diff options
Diffstat (limited to 'src/plugins/avfoundation/camera/avfmediaassetwriter.mm')
-rw-r--r-- | src/plugins/avfoundation/camera/avfmediaassetwriter.mm | 91 |
1 files changed, 50 insertions, 41 deletions
diff --git a/src/plugins/avfoundation/camera/avfmediaassetwriter.mm b/src/plugins/avfoundation/camera/avfmediaassetwriter.mm index 4e227114b..464d90db0 100644 --- a/src/plugins/avfoundation/camera/avfmediaassetwriter.mm +++ b/src/plugins/avfoundation/camera/avfmediaassetwriter.mm @@ -85,17 +85,11 @@ enum WriterState @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_state.store(WriterStateIdle); @@ -126,6 +120,12 @@ enum WriterState 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"; @@ -172,20 +172,10 @@ enum WriterState - (void)start { - // 'start' is executed on a special writer's queue. - // We lock a mutex for the whole function body - // - render control probably was deleted - // 'immediately' after submitting 'start' - // and before 'start' is actually executed ... - // So if we're starting, render control can not - // abort us 'in the middle'. - const QMutexLocker lock(&m_writerMutex); - if (m_state.load() == WriterStateAborted) - return; - [self setQueues]; m_setStartTime = true; + m_state.storeRelease(WriterStateActive); [m_assetWriter startWriting]; @@ -196,40 +186,65 @@ enum WriterState - (void)stop { - // To be executed on a writer's queue. - { - const QMutexLocker lock(&m_writerMutex); - if (m_state.load() != WriterStateActive) + if (m_state.loadAcquire() != WriterStateActive) return; - } + if ([m_assetWriter status] != AVAssetWriterStatusWriting) + return; + + // 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 ... - // We lock so that nobody can call 'abort' in the middle ... - const QMutexLocker lock(&m_writerMutex); - if (m_state.load() != WriterStateActive) + 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]; - m_state.storeRelease(WriterStateIdle); QMetaObject::invokeMethod(m_delegate, "assetWriterFinished", Qt::QueuedConnection); }]; } - (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); + // -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:^{ }]; } @@ -240,13 +255,12 @@ enum WriterState Q_ASSERT(m_setStartTime); Q_ASSERT(sampleBuffer); - const QMutexLocker lock(&m_writerMutex); - if (m_state.load() != WriterStateActive) + 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]; @@ -255,9 +269,9 @@ enum WriterState - (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_state.loadAcquire() == WriterStateActive) { if (m_setStartTime) [self setStartTimeFrom:sampleBuffer]; @@ -268,7 +282,6 @@ enum WriterState } } - CFRelease(sampleBuffer); } @@ -296,9 +309,6 @@ enum WriterState { 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_state.loadAcquire() != WriterStateActive) return; @@ -310,7 +320,6 @@ enum WriterState CFRetain(sampleBuffer); if (captureOutput != m_audioOutput.data()) { - const QMutexLocker lock(&m_writerMutex); if (m_state.load() != WriterStateActive) { CFRelease(sampleBuffer); return; @@ -450,7 +459,7 @@ enum WriterState if (!CMTimeCompare(duration, kCMTimeInvalid)) return; - m_durationInMs.store(CMTimeGetSeconds(duration) * 1000); + m_durationInMs.storeRelease(CMTimeGetSeconds(duration) * 1000); m_lastTimeStamp = newTimeStamp; } } |