src/common/AudioStreamBuilder.cpp

/*
 * Copyright 2016 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 <sys/types.h>

#include "aaudio/AudioStreamAAudio.h"
#include "OboeDebug.h"
#include "oboe/Oboe.h"
#include "oboe/AudioStreamBuilder.h"
#include "opensles/AudioInputStreamOpenSLES.h"
#include "opensles/AudioOutputStreamOpenSLES.h"
#include "opensles/AudioStreamOpenSLES.h"

namespace oboe {

/**
 * The following default values are used when oboe does not have any better way of determining the optimal values
 * for an audio stream. This can happen when:
 *
 * - Client is creating a stream on API < 26 (OpenSLES) but has not supplied the optimal sample
 * rate and/or frames per burst
 * - Client is creating a stream on API 16 (OpenSLES) where AudioManager.PROPERTY_OUTPUT_* values
 * are not available
 */
int32_t DefaultStreamValues::SampleRate = 48000; // Common rate for mobile audio and video
int32_t DefaultStreamValues::FramesPerBurst = 192; // 4 msec at 48000 Hz
int32_t DefaultStreamValues::ChannelCount = 2; // Stereo

constexpr int kBufferSizeInBurstsForLowLatencyStreams = 2;

#ifndef OBOE_ENABLE_AAUDIO
// Set OBOE_ENABLE_AAUDIO to 0 if you want to disable the AAudio API.
// This might be useful if you want to force all the unit tests to use OpenSL ES.
#define OBOE_ENABLE_AAUDIO 1
#endif

bool AudioStreamBuilder::isAAudioSupported() {
    return AudioStreamAAudio::isSupported() && OBOE_ENABLE_AAUDIO;
}

bool AudioStreamBuilder::isAAudioRecommended() {
    // See https://github.com/google/oboe/issues/40,
    // AAudio may not be stable on Android O, depending on how it is used.
    // To be safe, use AAudio only on O_MR1 and above.
    return (getSdkVersion() >= __ANDROID_API_O_MR1__) && isAAudioSupported();
}

AudioStream *AudioStreamBuilder::build() {
    AudioStream *stream = nullptr;
    if (isAAudioRecommended() && mAudioApi != AudioApi::OpenSLES) {
        stream = new AudioStreamAAudio(*this);
    } else if (isAAudioSupported() && mAudioApi == AudioApi::AAudio) {
        stream = new AudioStreamAAudio(*this);
        LOGE("Creating AAudio stream on 8.0 because it was specified. This is error prone.");
    } else {
        if (getDirection() == oboe::Direction::Output) {
            stream = new AudioOutputStreamOpenSLES(*this);
        } else if (getDirection() == oboe::Direction::Input) {
            stream = new AudioInputStreamOpenSLES(*this);
        }
    }
    return stream;
}

Result AudioStreamBuilder::openStream(AudioStream **streamPP) {
    LOGD("%s() %s -------- %s --------",
         __func__, getDirection() == Direction::Input ? "INPUT" : "OUTPUT", getVersionText());

    if (streamPP == nullptr) {
        return Result::ErrorNull;
    }
    *streamPP = nullptr;
    AudioStream *streamP = build();
    if (streamP == nullptr) {
        return Result::ErrorNull;
    }
    Result result = streamP->open(); // TODO review API
    if (result == Result::OK) {

        // Use a reasonable default buffer size for low latency streams.
        if (streamP->getPerformanceMode() == PerformanceMode::LowLatency){
            int32_t optimalBufferSize = streamP->getFramesPerBurst() *
                                        kBufferSizeInBurstsForLowLatencyStreams;
            auto setBufferResult = streamP->setBufferSizeInFrames(optimalBufferSize);
            if (!setBufferResult){
                LOGW("Failed to set buffer size to %d. Error was %s",
                     optimalBufferSize,
                     convertToText(setBufferResult.error()));
            }
        }
        *streamPP = streamP;
    } else {
        delete streamP;
    }
    return result;
}

Result AudioStreamBuilder::openManagedStream(oboe::ManagedStream &stream) {
    stream.reset();
    AudioStream *streamptr;
    auto result = openStream(&streamptr);
    stream.reset(streamptr);
    return result;
}

} // namespace oboe