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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>()),
mErrorCallback(std::make_unique<DefaultErrorCallback>(*this)) {
}
double HelloOboeEngine::getCurrentOutputLatencyMillis() {
if (!mIsLatencyDetectionSupported) return -1.0;
std::lock_guard<std::mutex> lock(mLock);
if (!mStream) return -1.0;
// 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) {
std::lock_guard<std::mutex> lock(mLock);
if (!mStream) return;
mLatencyCallback->setBufferTuneEnabled(numBursts == kBufferSizeAutomatic);
auto result = mStream->setBufferSizeInFrames(
numBursts * mStream->getFramesPerBurst());
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) {
mAudioApi = audioApi;
reopenStream();
}
void HelloOboeEngine::setChannelCount(int channelCount) {
mChannelCount = channelCount;
reopenStream();
}
void HelloOboeEngine::setDeviceId(int32_t deviceId) {
mDeviceId = deviceId;
if (reopenStream() != oboe::Result::OK) {
LOGW("Open stream failed, forcing deviceId to Unspecified");
mDeviceId = oboe::Unspecified;
}
}
bool HelloOboeEngine::isLatencyDetectionSupported() {
return mIsLatencyDetectionSupported;
}
void HelloOboeEngine::tap(bool isDown) {
mAudioSource->tap(isDown);
}
oboe::Result HelloOboeEngine::createPlaybackStream() {
oboe::AudioStreamBuilder builder;
return builder.setSharingMode(oboe::SharingMode::Exclusive)
->setPerformanceMode(oboe::PerformanceMode::LowLatency)
->setFormat(oboe::AudioFormat::Float)
->setDataCallback(mLatencyCallback.get())
->setErrorCallback(mErrorCallback.get())
->setAudioApi(mAudioApi)
->setChannelCount(mChannelCount)
->setDeviceId(mDeviceId)
->openStream(mStream);
}
void HelloOboeEngine::restart() {
// The stream will have already been closed by the error callback.
mLatencyCallback->reset();
start();
}
oboe::Result HelloOboeEngine::start() {
std::lock_guard<std::mutex> lock(mLock);
auto result = createPlaybackStream();
if (result == oboe::Result::OK){
mAudioSource = std::make_shared<SoundGenerator>(mStream->getSampleRate(),
mStream->getChannelCount());
mLatencyCallback->setSource(std::dynamic_pointer_cast<IRenderableAudio>(mAudioSource));
mStream->start();
mIsLatencyDetectionSupported = (mStream->getTimestamp((CLOCK_MONOTONIC)) !=
oboe::Result::ErrorUnimplemented);
LOGD("Stream opened: AudioAPI = %d, channelCount = %d, deviceID = %d",
mStream->getAudioApi(),
mStream->getChannelCount(),
mStream->getDeviceId());
} else {
LOGE("Error creating playback stream. Error: %s", oboe::convertToText(result));
mIsLatencyDetectionSupported = false;
}
return result;
}
void HelloOboeEngine::stop() {
// Stop, close and delete in case not already closed.
std::lock_guard<std::mutex> lock(mLock);
if (mStream) {
mStream->stop();
mStream->close();
mStream.reset();
}
}
oboe::Result HelloOboeEngine::reopenStream() {
stop();
return start();
}
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