ref: 566905e91ec746835ffc91b1a87ddd6d352aed08
parent: b358f9076f153835680cd3af3765c7e30474c030
author: angiebird <angiebird@google.com>
date: Sat Aug 1 09:03:46 EDT 2020
Add recode loop logics for rate_ctrl experiment Change-Id: I4de5a38e25d6b0836d90e8fcd0e56d268e5fd838
--- a/vp9/encoder/vp9_encoder.c
+++ b/vp9/encoder/vp9_encoder.c
@@ -4201,6 +4201,134 @@
return VPXMIN(qstep, MAX_QSTEP_ADJ);
}
+#if CONFIG_RATE_CTRL
+#define RATE_CTRL_MAX_RECODE_NUM 7
+
+typedef struct RATE_QINDEX_HISTORY {+ int recode_count;
+ int q_index_history[RATE_CTRL_MAX_RECODE_NUM];
+ int rate_history[RATE_CTRL_MAX_RECODE_NUM];
+ int q_index_high;
+ int q_index_low;
+} RATE_QINDEX_HISTORY;
+
+static void init_rq_history(RATE_QINDEX_HISTORY *rq_history) {+ rq_history->recode_count = 0;
+ rq_history->q_index_high = 255;
+ rq_history->q_index_low = 0;
+}
+
+static void update_rq_history(RATE_QINDEX_HISTORY *rq_history, int target_bits,
+ int actual_bits, int q_index) {+ rq_history->q_index_history[rq_history->recode_count] = q_index;
+ rq_history->rate_history[rq_history->recode_count] = actual_bits;
+ if (actual_bits <= target_bits) {+ rq_history->q_index_high = q_index;
+ }
+ if (actual_bits >= target_bits) {+ rq_history->q_index_low = q_index;
+ }
+ rq_history->recode_count += 1;
+}
+
+static int guess_q_index_from_model(const RATE_QSTEP_MODEL *rq_model,
+ int target_bits) {+ // The model predicts bits as follows.
+ // target_bits = bias - ratio * log2(q_step)
+ // Given the target_bits, we compute the q_step as follows.
+ const double q_step =
+ pow(2.0, (rq_model->bias - target_bits) / rq_model->ratio);
+ // TODO(angiebird): Make this function support highbitdepth.
+ return vp9_convert_q_to_qindex(q_step, VPX_BITS_8);
+}
+
+static int guess_q_index_linear(int prev_q_index, int target_bits,
+ int actual_bits, int gap) {+ int q_index = prev_q_index;
+ if (actual_bits < target_bits) {+ q_index -= gap;
+ q_index = VPXMAX(q_index, 0);
+ } else {+ q_index += gap;
+ q_index = VPXMIN(q_index, 255);
+ }
+ return q_index;
+}
+
+static double get_bits_percent_diff(int target_bits, int actual_bits) {+ double diff = abs(target_bits - actual_bits) * 1. / target_bits;
+ diff *= 100;
+ return diff;
+}
+
+static int rq_model_predict_q_index(const RATE_QSTEP_MODEL *rq_model,
+ const RATE_QINDEX_HISTORY *rq_history,
+ int target_bits) {+ int q_index = -1;
+ if (rq_history->recode_count > 0) {+ const int actual_bits =
+ rq_history->rate_history[rq_history->recode_count - 1];
+ const int prev_q_index =
+ rq_history->q_index_history[rq_history->recode_count - 1];
+ const double percent_diff = get_bits_percent_diff(target_bits, actual_bits);
+ if (percent_diff > 50) {+ // Binary search.
+ // When the actual_bits and target_bits are far apart, binary search
+ // q_index is faster.
+ q_index = (rq_history->q_index_low + rq_history->q_index_high) / 2;
+ } else {+ if (rq_model->ready) {+ q_index = guess_q_index_from_model(rq_model, target_bits);
+ } else {+ // TODO(angiebird): Find a better way to set the gap.
+ q_index =
+ guess_q_index_linear(prev_q_index, target_bits, actual_bits, 20);
+ }
+ }
+ } else {+ if (rq_model->ready) {+ q_index = guess_q_index_from_model(rq_model, target_bits);
+ }
+ }
+
+ assert(rq_history->q_index_low <= rq_history->q_index_high);
+ if (q_index <= rq_history->q_index_low) {+ q_index = rq_history->q_index_low + 1;
+ }
+ if (q_index >= rq_history->q_index_high) {+ q_index = rq_history->q_index_high - 1;
+ }
+ return q_index;
+}
+
+static void rq_model_update(const RATE_QINDEX_HISTORY *rq_history,
+ int target_bits, RATE_QSTEP_MODEL *rq_model) {+ const int recode_count = rq_history->recode_count;
+ if (recode_count >= 2) {+ // Fit the ratio and bias of rq_model based on last two recode histories.
+ const double s1 = vp9_convert_qindex_to_q(
+ rq_history->q_index_history[recode_count - 2], VPX_BITS_8);
+ const double s2 = vp9_convert_qindex_to_q(
+ rq_history->q_index_history[recode_count - 1], VPX_BITS_8);
+ const double r1 = rq_history->rate_history[recode_count - 2];
+ const double r2 = rq_history->rate_history[recode_count - 1];
+ rq_model->ratio = (r2 - r1) / (log2(s1) - log2(s2));
+ rq_model->bias = r1 + (rq_model->ratio) * log2(s1);
+ rq_model->ready = 1;
+ } else if (recode_count == 1) {+ if (rq_model->ready) {+ // Update the ratio only when the initial model exists and we only have
+ // one recode history.
+ const int prev_q = rq_history->q_index_history[recode_count - 1];
+ const double prev_q_step = vp9_convert_qindex_to_q(prev_q, VPX_BITS_8);
+ const int actual_bits = rq_history->rate_history[recode_count - 1];
+ rq_model->ratio =
+ rq_model->ratio - (target_bits - actual_bits) / log2(prev_q_step);
+ }
+ }
+}
+#endif // CONFIG_RATE_CTRL
+
static void encode_with_recode_loop(VP9_COMP *cpi, size_t *size,
uint8_t *dest) {const VP9EncoderConfig *const oxcf = &cpi->oxcf;
@@ -4220,6 +4348,15 @@
int qrange_adj = 1;
#endif
+#if CONFIG_RATE_CTRL
+ const FRAME_UPDATE_TYPE update_type =
+ cpi->twopass.gf_group.update_type[cpi->twopass.gf_group.index];
+ const ENCODE_FRAME_TYPE frame_type = get_encode_frame_type(update_type);
+ RATE_QSTEP_MODEL *rq_model = &cpi->rq_model[frame_type];
+ RATE_QINDEX_HISTORY rq_history;
+ init_rq_history(&rq_history);
+#endif // CONFIG_RATE_CTRL
+
if (cm->show_existing_frame) {rc->this_frame_target = 0;
if (is_psnr_calc_enabled(cpi)) set_raw_source_frame(cpi);
@@ -4266,6 +4403,15 @@
loop_at_this_size = 0;
}
+#if CONFIG_RATE_CTRL
+ {+ const int suggested_q_index = rq_model_predict_q_index(
+ rq_model, &rq_history, rc->this_frame_target);
+ if (suggested_q_index != -1) {+ q = suggested_q_index;
+ }
+ }
+#endif // CONFIG_RATE_CTRL
// Decide frame size bounds first time through.
if (loop_count == 0) {vp9_rc_compute_frame_size_bounds(cpi, rc->this_frame_target,
@@ -4359,7 +4505,28 @@
if (cpi->encode_command.use_external_quantize_index) {break;
}
-#endif
+
+ if (cpi->encode_command.use_external_target_frame_bits) {+ const double percent_diff = get_bits_percent_diff(
+ rc->this_frame_target, rc->projected_frame_size);
+ update_rq_history(&rq_history, rc->this_frame_target,
+ rc->projected_frame_size, q);
+ loop_count += 1;
+
+ rq_model_update(&rq_history, rc->this_frame_target, rq_model);
+
+ // Check if we hit the target bitrate.
+ if (percent_diff <= 15 ||
+ rq_history.recode_count >= RATE_CTRL_MAX_RECODE_NUM ||
+ rq_history.q_index_low >= rq_history.q_index_high) {+ break;
+ }
+
+ loop = 1;
+ restore_coding_context(cpi);
+ continue;
+ }
+#endif // CONFIG_RATE_CTRL
if (oxcf->rc_mode == VPX_Q) {loop = 0;
--- a/vp9/encoder/vp9_encoder.h
+++ b/vp9/encoder/vp9_encoder.h
@@ -560,6 +560,41 @@
return gop_command->show_frame_count + gop_command->use_alt_ref;
}
+// TODO(angiebird): See if we can merge this one with FrameType in
+// simple_encode.h
+typedef enum ENCODE_FRAME_TYPE {+ ENCODE_FRAME_TYPE_KEY,
+ ENCODE_FRAME_TYPE_INTER,
+ ENCODE_FRAME_TYPE_ALTREF,
+ ENCODE_FRAME_TYPE_OVERLAY,
+ ENCODE_FRAME_TYPE_GOLDEN,
+ ENCODE_FRAME_TYPES,
+} ENCODE_FRAME_TYPE;
+
+// TODO(angiebird): Merge this function with get_frame_type_from_update_type()
+static INLINE ENCODE_FRAME_TYPE
+get_encode_frame_type(FRAME_UPDATE_TYPE update_type) {+ switch (update_type) {+ case KF_UPDATE: return ENCODE_FRAME_TYPE_KEY;
+ case ARF_UPDATE: return ENCODE_FRAME_TYPE_ALTREF;
+ case GF_UPDATE: return ENCODE_FRAME_TYPE_GOLDEN;
+ case OVERLAY_UPDATE: return ENCODE_FRAME_TYPE_OVERLAY;
+ case LF_UPDATE: return ENCODE_FRAME_TYPE_INTER;
+ default:
+ fprintf(stderr, "Unsupported update_type %d\n", update_type);
+ abort();
+ return ENCODE_FRAME_TYPE_INTER;
+ }
+}
+
+typedef struct RATE_QSTEP_MODEL {+ // The rq model predict the bit usage as follows.
+ // rate = bias - ratio * log2(q_step)
+ int ready;
+ double bias;
+ double ratio;
+} RATE_QSTEP_MODEL;
+
typedef struct ENCODE_COMMAND {int use_external_quantize_index;
int external_quantize_index;
@@ -917,6 +952,8 @@
ENCODE_COMMAND encode_command;
PARTITION_INFO *partition_info;
MOTION_VECTOR_INFO *motion_vector_info;
+
+ RATE_QSTEP_MODEL rq_model[ENCODE_FRAME_TYPES];
#endif
} VP9_COMP;