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- // 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 <cmath>
- #include <sstream>
- #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<uint32_t>(audio_bus->channels());
- ++ch) {
- const float* channel = audio_bus->channel(ch);
- for (uint32_t i = 0; i < static_cast<uint32_t>(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<uint32_t>(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
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