}
-// Read frame stats at an offset from the current position
+// Read frame stats at an offset from the current position.
static int read_frame_stats(const struct twopass_rc *p,
FIRSTPASS_STATS *frame_stats, int offset) {
const FIRSTPASS_STATS *fps_ptr = p->stats_in;
- // Check legality of offset
+ // Check legality of offset.
if (offset >= 0) {
if (&fps_ptr[offset] >= p->stats_in_end)
return EOF;
// TEMP debug code
#if OUTPUT_FPF
-
{
FILE *fpfile;
fpfile = fopen("firstpass.stt", "a");
const int src_stride = x->plane[0].src.stride;
const uint8_t *const ref = xd->plane[0].pre[0].buf;
const int ref_stride = xd->plane[0].pre[0].stride;
-
unsigned int sse;
vp9_variance_fn_t fn = get_block_variance_fn(xd->mi_8x8[0]->mbmi.sb_type);
fn(src, src_stride, ref, ref_stride, &sse);
int new_mv_mode_penalty = 256;
const int quart_frm = MIN(cpi->common.width, cpi->common.height);
- // refine the motion search range accroding to the frame dimension
- // for first pass test
+ // Refine the motion search range according to the frame dimension
+ // for first pass test.
while ((quart_frm << sr) < MAX_FULL_PEL_VAL)
sr++;
step_param += sr;
further_steps -= sr;
- // override the default variance function to use MSE
+ // Override the default variance function to use MSE.
v_fn_ptr.vf = get_block_variance_fn(bsize);
- // Initial step/diamond search centred on best mv
+ // Center the initial step/diamond search on best mv.
tmp_err = cpi->diamond_search_sad(x, &ref_mv_full, &tmp_mv,
step_param,
x->sadperbit16, &num00, &v_fn_ptr,
best_mv->col = tmp_mv.col;
}
- // Further step/diamond searches as necessary
+ // Carry out further step/diamond searches as necessary.
n = num00;
num00 = 0;
setup_dst_planes(xd, new_yv12, 0, 0);
xd->mi_8x8 = cm->mi_grid_visible;
- xd->mi_8x8[0] = cm->mi; // required for vp9_frame_init_quantizer
+ xd->mi_8x8[0] = cm->mi;
vp9_setup_block_planes(&x->e_mbd, cm->subsampling_x, cm->subsampling_y);
vp9_init_mv_probs(cm);
vp9_initialize_rd_consts(cpi);
- // tiling is ignored in the first pass
+ // Tiling is ignored in the first pass.
vp9_tile_init(&tile, cm, 0, 0);
- // for each macroblock row in image
for (mb_row = 0; mb_row < cm->mb_rows; mb_row++) {
int_mv best_ref_mv;
best_ref_mv.as_int = 0;
- // reset above block coeffs
+ // Reset above block coeffs.
xd->up_available = (mb_row != 0);
recon_yoffset = (mb_row * recon_y_stride * 16);
recon_uvoffset = (mb_row * recon_uv_stride * uv_mb_height);
// Set up limit values for motion vectors to prevent them extending
- // outside the UMV borders
+ // outside the UMV borders.
x->mv_row_min = -((mb_row * 16) + BORDER_MV_PIXELS_B16);
x->mv_row_max = ((cm->mb_rows - 1 - mb_row) * 16)
+ BORDER_MV_PIXELS_B16;
- // for each macroblock col in image
for (mb_col = 0; mb_col < cm->mb_cols; mb_col++) {
int this_error;
const int use_dc_pred = (mb_col || mb_row) && (!mb_col || !mb_row);
error_weight = vp9_vaq_inv_q_ratio(energy);
}
- // do intra 16x16 prediction
+ // Do intra 16x16 prediction.
this_error = vp9_encode_intra(x, use_dc_pred);
if (cpi->oxcf.aq_mode == VARIANCE_AQ) {
vp9_clear_system_state(); // __asm emms;
this_error = (int)(this_error * error_weight);
}
- // intrapenalty below deals with situations where the intra and inter
- // error scores are very low (eg a plain black frame).
+ // Intrapenalty below deals with situations where the intra and inter
+ // error scores are very low (e.g. 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 for the mv.
// When the error score is very low this causes us to pick all or lots of
// This penalty adds a cost matching that of a 0,0 mv to the intra case.
this_error += intrapenalty;
- // Cumulative intra error total
+ // Accumulate the intra error.
intra_error += (int64_t)this_error;
// Set up limit values for motion vectors to prevent them extending
x->mv_col_min = -((mb_col * 16) + BORDER_MV_PIXELS_B16);
x->mv_col_max = ((cm->mb_cols - 1 - mb_col) * 16) + BORDER_MV_PIXELS_B16;
- // Other than for the first frame do a motion search
+ // Other than for the first frame do a motion search.
if (cm->current_video_frame > 0) {
int tmp_err, motion_error;
int_mv mv, tmp_mv;
xd->plane[0].pre[0].buf = lst_yv12->y_buffer + recon_yoffset;
motion_error = zz_motion_search(cpi, x);
- // Simple 0,0 motion with no mv overhead
+ // Assume 0,0 motion with no mv overhead.
mv.as_int = tmp_mv.as_int = 0;
// Test last reference frame using the previous best mv as the
- // starting point (best reference) for the search
+ // starting point (best reference) for the search.
first_pass_motion_search(cpi, x, &best_ref_mv.as_mv, &mv.as_mv,
&motion_error);
if (cpi->oxcf.aq_mode == VARIANCE_AQ) {
}
}
- // Experimental search in an older reference frame
+ // Search in an older reference frame.
if (cm->current_video_frame > 1) {
- // Simple 0,0 motion with no mv overhead
+ // Assume 0,0 motion with no mv overhead.
int gf_motion_error;
xd->plane[0].pre[0].buf = gld_yv12->y_buffer + recon_yoffset;
if (gf_motion_error < motion_error && gf_motion_error < this_error)
second_ref_count++;
- // Reset to last frame as reference buffer
+ // Reset to last frame as reference buffer.
xd->plane[0].pre[0].buf = lst_yv12->y_buffer + recon_yoffset;
xd->plane[1].pre[0].buf = lst_yv12->u_buffer + recon_uvoffset;
xd->plane[2].pre[0].buf = lst_yv12->v_buffer + recon_uvoffset;
- // In accumulating a score for the older reference frame
- // take the best of the motion predicted score and
- // the intra coded error (just as will be done for)
- // accumulation of "coded_error" for the last frame.
+ // In accumulating a score for the older reference frame take the
+ // best of the motion predicted score and the intra coded error
+ // (just as will be done for) accumulation of "coded_error" for
+ // the last frame.
if (gf_motion_error < this_error)
sr_coded_error += gf_motion_error;
else
} else {
sr_coded_error += motion_error;
}
- /* Intra assumed best */
+ // Start by assuming that intra mode is 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.
+ // 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++;
best_ref_mv.as_int = mv.as_int;
- // Was the vector non-zero
if (mv.as_int) {
mvcount++;
- // Was it different from the last non zero vector
+ // Non-zero vector, was it different from the last non zero vector?
if (mv.as_int != lastmv_as_int)
new_mv_count++;
lastmv_as_int = mv.as_int;
- // Does the Row vector point inwards or outwards
+ // Does the row vector point inwards or outwards?
if (mb_row < cm->mb_rows / 2) {
if (mv.as_mv.row > 0)
sum_in_vectors--;
sum_in_vectors--;
}
- // Does the Row vector point inwards or outwards
+ // Does the col vector point inwards or outwards?
if (mb_col < cm->mb_cols / 2) {
if (mv.as_mv.col > 0)
sum_in_vectors--;
}
coded_error += (int64_t)this_error;
- // adjust to the next column of macroblocks
+ // Adjust to the next column of MBs.
x->plane[0].src.buf += 16;
x->plane[1].src.buf += uv_mb_height;
x->plane[2].src.buf += uv_mb_height;
recon_uvoffset += uv_mb_height;
}
- // adjust to the next row of mbs
+ // Adjust to the next row of MBs.
x->plane[0].src.buf += 16 * x->plane[0].src.stride - 16 * cm->mb_cols;
x->plane[1].src.buf += uv_mb_height * x->plane[1].src.stride -
uv_mb_height * cm->mb_cols;
// cpi->source_time_stamp.
fps.duration = (double)(cpi->source->ts_end - cpi->source->ts_start);
- // don't want to do output stats with a stack variable!
+ // Don't want to do output stats with a stack variable!
twopass->this_frame_stats = fps;
output_stats(cpi, cpi->output_pkt_list, &twopass->this_frame_stats);
accumulate_stats(&twopass->total_stats, &fps);
}
// Copy the previous Last Frame back into gf and and arf buffers if
- // the prediction is good enough... but also dont allow it to lag too far
+ // the prediction is good enough... but also don't allow it to lag too far.
if ((twopass->sr_update_lag > 3) ||
((cm->current_video_frame > 0) &&
(twopass->this_frame_stats.pcnt_inter > 0.20) &&
} else {
twopass->sr_update_lag++;
}
- // swap frame pointers so last frame refers to the frame we just compressed
+ // Swap frame pointers so last frame refers to the frame we just compressed.
swap_yv12(lst_yv12, new_yv12);
vp9_extend_frame_borders(lst_yv12, cm->subsampling_x, cm->subsampling_y);
if (cm->current_video_frame == 0)
vp8_yv12_copy_frame(lst_yv12, gld_yv12);
- // use this to see what the first pass reconstruction looks like
+ // Use this to see what the first pass reconstruction looks like.
if (0) {
char filename[512];
FILE *recon_file;
cm->current_video_frame++;
}
-// 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 a cost per mb attributable to overheads such as the coding of modes
+// and motion vectors. This currently makes simplistic assumptions for testing.
static double bitcost(double prob) {
return -(log(prob) / log(2.0));
}
motion_cost = bitcost(av_pct_motion);
intra_cost = bitcost(av_intra);
- // Estimate of extra bits per mv overhead for mbs
- // << 9 is the normalization to the (bits * 512) used in vp9_rc_bits_per_mb
+ // Estimate the number of extra bits per mv overhead for mbs. We shift (<< 9)
+ // to match the scaling of number of bits by 512.
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 vp9_rc_bits_per_mb
+ // Produce a crude estimate of the overhead cost from modes. We shift (<< 9)
+ // to match the scaling of number of bits by 512.
mode_cost =
(int)((((av_pct_inter - av_pct_motion) * zz_cost) +
(av_pct_motion * motion_cost) +
(av_intra * intra_cost)) * cpi->common.MBs) << 9;
- // return mv_cost + mode_cost;
// TODO(paulwilkins): Fix overhead costs for extended Q range.
#endif
return 0;
const double power_term = MIN(vp9_convert_qindex_to_q(q) * 0.0125 + pt_low,
pt_high);
- // Calculate correction factor
+ // Calculate correction factor.
if (power_term < 1.0)
assert(error_term >= 0.0);
twopass->total_stats = *twopass->stats_in_end;
twopass->total_left_stats = twopass->total_stats;
- // 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.
+ // 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.
+ // It is calculated based on the actual durations of all frames from the
+ // first pass.
vp9_new_framerate(cpi, 10000000.0 * twopass->total_stats.count /
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
+ // are still boosted appropriately for KF/GF/ARF.
twopass->kf_intra_err_min = KF_MB_INTRA_MIN * cpi->common.MBs;
twopass->gf_intra_err_min = GF_MB_INTRA_MIN * cpi->common.MBs;
- // This variable monitors how far behind the second ref update is lagging
+ // This variable monitors how far behind the second ref update is lagging.
twopass->sr_update_lag = 1;
// Scan the first pass file and calculate an average Intra / Inter error score
// ratio for the sequence.
{
double sum_iiratio = 0.0;
- start_pos = twopass->stats_in; // Note the starting "file" position.
+ start_pos = twopass->stats_in;
while (input_stats(twopass, &this_frame) != EOF) {
const double iiratio = this_frame.intra_error /
twopass->avg_iiratio = sum_iiratio /
DOUBLE_DIVIDE_CHECK((double)twopass->total_stats.count);
- // Reset file position
reset_fpf_position(twopass, start_pos);
}
double av_error = twopass->total_stats.ssim_weighted_pred_err /
DOUBLE_DIVIDE_CHECK(twopass->total_stats.count);
- start_pos = twopass->stats_in; // Note starting "file" position
+ start_pos = twopass->stats_in;
twopass->modified_error_total = 0.0;
twopass->modified_error_min =
void vp9_end_second_pass(VP9_COMP *cpi) {
}
-// This function gives and estimate of how badly we believe
-// the prediction quality is decaying from frame to frame.
+// This function gives an estimate of how badly we believe the prediction
+// quality is decaying from frame to frame.
static double get_prediction_decay_rate(const VP9_COMMON *cm,
const FIRSTPASS_STATS *next_frame) {
// Look at the observed drop in prediction quality between the last frame
FIRSTPASS_STATS *position = cpi->twopass.stats_in;
FIRSTPASS_STATS tmp_next_frame;
- // Look ahead a few frames to see if static condition
- // persists...
+ // Look ahead a few frames to see if static condition persists...
for (j = 0; j < still_interval; j++) {
if (EOF == input_stats(&cpi->twopass, &tmp_next_frame))
break;
reset_fpf_position(&cpi->twopass, position);
- // Only if it does do we signal a transition to still
+ // Only if it does do we signal a transition to still.
if (j == still_interval)
trans_to_still = 1;
}
// 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
+// reflect this.
static int detect_flash(const struct twopass_rc *twopass, int offset) {
FIRSTPASS_STATS next_frame;
// 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.
+ // compared to pcnt_inter.
if (next_frame.pcnt_second_ref > next_frame.pcnt_inter &&
next_frame.pcnt_second_ref >= 0.5)
flash_detected = 1;
return flash_detected;
}
-// Update the motion related elements to the GF arf boost calculation
+// Update the motion related elements to the GF arf boost calculation.
static void accumulate_frame_motion_stats(
FIRSTPASS_STATS *this_frame,
double *this_frame_mv_in_out,
// Accumulate motion stats.
motion_pct = this_frame->pcnt_motion;
- // Accumulate Motion In/Out of frame stats
+ // Accumulate Motion In/Out of frame stats.
*this_frame_mv_in_out = this_frame->mv_in_out_count * motion_pct;
*mv_in_out_accumulator += this_frame->mv_in_out_count * motion_pct;
*abs_mv_in_out_accumulator += fabs(this_frame->mv_in_out_count * motion_pct);
// Accumulate a measure of how uniform (or conversely how random)
- // the motion field is. (A ratio of absmv / mv)
+ // the motion field is (a ratio of absmv / mv).
if (motion_pct > 0.05) {
const double this_frame_mvr_ratio = fabs(this_frame->mvr_abs) /
DOUBLE_DIVIDE_CHECK(fabs(this_frame->MVr));
double this_frame_mv_in_out) {
double frame_boost;
- // Underlying boost factor is based on inter intra error ratio
+ // 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));
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
+ // Increase boost for frames where new data coming into frame (e.g. 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
+ // In the extreme case the boost is halved.
else
frame_boost += frame_boost * (this_frame_mv_in_out / 2.0);
int arf_boost;
int flash_detected = 0;
- // Search forward from the proposed arf/next gf position
+ // Search forward from the proposed arf/next gf position.
for (i = 0; i < f_frames; i++) {
if (read_frame_stats(twopass, &this_frame, (i + offset)) == EOF)
break;
- // Update the motion related elements to the boost calculation
+ // 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,
flash_detected = detect_flash(twopass, i + offset) ||
detect_flash(twopass, i + offset + 1);
- // Cumulative effect of prediction quality decay
+ // Accumulate the effect of prediction quality decay.
if (!flash_detected) {
decay_accumulator *= get_prediction_decay_rate(&cpi->common, &this_frame);
decay_accumulator = decay_accumulator < MIN_DECAY_FACTOR
*f_boost = (int)boost_score;
- // Reset for backward looking loop
+ // Reset for backward looking loop.
boost_score = 0.0;
mv_ratio_accumulator = 0.0;
decay_accumulator = 1.0;
mv_in_out_accumulator = 0.0;
abs_mv_in_out_accumulator = 0.0;
- // Search backward towards last gf position
+ // Search backward towards last gf position.
for (i = -1; i >= -b_frames; i--) {
if (read_frame_stats(twopass, &this_frame, (i + offset)) == EOF)
break;
- // Update the motion related elements to the boost calculation
+ // 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,
flash_detected = detect_flash(twopass, i + offset) ||
detect_flash(twopass, i + offset + 1);
- // Cumulative effect of prediction quality decay
+ // Cumulative effect of prediction quality decay.
if (!flash_detected) {
decay_accumulator *= get_prediction_decay_rate(&cpi->common, &this_frame);
decay_accumulator = decay_accumulator < MIN_DECAY_FACTOR
return;
}
- // ARF Group: work out the ARF schedule.
- // Mark ARF frames as negative.
+ // ARF Group: Work out the ARF schedule and mark ARF frames as negative.
if (end < 0) {
// printf("start:%d end:%d\n", -end, -end);
// ARF frame is at the end of the range.
double decay_accumulator = 1.0;
double zero_motion_accumulator = 1.0;
- double loop_decay_rate = 1.00; // Starting decay rate
+ double loop_decay_rate = 1.00;
double last_loop_decay_rate = 1.00;
double this_frame_mv_in_out = 0.0;
double mv_in_out_accumulator = 0.0;
double abs_mv_in_out_accumulator = 0.0;
double mv_ratio_accumulator_thresh;
- const int max_bits = frame_max_bits(cpi); // Max for a single frame
+ const int max_bits = frame_max_bits(cpi); // Max bits for a single frame.
unsigned int allow_alt_ref = cpi->oxcf.play_alternate &&
cpi->oxcf.lag_in_frames;
// 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
+ // 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;
// If this is a key frame or the overlay from a previous arf then
- // The error score / cost of this frame has already been accounted for.
+ // the error score / cost of this frame has already been accounted for.
if (cpi->common.frame_type == KEY_FRAME || rc->source_alt_ref_active)
gf_group_err -= gf_first_frame_err;
active_max_gf_interval = rc->max_gf_interval;
i = 0;
- while (i < twopass->static_scene_max_gf_interval &&
- i < rc->frames_to_key) {
- i++; // Increment the loop counter
+ while (i < twopass->static_scene_max_gf_interval && i < rc->frames_to_key) {
+ i++;
- // Accumulate error score of frames in this gf group
+ // Accumulate error score of frames in this gf group.
mod_frame_err = calculate_modified_err(cpi, this_frame);
gf_group_err += mod_frame_err;
// quality back to an earlier frame is then restored.
flash_detected = detect_flash(twopass, 0);
- // Update the motion related elements to the boost calculation
+ // 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);
- // Cumulative effect of prediction quality decay
+ // Accumulate the effect of prediction quality decay.
if (!flash_detected) {
last_loop_decay_rate = loop_decay_rate;
loop_decay_rate = get_prediction_decay_rate(&cpi->common, &next_frame);
next_frame.pcnt_motion;
}
- // Break clause to detect very still sections after motion
- // (for example a static image after a fade or other transition).
+ // Break clause to detect very still sections after motion. For example,
+ // a static image after a fade or other transition.
if (detect_transition_to_still(cpi, i, 5, loop_decay_rate,
last_loop_decay_rate)) {
allow_alt_ref = 0;
}
}
- // Calculate a boost number for this frame
+ // Calculate a boost number for this frame.
boost_score += (decay_accumulator *
calc_frame_boost(cpi, &next_frame, this_frame_mv_in_out));
// Break out conditions.
if (
- // Break at cpi->max_gf_interval unless almost totally static
+ // Break at cpi->max_gf_interval unless almost totally static.
(i >= active_max_gf_interval && (zero_motion_accumulator < 0.995)) ||
(
- // Don't break out with a very short interval
+ // Don't break out with a very short interval.
(i > MIN_GF_INTERVAL) &&
((boost_score > 125.0) || (next_frame.pcnt_inter < 0.75)) &&
(!flash_detected) &&
twopass->gf_zeromotion_pct = (int)(zero_motion_accumulator * 1000.0);
- // Don't allow a gf too near the next kf
+ // Don't allow a gf too near the next kf.
if ((rc->frames_to_key - i) < MIN_GF_INTERVAL) {
while (i < (rc->frames_to_key + !rc->next_key_frame_forced)) {
i++;
else
rc->baseline_gf_interval = i;
- // Should we use the alternate reference frame
+ // Should we use the alternate reference frame.
if (allow_alt_ref &&
(i < cpi->oxcf.lag_in_frames) &&
(i >= MIN_GF_INTERVAL) &&
- // for real scene cuts (not forced kfs) dont allow arf very near kf.
+ // For real scene cuts (not forced kfs) don't allow arf very near kf.
(rc->next_key_frame_forced ||
(i <= (rc->frames_to_key - MIN_GF_INTERVAL)))) {
- // Alternative boost calculation for alt ref
+ // Calculate the boost for alt ref.
rc->gfu_boost = calc_arf_boost(cpi, 0, (i - 1), (i - 1), &f_boost,
&b_boost);
rc->source_alt_ref_pending = 1;
#endif
#endif
- // Calculate the bits to be allocated to the group as a whole
+ // Calculate the bits to be allocated to the group as a whole.
if (twopass->kf_group_bits > 0 && twopass->kf_group_error_left > 0) {
twopass->gf_group_bits = (int64_t)(cpi->twopass.kf_group_bits *
(gf_group_err / cpi->twopass.kf_group_error_left));
twopass->kf_group_bits : twopass->gf_group_bits;
// Clip cpi->twopass.gf_group_bits based on user supplied data rate
- // variability limit (cpi->oxcf.two_pass_vbrmax_section)
+ // variability limit, cpi->oxcf.two_pass_vbrmax_section.
if (twopass->gf_group_bits > (int64_t)max_bits * rc->baseline_gf_interval)
twopass->gf_group_bits = (int64_t)max_bits * rc->baseline_gf_interval;
- // Reset the file position
+ // Reset the file position.
reset_fpf_position(twopass, start_pos);
// Assign bits to the arf or gf.
int boost = (rc->gfu_boost * gfboost_qadjust(q)) / 100;
- // Set max and minimum boost and hence minimum allocation
+ // Set max and minimum boost and hence minimum allocation.
boost = clamp(boost, 125, (rc->baseline_gf_interval + 1) * 200);
if (rc->source_alt_ref_pending && i == 0)
else
allocation_chunks = (rc->baseline_gf_interval * 100) + (boost - 100);
- // Prevent overflow
+ // Prevent overflow.
if (boost > 1023) {
int divisor = boost >> 10;
boost /= divisor;
}
// Calculate the number of bits to be spent on the gf or arf based on
- // the boost number
+ // the boost number.
gf_bits = (int)((double)boost * (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
+ // based on the error score of the frame itself.
if (rc->baseline_gf_interval < 1 ||
mod_frame_err < gf_group_err / (double)rc->baseline_gf_interval) {
double alt_gf_grp_bits = (double)twopass->kf_group_bits *
gf_bits = alt_gf_bits;
}
- // Dont allow a negative value for gf_bits
+ // Don't allow a negative value for gf_bits.
if (gf_bits < 0)
gf_bits = 0;
if (i == 1 ||
(!rc->source_alt_ref_pending &&
cpi->common.frame_type != KEY_FRAME)) {
- // Per frame bit target for this frame
+ // Calculate the per frame bit target for this frame.
vp9_rc_set_frame_target(cpi, gf_bits);
}
}
{
- // Adjust KF group bits and error remaining
+ // Adjust KF group bits and error remaining.
twopass->kf_group_error_left -= (int64_t)gf_group_err;
twopass->kf_group_bits -= twopass->gf_group_bits;
if (twopass->kf_group_bits < 0)
twopass->kf_group_bits = 0;
- // If this is an arf update we want to remove the score for the
- // overlay frame at the end which will usually be very cheap to code.
- // The overlay frame has already in effect been coded so we want to spread
- // the remaining bits amoung the other frames/
+ // If this is an arf update we want to remove the score for the overlay
+ // frame at the end which will usually be very cheap to code.
+ // The overlay frame has already, in effect, been coded so we want to spread
+ // the remaining bits among the other frames.
// For normal GFs remove the score for the GF itself unless this is
// also a key frame in which case it has already been accounted for.
if (rc->source_alt_ref_pending) {
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
+ // despite MIN_GF_INTERVAL and would cause a divide by 0 in the
// calculation of alt_extra_bits.
if (rc->baseline_gf_interval >= 3) {
const int boost = rc->source_alt_ref_pending ? b_boost : rc->gfu_boost;
const FIRSTPASS_STATS *next_frame) {
int is_viable_kf = 0;
- // Does the frame satisfy the primary criteria of a key frame
- // If so, then examine how well it predicts subsequent frames
+ // Does the frame satisfy the primary criteria of a key frame?
+ // If so, then examine how well it predicts subsequent frames.
if ((this_frame->pcnt_second_ref < 0.10) &&
(next_frame->pcnt_second_ref < 0.10) &&
((this_frame->pcnt_inter < 0.05) ||
- (((this_frame->pcnt_inter - this_frame->pcnt_neutral) < .35) &&
+ (((this_frame->pcnt_inter - this_frame->pcnt_neutral) < 0.35) &&
((this_frame->intra_error /
DOUBLE_DIVIDE_CHECK(this_frame->coded_error)) < 2.5) &&
((fabs(last_frame->coded_error - this_frame->coded_error) /
- DOUBLE_DIVIDE_CHECK(this_frame->coded_error) >
- .40) ||
+ DOUBLE_DIVIDE_CHECK(this_frame->coded_error) > 0.40) ||
(fabs(last_frame->intra_error - this_frame->intra_error) /
- DOUBLE_DIVIDE_CHECK(this_frame->intra_error) >
- .40) ||
+ DOUBLE_DIVIDE_CHECK(this_frame->intra_error) > 0.40) ||
((next_frame->intra_error /
DOUBLE_DIVIDE_CHECK(next_frame->coded_error)) > 3.5))))) {
int i;
local_next_frame = *next_frame;
- // Note the starting file position so we can reset to it
+ // 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
+ // Examine how well the key frame predicts subsequent frames.
for (i = 0; i < 16; i++) {
double next_iiratio = (IIKFACTOR1 * local_next_frame.intra_error /
DOUBLE_DIVIDE_CHECK(local_next_frame.coded_error));
if (next_iiratio > RMAX)
next_iiratio = RMAX;
- // Cumulative effect of decay in prediction quality
+ // Cumulative effect of decay in prediction quality.
if (local_next_frame.pcnt_inter > 0.85)
decay_accumulator *= local_next_frame.pcnt_inter;
else
decay_accumulator *= (0.85 + local_next_frame.pcnt_inter) / 2.0;
- // decay_accumulator = decay_accumulator * local_next_frame.pcnt_inter;
-
- // Keep a running total
+ // Keep a running total.
boost_score += (decay_accumulator * next_iiratio);
- // Test various breakout clauses
+ // Test various breakout clauses.
if ((local_next_frame.pcnt_inter < 0.05) ||
(next_iiratio < 1.5) ||
(((local_next_frame.pcnt_inter -
local_next_frame.pcnt_neutral) < 0.20) &&
(next_iiratio < 3.0)) ||
((boost_score - old_boost_score) < 3.0) ||
- (local_next_frame.intra_error < 200)
- ) {
+ (local_next_frame.intra_error < 200)) {
break;
}
start_position = twopass->stats_in;
cpi->common.frame_type = KEY_FRAME;
- // is this a forced key frame by interval
+ // Is this a forced key frame by interval.
rc->this_key_frame_forced = rc->next_key_frame_forced;
- // Clear the alt ref active flag as this can never be active on a key frame
+ // Clear the alt ref active flag as this can never be active on a key frame.
rc->source_alt_ref_active = 0;
- // Kf is always a gf so clear frames till next gf counter
+ // KF is always a GF so clear frames till next gf counter.
rc->frames_till_gf_update_due = 0;
rc->frames_to_key = 1;
- // Take a copy of the initial frame details
+ // Take a copy of the initial frame details.
first_frame = *this_frame;
twopass->kf_group_bits = 0; // Total bits available to kf group
kf_mod_err = calculate_modified_err(cpi, this_frame);
- // find the next keyframe
+ // Find the next keyframe.
i = 0;
while (twopass->stats_in < twopass->stats_in_end) {
- // Accumulate kf group error
+ // Accumulate kf group error.
kf_group_err += calculate_modified_err(cpi, this_frame);
- // load a the next frame's stats
+ // Load the next frame's stats.
last_frame = *this_frame;
input_stats(twopass, this_frame);
// Provided that we are not at the end of the file...
if (cpi->oxcf.auto_key &&
lookup_next_frame_stats(twopass, &next_frame) != EOF) {
- // Normal scene cut check
+ // Check for a scene cut.
if (test_candidate_kf(cpi, &last_frame, this_frame, &next_frame))
break;
-
- // How fast is prediction quality decaying
+ // How fast is the prediction quality decaying?
loop_decay_rate = get_prediction_decay_rate(&cpi->common, &next_frame);
// We want to know something about the recent past... rather than
- // as used elsewhere where we are concened with decay in prediction
+ // as used elsewhere where we are concerned with decay in prediction
// quality since the last GF or KF.
recent_loop_decay[i % 8] = loop_decay_rate;
decay_accumulator = 1.0;
decay_accumulator *= recent_loop_decay[j];
// Special check for transition or high motion followed by a
- // to a static scene.
+ // static scene.
if (detect_transition_to_still(cpi, i, cpi->key_frame_frequency - i,
loop_decay_rate, decay_accumulator))
break;
- // Step on to the next frame
+ // Step on to the next frame.
rc->frames_to_key++;
// If we don't have a real key frame within the next two
- // forcekeyframeevery intervals then break out of the loop.
+ // key_frame_frequency intervals then break out of the loop.
if (rc->frames_to_key >= 2 * (int)cpi->key_frame_frequency)
break;
} else {
- rc->frames_to_key++;
+ ++rc->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
+ // This code centers the extra kf if the actual natural interval
+ // is between 1x and 2x.
if (cpi->oxcf.auto_key &&
rc->frames_to_key > (int)cpi->key_frame_frequency) {
FIRSTPASS_STATS tmp_frame;
rc->frames_to_key /= 2;
- // Copy first frame details
+ // Copy first frame details.
tmp_frame = first_frame;
- // Reset to the start of the group
+ // Reset to the start of the group.
reset_fpf_position(twopass, start_position);
kf_group_err = 0;
- // Rescan to get the correct error data for the forced kf group
+ // Rescan to get the correct error data for the forced kf group.
for (i = 0; i < rc->frames_to_key; i++) {
- // Accumulate kf group errors
+ // Accumulate kf group errors.
kf_group_err += calculate_modified_err(cpi, &tmp_frame);
// Load the next frame's stats.
rc->next_key_frame_forced = 0;
}
- // Special case for the last key frame of the file
+ // Special case for the last key frame of the file.
if (twopass->stats_in >= twopass->stats_in_end) {
- // Accumulate kf group error
+ // Accumulate kf group error.
kf_group_err += calculate_modified_err(cpi, this_frame);
}
// Calculate the number of bits that should be assigned to the kf group.
if (twopass->bits_left > 0 && twopass->modified_error_left > 0.0) {
- // Max for a single normal frame (not key frame)
+ // Maximum number of bits for a single normal frame (not key frame).
int max_bits = frame_max_bits(cpi);
- // Maximum bits for the kf group
+ // Maximum number of bits allocated to the key frame group.
int64_t max_grp_bits;
// Default allocation based on bits left and relative
- // complexity of the section
+ // complexity of the section.
twopass->kf_group_bits = (int64_t)(twopass->bits_left *
(kf_group_err / twopass->modified_error_left));
} else {
twopass->kf_group_bits = 0;
}
- // Reset the first pass file position
+ // Reset the first pass file position.
reset_fpf_position(twopass, start_position);
// Determine how big to make this keyframe based on how well the subsequent
if (r > RMAX)
r = RMAX;
- // How fast is prediction quality decaying
+ // How fast is prediction quality decaying.
if (!detect_flash(twopass, 0)) {
loop_decay_rate = get_prediction_decay_rate(&cpi->common, &next_frame);
decay_accumulator *= loop_decay_rate;
DOUBLE_DIVIDE_CHECK(sectionstats.coded_error));
}
- // Reset the first pass file position
+ // Reset the first pass file position.
reset_fpf_position(twopass, start_position);
- // Work out how many bits to allocate for the key frame itself
+ // Work out how many bits to allocate for the key frame itself.
if (1) {
int kf_boost = (int)boost_score;
int allocation_chunks;
rc->kf_boost = kf_boost;
twopass->kf_zeromotion_pct = (int)(zero_motion_accumulator * 100.0);
- // We do three calculations for kf size.
- // The first is based on the error score for the whole kf group.
- // The second (optionally) 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
- // In this case we want to spend almost all of the bits on the
- // key frame.
- // cpi->rc.frames_to_key-1 because key frame itself is taken
- // care of by kf_boost.
+ // Key frame size depends on:
+ // (1) the error score for the whole key frame group,
+ // (2) the key frames' own error if this is smaller than the
+ // average for the group (optional),
+ // (3) insuring 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 totally static we want to spend almost
+ // all of the bits on the key frame.
+ //
+ // We use (cpi->rc.frames_to_key - 1) below because the key frame itself is
+ // taken care of by kf_boost.
if (zero_motion_accumulator >= 0.99) {
allocation_chunks = ((rc->frames_to_key - 1) * 10) + kf_boost;
} else {
allocation_chunks = ((rc->frames_to_key - 1) * 100) + kf_boost;
}
- // Prevent overflow
+ // Prevent overflow.
if (kf_boost > 1028) {
int divisor = kf_boost >> 10;
kf_boost /= divisor;
twopass->kf_group_bits = (twopass->kf_group_bits < 0) ? 0
: twopass->kf_group_bits;
- // Calculate the number of bits to be spent on the key frame
+ // Calculate the number of bits to be spent on the key frame.
twopass->kf_bits = (int)((double)kf_boost *
((double)twopass->kf_group_bits / allocation_chunks));
if (twopass->kf_bits > alt_kf_bits)
twopass->kf_bits = alt_kf_bits;
} else {
- // 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 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.
alt_kf_bits = (int)((double)twopass->bits_left * (kf_mod_err /
DOUBLE_DIVIDE_CHECK(twopass->modified_error_left)));
vp9_rc_set_frame_target(cpi, twopass->kf_bits);
}
- // Note the total error score of the kf group minus the key frame itself
+ // Note the total error score of the kf group minus the key frame itself.
twopass->kf_group_error_left = (int)(kf_group_err - kf_mod_err);
// Adjust the count of total modified error left.
} else {
cm->frame_type = INTER_FRAME;
}
- // Do not use periodic key frames
+ // Do not use periodic key frames.
cpi->rc.frames_to_key = INT_MAX;
}
twopass->active_worst_quality = tmp_q;
rc->ni_av_qi = tmp_q;
rc->avg_q = vp9_convert_qindex_to_q(tmp_q);
-
- // 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
- // adjust_maxq_qrange(cpi);
}
vp9_zero(this_frame);
if (EOF == input_stats(twopass, &this_frame))
this_frame_intra_error = this_frame.intra_error;
this_frame_coded_error = this_frame.coded_error;
- // keyframe and section processing !
+ // Keyframe and section processing.
if (rc->frames_to_key == 0 ||
(cm->frame_flags & FRAMEFLAGS_KEY)) {
- // Define next KF group and assign bits to it
+ // Define next KF group and assign bits to it.
this_frame_copy = this_frame;
find_next_key_frame(cpi, &this_frame_copy);
} else {
cm->frame_type = INTER_FRAME;
}
- // Is this a GF / ARF (Note that a KF is always also a GF)
+ // Is this frame a GF / ARF? (Note: a key frame is always also a GF).
if (rc->frames_till_gf_update_due == 0) {
- // Define next gf group and assign bits to it
+ // Define next gf group and assign bits to it.
this_frame_copy = this_frame;
#if CONFIG_MULTIPLE_ARF
if (twopass->gf_zeromotion_pct > 995) {
// As long as max_thresh for encode breakout is small enough, it is ok
- // to enable it for show frame, i.e. set allow_encode_breakout to 2.
+ // to enable it for show frame, i.e. set allow_encode_breakout to
+ // ENCODE_BREAKOUT_LIMITED.
if (!cm->show_frame)
cpi->allow_encode_breakout = ENCODE_BREAKOUT_DISABLED;
else
rc->frames_till_gf_update_due = rc->baseline_gf_interval;
cpi->refresh_golden_frame = 1;
} else {
- // Otherwise this is an ordinary frame
- // Assign bits from those allocated to the GF group
+ // Otherwise this is an ordinary frame.
+ // Assign bits from those allocated to the GF group.
this_frame_copy = this_frame;
assign_std_frame_bits(cpi, &this_frame_copy);
}
target = vp9_rc_clamp_pframe_target_size(cpi, rc->this_frame_target);
vp9_rc_set_frame_target(cpi, target);
- // Update the total stats remaining structure
+ // Update the total stats remaining structure.
subtract_stats(&twopass->total_left_stats, &this_frame);
}
#else
cpi->twopass.bits_left -= 8 * bytes_used;
// Update bits left to the kf and gf groups to account for overshoot or
- // undershoot on these frames
+ // undershoot on these frames.
if (cm->frame_type == KEY_FRAME) {
cpi->twopass.kf_group_bits += cpi->rc.this_frame_target -
cpi->rc.projected_frame_size;
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