/* * Copyright (c) 2010 The WebM project authors. All Rights Reserved. * * Use of this source code is governed by a BSD-style license * that can be found in the LICENSE file in the root of the source * tree. An additional intellectual property rights grant can be found * in the file PATENTS. All contributing project authors may * be found in the AUTHORS file in the root of the source tree.
*/
/* Resets the first pass file to the given position using a relative seek * from the current position
*/ staticvoid reset_fpf_position(VP8_COMP *cpi, FIRSTPASS_STATS *Position) {
cpi->twopass.stats_in = Position;
}
/* Read frame stats at an offset from the current position */ staticint read_frame_stats(VP8_COMP *cpi, FIRSTPASS_STATS *frame_stats, int offset) {
FIRSTPASS_STATS *fps_ptr = cpi->twopass.stats_in;
/* Check legality of offset */ if (offset >= 0) { if (&fps_ptr[offset] >= cpi->twopass.stats_in_end) return EOF;
} elseif (offset < 0) { if (&fps_ptr[offset] < cpi->twopass.stats_in_start) return EOF;
}
/* Loop throught the Y plane raw examining levels and creating a weight * for the image
*/
i = source->y_height; do {
j = source->y_width; do {
sum_weights += weight_table[*src];
src++;
} while (--j);
src -= source->y_width;
src += source->y_stride;
} while (--i);
/* This function returns the current per frame maximum bitrate target */ staticint frame_max_bits(VP8_COMP *cpi) { /* Max allocation for a single frame based on the max section guidelines * passed in and how many bits are left
*/ int max_bits;
/* For CBR we need to also consider buffer fullness. * If we are running below the optimal level then we need to gradually * tighten up on max_bits.
*/ if (cpi->oxcf.end_usage == USAGE_STREAM_FROM_SERVER) { double buffer_fullness_ratio =
(double)cpi->buffer_level /
DOUBLE_DIVIDE_CHECK((double)cpi->oxcf.optimal_buffer_level);
/* For CBR base this on the target average bits per frame plus the * maximum sedction rate passed in by the user
*/
max_bits = (int)(cpi->av_per_frame_bandwidth *
((double)cpi->oxcf.two_pass_vbrmax_section / 100.0));
/* If our buffer is below the optimum level */ if (buffer_fullness_ratio < 1.0) { /* The lower of max_bits / 4 or cpi->av_per_frame_bandwidth / 4. */ int min_max_bits = ((cpi->av_per_frame_bandwidth >> 2) < (max_bits >> 2))
? cpi->av_per_frame_bandwidth >> 2
: max_bits >> 2;
/* Lowest value we will set ... which should allow the buffer to * refill.
*/ if (max_bits < min_max_bits) max_bits = min_max_bits;
}
} /* VBR */ else { /* For VBR base this on the bits and frames left plus the * two_pass_vbrmax_section rate passed in by the user
*/
max_bits = saturate_cast_double_to_int(
((double)cpi->twopass.bits_left /
(cpi->twopass.total_stats.count -
(double)cpi->common.current_video_frame)) *
((double)cpi->oxcf.two_pass_vbrmax_section / 100.0));
}
/* Trap case where we are out of bits */ if (max_bits < 0) max_bits = 0;
staticvoid zz_motion_search(MACROBLOCK *x, YV12_BUFFER_CONFIG *raw_buffer, int *raw_motion_err,
YV12_BUFFER_CONFIG *recon_buffer, int *best_motion_err, int recon_yoffset) {
MACROBLOCKD *const xd = &x->e_mbd;
BLOCK *b = &x->block[0];
BLOCKD *d = &x->e_mbd.block[0];
unsignedchar *src_ptr = (*(b->base_src) + b->src); int src_stride = b->src_stride; unsignedchar *raw_ptr; int raw_stride = raw_buffer->y_stride; unsignedchar *ref_ptr; int ref_stride = x->e_mbd.pre.y_stride;
/* Set up pointers for this macro block raw buffer */
raw_ptr = (unsignedchar *)(raw_buffer->y_buffer + recon_yoffset + d->offset);
vpx_mse16x16(src_ptr, src_stride, raw_ptr, raw_stride,
(unsignedint *)(raw_motion_err));
/* Set up pointers for this macro block recon buffer */
xd->pre.y_buffer = recon_buffer->y_buffer + recon_yoffset;
ref_ptr = (unsignedchar *)(xd->pre.y_buffer + d->offset);
vpx_mse16x16(src_ptr, src_stride, ref_ptr, ref_stride,
(unsignedint *)(best_motion_err));
}
int tmp_err; int step_param = 3; /* Don't search over full range for first pass */ int further_steps = (MAX_MVSEARCH_STEPS - 1) - step_param; int n;
vp8_variance_fn_ptr_t v_fn_ptr = cpi->fn_ptr[BLOCK_16X16]; int new_mv_mode_penalty = 256;
/* override the default variance function to use MSE */
v_fn_ptr.vf = vpx_mse16x16;
/* Set up pointers for this macro block recon buffer */
xd->pre.y_buffer = recon_buffer->y_buffer + recon_yoffset;
/* Set up limit values for motion vectors to prevent them extending * outside the UMV borders
*/
x->mv_row_min = -((mb_row * 16) + (VP8BORDERINPIXELS - 16));
x->mv_row_max =
((cm->mb_rows - 1 - mb_row) * 16) + (VP8BORDERINPIXELS - 16);
/* for each macroblock col in image */ for (mb_col = 0; mb_col < cm->mb_cols; ++mb_col) { int this_error; int gf_motion_error = INT_MAX; int use_dc_pred = (mb_col || mb_row) && (!mb_col || !mb_row);
/* Copy current mb to a buffer */
vp8_copy_mem16x16(x->src.y_buffer, x->src.y_stride, x->thismb, 16);
/* do intra 16x16 prediction */
this_error = vp8_encode_intra(x, use_dc_pred);
/* "intrapenalty" below deals with situations where the intra * and inter error scores are very low (eg a plain black frame) * We do not have special cases in first pass for 0,0 and * nearest etc so all inter modes carry an overhead cost * estimate fot the mv. When the error score is very low this * causes us to pick all or lots of INTRA modes and throw lots * of key frames. This penalty adds a cost matching that of a * 0,0 mv to the intra case.
*/
this_error += intrapenalty;
/* Cumulative intra error total */
intra_error += (int64_t)this_error;
/* Set up limit values for motion vectors to prevent them * extending outside the UMV borders
*/
x->mv_col_min = -((mb_col * 16) + (VP8BORDERINPIXELS - 16));
x->mv_col_max =
((cm->mb_cols - 1 - mb_col) * 16) + (VP8BORDERINPIXELS - 16);
/* Other than for the first frame do a motion search */ if (cm->current_video_frame > 0) {
BLOCKD *d = &x->e_mbd.block[0];
MV tmp_mv = { 0, 0 }; int tmp_err; int motion_error = INT_MAX; int raw_motion_error = INT_MAX;
if (raw_motion_error < cpi->oxcf.encode_breakout) { goto skip_motion_search;
}
/* Test last reference frame using the previous best mv as the * starting point (best reference) for the search
*/
first_pass_motion_search(cpi, x, &best_ref_mv, &d->bmi.mv.as_mv,
lst_yv12, &motion_error, recon_yoffset);
/* If the current best reference mv is not centred on 0,0 * then do a 0,0 based search as well
*/ if (best_ref_mv.as_int) {
tmp_err = INT_MAX;
first_pass_motion_search(cpi, x, &zero_ref_mv, &tmp_mv, lst_yv12,
&tmp_err, recon_yoffset);
/* Experimental search in a second reference frame ((0,0) * based only)
*/ if (cm->current_video_frame > 1) {
first_pass_motion_search(cpi, x, &zero_ref_mv, &tmp_mv, gld_yv12,
&gf_motion_error, recon_yoffset);
/* Reset to last frame as reference buffer */
xd->pre.y_buffer = lst_yv12->y_buffer + recon_yoffset;
xd->pre.u_buffer = lst_yv12->u_buffer + recon_uvoffset;
xd->pre.v_buffer = lst_yv12->v_buffer + recon_uvoffset;
}
skip_motion_search: /* Intra assumed best */
best_ref_mv.as_int = 0;
if (motion_error <= this_error) { /* Keep a count of cases where the inter and intra were * very close and very low. This helps with scene cut * detection for example in cropped clips with black bars * at the sides or top and bottom.
*/ if ((((this_error - intrapenalty) * 9) <= (motion_error * 10)) &&
(this_error < (2 * intrapenalty))) {
neutral_count++;
}
/* TODO: handle the case when duration is set to 0, or something less * than the full time between subsequent cpi->source_time_stamps
*/
fps.duration = (double)(cpi->source->ts_end - cpi->source->ts_start);
/* don't want to do output stats with a stack variable! */
memcpy(&cpi->twopass.this_frame_stats, &fps, sizeof(FIRSTPASS_STATS));
output_stats(cpi->output_pkt_list, &cpi->twopass.this_frame_stats);
accumulate_stats(&cpi->twopass.total_stats, &fps);
}
/* Copy the previous Last Frame into the GF buffer if specific * conditions for doing so are met
*/ if ((cm->current_video_frame > 0) &&
(cpi->twopass.this_frame_stats.pcnt_inter > 0.20) &&
((cpi->twopass.this_frame_stats.intra_error /
DOUBLE_DIVIDE_CHECK(cpi->twopass.this_frame_stats.coded_error)) >
2.0)) {
vp8_yv12_copy_frame(lst_yv12, gld_yv12);
}
/* swap frame pointers so last frame refers to the frame we just * compressed
*/
vp8_swap_yv12_buffer(lst_yv12, new_yv12);
vp8_yv12_extend_frame_borders(lst_yv12);
/* Special case for the first frame. Copy into the GF buffer as a * second reference.
*/ if (cm->current_video_frame == 0) {
vp8_yv12_copy_frame(lst_yv12, gld_yv12);
}
/* Estimate a cost per mb attributable to overheads such as the coding of * modes and motion vectors. * Currently simplistic in its assumptions for testing.
*/
/* Estimate of extra bits per mv overhead for mbs * << 9 is the normalization to the (bits * 512) used in vp8_bits_per_mb
*/
mv_cost = ((int)(fpstats->new_mv_count / fpstats->count) * 8) << 9;
/* Crude estimate of overhead cost from modes * << 9 is the normalization to (bits * 512) used in vp8_bits_per_mb
*/
mode_cost =
(int64_t)((((av_pct_inter - av_pct_motion) * zz_cost) +
(av_pct_motion * motion_cost) + (av_intra * intra_cost)) *
cpi->common.MBs) *
512;
staticint estimate_max_q(VP8_COMP *cpi, FIRSTPASS_STATS *fpstats, int section_target_bandwitdh, int overhead_bits) { int Q; int num_mbs = cpi->common.MBs; int target_norm_bits_per_mb;
/* Calculate a corrective factor based on a rolling ratio of bits spent * vs target bits
*/ if ((cpi->rolling_target_bits > 0) &&
(cpi->active_worst_quality < cpi->worst_quality)) { double rolling_ratio;
/* Estimate of overhead bits per mb */ /* Correction to overhead bits for min allowed Q. */
overhead_bits_per_mb = overhead_bits / num_mbs;
overhead_bits_per_mb = (int)(overhead_bits_per_mb *
pow(0.98, (double)cpi->twopass.maxq_min_limit));
/* Try and pick a max Q that will be high enough to encode the * content at the given rate.
*/ for (Q = cpi->twopass.maxq_min_limit; Q < cpi->twopass.maxq_max_limit; ++Q) { int bits_per_mb_at_this_q;
/* Error per MB based correction factor */
err_correction_factor =
calc_correction_factor(err_per_mb, 150.0, 0.40, 0.90, Q);
/* Mode and motion overhead */ /* As Q rises in real encode loop rd code will force overhead down * We make a crude adjustment for this here as *.98 per Q step.
*/
overhead_bits_per_mb = (int)((double)overhead_bits_per_mb * 0.98);
if (bits_per_mb_at_this_q <= target_norm_bits_per_mb) 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->cq_target_quality;
}
/* Adjust maxq_min_limit and maxq_max_limit limits based on * average q observed in clip for non kf/gf.arf frames * Give average a chance to settle though.
*/ if ((cpi->ni_frames > ((int)cpi->twopass.total_stats.count >> 8)) &&
(cpi->ni_frames > 150)) {
cpi->twopass.maxq_max_limit = ((cpi->ni_av_qi + 32) < cpi->worst_quality)
? (cpi->ni_av_qi + 32)
: cpi->worst_quality;
cpi->twopass.maxq_min_limit = ((cpi->ni_av_qi - 32) > cpi->best_quality)
? (cpi->ni_av_qi - 32)
: cpi->best_quality;
}
return Q;
}
/* For cq mode estimate a cq level that matches the observed * complexity and data rate.
*/ staticint estimate_cq(VP8_COMP *cpi, FIRSTPASS_STATS *fpstats, int section_target_bandwitdh, int overhead_bits) { int Q; int num_mbs = cpi->common.MBs; int target_norm_bits_per_mb;
/* Mode and motion overhead */ /* As Q rises in real encode loop rd code will force overhead down * We make a crude adjustment for this here as *.98 per Q step.
*/
overhead_bits_per_mb = (int)((double)overhead_bits_per_mb * 0.98);
if (bits_per_mb_at_this_q <= target_norm_bits_per_mb) break;
}
/* Clip value to range "best allowed to (worst allowed - 1)" */
Q = cq_level[Q]; if (Q >= cpi->worst_quality) Q = cpi->worst_quality - 1; if (Q < cpi->best_quality) Q = cpi->best_quality;
return Q;
}
staticint estimate_q(VP8_COMP *cpi, double section_err, int section_target_bandwitdh) { int Q; int num_mbs = cpi->common.MBs; int target_norm_bits_per_mb;
if (bits_per_mb_at_this_q <= target_norm_bits_per_mb) break;
}
return Q;
}
/* Estimate a worst case Q for a KF group */ staticint estimate_kf_group_q(VP8_COMP *cpi, double section_err, int section_target_bandwitdh, double group_iiratio) { int Q; int num_mbs = cpi->common.MBs; int target_norm_bits_per_mb = (512 * section_target_bandwitdh) / num_mbs; int bits_per_mb_at_this_q;
/* Trap special case where the target is <= 0 */ if (target_norm_bits_per_mb <= 0) return MAXQ * 2;
/* Calculate a corrective factor based on a rolling ratio of bits spent * vs target bits * This is clamped to the range 0.1 to 10.0
*/ if (cpi->long_rolling_target_bits <= 0) {
current_spend_ratio = 10.0;
} else {
current_spend_ratio = (double)cpi->long_rolling_actual_bits /
(double)cpi->long_rolling_target_bits;
current_spend_ratio = (current_spend_ratio > 10.0) ? 10.0
: (current_spend_ratio < 0.1) ? 0.1
: current_spend_ratio;
}
/* Calculate a correction factor based on the quality of prediction in * the sequence as indicated by intra_inter error score ratio (IIRatio) * The idea here is to favour subsampling in the hardest sections vs * the easyest.
*/
iiratio_correction_factor = 1.0 - ((group_iiratio - 6.0) * 0.1);
if (iiratio_correction_factor < 0.5) iiratio_correction_factor = 0.5;
/* Combine the various factors calculated above */
combined_correction_factor =
speed_correction * iiratio_correction_factor * current_spend_ratio;
/* Try and pick a Q that should be high enough to encode the content at * the given rate.
*/ for (Q = 0; Q < MAXQ; ++Q) { /* Error per MB based correction factor */
err_correction_factor =
calc_correction_factor(err_per_mb, 150.0, pow_lowq, pow_highq, Q);
if (bits_per_mb_at_this_q <= target_norm_bits_per_mb) break;
}
/* If we could not hit the target even at Max Q then estimate what Q * would have been required
*/ while ((bits_per_mb_at_this_q > target_norm_bits_per_mb) &&
(Q < (MAXQ * 2))) {
bits_per_mb_at_this_q = (int)(0.96 * bits_per_mb_at_this_q);
Q++;
}
/* each frame can have a different duration, as the frame rate in the * source isn't guaranteed to be constant. The frame rate prior to * the first frame encoded in the second pass is a guess. However the * sum duration is not. Its calculated based on the actual durations of * all frames from the first pass.
*/
vp8_new_framerate(cpi, 10000000.0 * cpi->twopass.total_stats.count /
cpi->twopass.total_stats.duration);
/* 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 * that clips that are static but "low complexity" in the intra domain * are still boosted appropriately for KF/GF/ARF
*/
cpi->twopass.kf_intra_err_min = KF_MB_INTRA_MIN * cpi->common.MBs;
cpi->twopass.gf_intra_err_min = GF_MB_INTRA_MIN * cpi->common.MBs;
/* Scan the first pass file and calculate an average Intra / Inter error * score ratio for the sequence
*/
{ double sum_iiratio = 0.0; double IIRatio;
start_pos = cpi->twopass.stats_in; /* Note starting "file" position */
/* Reset file position */
reset_fpf_position(cpi, start_pos);
}
/* Scan the first pass file and calculate a modified total error based * upon the bias/power function used to allocate bits
*/
{
start_pos = cpi->twopass.stats_in; /* Note starting "file" position */
/* This function gives and estimate of how badly we believe the prediction * quality is decaying from frame to frame.
*/ staticdouble get_prediction_decay_rate(FIRSTPASS_STATS *next_frame) { double prediction_decay_rate; double motion_decay; double motion_pct = next_frame->pcnt_motion;
/* Initial basis is the % mbs inter coded */
prediction_decay_rate = next_frame->pcnt_inter;
/* Function to test for a condition where a complex transition is followed * by a static section. For example in slide shows where there is a fade * between slides. This is to help with more optimal kf and gf positioning.
*/ staticint detect_transition_to_still(VP8_COMP *cpi, int frame_interval, int still_interval, double loop_decay_rate, double decay_accumulator) { int trans_to_still = 0;
/* Break clause to detect very still sections after motion * For example a static image after a fade or other transition * instead of a clean scene cut.
*/ if ((frame_interval > MIN_GF_INTERVAL) && (loop_decay_rate >= 0.999) &&
(decay_accumulator < 0.9)) { int j;
FIRSTPASS_STATS *position = cpi->twopass.stats_in;
FIRSTPASS_STATS tmp_next_frame; double decay_rate;
/* Look ahead a few frames to see if static condition persists... */ for (j = 0; j < still_interval; ++j) { if (EOF == input_stats(cpi, &tmp_next_frame)) break;
decay_rate = get_prediction_decay_rate(&tmp_next_frame); if (decay_rate < 0.999) break;
} /* Reset file position */
reset_fpf_position(cpi, position);
/* Only if it does do we signal a transition to still */ if (j == still_interval) trans_to_still = 1;
}
return trans_to_still;
}
/* This function detects a flash through the high relative pcnt_second_ref * score in the frame following a flash frame. The offset passed in should * reflect this
*/ staticint detect_flash(VP8_COMP *cpi, int offset) {
FIRSTPASS_STATS next_frame;
int flash_detected = 0;
/* Read the frame data. */ /* The return is 0 (no flash detected) if not a valid frame */ if (read_frame_stats(cpi, &next_frame, offset) != EOF) { /* What we are looking for here is a situation where there is a * brief break in prediction (such as a flash) but subsequent frames * are reasonably well predicted by an earlier (pre flash) frame. * The recovery after a flash is indicated by a high pcnt_second_ref * comapred to pcnt_inter.
*/ if ((next_frame.pcnt_second_ref > next_frame.pcnt_inter) &&
(next_frame.pcnt_second_ref >= 0.5)) {
flash_detected = 1;
/* Accumulate a measure of how uniform (or conversely how random) * the motion field is. (A ratio of absmv / mv)
*/ if (motion_pct > 0.05) {
this_frame_mvr_ratio =
fabs(this_frame->mvr_abs) / DOUBLE_DIVIDE_CHECK(fabs(this_frame->MVr));
/* Calculate a baseline boost number for the current frame. */ staticdouble calc_frame_boost(VP8_COMP *cpi, FIRSTPASS_STATS *this_frame, double this_frame_mv_in_out) { double frame_boost;
/* Underlying boost factor is based on inter intra error ratio */ if (this_frame->intra_error > cpi->twopass.gf_intra_err_min) {
frame_boost = (IIFACTOR * this_frame->intra_error /
DOUBLE_DIVIDE_CHECK(this_frame->coded_error));
} else {
frame_boost = (IIFACTOR * cpi->twopass.gf_intra_err_min /
DOUBLE_DIVIDE_CHECK(this_frame->coded_error));
}
/* Increase boost for frames where new data coming into frame * (eg zoom out). Slightly reduce boost if there is a net balance * of motion out of the frame (zoom in). * The range for this_frame_mv_in_out is -1.0 to +1.0
*/ if (this_frame_mv_in_out > 0.0) {
frame_boost += frame_boost * (this_frame_mv_in_out * 2.0); /* In extreme case boost is halved */
} else {
frame_boost += frame_boost * (this_frame_mv_in_out / 2.0);
}
/* Clip to maximum */ if (frame_boost > GF_RMAX) frame_boost = GF_RMAX;
return frame_boost;
}
#if NEW_BOOST staticint calc_arf_boost(VP8_COMP *cpi, int offset, int f_frames, int b_frames, int *f_boost, int *b_boost) {
FIRSTPASS_STATS this_frame;
/* Search forward from the proposed arf/next gf position */ for (i = 0; i < f_frames; ++i) { if (read_frame_stats(cpi, &this_frame, (i + offset)) == EOF) break;
/* Update the motion related elements to the boost calculation */
accumulate_frame_motion_stats(
&this_frame, &this_frame_mv_in_out, &mv_in_out_accumulator,
&abs_mv_in_out_accumulator, &mv_ratio_accumulator);
/* Calculate the baseline boost number for this frame */
r = calc_frame_boost(cpi, &this_frame, this_frame_mv_in_out);
/* We want to discount the flash frame itself and the recovery * frame that follows as both will have poor scores.
*/
flash_detected =
detect_flash(cpi, (i + offset)) || detect_flash(cpi, (i + offset + 1));
/* Search forward from the proposed arf/next gf position */ for (i = -1; i >= -b_frames; i--) { if (read_frame_stats(cpi, &this_frame, (i + offset)) == EOF) break;
/* Update the motion related elements to the boost calculation */
accumulate_frame_motion_stats(
&this_frame, &this_frame_mv_in_out, &mv_in_out_accumulator,
&abs_mv_in_out_accumulator, &mv_ratio_accumulator);
/* Calculate the baseline boost number for this frame */
r = calc_frame_boost(cpi, &this_frame, this_frame_mv_in_out);
/* We want to discount the flash frame itself and the recovery * frame that follows as both will have poor scores.
*/
flash_detected =
detect_flash(cpi, (i + offset)) || detect_flash(cpi, (i + offset + 1));
/* Load stats for the current frame. */
mod_frame_err = calculate_modified_err(cpi, this_frame);
/* Note the error of the frame at the start of the group (this will be * the GF frame error if we code a normal gf
*/
gf_first_frame_err = mod_frame_err;
/* Special treatment if the current frame is a key frame (which is also * a gf). If it is then its error score (and hence bit allocation) need * to be subtracted out from the calculation for the GF group
*/ if (cpi->common.frame_type == KEY_FRAME) gf_group_err -= gf_first_frame_err;
/* Scan forward to try and work out how many frames the next gf group * should contain and what level of boost is appropriate for the GF * or ARF that will be coded with the group
*/
i = 0;
while (((i < cpi->twopass.static_scene_max_gf_interval) ||
((cpi->twopass.frames_to_key - i) < MIN_GF_INTERVAL)) &&
(i < cpi->twopass.frames_to_key)) {
i++;
/* Accumulate error score of frames in this gf group */
mod_frame_err = calculate_modified_err(cpi, this_frame);
gf_group_err += mod_frame_err;
if (EOF == input_stats(cpi, &next_frame)) break;
/* Test for the case where there is a brief flash but the prediction * quality back to an earlier frame is then restored.
*/
flash_detected = detect_flash(cpi, 0);
/* Update the motion related elements to the boost calculation */
accumulate_frame_motion_stats(
&next_frame, &this_frame_mv_in_out, &mv_in_out_accumulator,
&abs_mv_in_out_accumulator, &mv_ratio_accumulator);
/* Calculate a baseline boost number for this frame */
r = calc_frame_boost(cpi, &next_frame, this_frame_mv_in_out);
/* Break clause to detect very still sections after motion * For example a staic image after a fade or other transition.
*/ if (detect_transition_to_still(cpi, i, 5, loop_decay_rate,
decay_accumulator)) {
allow_alt_ref = 0;
boost_score = old_boost_score; break;
}
/* Break out conditions. */ if ( /* Break at cpi->max_gf_interval unless almost totally static */
(i >= cpi->max_gf_interval && (decay_accumulator < 0.995)) ||
( /* Don't break out with a very short interval */
(i > MIN_GF_INTERVAL) && /* Don't break out very close to a key frame */
((cpi->twopass.frames_to_key - i) >= MIN_GF_INTERVAL) &&
((boost_score > 20.0) || (next_frame.pcnt_inter < 0.75)) &&
(!flash_detected) &&
((mv_ratio_accumulator > 100.0) ||
(abs_mv_in_out_accumulator > 3.0) ||
(mv_in_out_accumulator < -2.0) ||
((boost_score - old_boost_score) < 2.0)))) {
boost_score = old_boost_score; break;
}
if (boost_score > max_boost) boost_score = max_boost;
}
/* Don't allow conventional gf too near the next kf */ if ((cpi->twopass.frames_to_key - i) < MIN_GF_INTERVAL) { while (i < cpi->twopass.frames_to_key) {
i++;
if (EOF == input_stats(cpi, this_frame)) break;
if (i < cpi->twopass.frames_to_key) {
mod_frame_err = calculate_modified_err(cpi, this_frame);
gf_group_err += mod_frame_err;
}
}
}
cpi->gfu_boost = (int)(boost_score * 100.0) >> 4;
#if NEW_BOOST /* Alterrnative boost calculation for alt ref */
alt_boost = calc_arf_boost(cpi, 0, (i - 1), (i - 1), &f_boost, &b_boost); #endif
/* Should we use the alternate reference frame */ if (allow_alt_ref && (i >= MIN_GF_INTERVAL) && /* don't use ARF very near next kf */
(i <= (cpi->twopass.frames_to_key - MIN_GF_INTERVAL)) && #if NEW_BOOST
((next_frame.pcnt_inter > 0.75) || (next_frame.pcnt_second_ref > 0.5)) &&
((mv_in_out_accumulator / (double)i > -0.2) ||
(mv_in_out_accumulator > -2.0)) &&
(b_boost > 100) && (f_boost > 100)) #else
(next_frame.pcnt_inter > 0.75) &&
((mv_in_out_accumulator / (double)i > -0.2) ||
(mv_in_out_accumulator > -2.0)) &&
(cpi->gfu_boost > 100) &&
(cpi->twopass.gf_decay_rate <=
(ARF_DECAY_THRESH + (cpi->gfu_boost / 200)))) #endif
{ int Boost; int allocation_chunks; int Q =
(cpi->oxcf.fixed_q < 0) ? cpi->last_q[INTER_FRAME] : cpi->oxcf.fixed_q; int tmp_q; int arf_frame_bits = 0; int group_bits;
#if NEW_BOOST
cpi->gfu_boost = alt_boost; #endif
/* Estimate the bits to be allocated to the group as a whole */ if ((cpi->twopass.kf_group_bits > 0) &&
(cpi->twopass.kf_group_error_left > 0)) {
group_bits =
(int)((double)cpi->twopass.kf_group_bits *
(gf_group_err / (double)cpi->twopass.kf_group_error_left));
} else {
group_bits = 0;
}
/* Set max and minimum boost and hence minimum allocation */ if (Boost > ((cpi->baseline_gf_interval + 1) * 200)) {
Boost = ((cpi->baseline_gf_interval + 1) * 200);
} elseif (Boost < 125) {
Boost = 125;
}
allocation_chunks = (i * 100) + Boost;
/* Normalize Altboost and allocations chunck down to prevent overflow */ while (Boost > 1000) {
Boost /= 2;
allocation_chunks /= 2;
}
/* Calculate the number of bits to be spent on the arf based on the * boost number
*/
arf_frame_bits =
(int)((double)Boost * (group_bits / (double)allocation_chunks));
/* Estimate if there are enough bits available to make worthwhile use * of an arf.
*/
tmp_q = estimate_q(cpi, mod_frame_err, (int)arf_frame_bits);
/* Only use an arf if it is likely we will be able to code * it at a lower Q than the surrounding frames.
*/ if (tmp_q < cpi->worst_quality) { int half_gf_int; int frames_after_arf; int frames_bwd = cpi->oxcf.arnr_max_frames - 1; int frames_fwd = cpi->oxcf.arnr_max_frames - 1;
cpi->source_alt_ref_pending = 1;
/* * For alt ref frames the error score for the end frame of the * group (the alt ref frame) should not contribute to the group * total and hence the number of bit allocated to the group. * Rather it forms part of the next group (it is the GF at the * start of the next group) * gf_group_err -= mod_frame_err; * * For alt ref frames alt ref frame is technically part of the * GF frame for the next group but we always base the error * calculation and bit allocation on the current group of frames. * * Set the interval till the next gf or arf. * For ARFs this is the number of frames to be coded before the * future frame that is coded as an ARF. * The future frame itself is part of the next group
*/
cpi->baseline_gf_interval = i;
/* * Define the arnr filter width for this group of frames: * We only filter frames that lie within a distance of half * the GF interval from the ARF frame. We also have to trap * cases where the filter extends beyond the end of clip. * Note: this_frame->frame has been updated in the loop * so it now points at the ARF frame.
*/
half_gf_int = cpi->baseline_gf_interval >> 1;
frames_after_arf =
(int)(cpi->twopass.total_stats.count - this_frame->frame - 1);
switch (cpi->oxcf.arnr_type) { case 1: /* Backward filter */
frames_fwd = 0; if (frames_bwd > half_gf_int) frames_bwd = half_gf_int; break;
case 2: /* Forward filter */ if (frames_fwd > half_gf_int) frames_fwd = half_gf_int; if (frames_fwd > frames_after_arf) frames_fwd = frames_after_arf;
frames_bwd = 0; break;
case 3: /* Centered filter */ default:
frames_fwd >>= 1; if (frames_fwd > frames_after_arf) frames_fwd = frames_after_arf; if (frames_fwd > half_gf_int) frames_fwd = half_gf_int;
frames_bwd = frames_fwd;
/* For even length filter there is one more frame backward * than forward: e.g. len=6 ==> bbbAff, len=7 ==> bbbAfff.
*/ if (frames_bwd < half_gf_int) {
frames_bwd += (cpi->oxcf.arnr_max_frames + 1) & 0x1;
} break;
}
/* * Now decide how many bits should be allocated to the GF group as a * proportion of those remaining in the kf group. * The final key frame group in the clip is treated as a special case * where cpi->twopass.kf_group_bits is tied to cpi->twopass.bits_left. * This is also important for short clips where there may only be one * key frame.
*/ if (cpi->twopass.frames_to_key >=
(int)(cpi->twopass.total_stats.count - cpi->common.current_video_frame)) {
cpi->twopass.kf_group_bits =
(cpi->twopass.bits_left > 0) ? cpi->twopass.bits_left : 0;
}
/* Calculate the bits to be allocated to the group as a whole */ if ((cpi->twopass.kf_group_bits > 0) &&
(cpi->twopass.kf_group_error_left > 0)) {
cpi->twopass.gf_group_bits =
(int64_t)(cpi->twopass.kf_group_bits *
(gf_group_err / cpi->twopass.kf_group_error_left));
} else {
cpi->twopass.gf_group_bits = 0;
}
/* Clip cpi->twopass.gf_group_bits based on user supplied data rate * variability limit (cpi->oxcf.two_pass_vbrmax_section)
*/ if (cpi->twopass.gf_group_bits >
(int64_t)max_bits * cpi->baseline_gf_interval) {
cpi->twopass.gf_group_bits = (int64_t)max_bits * cpi->baseline_gf_interval;
}
/* Reset the file position */
reset_fpf_position(cpi, start_pos);
/* Update the record of error used so far (only done once per gf group) */
cpi->twopass.modified_error_used += gf_group_err;
/* Assign bits to the arf or gf. */ for (i = 0; i <= (cpi->source_alt_ref_pending &&
cpi->common.frame_type != KEY_FRAME);
i++) { int Boost; int allocation_chunks; int Q =
(cpi->oxcf.fixed_q < 0) ? cpi->last_q[INTER_FRAME] : cpi->oxcf.fixed_q; int gf_bits;
/* Set max and minimum boost and hence minimum allocation */ if (Boost > ((cpi->baseline_gf_interval + 1) * 200)) {
Boost = ((cpi->baseline_gf_interval + 1) * 200);
} elseif (Boost < 125) {
Boost = 125;
}
allocation_chunks = ((cpi->baseline_gf_interval + 1) * 100) + Boost;
} /* Else for standard golden frames */ else { /* boost based on inter / intra ratio of subsequent frames */
Boost = (cpi->gfu_boost * GFQ_ADJUSTMENT) / 100;
/* Set max and minimum boost and hence minimum allocation */ if (Boost > (cpi->baseline_gf_interval * 150)) {
Boost = (cpi->baseline_gf_interval * 150);
} elseif (Boost < 125) {
Boost = 125;
}
/* Normalize Altboost and allocations chunck down to prevent overflow */ while (Boost > 1000) {
Boost /= 2;
allocation_chunks /= 2;
}
/* Calculate the number of bits to be spent on the gf or arf based on * the boost number
*/
gf_bits = saturate_cast_double_to_int(
(double)Boost *
(cpi->twopass.gf_group_bits / (double)allocation_chunks));
/* If the frame that is to be boosted is simpler than the average for * the gf/arf group then use an alternative calculation * based on the error score of the frame itself
*/ if (mod_frame_err < gf_group_err / (double)cpi->baseline_gf_interval) { double alt_gf_grp_bits; int alt_gf_bits;
if (gf_bits > alt_gf_bits) {
gf_bits = alt_gf_bits;
}
} /* Else if it is harder than other frames in the group make sure it at * least receives an allocation in keeping with its relative error * score, otherwise it may be worse off than an "un-boosted" frame
*/ else { // Avoid division by 0 by clamping cpi->twopass.kf_group_error_left to 1 int alt_gf_bits = saturate_cast_double_to_int(
(double)cpi->twopass.kf_group_bits * mod_frame_err /
(double)VPXMAX(cpi->twopass.kf_group_error_left, 1));
if (alt_gf_bits > gf_bits) {
gf_bits = alt_gf_bits;
}
}
/* Apply an additional limit for CBR */ if (cpi->oxcf.end_usage == USAGE_STREAM_FROM_SERVER) { if (cpi->twopass.gf_bits > (int)(cpi->buffer_level >> 1)) {
cpi->twopass.gf_bits = (int)(cpi->buffer_level >> 1);
}
}
/* Don't allow a negative value for gf_bits */ if (gf_bits < 0) gf_bits = 0;
/* Add in minimum for a frame */
gf_bits += cpi->min_frame_bandwidth;
if (i == 0) {
cpi->twopass.gf_bits = gf_bits;
} if (i == 1 || (!cpi->source_alt_ref_pending &&
(cpi->common.frame_type != KEY_FRAME))) { /* Per frame bit target for this frame */
cpi->per_frame_bandwidth = gf_bits;
}
}
{ /* Adjust KF group bits and error remainin */
cpi->twopass.kf_group_error_left -= (int64_t)gf_group_err;
cpi->twopass.kf_group_bits -= cpi->twopass.gf_group_bits;
if (cpi->twopass.kf_group_bits < 0) cpi->twopass.kf_group_bits = 0;
/* Note the error score left in the remaining frames of the group. * For normal GFs we want to remove the error score for the first * frame of the group (except in Key frame case where this has * already happened)
*/ if (!cpi->source_alt_ref_pending && cpi->common.frame_type != KEY_FRAME) {
cpi->twopass.gf_group_error_left =
(int)(gf_group_err - gf_first_frame_err);
} else {
cpi->twopass.gf_group_error_left = (int)gf_group_err;
}
if (cpi->twopass.gf_group_bits < 0) cpi->twopass.gf_group_bits = 0;
/* This condition could fail if there are two kfs very close together * despite (MIN_GF_INTERVAL) and would cause a divide by 0 in the * calculation of cpi->twopass.alt_extra_bits.
*/ if (cpi->baseline_gf_interval >= 3) { #if NEW_BOOST int boost = (cpi->source_alt_ref_pending) ? b_boost : cpi->gfu_boost; #else int boost = cpi->gfu_boost; #endif if (boost >= 150) { int pct_extra;
/* Adjustments based on a measure of complexity of the section */ if (cpi->common.frame_type != KEY_FRAME) {
FIRSTPASS_STATS sectionstats; double Ratio;
if (cpi->twopass.section_max_qfactor < 0.80) {
cpi->twopass.section_max_qfactor = 0.80;
}
reset_fpf_position(cpi, start_pos);
}
}
/* Allocate bits to a normal frame that is neither a gf an arf or a key frame.
*/ staticvoid assign_std_frame_bits(VP8_COMP *cpi, FIRSTPASS_STATS *this_frame) { int target_frame_size;
double modified_err; double err_fraction;
int max_bits = frame_max_bits(cpi); /* Max for a single frame */
/* Calculate modified prediction error used in bit allocation */
modified_err = calculate_modified_err(cpi, this_frame);
/* What portion of the remaining GF group error is used by this frame */ if (cpi->twopass.gf_group_error_left > 0) {
err_fraction = modified_err / cpi->twopass.gf_group_error_left;
} else {
err_fraction = 0.0;
}
/* How many of those bits available for allocation should we give it? */
target_frame_size = saturate_cast_double_to_int(
(double)cpi->twopass.gf_group_bits * err_fraction);
/* Clip to target size to 0 - max_bits (or cpi->twopass.gf_group_bits) * at the top end.
*/ if (target_frame_size < 0) {
target_frame_size = 0;
} else { if (target_frame_size > max_bits) target_frame_size = max_bits;
if (target_frame_size > cpi->twopass.gf_group_bits) {
target_frame_size = (int)cpi->twopass.gf_group_bits;
}
}
if (cpi->twopass.gf_group_bits < 0) cpi->twopass.gf_group_bits = 0;
/* Add in the minimum number of bits that is set aside for every frame. */
target_frame_size += cpi->min_frame_bandwidth;
/* Every other frame gets a few extra bits */ if ((cpi->frames_since_golden & 0x01) &&
(cpi->frames_till_gf_update_due > 0)) {
target_frame_size += cpi->twopass.alt_extra_bits;
}
/* Per frame bit target for this frame */
cpi->per_frame_bandwidth = target_frame_size;
}
void vp8_second_pass(VP8_COMP *cpi) { int tmp_q; int frames_left =
(int)(cpi->twopass.total_stats.count - cpi->common.current_video_frame);
/* keyframe and section processing ! */ if (cpi->twopass.frames_to_key == 0) { /* Define next KF group and assign bits to it */
memcpy(&this_frame_copy, &this_frame, sizeof(this_frame));
find_next_key_frame(cpi, &this_frame_copy);
/* Special case: Error error_resilient_mode mode does not make much * sense for two pass but with its current meaning this code is * designed to stop outlandish behaviour if someone does set it when * using two pass. It effectively disables GF groups. This is * temporary code until we decide what should really happen in this * case.
*/ if (cpi->oxcf.error_resilient_mode) {
cpi->twopass.gf_group_bits = cpi->twopass.kf_group_bits;
cpi->twopass.gf_group_error_left = (int)cpi->twopass.kf_group_error_left;
cpi->baseline_gf_interval = cpi->twopass.frames_to_key;
cpi->frames_till_gf_update_due = cpi->baseline_gf_interval;
cpi->source_alt_ref_pending = 0;
}
}
/* Is this a GF / ARF (Note that a KF is always also a GF) */ if (cpi->frames_till_gf_update_due == 0) { /* Define next gf group and assign bits to it */
memcpy(&this_frame_copy, &this_frame, sizeof(this_frame));
define_gf_group(cpi, &this_frame_copy);
/* If we are going to code an altref frame at the end of the group * and the current frame is not a key frame.... If the previous * group used an arf this frame has already benefited from that arf * boost and it should not be given extra bits If the previous * group was NOT coded using arf we may want to apply some boost to * this GF as well
*/ if (cpi->source_alt_ref_pending && (cpi->common.frame_type != KEY_FRAME)) { /* Assign a standard frames worth of bits from those allocated * to the GF group
*/ int bak = cpi->per_frame_bandwidth;
memcpy(&this_frame_copy, &this_frame, sizeof(this_frame));
assign_std_frame_bits(cpi, &this_frame_copy);
cpi->per_frame_bandwidth = bak;
}
}
/* Otherwise this is an ordinary frame */ else { /* Special case: Error error_resilient_mode mode does not make much * sense for two pass but with its current meaning but this code is * designed to stop outlandish behaviour if someone does set it * when using two pass. It effectively disables GF groups. This is * temporary code till we decide what should really happen in this * case.
*/ if (cpi->oxcf.error_resilient_mode) {
cpi->frames_till_gf_update_due = cpi->twopass.frames_to_key;
if (cpi->common.frame_type != KEY_FRAME) { /* Assign bits from those allocated to the GF group */
memcpy(&this_frame_copy, &this_frame, sizeof(this_frame));
assign_std_frame_bits(cpi, &this_frame_copy);
}
} else { /* Assign bits from those allocated to the GF group */
memcpy(&this_frame_copy, &this_frame, sizeof(this_frame));
assign_std_frame_bits(cpi, &this_frame_copy);
}
}
/* Keep a globally available copy of this and the next frame's iiratio. */
cpi->twopass.this_iiratio =
(unsignedint)(this_frame_intra_error /
DOUBLE_DIVIDE_CHECK(this_frame_coded_error));
{
FIRSTPASS_STATS next_frame; if (lookup_next_frame_stats(cpi, &next_frame) != EOF) {
cpi->twopass.next_iiratio =
(unsignedint)(next_frame.intra_error /
DOUBLE_DIVIDE_CHECK(next_frame.coded_error));
}
}
/* Set nominal per second bandwidth for this frame */
cpi->target_bandwidth =
(int)(cpi->per_frame_bandwidth * cpi->output_framerate); if (cpi->target_bandwidth < 0) cpi->target_bandwidth = 0;
/* Account for mv, mode and other overheads. */
overhead_bits = (int)estimate_modemvcost(cpi, &cpi->twopass.total_left_stats);
/* Special case code for first frame. */ if (cpi->common.current_video_frame == 0) {
cpi->twopass.est_max_qcorrection_factor = 1.0;
/* Limit the maxq value returned subsequently. * This increases the risk of overspend or underspend if the initial * estimate for the clip is bad, but helps prevent excessive * variation in Q, especially near the end of a clip * where for example a small overspend may cause Q to crash
*/
cpi->twopass.maxq_max_limit =
((tmp_q + 32) < cpi->worst_quality) ? (tmp_q + 32) : cpi->worst_quality;
cpi->twopass.maxq_min_limit =
((tmp_q - 32) > cpi->best_quality) ? (tmp_q - 32) : cpi->best_quality;
/* 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 don't want to make * radical adjustments to the allowed quantizer range just to use up a * few surplus bits or get beneath the target rate.
*/ elseif ((cpi->common.current_video_frame <
(((unsignedint)cpi->twopass.total_stats.count * 255) >> 8)) &&
((cpi->common.current_video_frame + cpi->baseline_gf_interval) <
(unsignedint)cpi->twopass.total_stats.count)) { if (frames_left < 1) frames_left = 1;
/* Move active_worst_quality but in a damped way */ if (tmp_q > cpi->active_worst_quality) {
cpi->active_worst_quality++;
} elseif (tmp_q < cpi->active_worst_quality) {
cpi->active_worst_quality--;
}
/* Note the starting file position so we can reset to it */
start_pos = cpi->twopass.stats_in;
/* Examine how well the key frame predicts subsequent frames */ for (i = 0; i < 16; ++i) {
next_iiratio = (IIKFACTOR1 * local_next_frame.intra_error /
DOUBLE_DIVIDE_CHECK(local_next_frame.coded_error));
/* Get the next frame details */ if (EOF == input_stats(cpi, &local_next_frame)) break;
}
/* If there is tolerable prediction for at least the next 3 frames * then break out else discard this pottential key frame and move on
*/ if (boost_score > 5.0 && (i > 3)) {
is_viable_kf = 1;
} else { /* Reset the file position */
reset_fpf_position(cpi, start_pos);
is_viable_kf = 0;
}
}
return is_viable_kf;
} staticvoid find_next_key_frame(VP8_COMP *cpi, FIRSTPASS_STATS *this_frame) { int i, j;
FIRSTPASS_STATS last_frame;
FIRSTPASS_STATS first_frame;
FIRSTPASS_STATS next_frame;
FIRSTPASS_STATS *start_position;
/* find the next keyframe */
i = 0; while (cpi->twopass.stats_in < cpi->twopass.stats_in_end) { /* Accumulate kf group error */
kf_group_err += calculate_modified_err(cpi, this_frame);
/* These figures keep intra and coded error counts for all frames * including key frames in the group. The effect of the key frame * itself can be subtracted out using the first_frame data * collected above
*/
kf_group_intra_err += this_frame->intra_error;
kf_group_coded_err += this_frame->coded_error;
/* Load the next frame's stats. */
memcpy(&last_frame, this_frame, sizeof(*this_frame));
input_stats(cpi, this_frame);
/* Provided that we are not at the end of the file... */ if (cpi->oxcf.auto_key &&
lookup_next_frame_stats(cpi, &next_frame) != EOF) { /* Normal scene cut check */ if ((i >= MIN_GF_INTERVAL) &&
test_candidate_kf(cpi, &last_frame, this_frame, &next_frame)) { break;
}
/* How fast is prediction quality decaying */
loop_decay_rate = get_prediction_decay_rate(&next_frame);
/* We want to know something about the recent past... rather than * as used elsewhere where we are concened with decay in prediction * quality since the last GF or KF.
*/
recent_loop_decay[i % 8] = loop_decay_rate;
decay_accumulator = 1.0; for (j = 0; j < 8; ++j) {
decay_accumulator = decay_accumulator * recent_loop_decay[j];
}
/* Special check for transition or high motion followed by a * static scene.
*/ if (detect_transition_to_still(cpi, i,
((int)(cpi->key_frame_frequency) - (int)i),
loop_decay_rate, decay_accumulator)) { break;
}
/* Step on to the next frame */
cpi->twopass.frames_to_key++;
/* If we don't have a real key frame within the next two * forcekeyframeevery intervals then break out of the loop.
*/ if (cpi->twopass.frames_to_key >= 2 * (int)cpi->key_frame_frequency) { break;
}
} else {
cpi->twopass.frames_to_key++;
}
i++;
}
/* If there is a max kf interval set by the user we must obey it. * We already breakout of the loop above at 2x max. * This code centers the extra kf if the actual natural * interval is between 1x and 2x
*/ if (cpi->oxcf.auto_key &&
cpi->twopass.frames_to_key > (int)cpi->key_frame_frequency) {
FIRSTPASS_STATS *current_pos = cpi->twopass.stats_in;
FIRSTPASS_STATS tmp_frame;
cpi->twopass.frames_to_key /= 2;
/* Copy first frame details */
memcpy(&tmp_frame, &first_frame, sizeof(first_frame));
/* Reset to the start of the group */
reset_fpf_position(cpi, start_position);
/* Rescan to get the correct error data for the forced kf group */ for (i = 0; i < cpi->twopass.frames_to_key; ++i) { /* Accumulate kf group errors */
kf_group_err += calculate_modified_err(cpi, &tmp_frame);
kf_group_intra_err += tmp_frame.intra_error;
kf_group_coded_err += tmp_frame.coded_error;
/* Load a the next frame's stats */
input_stats(cpi, &tmp_frame);
}
/* Reset to the start of the group */
reset_fpf_position(cpi, current_pos);
/* Special case for the last frame of the file */ if (cpi->twopass.stats_in >= cpi->twopass.stats_in_end) { /* Accumulate kf group error */
kf_group_err += calculate_modified_err(cpi, this_frame);
/* These figures keep intra and coded error counts for all frames * including key frames in the group. The effect of the key frame * itself can be subtracted out using the first_frame data * collected above
*/
kf_group_intra_err += this_frame->intra_error;
kf_group_coded_err += this_frame->coded_error;
}
/* Calculate the number of bits that should be assigned to the kf group. */ if ((cpi->twopass.bits_left > 0) &&
(cpi->twopass.modified_error_left > 0.0)) { /* Max for a single normal frame (not key frame) */ int max_bits = frame_max_bits(cpi);
/* Maximum bits for the kf group */
int64_t max_grp_bits;
/* Default allocation based on bits left and relative * complexity of the section
*/
cpi->twopass.kf_group_bits =
(int64_t)(cpi->twopass.bits_left *
(kf_group_err / cpi->twopass.modified_error_left));
/* Clip based on maximum per frame rate defined by the user. */
max_grp_bits = (int64_t)max_bits * (int64_t)cpi->twopass.frames_to_key; if (cpi->twopass.kf_group_bits > max_grp_bits) {
cpi->twopass.kf_group_bits = max_grp_bits;
}
/* Additional special case for CBR if buffer is getting full. */ if (cpi->oxcf.end_usage == USAGE_STREAM_FROM_SERVER) {
int64_t opt_buffer_lvl = cpi->oxcf.optimal_buffer_level;
int64_t buffer_lvl = cpi->buffer_level;
/* If the buffer is near or above the optimal and this kf group is * not being allocated much then increase the allocation a bit.
*/ if (buffer_lvl >= opt_buffer_lvl) {
int64_t high_water_mark =
(opt_buffer_lvl + cpi->oxcf.maximum_buffer_size) >> 1;
int64_t av_group_bits;
/* Av bits per frame * number of frames */
av_group_bits = (int64_t)cpi->av_per_frame_bandwidth *
(int64_t)cpi->twopass.frames_to_key;
/* We are at or above the maximum. */ if (cpi->buffer_level >= high_water_mark) {
int64_t min_group_bits;
if (boost_score > max_boost) boost_score = max_boost;
}
/* Reset the first pass file position */
reset_fpf_position(cpi, start_position);
/* Work out how many bits to allocate for the key frame itself */ if (1) { int kf_boost = (int)boost_score; int allocation_chunks; int Counter = cpi->twopass.frames_to_key; int alt_kf_bits;
YV12_BUFFER_CONFIG *lst_yv12 = &cpi->common.yv12_fb[cpi->common.lst_fb_idx]; /* Min boost based on kf interval */ #if 0
/* Min KF boost */
kf_boost = (int)((double)kf_boost * 100.0) >> 4; /* Scale 16 to 100 */ if (kf_boost < 250) kf_boost = 250;
/* * We do three calculations for kf size. * The first is based on the error score for the whole kf group. * The second (optionaly) on the key frames own error if this is * smaller than the average for the group. * The final one insures that the frame receives at least the * allocation it would have received based on its own error score vs * the error score remaining * Special case if the sequence appears almost totaly static * as measured by the decay accumulator. In this case we want to * spend almost all of the bits on the key frame. * cpi->twopass.frames_to_key-1 because key frame itself is taken * care of by kf_boost.
*/ if (decay_accumulator >= 0.99) {
allocation_chunks = ((cpi->twopass.frames_to_key - 1) * 10) + kf_boost;
} else {
allocation_chunks = ((cpi->twopass.frames_to_key - 1) * 100) + kf_boost;
}
/* Normalize Altboost and allocations chunck down to prevent overflow */ while (kf_boost > 1000) {
kf_boost /= 2;
allocation_chunks /= 2;
}
/* Calculate the number of bits to be spent on the key frame */
cpi->twopass.kf_bits =
(int)((double)kf_boost *
((double)cpi->twopass.kf_group_bits / (double)allocation_chunks));
/* Apply an additional limit for CBR */ if (cpi->oxcf.end_usage == USAGE_STREAM_FROM_SERVER) { if (cpi->twopass.kf_bits > (int)((3 * cpi->buffer_level) >> 2)) {
cpi->twopass.kf_bits = (int)((3 * cpi->buffer_level) >> 2);
}
}
/* If the key frame is actually easier than the average for the * kf group (which does sometimes happen... eg a blank intro frame) * Then use an alternate calculation based on the kf error score * which should give a smaller key frame.
*/ if (kf_mod_err < kf_group_err / cpi->twopass.frames_to_key) { double alt_kf_grp_bits =
((double)cpi->twopass.bits_left *
(kf_mod_err * (double)cpi->twopass.frames_to_key) /
DOUBLE_DIVIDE_CHECK(cpi->twopass.modified_error_left));
if (cpi->twopass.kf_bits > alt_kf_bits) {
cpi->twopass.kf_bits = alt_kf_bits;
}
} /* Else if it is much harder than other frames in the group make sure * it at least receives an allocation in keeping with its relative * error score
*/ else {
alt_kf_bits = (int)((double)cpi->twopass.bits_left *
(kf_mod_err / DOUBLE_DIVIDE_CHECK(
cpi->twopass.modified_error_left)));
if (alt_kf_bits > cpi->twopass.kf_bits) {
cpi->twopass.kf_bits = alt_kf_bits;
}
}
cpi->twopass.kf_group_bits -= cpi->twopass.kf_bits; /* Add in the minimum frame allowance */
cpi->twopass.kf_bits += cpi->min_frame_bandwidth;
/* Peer frame bit target for this frame */
cpi->per_frame_bandwidth = cpi->twopass.kf_bits;
/* Convert to a per second bitrate */
cpi->target_bandwidth = (int)(cpi->twopass.kf_bits * cpi->output_framerate);
}
/* Note the total error score of the kf group minus the key frame itself */
cpi->twopass.kf_group_error_left = (int)(kf_group_err - kf_mod_err);
/* Adjust the count of total modified error left. The count of bits left * is adjusted elsewhere based on real coded frame sizes
*/
cpi->twopass.modified_error_left -= kf_group_err;
if (cpi->oxcf.allow_spatial_resampling) { int resample_trigger = 0; int last_kf_resampled = 0; int kf_q; int scale_val = 0; int hr, hs, vr, vs; int new_width = cpi->oxcf.Width; int new_height = cpi->oxcf.Height;
/* Set back to unscaled by defaults */
cpi->common.horiz_scale = VP8E_NORMAL;
cpi->common.vert_scale = VP8E_NORMAL;
/* Calculate Average bits per frame. */
av_bits_per_frame =
cpi->oxcf.target_bandwidth / DOUBLE_DIVIDE_CHECK(cpi->framerate);
/* CBR... Use the clip average as the target for deciding resample */ if (cpi->oxcf.end_usage == USAGE_STREAM_FROM_SERVER) {
bits_per_frame = av_bits_per_frame;
}
/* In VBR we want to avoid downsampling in easy section unless we * are under extreme pressure So use the larger of target bitrate * for this section or average bitrate for sequence
*/ else { /* This accounts for how hard the section is... */
bits_per_frame =
(double)(cpi->twopass.kf_group_bits / cpi->twopass.frames_to_key);
/* Don't turn to resampling in easy sections just because they * have been assigned a small number of bits
*/ if (bits_per_frame < av_bits_per_frame) {
bits_per_frame = av_bits_per_frame;
}
}
/* bits_per_frame should comply with our minimum */ if (bits_per_frame < (cpi->oxcf.target_bandwidth *
cpi->oxcf.two_pass_vbrmin_section / 100)) {
bits_per_frame = (cpi->oxcf.target_bandwidth *
cpi->oxcf.two_pass_vbrmin_section / 100);
}
/* Work out if spatial resampling is necessary */
kf_q = estimate_kf_group_q(cpi, err_per_frame, (int)bits_per_frame,
group_iiratio);
/* If we project a required Q higher than the maximum allowed Q then * make a guess at the actual size of frames in this section
*/
projected_bits_perframe = bits_per_frame;
tmp_q = kf_q;
while (tmp_q > cpi->worst_quality) {
projected_bits_perframe *= 1.04;
tmp_q--;
}
/* Guess at buffer level at the end of the section */
projected_buffer_level =
(int)(cpi->buffer_level -
(int)((projected_bits_perframe - av_bits_per_frame) *
cpi->twopass.frames_to_key));
/* The trigger for spatial resampling depends on the various * parameters such as whether we are streaming (CBR) or VBR.
*/ if (cpi->oxcf.end_usage == USAGE_STREAM_FROM_SERVER) { /* Trigger resample if we are projected to fall below down * sample level or resampled last time and are projected to * remain below the up sample level
*/ if ((projected_buffer_level < (cpi->oxcf.resample_down_water_mark *
cpi->oxcf.optimal_buffer_level / 100)) ||
(last_kf_resampled &&
(projected_buffer_level < (cpi->oxcf.resample_up_water_mark *
cpi->oxcf.optimal_buffer_level / 100)))) {
resample_trigger = 1;
} else {
resample_trigger = 0;
}
} else {
int64_t clip_bits = (int64_t)(cpi->twopass.total_stats.count *
cpi->oxcf.target_bandwidth /
DOUBLE_DIVIDE_CHECK(cpi->framerate));
int64_t over_spend = cpi->oxcf.starting_buffer_level - cpi->buffer_level;
/* If triggered last time the threshold for triggering again is * reduced: * * Projected Q higher than allowed and Overspend > 5% of total * bits
*/ if ((last_kf_resampled && (kf_q > cpi->worst_quality)) ||
((kf_q > cpi->worst_quality) && (over_spend > clip_bits / 20))) {
resample_trigger = 1;
} else {
resample_trigger = 0;
}
}
if (resample_trigger) { while ((kf_q >= cpi->worst_quality) && (scale_val < 6)) {
scale_val++;
/* Reducing the area to 1/4 does not reduce the complexity * (err_per_frame) to 1/4... effective_sizeratio attempts * to provide a crude correction for this
*/
effective_size_ratio = (double)(new_width * new_height) /
(double)(cpi->oxcf.Width * cpi->oxcf.Height);
effective_size_ratio = (1.0 + (3.0 * effective_size_ratio)) / 4.0;
/* Now try again and see what Q we get with the smaller * image size
*/
kf_q = estimate_kf_group_q(cpi, err_per_frame * effective_size_ratio,
(int)bits_per_frame, group_iiratio);
}
}
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