Setting maximum input framerate

fix #83

Author: fjcaetano

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

@@ -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]];
@@ -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);
         }
@@ -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));
@@ -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)];
 
@@ -693,6 +715,7 @@ - (BOOL)appendVideoSampleBuffer:(CMSampleBufferRef)videoSampleBuffer {
             CFRelease(adjustedBuffer);
         }
 
+        _lastAppendedVideo = actualBufferTime;
         _lastTimeVideo = actualBufferTime;
         _currentSegmentDuration = bufferTimestamp;
 

Library/Sources/SCRecordSession_Internal.h

@@ -23,6 +23,8 @@
     CMTime _timeOffset;
     CMTime _lastTimeVideo;
     CMTime _lastTimeAudio;
+    CMTime _lastAppendedVideo;
+    CMTime _sessionBegan;
 
     SCVideoConfiguration *_videoConfiguration;
     SCAudioConfiguration *_audioConfiguration;

Library/Sources/SCVideoConfiguration.h

@@ -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.