot or
- // undershoot on these frames.
+
+#ifdef LONG_TERM_VBR_CORRECTION
+ if (cpi->common.frame_type != KEY_FRAME) {+#else
if (cpi->common.frame_type == KEY_FRAME) {// For key frames kf_group_bits already had the target bits subtracted out.
// So now update to the correct value based on the actual bits used.
cpi->twopass.kf_group_bits += cpi->rc.this_frame_target - bits_used;
} else {+#endif
cpi->twopass.kf_group_bits -= bits_used;
cpi->twopass.gf_group_bits -= bits_used;
cpi->twopass.gf_group_bits = MAX(cpi->twopass.gf_group_bits, 0);
--- a/vp9/encoder/vp9_onyx_if.c
+++ b/vp9/encoder/vp9_onyx_if.c
@@ -1997,8 +1997,8 @@
recon_err = vp9_get_y_sse(cpi->Source, get_frame_new_buffer(cm));
if (cpi->twopass.total_left_stats.coded_error != 0.0)
- fprintf(f, "%10u %10d %10d %10d %10d %10d "
- "%10"PRId64" %10"PRId64" %10d "
+ fprintf(f, "%10u %10d %10d %10d %10d"
+ "%10"PRId64" %10"PRId64" %10"PRId64" %10"PRId64" %10d "
"%7.2lf %7.2lf %7.2lf %7.2lf %7.2lf"
"%6d %6d %5d %5d %5d "
"%10"PRId64" %10.3lf"
@@ -2007,6 +2007,7 @@
cpi->rc.projected_frame_size,
cpi->rc.projected_frame_size / cpi->common.MBs,
(cpi->rc.projected_frame_size - cpi->rc.this_frame_target),
+ cpi->rc.vbr_bits_off_target,
cpi->rc.total_target_vs_actual,
(cpi->oxcf.starting_buffer_level - cpi->rc.bits_off_target),
cpi->rc.total_actual_bits, cm->base_qindex,
--- a/vp9/encoder/vp9_ratectrl.c
+++ b/vp9/encoder/vp9_ratectrl.c
@@ -1043,6 +1043,7 @@
RATE_CONTROL *const rc = &cpi->rc;
rc->this_frame_target = target;
+
// Target rate per SB64 (including partial SB64s.
rc->sb64_target_rate = ((int64_t)rc->this_frame_target * 64 * 64) /
(cm->width * cm->height);
--- a/vp9/encoder/vp9_ratectrl.h
+++ b/vp9/encoder/vp9_ratectrl.h
@@ -27,7 +27,9 @@
typedef struct {// Rate targetting variables
- int this_frame_target;
+ int base_frame_target; // A baseline frame target before adjustment
+ // for previous under or over shoot.
+ int this_frame_target; // Actual frame target after rc adjustment.
int projected_frame_size;
int sb64_target_rate;
int last_q[3]; // Separate values for Intra/Inter/ARF-GF
@@ -67,6 +69,7 @@
int64_t buffer_level;
int64_t bits_off_target;
+ int64_t vbr_bits_off_target;
int decimation_factor;
int decimation_count;