1/* 2 * Copyright (c) 2013 The WebRTC project authors. All Rights Reserved. 3 * 4 * Use of this source code is governed by a BSD-style license 5 * that can be found in the LICENSE file in the root of the source 6 * tree. An additional intellectual property rights grant can be found 7 * in the file PATENTS. All contributing project authors may 8 * be found in the AUTHORS file in the root of the source tree. 9 */ 10 11#include "webrtc/common_audio/resampler/push_sinc_resampler.h" 12 13#include <cstring> 14 15#include "webrtc/base/checks.h" 16#include "webrtc/common_audio/include/audio_util.h" 17 18namespace webrtc { 19 20PushSincResampler::PushSincResampler(size_t source_frames, 21 size_t destination_frames) 22 : resampler_(new SincResampler(source_frames * 1.0 / destination_frames, 23 source_frames, 24 this)), 25 source_ptr_(nullptr), 26 source_ptr_int_(nullptr), 27 destination_frames_(destination_frames), 28 first_pass_(true), 29 source_available_(0) {} 30 31PushSincResampler::~PushSincResampler() { 32} 33 34size_t PushSincResampler::Resample(const int16_t* source, 35 size_t source_length, 36 int16_t* destination, 37 size_t destination_capacity) { 38 if (!float_buffer_.get()) 39 float_buffer_.reset(new float[destination_frames_]); 40 41 source_ptr_int_ = source; 42 // Pass nullptr as the float source to have Run() read from the int16 source. 43 Resample(nullptr, source_length, float_buffer_.get(), destination_frames_); 44 FloatS16ToS16(float_buffer_.get(), destination_frames_, destination); 45 source_ptr_int_ = nullptr; 46 return destination_frames_; 47} 48 49size_t PushSincResampler::Resample(const float* source, 50 size_t source_length, 51 float* destination, 52 size_t destination_capacity) { 53 RTC_CHECK_EQ(source_length, resampler_->request_frames()); 54 RTC_CHECK_GE(destination_capacity, destination_frames_); 55 // Cache the source pointer. Calling Resample() will immediately trigger 56 // the Run() callback whereupon we provide the cached value. 57 source_ptr_ = source; 58 source_available_ = source_length; 59 60 // On the first pass, we call Resample() twice. During the first call, we 61 // provide dummy input and discard the output. This is done to prime the 62 // SincResampler buffer with the correct delay (half the kernel size), thereby 63 // ensuring that all later Resample() calls will only result in one input 64 // request through Run(). 65 // 66 // If this wasn't done, SincResampler would call Run() twice on the first 67 // pass, and we'd have to introduce an entire |source_frames| of delay, rather 68 // than the minimum half kernel. 69 // 70 // It works out that ChunkSize() is exactly the amount of output we need to 71 // request in order to prime the buffer with a single Run() request for 72 // |source_frames|. 73 if (first_pass_) 74 resampler_->Resample(resampler_->ChunkSize(), destination); 75 76 resampler_->Resample(destination_frames_, destination); 77 source_ptr_ = nullptr; 78 return destination_frames_; 79} 80 81void PushSincResampler::Run(size_t frames, float* destination) { 82 // Ensure we are only asked for the available samples. This would fail if 83 // Run() was triggered more than once per Resample() call. 84 RTC_CHECK_EQ(source_available_, frames); 85 86 if (first_pass_) { 87 // Provide dummy input on the first pass, the output of which will be 88 // discarded, as described in Resample(). 89 std::memset(destination, 0, frames * sizeof(*destination)); 90 first_pass_ = false; 91 return; 92 } 93 94 if (source_ptr_) { 95 std::memcpy(destination, source_ptr_, frames * sizeof(*destination)); 96 } else { 97 for (size_t i = 0; i < frames; ++i) 98 destination[i] = static_cast<float>(source_ptr_int_[i]); 99 } 100 source_available_ -= frames; 101} 102 103} // namespace webrtc 104