// Copyright 2013 The Chromium Authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. #include "media/base/audio_hash.h" #include #include #include "base/numerics/math_constants.h" #include "base/strings/stringprintf.h" #include "media/base/audio_bus.h" namespace media { AudioHash::AudioHash() : audio_hash_(), sample_count_(0) { } AudioHash::~AudioHash() = default; void AudioHash::Update(const AudioBus* audio_bus, int frames) { // Use uint32_t to ensure overflow is a defined operation. for (uint32_t ch = 0; ch < static_cast(audio_bus->channels()); ++ch) { const float* channel = audio_bus->channel(ch); for (uint32_t i = 0; i < static_cast(frames); ++i) { const uint32_t kSampleIndex = sample_count_ + i; const uint32_t kHashIndex = (kSampleIndex * (ch + 1)) % std::size(audio_hash_); // Mix in a sine wave with the result so we ensure that sequences of empty // buffers don't result in an empty hash. if (ch == 0) { audio_hash_[kHashIndex] += channel[i] + std::sin(2.0 * base::kPiDouble * base::kPiDouble * kSampleIndex); } else { audio_hash_[kHashIndex] += channel[i]; } } } sample_count_ += static_cast(frames); } std::string AudioHash::ToString() const { std::string result; for (size_t i = 0; i < std::size(audio_hash_); ++i) result += base::StringPrintf("%.2f,", audio_hash_[i]); return result; } bool AudioHash::IsEquivalent(const std::string& other, double tolerance) const { float other_hash; char comma; std::stringstream is(other); for (size_t i = 0; i < std::size(audio_hash_); ++i) { is >> other_hash >> comma; if (std::fabs(audio_hash_[i] - other_hash) > tolerance) return false; } return true; } } // namespace media