WaveformSummary.hpp

#pragma once
#include <algorithm>
#include <cstdint>
#include <memory>
 
namespace Media
{
// Remove the compile time overhead of std::pair for this
struct FloatPair
{
  float first, second;
};
 
struct WaveformSummary
{
  int64_t bucket{};
 
  int64_t bucketCount{};
 
  int32_t channels{};
 
  int64_t frames{};
 
  std::unique_ptr<FloatPair[]> data;
 
  const FloatPair* channel(int c) const noexcept
  {
    return data.get() + c * bucketCount;
  }
 
  static int64_t bucketFor(int64_t frames, int32_t channels) noexcept
  {
    constexpr int64_t max_bytes = 32ll * 1024 * 1024;
    constexpr int64_t max_bucket = 1ll << 20;
    const int64_t max_buckets
        = max_bytes / (int64_t(sizeof(FloatPair)) * std::max(1, int(channels)));
 
    int64_t b = 64;
    while(b < max_bucket && frames / b > max_buckets)
      b *= 2;
    return b;
  }
};
}