We're using code based on AVAssetReader to get decoded video frames through AVFoundation. The decoding part per se works great but the seeking just doesn't work reliably. For a given H.264 file (in the MOV container) the decoded frames have presentation time stamps that sometimes don't correspond to the actual decoded frames. So for example: the decoded frame's PTS is 2002/24000 but the frame's actual PTS is 6006/24000. The frames have burnt-in timecode so we can clearly tell. Here is our code: - (BOOL) setupAssetReaderForFrameIndex:(int32_t) frameIndex { NSError* theError = nil; NSDictionary* assetOptions = @{ AVURLAssetPreferPreciseDurationAndTimingKey: @YES }; self.movieAsset = [[AVURLAsset alloc] initWithURL:self.filePat options:assetOptions]; if (self.assetReader) [self.assetReader cancelReading]; self.assetReader = [AVAssetReader assetReaderWithAsset:self.movieAsset error:&theError]; NSArray<AVAssetTrack*>* videoTracks = [self.movieAsset tracksWithMediaType:AVMediaTypeVideo]; if ([videoTracks count] == 0) return NO; self.videoTrack = [videoTracks objectAtIndex:0]; [self retrieveMetadata]; NSDictionary* outputSettings = @{ (id)kCVPixelBufferPixelFormatTypeKey: @(self.cvPixelFormat) }; self.videoTrackOutput = [AVAssetReaderTrackOutput assetReaderTrackOutputWithTrack:self.videoTrack outputSettings:outputSettings]; self.videoTrackOutput.alwaysCopiesSampleData = NO; [self.assetReader addOutput:self.videoTrackOutput]; CMTimeScale timeScale = self.videoTrack.naturalTimeScale; CMTimeValue frameDuration = (CMTimeValue)round((float)timeScale/self.videoTrack.nominalFrameRate); CMTimeValue startTimeValue = (CMTimeValue)frameIndex * frameDuration; CMTimeRange timeRange = CMTimeRangeMake(CMTimeMake(startTimeValue, timeScale), kCMTimePositiveInfinity); self.assetReader.timeRange = timeRange; [self.assetReader startReading]; return YES; } This is then followed by this code to actually decode the frame: CMSampleBufferRef sampleBuffer = [self.videoTrackOutput copyNextSampleBuffer]; CVPixelBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer); if (!imageBuffer) { CMSampleBufferInvalidate(sampleBuffer); AVAssetReaderStatus theStatus = self.assetReader.status; NSError* theError = self.assetReader.error; NSLog(@"[AVAssetVideoTrackOutput copyNextSampleBuffer] didn't deliver a frame - %@", theError); return false; } Is this method by itself the correct way of seeking and if not: what is the correct way? Thanks!

Hi everyone, In my app i use AVCaptureSession to record video. I add videoDeviceInput and audioDeviceInput. And as output I use AVCaptureMovieFileOutput. And the result for some iPhone specially the iPhones after IPhoneX(iPhone 11,12, 13,14) has bad audio quality, The sound is like so low then after some seconds(around 7 secs) become normal. I have tried setting the audio setting for movie file out but it's still happen. Anyone know how to solve this issue?