rate_hist.c

/*
 *  Copyright (c) 2014 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.
 */

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

#include "./rate_hist.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 vpx_codec_enc_cfg_t *cfg,
                                      const vpx_rational_t *fps) {
  int i;
  struct rate_hist *hist = malloc(sizeof(*hist));

  // 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 = 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));
  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;
}

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