tor-browser

rate_hist.c (8271B)

---

/*
* Copyright (c) 2016, Alliance for Open Media. All rights reserved.
*
* This source code is subject to the terms of the BSD 2 Clause License and
* the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
* was not distributed with this source code in the LICENSE file, you can
* obtain it at www.aomedia.org/license/software. If the Alliance for Open
* Media Patent License 1.0 was not distributed with this source code in the
* PATENTS file, you can obtain it at www.aomedia.org/license/patent.
*/

#include "stats/rate_hist.h"

#include <assert.h>
#include <limits.h>
#include <math.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>

#define RATE_BINS 100
#define HIST_BAR_MAX 40

struct hist_bucket {
 int low;
 int high;
 int count;
};

struct rate_hist {
 int64_t *pts;
 int *sz;
 int samples;
 int frames;
 struct hist_bucket bucket[RATE_BINS];
 int total;
};

struct rate_hist *init_rate_histogram(const aom_codec_enc_cfg_t *cfg,
                                     const aom_rational_t *fps) {
 int i;
 struct rate_hist *hist = calloc(1, sizeof(*hist));

 if (hist == NULL || cfg == NULL || fps == NULL || fps->num == 0 ||
     fps->den == 0) {
   goto fail;
 }

 // Determine the number of samples in the buffer. Use the file's framerate
 // to determine the number of frames in rc_buf_sz milliseconds, with an
 // adjustment (5/4) to account for alt-refs
 hist->samples =
     (int)((int64_t)cfg->rc_buf_sz * 5 / 4 * fps->num / fps->den / 1000);

 // prevent division by zero
 if (hist->samples == 0) hist->samples = 1;

 hist->frames = 0;
 hist->total = 0;

 hist->pts = calloc(hist->samples, sizeof(*hist->pts));
 hist->sz = calloc(hist->samples, sizeof(*hist->sz));
 if (hist->pts == NULL || hist->sz == NULL) goto fail;
 for (i = 0; i < RATE_BINS; i++) {
   hist->bucket[i].low = INT_MAX;
   hist->bucket[i].high = 0;
   hist->bucket[i].count = 0;
 }

 return hist;

fail:
 fprintf(stderr,
         "Warning: Unable to allocate buffers required for "
         "show_rate_histogram().\n"
         "Continuing without rate histogram feature...\n");
 destroy_rate_histogram(hist);
 return NULL;
}

void destroy_rate_histogram(struct rate_hist *hist) {
 if (hist) {
   free(hist->pts);
   free(hist->sz);
   free(hist);
 }
}

void update_rate_histogram(struct rate_hist *hist,
                          const aom_codec_enc_cfg_t *cfg,
                          const aom_codec_cx_pkt_t *pkt) {
 int i;
 int64_t then = 0;
 int64_t avg_bitrate = 0;
 int64_t sum_sz = 0;
 const int64_t now = pkt->data.frame.pts * 1000 *
                     (uint64_t)cfg->g_timebase.num /
                     (uint64_t)cfg->g_timebase.den;

 int idx;

 if (hist == NULL || cfg == NULL || pkt == NULL) return;

 idx = hist->frames++ % hist->samples;
 hist->pts[idx] = now;
 hist->sz[idx] = (int)pkt->data.frame.sz;

 if (now < cfg->rc_buf_initial_sz) return;

 if (!cfg->rc_target_bitrate) return;

 then = now;

 /* Sum the size over the past rc_buf_sz ms */
 for (i = hist->frames; i > 0 && hist->frames - i < hist->samples; i--) {
   const int i_idx = (i - 1) % hist->samples;

   then = hist->pts[i_idx];
   if (now - then > cfg->rc_buf_sz) break;
   sum_sz += hist->sz[i_idx];
 }

 if (now == then) return;

 avg_bitrate = sum_sz * 8 * 1000 / (now - then);
 idx = (int)(avg_bitrate * (RATE_BINS / 2) / (cfg->rc_target_bitrate * 1000));
 if (idx < 0) idx = 0;
 if (idx > RATE_BINS - 1) idx = RATE_BINS - 1;
 if (hist->bucket[idx].low > avg_bitrate)
   hist->bucket[idx].low = (int)avg_bitrate;
 if (hist->bucket[idx].high < avg_bitrate)
   hist->bucket[idx].high = (int)avg_bitrate;
 hist->bucket[idx].count++;
 hist->total++;
}

static int merge_hist_buckets(struct hist_bucket *bucket, int max_buckets,
                             int *num_buckets) {
 int small_bucket = 0, merge_bucket = INT_MAX, big_bucket = 0;
 int buckets;
 int i;

 assert(bucket != NULL);
 assert(num_buckets != NULL);

 buckets = *num_buckets;

 /* Find the extrema for this list of buckets */
 big_bucket = small_bucket = 0;
 for (i = 0; i < buckets; i++) {
   if (bucket[i].count < bucket[small_bucket].count) small_bucket = i;
   if (bucket[i].count > bucket[big_bucket].count) big_bucket = i;
 }

 /* If we have too many buckets, merge the smallest with an adjacent
  * bucket.
  */
 while (buckets > max_buckets) {
   int last_bucket = buckets - 1;

   /* merge the small bucket with an adjacent one. */
   if (small_bucket == 0)
     merge_bucket = 1;
   else if (small_bucket == last_bucket)
     merge_bucket = last_bucket - 1;
   else if (bucket[small_bucket - 1].count < bucket[small_bucket + 1].count)
     merge_bucket = small_bucket - 1;
   else
     merge_bucket = small_bucket + 1;

   assert(abs(merge_bucket - small_bucket) <= 1);
   assert(small_bucket < buckets);
   assert(big_bucket < buckets);
   assert(merge_bucket < buckets);

   if (merge_bucket < small_bucket) {
     bucket[merge_bucket].high = bucket[small_bucket].high;
     bucket[merge_bucket].count += bucket[small_bucket].count;
   } else {
     bucket[small_bucket].high = bucket[merge_bucket].high;
     bucket[small_bucket].count += bucket[merge_bucket].count;
     merge_bucket = small_bucket;
   }

   assert(bucket[merge_bucket].low != bucket[merge_bucket].high);

   buckets--;

   /* Remove the merge_bucket from the list, and find the new small
    * and big buckets while we're at it
    */
   big_bucket = small_bucket = 0;
   for (i = 0; i < buckets; i++) {
     if (i > merge_bucket) bucket[i] = bucket[i + 1];

     if (bucket[i].count < bucket[small_bucket].count) small_bucket = i;
     if (bucket[i].count > bucket[big_bucket].count) big_bucket = i;
   }
 }

 *num_buckets = buckets;
 return bucket[big_bucket].count;
}

static void show_histogram(const struct hist_bucket *bucket, int buckets,
                          int total, int scale) {
 int width1, width2;
 int i;

 if (!buckets) return;
 assert(bucket != NULL);
 assert(buckets > 0);

 switch ((int)(log(bucket[buckets - 1].high) / log(10)) + 1) {
   case 1:
   case 2:
     width1 = 4;
     width2 = 2;
     break;
   case 3:
     width1 = 5;
     width2 = 3;
     break;
   case 4:
     width1 = 6;
     width2 = 4;
     break;
   case 5:
     width1 = 7;
     width2 = 5;
     break;
   case 6:
     width1 = 8;
     width2 = 6;
     break;
   case 7:
     width1 = 9;
     width2 = 7;
     break;
   default:
     width1 = 12;
     width2 = 10;
     break;
 }

 for (i = 0; i < buckets; i++) {
   int len;
   int j;
   float pct;

   pct = (float)(100.0 * bucket[i].count / total);
   len = HIST_BAR_MAX * bucket[i].count / scale;
   if (len < 1) len = 1;
   assert(len <= HIST_BAR_MAX);

   if (bucket[i].low == bucket[i].high)
     fprintf(stderr, "%*d %*s: ", width1, bucket[i].low, width2, "");
   else
     fprintf(stderr, "%*d-%*d: ", width1, bucket[i].low, width2,
             bucket[i].high);

   for (j = 0; j < HIST_BAR_MAX; j++) fprintf(stderr, j < len ? "=" : " ");
   fprintf(stderr, "\t%5d (%6.2f%%)\n", bucket[i].count, pct);
 }
}

void show_q_histogram(const int counts[64], int max_buckets) {
 struct hist_bucket bucket[64];
 int buckets = 0;
 int total = 0;
 int scale;
 int i;

 for (i = 0; i < 64; i++) {
   if (counts[i]) {
     bucket[buckets].low = bucket[buckets].high = i;
     bucket[buckets].count = counts[i];
     buckets++;
     total += counts[i];
   }
 }

 fprintf(stderr, "\nQuantizer Selection:\n");
 scale = merge_hist_buckets(bucket, max_buckets, &buckets);
 show_histogram(bucket, buckets, total, scale);
}

void show_rate_histogram(struct rate_hist *hist, const aom_codec_enc_cfg_t *cfg,
                        int max_buckets) {
 int i, scale;
 int buckets = 0;

 if (hist == NULL || cfg == NULL) return;

 for (i = 0; i < RATE_BINS; i++) {
   if (hist->bucket[i].low == INT_MAX) continue;
   hist->bucket[buckets++] = hist->bucket[i];
 }

 fprintf(stderr, "\nRate (over %dms window):\n", cfg->rc_buf_sz);
 scale = merge_hist_buckets(hist->bucket, max_buckets, &buckets);
 show_histogram(hist->bucket, buckets, hist->total, scale);
}