Commit 42b67917 authored by Marco's avatar Marco
Browse files

Allow for re-encoding frame if high overshoot.

For 1 pass CBR mode under screen content mode:
if pre-analysis (source temporal-sad) indicates significant
change in content, then check the projected frame size after
encode_frame(), and if size is above threshold, force re-encode
of that frame at max QP.

Change-Id: I91e66d9f3167aff2ffcc6f16f47f19f1c21dc688
parent 0092960d
......@@ -1623,6 +1623,8 @@ VP9_COMP *vp9_create_compressor(VP9EncoderConfig *oxcf,
cpi->resize_buffer_underflow = 0;
cpi->common.buffer_pool = pool;
cpi->rc.high_source_sad = 0;
init_config(cpi, oxcf);
vp9_rc_init(&cpi->oxcf, oxcf->pass, &cpi->rc);
......@@ -3180,7 +3182,9 @@ static void set_frame_size(VP9_COMP *cpi) {
set_ref_ptrs(cm, xd, LAST_FRAME, LAST_FRAME);
}
static void encode_without_recode_loop(VP9_COMP *cpi) {
static void encode_without_recode_loop(VP9_COMP *cpi,
size_t *size,
uint8_t *dest) {
VP9_COMMON *const cm = &cpi->common;
int q = 0, bottom_index = 0, top_index = 0; // Dummy variables.
......@@ -3210,6 +3214,13 @@ static void encode_without_recode_loop(VP9_COMP *cpi) {
&cpi->scaled_last_source);
}
if (cpi->oxcf.pass == 0 &&
cpi->oxcf.rc_mode == VPX_CBR &&
cpi->resize_state == 0 &&
cm->frame_type != KEY_FRAME &&
cpi->oxcf.content == VP9E_CONTENT_SCREEN)
vp9_avg_source_sad(cpi);
if (frame_is_intra_only(cm) == 0) {
vp9_scale_references(cpi);
}
......@@ -3237,6 +3248,38 @@ static void encode_without_recode_loop(VP9_COMP *cpi) {
// transform / motion compensation build reconstruction frame
vp9_encode_frame(cpi);
// Check if we should drop this frame because of high overshoot.
// Only for frames where high temporal-source sad is detected.
if (cpi->oxcf.pass == 0 &&
cpi->oxcf.rc_mode == VPX_CBR &&
cpi->resize_state == 0 &&
cm->frame_type != KEY_FRAME &&
cpi->oxcf.content == VP9E_CONTENT_SCREEN &&
cpi->rc.high_source_sad == 1) {
int frame_size = 0;
// Get an estimate of the encoded frame size.
save_coding_context(cpi);
vp9_pack_bitstream(cpi, dest, size);
restore_coding_context(cpi);
frame_size = (int)(*size) << 3;
// Check if encoded frame will overshoot too much, and if so, set the q and
// adjust some rate control parameters, and return to re-encode the frame.
if (vp9_encodedframe_overshoot(cpi, frame_size, &q)) {
vpx_clear_system_state();
vp9_set_quantizer(cm, q);
vp9_set_variance_partition_thresholds(cpi, q);
suppress_active_map(cpi);
// Turn-off cyclic refresh for re-encoded frame.
if (cpi->oxcf.aq_mode == CYCLIC_REFRESH_AQ) {
unsigned char *const seg_map = cpi->segmentation_map;
memset(seg_map, 0, cm->mi_rows * cm->mi_cols);
vp9_disable_segmentation(&cm->seg);
}
apply_active_map(cpi);
vp9_encode_frame(cpi);
}
}
// Update some stats from cyclic refresh, and check if we should not update
// golden reference, for non-SVC 1 pass CBR.
if (cpi->oxcf.aq_mode == CYCLIC_REFRESH_AQ &&
......@@ -3736,7 +3779,7 @@ static void encode_frame_to_data_rate(VP9_COMP *cpi,
#endif
if (cpi->sf.recode_loop == DISALLOW_RECODE) {
encode_without_recode_loop(cpi);
encode_without_recode_loop(cpi, size, dest);
} else {
encode_with_recode_loop(cpi, size, dest);
}
......
......@@ -1900,3 +1900,86 @@ int vp9_resize_one_pass_cbr(VP9_COMP *cpi) {
}
return resize_now;
}
// Compute average source sad (temporal sad: between current source and
// previous source) over a subset of superblocks. Use this is detect big changes
// in content and allow rate control to react.
// TODO(marpan): Superblock sad is computed again in variance partition for
// non-rd mode (but based on last reconstructed frame). Should try to reuse
// these computations.
void vp9_avg_source_sad(VP9_COMP *cpi) {
VP9_COMMON * const cm = &cpi->common;
RATE_CONTROL *const rc = &cpi->rc;
rc->high_source_sad = 0;
if (cpi->Last_Source != NULL) {
const uint8_t *src_y = cpi->Source->y_buffer;
const int src_ystride = cpi->Source->y_stride;
const uint8_t *last_src_y = cpi->Last_Source->y_buffer;
const int last_src_ystride = cpi->Last_Source->y_stride;
int sbi_row, sbi_col;
const BLOCK_SIZE bsize = BLOCK_64X64;
// Loop over sub-sample of frame, and compute average sad over 64x64 blocks.
uint64_t avg_sad = 0;
int num_samples = 0;
int sb_cols = (cm->mi_cols + MI_BLOCK_SIZE - 1) / MI_BLOCK_SIZE;
int sb_rows = (cm->mi_rows + MI_BLOCK_SIZE - 1) / MI_BLOCK_SIZE;
for (sbi_row = 0; sbi_row < sb_rows; sbi_row ++) {
for (sbi_col = 0; sbi_col < sb_cols; sbi_col ++) {
// Checker-board pattern, ignore boundary.
if ((sbi_row > 0 && sbi_col > 0) &&
(sbi_row < sb_rows - 1 && sbi_col < sb_cols - 1) &&
((sbi_row % 2 == 0 && sbi_col % 2 == 0) ||
(sbi_row % 2 != 0 && sbi_col % 2 != 0))) {
num_samples++;
avg_sad += cpi->fn_ptr[bsize].sdf(src_y,
src_ystride,
last_src_y,
last_src_ystride);
}
src_y += 64;
last_src_y += 64;
}
src_y += (src_ystride << 6) - (sb_cols << 6);
last_src_y += (last_src_ystride << 6) - (sb_cols << 6);
}
if (num_samples > 0)
avg_sad = avg_sad / num_samples;
// Set high_source_sad flag if we detect very high increase in avg_sad
// between current and the previous frame value(s). Use a minimum threshold
// for cases where there is small change from content that is completely
// static.
if (avg_sad > MAX(4000, (rc->avg_source_sad << 3)) &&
rc->frames_since_key > 1)
rc->high_source_sad = 1;
else
rc->high_source_sad = 0;
rc->avg_source_sad = (rc->avg_source_sad + avg_sad) >> 1;
}
}
// Test if encoded frame will significantly overshoot the target bitrate, and
// if so, set the QP, reset/adjust some rate control parameters, and return 1.
int vp9_encodedframe_overshoot(VP9_COMP *cpi,
int frame_size,
int *q) {
VP9_COMMON * const cm = &cpi->common;
RATE_CONTROL *const rc = &cpi->rc;
int thresh_qp = 3 * (rc->worst_quality >> 2);
int thresh_rate = rc->avg_frame_bandwidth * 10;
if (cm->base_qindex < thresh_qp &&
frame_size > thresh_rate) {
// Force a re-encode, and for now use max-QP.
*q = cpi->rc.worst_quality;
// Adjust avg_frame_qindex and buffer_level, as these parameters will affect
// QP selection for subsequent frames. If they have settled down to a very
// different (low QP) state, then not re-adjusting them may cause next
// frame to select low QP and overshoot again.
// TODO(marpan): Check if rate correction factor should also be adjusted.
cpi->rc.avg_frame_qindex[INTER_FRAME] = *q;
rc->buffer_level = rc->optimal_buffer_level;
rc->bits_off_target = rc->optimal_buffer_level;
return 1;
} else {
return 0;
}
}
......@@ -142,6 +142,9 @@ typedef struct {
int frame_width[FRAME_SCALE_STEPS];
int frame_height[FRAME_SCALE_STEPS];
int rf_level_maxq[RATE_FACTOR_LEVELS];
uint64_t avg_source_sad;
int high_source_sad;
} RATE_CONTROL;
struct VP9_COMP;
......@@ -256,6 +259,10 @@ void vp9_set_target_rate(struct VP9_COMP *cpi);
int vp9_resize_one_pass_cbr(struct VP9_COMP *cpi);
void vp9_avg_source_sad(struct VP9_COMP *cpi);
int vp9_encodedframe_overshoot(struct VP9_COMP *cpi, int frame_size, int *q);
#ifdef __cplusplus
} // extern "C"
#endif
......
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