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add audio-visual decoding functionalities
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weiyaowang
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Weiyao Wang
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Jul 11, 2020
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| Original file line number | Diff line number | Diff line change |
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| /** | ||
| * Copyright (c) 2020-present, Facebook, Inc. | ||
| * | ||
| * Licensed under the Apache License, Version 2.0 (the "License"); | ||
| * you may not use this file except in compliance with the License. | ||
| * You may obtain a copy of the License at | ||
| * | ||
| * http://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * Unless required by applicable law or agreed to in writing, software | ||
| * distributed under the License is distributed on an "AS IS" BASIS, | ||
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| * See the License for the specific language governing permissions and | ||
| * limitations under the License. | ||
| */ | ||
|
|
||
| #include "LogMels.h" | ||
|
|
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| #include <glog/logging.h> | ||
| #include <complex> | ||
|
|
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| const int kAudioBufferSize = 20480; | ||
| const double kGain = 1080674186.3482928; | ||
|
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| inline float hz2Mel(float hz) { | ||
| return 1127 * std::log(1 + hz / 700); | ||
| } | ||
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| inline float mel2Hz(float mel) { | ||
| return 700 * (std::exp(mel / 1127) - 1); | ||
| } | ||
|
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| LogSpectrum::LogSpectrum( | ||
| int numChannels, | ||
| float samplingRate, | ||
| int windowLength, | ||
| int windowStep, | ||
| float startFreq, | ||
| float endFreq, | ||
| bool normalized) | ||
| : numChannels_(numChannels), | ||
| samplingRate_(samplingRate), | ||
| windowLength_(windowLength * samplingRate / 1000.0f), | ||
| windowStep_(windowStep * samplingRate / 1000.0f), | ||
| startFreq_(startFreq), | ||
| endFreq_(endFreq > 0 ? endFreq : samplingRate * .5f), | ||
| normalized_(normalized), | ||
| fifo_(nullptr), | ||
| inited_(false) { | ||
| int bits = log2(windowLength_); | ||
| if (pow(2, bits) != windowLength_) { | ||
| bits += 1; | ||
| } | ||
| fftSize_ = (int)pow(2, bits); | ||
| filterLength_ = fftSize_ / 2 + 1; | ||
|
|
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| filters_ = (float*)calloc(numChannels_ * filterLength_, sizeof(float)); | ||
| featFrame_ = (double*)calloc(numChannels_, sizeof(double)); | ||
| tempFrame_ = (float*)calloc(fftSize_, sizeof(float)); | ||
| window_ = (float*)calloc(windowLength_, sizeof(float)); | ||
|
|
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| dftContext_ = av_rdft_init(bits, DFT_R2C); | ||
| for (int i = 0; i < windowLength_; i++) { | ||
| window_[i] = .5f * (1 - cos(2 * M_PI * i / (windowLength_ - 1))); | ||
| } | ||
|
|
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| CHECK(Init()); | ||
| } | ||
|
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| void LogSpectrum::Cleanup() { | ||
| if (filters_) { | ||
| free(filters_); | ||
| filters_ = nullptr; | ||
| } | ||
| if (featFrame_) { | ||
| free(featFrame_); | ||
| featFrame_ = nullptr; | ||
| } | ||
| if (tempFrame_) { | ||
| free(tempFrame_); | ||
| tempFrame_ = nullptr; | ||
| } | ||
| if (window_) { | ||
| free(window_); | ||
| window_ = nullptr; | ||
| } | ||
| if (dftContext_) { | ||
| av_rdft_end(dftContext_); | ||
| dftContext_ = nullptr; | ||
| } | ||
| if (fifo_) { | ||
| av_audio_fifo_reset(fifo_); | ||
| av_audio_fifo_free(fifo_); | ||
| fifo_ = nullptr; | ||
| } | ||
| } | ||
|
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| LogSpectrum::~LogSpectrum() { | ||
| Cleanup(); | ||
| } | ||
|
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| bool LogSpectrum::Init() { | ||
| if (inited_) { | ||
| return true; | ||
| } | ||
| if (!fifo_) { | ||
| if (!(fifo_ = | ||
| av_audio_fifo_alloc(AV_SAMPLE_FMT_FLT, 1, kAudioBufferSize))) { | ||
| LOG(ERROR) << "Could not allocate FIFO"; | ||
| return false; | ||
| } | ||
| } | ||
|
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| float maxFreq = samplingRate_ / 2.0f; | ||
| CHECK_LT(startFreq_, endFreq_) << "End frequency is larger than start freq"; | ||
| CHECK_LE(endFreq_, maxFreq) << "End frequency is larger than maxFreq"; | ||
|
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| float startMel = hz2Mel(startFreq_); | ||
| float endMel = hz2Mel(endFreq_); | ||
| float dx = (endMel - startMel) / (numChannels_ + 1); | ||
| float freqStep = samplingRate_ / 2 / filterLength_; | ||
| for (int filter = 0; filter < numChannels_; ++filter) { | ||
| float start = mel2Hz(filter * dx) / freqStep; | ||
| float mid = mel2Hz((filter + 1) * dx) / freqStep; | ||
| float end = mel2Hz((filter + 2) * dx) / freqStep; | ||
| int from = int(start); | ||
| int to = int(end) + 1; | ||
| float leftWidth = std::max<float>(1.0, mid - start); | ||
| float rightWidth = std::max<float>(1.0, end - mid); | ||
| float sum = 0; | ||
| from = std::max<int>(0, from); | ||
| to = std::min<int>(filterLength_ - 1, to); | ||
| filterRanges_.emplace_back(from, to); | ||
| for (int i = from; i <= to; i++) { | ||
| float value = | ||
| 1.f - ((i < mid) ? (mid - i) / leftWidth : (i - mid) / rightWidth); | ||
| if (value > 0) { | ||
| filters_[filter * filterLength_ + i] = value; | ||
| sum += value; | ||
| } | ||
| } | ||
| if (normalized_ && sum > 0) { | ||
| for (int inX = from; inX <= to; inX++) { | ||
| filters_[filter * filterLength_ + inX] /= sum; | ||
| } | ||
| } | ||
| } | ||
| inited_ = true; | ||
| return true; | ||
| } | ||
|
|
||
| int LogSpectrum::Write(float* samples, size_t numSamples) { | ||
| int samplesW = 0; | ||
| if ((samplesW = av_audio_fifo_write(fifo_, (void**)&samples, numSamples)) < | ||
| numSamples) { | ||
| LOG(ERROR) << "Could not write data to FIFO"; | ||
| return -1; | ||
| } | ||
| return samplesW; | ||
| } | ||
|
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| int LogSpectrum::Read(float* feat) { | ||
| if (av_audio_fifo_size(fifo_) > windowLength_) { | ||
| memset(tempFrame_, 0, fftSize_ * sizeof(float)); | ||
| if (av_audio_fifo_peek(fifo_, (void**)&tempFrame_, windowLength_) < | ||
| windowLength_) { | ||
| LOG(ERROR) << "Could not read data from FIFO"; | ||
| return -1; | ||
| } | ||
| if (av_audio_fifo_drain(fifo_, windowStep_)) { | ||
| LOG(ERROR) << "Could not drain data from FIFO"; | ||
| return -1; | ||
| } | ||
| Apply(feat); | ||
| return 1; | ||
| } | ||
| return 0; | ||
| } | ||
|
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| void LogSpectrum::Apply(float* feat) { | ||
| PowerSpectrum(); | ||
| for (int i = 0; i < numChannels_; ++i) { | ||
| featFrame_[i] = 0; | ||
| } | ||
| for (int i = 0; i < numChannels_; ++i) { | ||
| for (int j = filterRanges_[i].first; j < filterRanges_[i].second; ++j) { | ||
| featFrame_[i] += tempFrame_[j] * filters_[i * filterLength_ + j] * kGain; | ||
| } | ||
| feat[i] = | ||
| featFrame_[i] > M_E ? std::log(featFrame_[i]) : featFrame_[i] / M_E; | ||
| } | ||
| } | ||
|
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| void LogSpectrum::PowerSpectrum() { | ||
| for (int i = 0; i < windowLength_; i++) { | ||
| tempFrame_[i] *= window_[i]; | ||
| } | ||
| av_rdft_calc(dftContext_, tempFrame_); | ||
| FFTComplex* comps = reinterpret_cast<FFTComplex*>(tempFrame_); | ||
| for (int i = 0; i < fftSize_ / 2; i++) { | ||
| tempFrame_[i] = comps[i].re * comps[i].re + comps[i].im * comps[i].im; | ||
| } | ||
| } |
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