Commit bd3088fd authored by Marco's avatar Marco

VP8: Update rate correction factor for drop_overshoot feature.

Update rate correction factor when we drop the frame due to overshoot.
Only affects when the drop_overshoot feature is on: screen_content_mode = 2.

Change-Id: I67e24de979b4c74744151d2ceb3cd75fec2a1e7a
parent db2056f3
......@@ -1593,15 +1593,38 @@ int vp8_drop_encodedframe_overshoot(VP8_COMP *cpi, int Q) {
if (Q < thresh_qp &&
cpi->projected_frame_size > thresh_rate &&
pred_err_mb > thresh_pred_err_mb) {
double new_correction_factor = cpi->rate_correction_factor;
const int target_size = cpi->av_per_frame_bandwidth;
int target_bits_per_mb;
// Drop this frame: advance frame counters, and set force_maxqp flag.
// Adjust rate correction factor upwards.
cpi->rate_correction_factor *= 2.0;
if (cpi->rate_correction_factor > MAX_BPB_FACTOR)
cpi->rate_correction_factor = MAX_BPB_FACTOR;
// Flag to indicate we will force next frame to be encoded at max QP.
cpi->force_maxqp = 1;
// Reset the buffer levels.
cpi->buffer_level = cpi->oxcf.optimal_buffer_level;
cpi->bits_off_target = cpi->oxcf.optimal_buffer_level;
// Compute a new rate correction factor, corresponding to the current
// target frame size and max_QP, and adjust the rate correction factor
// upwards, if needed.
// This is to prevent a bad state where the re-encoded frame at max_QP
// undershoots significantly, and then we end up dropping every other
// frame because the QP/rate_correction_factor may have been too low
// before the drop and then takes too long to come up.
if (target_size >= (INT_MAX >> BPER_MB_NORMBITS))
target_bits_per_mb =
(target_size / cpi->common.MBs) << BPER_MB_NORMBITS;
target_bits_per_mb =
(target_size << BPER_MB_NORMBITS) / cpi->common.MBs;
// Rate correction factor based on target_size_per_mb and max_QP.
new_correction_factor = (double)target_bits_per_mb /
if (new_correction_factor > cpi->rate_correction_factor)
cpi->rate_correction_factor =
VPXMIN(2.0 * cpi->rate_correction_factor, new_correction_factor);
if (cpi->rate_correction_factor > MAX_BPB_FACTOR)
cpi->rate_correction_factor = MAX_BPB_FACTOR;
return 1;
} else {
cpi->force_maxqp = 0;
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