Master Video with AV Foundation
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Slides for my Master Video session at Renaissance 2014. This session provided a high-level overview of some of AV Foundation's video playback and editing capabilities. The demo app for this talk can be found at: https://github.com/tapharmonic/AVFoundationEditor
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Master Video with AV Foundation
- 1. Renaissance 2014: Master Video Bob McCune @bobmccune
- 2. Vatican Square Anything look different?
- 3. Vatican Square Anything look different?
- 4. Vatican Square Anything look different?
- 5. Vatican Square Anything look different?
- 7. AV Foundation Overview ‣ Objective-C framework for advanced media processing ‣ ‣ ‣ High performance, asynchronous processing Hardware accelerated handling of AV media Available in its current form since iOS 4 ‣ ‣ Significant additions and enhancements iOS 6 and 7 Apple’s focus for media apps on both iOS and Mac
- 8. iOS Media Environment An Embarrassment of Riches AssetsLibrary UIKit MediaPlayer AV Founda6on CoreAudio CoreMedia CoreVideo CoreAnima6on
- 9. Media Assets Understanding Assets AVAsset provides abstract representation of media resource ‣ Abstracts away the format and location AVAssetTrack models the individual media streams within an asset ‣ Tracks are of a uniform type (video, audio, etc.) AVAssetTrack (Video) AVAssetTrack (Audio)
- 10. Media Playback
- 11. AVPlayer Playback Controller ‣ AVPlayer is a controller for managing playback - pause - ‣ play seekToTime: Use KVO to observe playback readiness and state - ‣ status Timed Observations - addPeriodicTimeObserverForInterval:queue:usingBlock - addBoundaryTimeObserverForInterval:queue:usingBlock
- 12. Playing Media Static vs Dynamic Models ‣ AV Foundation distinguishes between static and dynamic aspects of media AVAsset AVAsset AVAssetTrack AVAsset S ta t i c AVPlayerItemTrack AVPlayerItemTrack AVPlayerItem AVPlayerItemTrack Dy n a m ic
- 13. Video Playback Playback In Action AVAsset AVAsset AVAsset AVAssetTrack AVPlayerItem AVPlayerItemTrack AVPlayerItemTrack AVPlayerItemTrack AVPlayer
- 14. Video Playback Playback In Action AVPlayerItem AVPlayerItemTrack AVPlayerItemTrack AVPlayerItemTrack AVPlayer AVPlayerLayer
- 15. Demo
- 16. Composing Media
- 17. Composing Assets AVComposition ‣ Concrete extension of AVAsset ‣ Composes asset segments on a timeline
- 18. Composing Assets Tracks and Segments AVMutableComposition *composition = [AVMutableComposition composition]; AVComposition
- 19. Composing Assets Tracks and Segments AVMutableCompositionTrack *videoTrack = [composition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:0]; AVMutableCompositionTrack *audioTrack = [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:1]; AVComposition AVCompositionTrack (Video) AVCompositionTrack (Audio)
- 20. Composing Assets Tracks and Segments AVAssetTrack *srcVideoTrack1 = // source video track 1 [videoTrack insertTimeRange:timeRange ofTrack:srcVideoTrack1 atTime:startTime error:&error]; AVAssetTrack *srcVideoTrack2 = // source video track 2 [videoTrack insertTimeRange:timeRange ofTrack:srcVideoTrack2 atTime:startTime error:&error]; AVAssetTrack *srcAudioTrack = // source audio track [audioTrack insertTimeRange:timeRange ofTrack:srcAudioTrack atTime:startTime error:&error]; AVComposition AVCompositionTrack (Video) AVCompositionTrackSegment AVCompositionTrackSegment Seconds 10-30 of “goldengate.m4v” Seconds 20-60 of “wharf.m4v” AVCompositionTrack (Audio) AVCompositionTrackSegment Seconds 0-60 of “soundtrack.m4a”
- 21. Demo
- 22. Mixing Audio
- 23. Audio Mixing AVAudioMix ‣ ‣ Composition tracks play at their natural volume AVAudioMix applies track-level volume adjustments ‣ Composed of AVAudioMixInputParameters ‣ Parameters control individual track volume over time Time Time Range
- 24. Demo
- 26. Video Transitions AVVideoComposition AVVideoComposition AVVideoCompositionInstruction AVVideoCompositionInstruction AVVideoCompositionInstruction Defines how two or more video tracks are composited together Configured through collection of composition instructions describing compositing behavior
- 27. Video Transitions AVVideoCompositionInstruction AVVideoComposition AVVideoCompositionInstruction AVVideoCompositionInstruction AVVideoCompositionInstruction AVAsset AVAsset AVVideoCompositionLayerInstruction Defines the time range of compositing behavior Composed of layer instructions describing compositing behavior
- 28. Video Transitions AVVideoCompositionLayerInstruction AVVideoComposition AVVideoCompositionInstruction AVVideoCompositionInstruction AVVideoCompositionInstruction AVAsset AVAsset AVVideoCompositionLayerInstruction Defines the transform and opacity ramps of input layers Transform and opacity changes modified over given time range
- 29. Demo
- 30. Layering Content
- 31. Layering Content Core Animation Core Animation a natural choice ‣ ‣ High performance, inherently time-based CALayer subclasses used for all video rendering CALayer: used to layer images and text CAAnimation: used to animate layered content CABasicAnimation CAKeyframeAnimation
- 32. Animation Timing AVSynchronizedLayer ‣ Core Animation operates on host time ‣ ‣ Starts at boot, marches towards infinity AVSynchronizedLayer Timeline animations need to use movie time ‣ Starts at time zero and runs to duration ‣ ‣ AVPlayerItem Can be started, stopped, rewound, etc. Timing CATextLayer Use AVSynchronizedLayer to use movie time ‣ Confers player item timing on to its sublayer tree CABasicAnimation
- 33. Core Animation Timeline vs Realtime Animations ‣ Exactly the same, almost... ‣ Animations with zero beginTime won’t be seen ‣ ‣ Set beginTime = AVCoreAnimationBeginTimeZero Animations removed by default ‣ Set removedOnCompletion = NO ‣ Unable to use CAAnimationGroup?
- 34. Demo
- 35. Summary Master iOS Video with AV Foundation! ‣ Powerful tools for audio and video playback ‣ ‣ AVPlayer, AVPlayerItem, AVPlayerLayer Powerful tools for composing/editing media: ‣ ‣ AVAudioMix ‣ AVVideoComposition ‣ ‣ AVComposition AVSynchronizedLayer Relatively steep learning curve, but worth the investment!
- 36. Resources Presentation Materials http://www.speakerdeck.com/bobmccune/ https://github.com/tapharmonic/AVFoundationEditor Learning AV Foundation http://my.safaribooksonline.com/9780133563856 Contact Info http://bobmccune.com @bobmccune