112 lines
2.4 KiB
C++
112 lines
2.4 KiB
C++
/***
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Olive - Non-Linear Video Editor
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Copyright (C) 2021 Olive Team
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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***/
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#include "previewaudiodevice.h"
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namespace olive {
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PreviewAudioDevice::PreviewAudioDevice(QObject *parent)
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{
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// These pointers are always valid
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using_ = &internal_buffer_[0];
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pushing_ = &internal_buffer_[1];
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// Default to swap being true because we'll have nothing in the main buffer at first
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swap_requested_ = true;
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}
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PreviewAudioDevice::~PreviewAudioDevice()
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{
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close();
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}
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bool PreviewAudioDevice::isSequential() const
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{
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return true;
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}
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qint64 PreviewAudioDevice::readData(char *data, qint64 maxSize)
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{
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if (swap_requested_) {
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SwapBuffers(kFullLock);
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swap_requested_ = false;
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}
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// This function should NEVER touch the buffer in `pushing_`
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qint64 copy_length = qMin(maxSize, qint64(using_->size()));
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if (copy_length) {
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memcpy(data, using_->constData(), copy_length);
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*using_ = using_->mid(copy_length);
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if (using_->isEmpty() && !SwapBuffers(kTryLock)) {
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// Ask push function to swap if it can. If it can't, we'll catch it next read.
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swap_requested_ = true;
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}
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}
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return copy_length;
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}
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qint64 PreviewAudioDevice::writeData(const char *, qint64)
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{
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// No writing to this device
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return -1;
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}
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void PreviewAudioDevice::Push(const QByteArray &b)
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{
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// This function should NEVER touch the buffer in `using_`
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QMutexLocker locker(&lock_);
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pushing_->append(b);
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// If swap requested, do this now
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if (swap_requested_) {
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SwapBuffers(kDontLock);
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swap_requested_ = false;
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}
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}
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bool PreviewAudioDevice::SwapBuffers(LockMethod m)
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{
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switch (m) {
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case kDontLock:
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break;
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case kTryLock:
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if (!lock_.tryLock()) {
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return false;
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}
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break;
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case kFullLock:
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lock_.lock();
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break;
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}
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std::swap(using_, pushing_);
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if (m != kDontLock) {
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lock_.unlock();
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}
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return true;
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}
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}
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