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Optionally dropping frames #83

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Optionally dropping frames #83

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2 changes: 2 additions & 0 deletions Examples/Sources/SCRecorderViewController.m
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Original file line number Diff line number Diff line change
Expand Up @@ -69,6 +69,8 @@ - (void)viewDidLoad {
_recorder = [SCRecorder recorder];
_recorder.sessionPreset = AVCaptureSessionPreset1280x720;
_recorder.maxRecordDuration = CMTimeMake(5, 1);
_recorder.videoConfiguration.maxFrameRate = 10;
_recorder.videoConfiguration.timeScale = 0.333;

_recorder.delegate = self;
_recorder.autoSetVideoOrientation = YES;
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27 changes: 25 additions & 2 deletions Library/Sources/SCRecordSession.m
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Original file line number Diff line number Diff line change
Expand Up @@ -93,8 +93,10 @@ - (id)init {
_timeOffset = kCMTimeZero;
_lastTimeVideo = kCMTimeZero;
_lastTimeAudio = kCMTimeZero;
_lastAppendedVideo = kCMTimeZero;
_currentSegmentDuration = kCMTimeZero;
_segmentsDuration = kCMTimeZero;
_sessionBegan = kCMTimeZero;
_date = [NSDate date];
_recordSegmentsDirectory = SCRecordSessionTemporaryDirectory;
_identifier = [NSString stringWithFormat:@"%ld", (long)[_date timeIntervalSince1970]];
Expand Down Expand Up @@ -612,6 +614,10 @@ - (BOOL)appendAudioSampleBuffer:(CMSampleBufferRef)audioSampleBuffer {
if ([_audioInput isReadyForMoreMediaData]) {
CMTime actualBufferTime = CMSampleBufferGetPresentationTimeStamp(audioSampleBuffer);

if (CMTIME_IS_INVALID(_sessionBegan)) {
_sessionBegan = actualBufferTime;
}

if (CMTIME_IS_INVALID(_timeOffset)) {
_timeOffset = CMTimeSubtract(actualBufferTime, _currentSegmentDuration);
}
Expand Down Expand Up @@ -644,6 +650,23 @@ - (BOOL)appendVideoSampleBuffer:(CMSampleBufferRef)videoSampleBuffer {
if ([_videoInput isReadyForMoreMediaData]) {
CMTime actualBufferTime = CMSampleBufferGetPresentationTimeStamp(videoSampleBuffer);

if (CMTIME_IS_INVALID(_sessionBegan)) {
_sessionBegan = actualBufferTime;
}

if (_videoConfiguration.maxFrameRate > 0) {
CMTime interval = CMTimeMake(1, _videoConfiguration.maxFrameRate);

CMTime offset = CMTimeSubtract(actualBufferTime, _lastAppendedVideo);
if (CMTIME_COMPARE_INLINE(_lastAppendedVideo, ==, kCMTimeZero)) {
offset = CMTimeSubtract(actualBufferTime, _sessionBegan);
}

if (CMTIME_COMPARE_INLINE(offset, <, interval)) {
return NO;
}
}

if (CMTIME_IS_INVALID(_timeOffset)) {
_timeOffset = CMTimeSubtract(actualBufferTime, _currentSegmentDuration);
// NSLog(@"Recomputed time offset to: %fs", CMTimeGetSeconds(_timeOffset));
Expand All @@ -662,8 +685,7 @@ - (BOOL)appendVideoSampleBuffer:(CMSampleBufferRef)videoSampleBuffer {
}
}

CMTime bufferTimestamp = CMTimeSubtract(CMSampleBufferGetPresentationTimeStamp(videoSampleBuffer), _timeOffset);

CMTime bufferTimestamp = CMTimeSubtract(actualBufferTime, _timeOffset);
if (_videoPixelBufferAdaptor != nil) {
CIImage *image = [CIImage imageWithCVPixelBuffer:CMSampleBufferGetImageBuffer(videoSampleBuffer)];

Expand Down Expand Up @@ -693,6 +715,7 @@ - (BOOL)appendVideoSampleBuffer:(CMSampleBufferRef)videoSampleBuffer {
CFRelease(adjustedBuffer);
}

_lastAppendedVideo = actualBufferTime;
_lastTimeVideo = actualBufferTime;
_currentSegmentDuration = bufferTimestamp;

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2 changes: 2 additions & 0 deletions Library/Sources/SCRecordSession_Internal.h
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,8 @@
CMTime _timeOffset;
CMTime _lastTimeVideo;
CMTime _lastTimeAudio;
CMTime _lastAppendedVideo;
CMTime _sessionBegan;

SCVideoConfiguration *_videoConfiguration;
SCAudioConfiguration *_audioConfiguration;
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2 changes: 1 addition & 1 deletion Library/Sources/SCVideoConfiguration.h
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Expand Up @@ -43,7 +43,7 @@
@property (copy, nonatomic) NSString *scalingMode;

/**
The maximum framerate that this SCRecordSession should handle
The maximum input framerate that this SCRecordSession should handle
If the camera appends too much frames, they will be dropped.
If this property's value is 0, it will use the current video
framerate from the camera.
Expand Down