Drop Frames

Examples/Sources/SCRecorderViewController.m

@@ -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;

Library/Sources/SCRecordSession.m

@@ -92,8 +92,10 @@ - (id)init {
         _currentSegmentCount = 0;
         _timeOffset = kCMTimeZero;
         _lastTimeAudio = kCMTimeZero;
+        _lastAppendedVideo = kCMTimeZero;
         _currentSegmentDuration = kCMTimeZero;
         _segmentsDuration = kCMTimeZero;
+        _sessionBegan = kCMTimeZero;
         _date = [NSDate date];
         _recordSegmentsDirectory = SCRecordSessionTemporaryDirectory;
         _identifier = [NSString stringWithFormat:@"%ld", (long)[_date timeIntervalSince1970]];
@@ -599,6 +601,10 @@ - (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);
         }
@@ -631,6 +637,23 @@ - (BOOL)appendVideoSampleBuffer:(CMSampleBufferRef)videoSampleBuffer duration:(C
     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));
@@ -644,7 +667,6 @@ - (BOOL)appendVideoSampleBuffer:(CMSampleBufferRef)videoSampleBuffer duration:(C
         }
 
         CMTime bufferTimestamp = CMTimeSubtract(actualBufferTime, _timeOffset);
-
         if (_videoPixelBufferAdaptor != nil) {
             CIImage *image = [CIImage imageWithCVPixelBuffer:CMSampleBufferGetImageBuffer(videoSampleBuffer)];
 
@@ -674,6 +696,7 @@ - (BOOL)appendVideoSampleBuffer:(CMSampleBufferRef)videoSampleBuffer duration:(C
             CFRelease(adjustedBuffer);
         }
 
+        _lastAppendedVideo = actualBufferTime;
         _currentSegmentDuration = CMTimeAdd(bufferTimestamp, duration);
 
         _currentSegmentHasVideo = YES;

Library/Sources/SCRecordSession_Internal.h

@@ -22,6 +22,8 @@
     int _currentSegmentCount;
     CMTime _timeOffset;
     CMTime _lastTimeAudio;
+    CMTime _lastAppendedVideo;
+    CMTime _sessionBegan;
 
     SCVideoConfiguration *_videoConfiguration;
     SCAudioConfiguration *_audioConfiguration;

Library/Sources/SCRecorder.m

@@ -155,7 +155,7 @@ - (void)commitSessionConfiguration {
     if (_captureSession != nil) {
         _beginSessionConfigurationCount--;
         if (_beginSessionConfigurationCount == 0) {
-            [_captureSession commitConfiguration];
+            [self.captureSession commitConfiguration];
         }
     }
 }
@@ -967,7 +967,31 @@ - (void)setPhotoOutputSettings:(NSDictionary *)photoOutputSettings {
 - (void)setDevice:(AVCaptureDevicePosition)device {
     _device = device;
     if (_captureSession != nil) {
-        [self reconfigureVideoInput:self.videoConfiguration.enabled audioInput:NO];
+
+        [self beginSessionConfiguration];
+        NSError *error = nil;
+        AVCaptureDeviceInput *currentInput = [self currentDeviceInputForMediaType:AVMediaTypeVideo];
+        AVCaptureDeviceInput *newInput = [[AVCaptureDeviceInput alloc] initWithDevice:[self videoDevice] error:&error];
+
+        if (error == nil) {
+            [_captureSession removeInput:currentInput];
+            if ([_captureSession canAddInput:newInput]) {
+                [_captureSession addInput:newInput];
+            } else {
+                [_captureSession addInput:currentInput];
+                error = [SCRecorder createError:@"Failed to add input to capture session"];
+            }
+        }
+
+        dispatch_sync(_recordSessionQueue, ^{
+            [self updateVideoOrientation];
+        });
+        [self commitSessionConfiguration];
+
+        id<SCRecorderDelegate> delegate = self.delegate;
+        if ([delegate respondsToSelector:@selector(recorder:didReconfigureVideoInput:)]) {
+            [delegate recorder:self didReconfigureVideoInput:error];
+        }
     }
 }
 

Library/Sources/SCVideoConfiguration.h

@@ -50,7 +50,7 @@ typedef enum : NSUInteger {
 @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.