diff options
Diffstat (limited to 'src/plugins/avfoundation/camera/avfmediaassetwriter.mm')
| -rw-r--r-- | src/plugins/avfoundation/camera/avfmediaassetwriter.mm | 114 |
1 files changed, 66 insertions, 48 deletions
diff --git a/src/plugins/avfoundation/camera/avfmediaassetwriter.mm b/src/plugins/avfoundation/camera/avfmediaassetwriter.mm index 98c8f99ff..28735bc6a 100644 --- a/src/plugins/avfoundation/camera/avfmediaassetwriter.mm +++ b/src/plugins/avfoundation/camera/avfmediaassetwriter.mm @@ -46,7 +46,6 @@ #include "avfcameradebug.h" #include "avfmediacontainercontrol.h" -//#include <QtCore/qmutexlocker.h> #include <QtCore/qmetaobject.h> #include <QtCore/qsysinfo.h> @@ -74,6 +73,13 @@ bool qt_camera_service_isValid(AVFCameraService *service) return true; } +enum WriterState +{ + WriterStateIdle, + WriterStateActive, + WriterStateAborted +}; + } // unnamed namespace @interface QT_MANGLE_NAMESPACE(AVFMediaAssetWriter) (PrivateAPI) @@ -85,21 +91,14 @@ bool qt_camera_service_isValid(AVFCameraService *service) @implementation QT_MANGLE_NAMESPACE(AVFMediaAssetWriter) -- (id)initWithQueue:(dispatch_queue_t)writerQueue - delegate:(AVFMediaRecorderControlIOS *)delegate +- (id)initWithDelegate:(AVFMediaRecorderControlIOS *)delegate { - Q_ASSERT(writerQueue); Q_ASSERT(delegate); if (self = [super init]) { - // "Shared" queue: - dispatch_retain(writerQueue); - m_writerQueue.reset(writerQueue); - m_delegate = delegate; m_setStartTime = true; - m_stopped.store(true); - m_aborted.store(false); + m_state.store(WriterStateIdle); m_startTime = kCMTimeInvalid; m_lastTimeStamp = kCMTimeInvalid; m_durationInMs.store(0); @@ -127,6 +126,12 @@ bool qt_camera_service_isValid(AVFCameraService *service) m_audioSettings = audioSettings; m_videoSettings = videoSettings; + m_writerQueue.reset(dispatch_queue_create("asset-writer-queue", DISPATCH_QUEUE_SERIAL)); + if (!m_writerQueue) { + qDebugCamera() << Q_FUNC_INFO << "failed to create an asset writer's queue"; + return false; + } + m_videoQueue.reset(dispatch_queue_create("video-output-queue", DISPATCH_QUEUE_SERIAL)); if (!m_videoQueue) { qDebugCamera() << Q_FUNC_INFO << "failed to create video queue"; @@ -173,15 +178,12 @@ bool qt_camera_service_isValid(AVFCameraService *service) - (void)start { - // To be executed on a writer's queue. - const QMutexLocker lock(&m_writerMutex); - if (m_aborted.load()) - return; - [self setQueues]; m_setStartTime = true; - m_stopped.store(false); + + m_state.storeRelease(WriterStateActive); + [m_assetWriter startWriting]; AVCaptureSession *session = m_service->session()->captureSession(); if (!session.running) @@ -190,27 +192,36 @@ bool qt_camera_service_isValid(AVFCameraService *service) - (void)stop { - // To be executed on a writer's queue. - { - const QMutexLocker lock(&m_writerMutex); - if (m_aborted.load()) + if (m_state.loadAcquire() != WriterStateActive) return; - if (m_stopped.load()) + if ([m_assetWriter status] != AVAssetWriterStatusWriting) return; - m_stopped.store(true); - } - + // Do this here so that - + // 1. '-abort' should not try calling finishWriting again and + // 2. async block (see below) will know if recorder control was deleted + // before the block's execution: + m_state.storeRelease(WriterStateIdle); + // Now, since we have to ensure no sample buffers are + // appended after a call to finishWriting, we must + // ensure writer's queue sees this change in m_state + // _before_ we call finishWriting: + dispatch_sync(m_writerQueue, ^{}); + // Done, but now we also want to prevent video queue + // from updating our viewfinder: + dispatch_sync(m_videoQueue, ^{}); + + // Now we're safe to stop: [m_assetWriter finishWritingWithCompletionHandler:^{ // This block is async, so by the time it's executed, // it's possible that render control was deleted already ... - const QMutexLocker lock(&m_writerMutex); - if (m_aborted.load()) + if (m_state.loadAcquire() == WriterStateAborted) return; AVCaptureSession *session = m_service->session()->captureSession(); - [session stopRunning]; + if (session.running) + [session stopRunning]; [session removeOutput:m_audioOutput]; [session removeInput:m_audioInput]; QMetaObject::invokeMethod(m_delegate, "assetWriterFinished", Qt::QueuedConnection); @@ -219,12 +230,26 @@ bool qt_camera_service_isValid(AVFCameraService *service) - (void)abort { - // To be executed on any thread (presumably, it's the main thread), - // prevents writer from accessing any shared object. - const QMutexLocker lock(&m_writerMutex); - m_aborted.store(true); - if (m_stopped.load()) + // -abort is to be called from recorder control's dtor. + + if (m_state.fetchAndStoreRelease(WriterStateAborted) != WriterStateActive) { + // Not recording, nothing to stop. return; + } + + // From Apple's docs: + // "To guarantee that all sample buffers are successfully written, + // you must ensure that all calls to appendSampleBuffer: and + // appendPixelBuffer:withPresentationTime: have returned before + // invoking this method." + // + // The only way we can ensure this is: + dispatch_sync(m_writerQueue, ^{}); + // At this point next block (if any) on the writer's queue + // will see m_state preventing it from any further processing. + dispatch_sync(m_videoQueue, ^{}); + // After this point video queue will not try to modify our + // viewfider, so we're safe to delete now. [m_assetWriter finishWritingWithCompletionHandler:^{ }]; @@ -236,13 +261,12 @@ bool qt_camera_service_isValid(AVFCameraService *service) Q_ASSERT(m_setStartTime); Q_ASSERT(sampleBuffer); - const QMutexLocker lock(&m_writerMutex); - if (m_aborted.load() || m_stopped.load()) + if (m_state.loadAcquire() != WriterStateActive) return; QMetaObject::invokeMethod(m_delegate, "assetWriterStarted", Qt::QueuedConnection); - m_durationInMs.store(0); + m_durationInMs.storeRelease(0); m_startTime = CMSampleBufferGetPresentationTimeStamp(sampleBuffer); m_lastTimeStamp = m_startTime; [m_assetWriter startSessionAtSourceTime:m_startTime]; @@ -251,10 +275,10 @@ bool qt_camera_service_isValid(AVFCameraService *service) - (void)writeVideoSampleBuffer:(CMSampleBufferRef)sampleBuffer { + // This code is executed only on a writer's queue. Q_ASSERT(sampleBuffer); - // This code is executed only on a writer's queue. - if (!m_aborted.load() && !m_stopped.load()) { + if (m_state.loadAcquire() == WriterStateActive) { if (m_setStartTime) [self setStartTimeFrom:sampleBuffer]; @@ -264,17 +288,15 @@ bool qt_camera_service_isValid(AVFCameraService *service) } } - CFRelease(sampleBuffer); } - (void)writeAudioSampleBuffer:(CMSampleBufferRef)sampleBuffer { - // This code is executed only on a writer's queue. - // it does not touch any shared/external data. Q_ASSERT(sampleBuffer); - if (!m_aborted.load() && !m_stopped.load()) { + // This code is executed only on a writer's queue. + if (m_state.loadAcquire() == WriterStateActive) { if (m_setStartTime) [self setStartTimeFrom:sampleBuffer]; @@ -293,10 +315,7 @@ bool qt_camera_service_isValid(AVFCameraService *service) { Q_UNUSED(connection) - // This method can be called on either video or audio queue, - // never on a writer's queue, it needs access to a shared data, so - // lock is required. - if (m_stopped.load()) + if (m_state.loadAcquire() != WriterStateActive) return; if (!CMSampleBufferDataIsReady(sampleBuffer)) { @@ -307,8 +326,7 @@ bool qt_camera_service_isValid(AVFCameraService *service) CFRetain(sampleBuffer); if (captureOutput != m_audioOutput.data()) { - const QMutexLocker lock(&m_writerMutex); - if (m_aborted.load() || m_stopped.load()) { + if (m_state.load() != WriterStateActive) { CFRelease(sampleBuffer); return; } @@ -447,7 +465,7 @@ bool qt_camera_service_isValid(AVFCameraService *service) if (!CMTimeCompare(duration, kCMTimeInvalid)) return; - m_durationInMs.store(CMTimeGetSeconds(duration) * 1000); + m_durationInMs.storeRelease(CMTimeGetSeconds(duration) * 1000); m_lastTimeStamp = newTimeStamp; } } |