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HelloOboeEngine.cpp
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HelloOboeEngine.cpp
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/**
* Copyright 2017 The Android Open Source Project
*
* 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 <inttypes.h>
#include <memory>
#include <Oscillator.h>
#include "HelloOboeEngine.h"
#include "SoundGenerator.h"
/**
* Main audio engine for the HelloOboe sample. It is responsible for:
*
* - Creating a callback object which is supplied when constructing the audio stream, and will be
* called when the stream starts
* - Restarting the stream when user-controllable properties (Audio API, channel count etc) are
* changed, and when the stream is disconnected (e.g. when headphones are attached)
* - Calculating the audio latency of the stream
*
*/
HelloOboeEngine::HelloOboeEngine(): mLatencyCallback(std::make_unique<LatencyTuningCallback>(*this)) {
start();
updateLatencyDetection();
}
double HelloOboeEngine::getCurrentOutputLatencyMillis() {
if (!mIsLatencyDetectionSupported) return -1;
// Get the time that a known audio frame was presented for playing
auto result = mStream->getTimestamp(CLOCK_MONOTONIC);
double outputLatencyMillis = -1;
const int64_t kNanosPerMillisecond = 1000000;
if (result == oboe::Result::OK) {
oboe::FrameTimestamp playedFrame = result.value();
// Get the write index for the next audio frame
int64_t writeIndex = mStream->getFramesWritten();
// Calculate the number of frames between our known frame and the write index
int64_t frameIndexDelta = writeIndex - playedFrame.position;
// Calculate the time which the next frame will be presented
int64_t frameTimeDelta = (frameIndexDelta * oboe::kNanosPerSecond) / (mStream->getSampleRate());
int64_t nextFramePresentationTime = playedFrame.timestamp + frameTimeDelta;
// Assume that the next frame will be written at the current time
using namespace std::chrono;
int64_t nextFrameWriteTime =
duration_cast<nanoseconds>(steady_clock::now().time_since_epoch()).count();
// Calculate the latency
outputLatencyMillis = static_cast<double>(nextFramePresentationTime - nextFrameWriteTime)
/ kNanosPerMillisecond;
} else {
LOGE("Error calculating latency: %s", oboe::convertToText(result.error()));
}
return outputLatencyMillis;
}
void HelloOboeEngine::setBufferSizeInBursts(int32_t numBursts) {
mIsLatencyDetectionSupported = false;
mLatencyCallback->setBufferTuneEnabled(numBursts == kBufferSizeAutomatic);
auto result = mStream->setBufferSizeInFrames(
numBursts * mStream->getFramesPerBurst());
updateLatencyDetection();
if (result) {
LOGD("Buffer size successfully changed to %d", result.value());
} else {
LOGW("Buffer size could not be changed, %d", result.error());
}
}
void HelloOboeEngine::setAudioApi(oboe::AudioApi audioApi) {
mIsLatencyDetectionSupported = false;
createPlaybackStream(*oboe::AudioStreamBuilder(*mStream)
.setAudioApi(audioApi));
updateAudioSource();
LOGD("AudioAPI is now %d", mStream->getAudioApi());
}
void HelloOboeEngine::setChannelCount(int channelCount) {
mIsLatencyDetectionSupported = false;
createPlaybackStream(*oboe::AudioStreamBuilder(*mStream)
.setChannelCount(channelCount));
updateAudioSource();
LOGD("Channel count is now %d", mStream->getChannelCount());
}
void HelloOboeEngine::setDeviceId(int32_t deviceId) {
mIsLatencyDetectionSupported = false;
createPlaybackStream(*oboe::AudioStreamBuilder(*mStream).
setDeviceId(deviceId));
updateAudioSource();
LOGD("Device ID is now %d", mStream->getDeviceId());
}
bool HelloOboeEngine::isLatencyDetectionSupported() {
return mIsLatencyDetectionSupported;
}
void HelloOboeEngine::updateLatencyDetection() {
mIsLatencyDetectionSupported = (mStream->getTimestamp((CLOCK_MONOTONIC)) !=
oboe::Result::ErrorUnimplemented);
}
void HelloOboeEngine::tap(bool isDown) {
mAudioSource->tap(isDown);
}
void HelloOboeEngine::updateAudioSource() {
*mAudioSource = SoundGenerator(mStream->getSampleRate(), mStream->getChannelCount());
mStream->start();
updateLatencyDetection();
}
oboe::Result HelloOboeEngine::createPlaybackStream(oboe::AudioStreamBuilder builder) {
return builder.setSharingMode(oboe::SharingMode::Exclusive)
->setPerformanceMode(oboe::PerformanceMode::LowLatency)
->setFormat(oboe::AudioFormat::Float)
->setCallback(mLatencyCallback.get())
->openManagedStream(mStream);
}
void HelloOboeEngine::restart() {
start();
}
void HelloOboeEngine::start() {
auto result = createPlaybackStream(oboe::AudioStreamBuilder());
if (result == oboe::Result::OK){
mAudioSource = std::make_shared<SoundGenerator>(mStream->getSampleRate(), mStream->getChannelCount());
mLatencyCallback->setSource(std::dynamic_pointer_cast<IRenderableAudio>(mAudioSource));
mStream->start();
} else {
LOGE("Error creating playback stream. Error: %s", oboe::convertToText(result));
}
}