feat: loop background audio

cardinalblue · Nov 28, 2022 · bd84275 · bd84275
1 parent 1be621b
commit bd84275
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Showing 8 changed files with 152 additions and 102 deletions.
diff --git a/CMTime+Extensions.swift b/CMTime+Extensions.swift
@@ -0,0 +1,26 @@
+//
+//  CMTime+Extensions.swift
+//  MTTransitions
+//
+//  Created by Jim Wang on 2022/11/28.
+//
+
+import CoreMedia
+import Foundation
+
+extension CMTime {
+
+    static func makeLoopTime(timeRange: CMTimeRange, at: CMTime = .zero, until: CMTime) -> [(at: CMTime, timeRange: CMTimeRange)] {
+        let duration = timeRange.duration
+        var t = at
+        var times = [(at: CMTime, timeRange: CMTimeRange)]()
+        while t < until {
+            let adjustedDuration = CMTimeMinimum(CMTimeSubtract(until, t), duration)
+            let adjustedTimeRange = CMTimeRange(start: timeRange.start, duration: adjustedDuration)
+            times.append((at: t, timeRange: adjustedTimeRange))
+            t = CMTimeAdd(t, adjustedDuration)
+        }
+        return times
+    }
+
+}
diff --git a/MTTransitionsDemo.xcodeproj/project.pbxproj b/MTTransitionsDemo.xcodeproj/project.pbxproj
@@ -47,6 +47,7 @@
 		A3F2636A243EF67B00A093D2 /* PickImageTransitionViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = A3F26369243EF67B00A093D2 /* PickImageTransitionViewController.swift */; };
 		FBB33DD328461993006FA36F /* TimelineSampleViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = FBB33DD228461993006FA36F /* TimelineSampleViewController.swift */; };
 		FBD7D02D2847486500E62822 /* APLCompositionDebugView.m in Sources */ = {isa = PBXBuildFile; fileRef = FBD7D02C2847486500E62822 /* APLCompositionDebugView.m */; };
+		FBE7123C29348D6500BC77FB /* audio1_trimmed.mp3 in Resources */ = {isa = PBXBuildFile; fileRef = FBE7123B29348D6500BC77FB /* audio1_trimmed.mp3 */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXFileReference section */
@@ -96,6 +97,7 @@
 		FBD7D02A2847486400E62822 /* MTTransitionsDemo-Bridging-Header.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = "MTTransitionsDemo-Bridging-Header.h"; sourceTree = "<group>"; };
 		FBD7D02B2847486500E62822 /* APLCompositionDebugView.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = APLCompositionDebugView.h; sourceTree = "<group>"; };
 		FBD7D02C2847486500E62822 /* APLCompositionDebugView.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = APLCompositionDebugView.m; sourceTree = "<group>"; };
+		FBE7123B29348D6500BC77FB /* audio1_trimmed.mp3 */ = {isa = PBXFileReference; lastKnownFileType = audio.mp3; path = audio1_trimmed.mp3; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -154,6 +156,7 @@
 			children = (
 				A3C9E22024373E4D002F82D9 /* audio1.mp3 */,
 				A3C9E1F42431D640002F82D9 /* audio2.mp3 */,
+				FBE7123B29348D6500BC77FB /* audio1_trimmed.mp3 */,
 				A369F7DC242A035C00546190 /* cut1.mp4 */,
 				A369F7DD242A035C00546190 /* cut2.mp4 */,
 				A3CFA84A242B96E900F2E660 /* cut3.mp4 */,
@@ -293,6 +296,7 @@
 				A3E0AD2D2205BEA6002DD092 /* 5.jpg in Resources */,
 				A3E0AD282205BEA6002DD092 /* 8.jpg in Resources */,
 				A3913EC3242886280083E7D3 /* clip1.mp4 in Resources */,
+				FBE7123C29348D6500BC77FB /* audio1_trimmed.mp3 in Resources */,
 				A3E0AD2F2205BEA6002DD092 /* 6.jpg in Resources */,
 				A3E0AD272205BEA6002DD092 /* 3.jpg in Resources */,
 				A374124121F98D9B0019F3A3 /* LaunchScreen.storyboard in Resources */,

diff --git a/MTTransitionsDemo/Resources/audio1_trimmed.mp3 b/MTTransitionsDemo/Resources/audio1_trimmed.mp3
diff --git a/MTTransitionsDemo/Samples/TimelineSampleViewController.swift b/MTTransitionsDemo/Samples/TimelineSampleViewController.swift
@@ -189,10 +189,8 @@ class TimelineSampleViewController: UIViewController {
 //            Clip(resource: resource4)
         ]
         timeline.backgroundAudioClip = { () -> Clip in
-            let timeRange = CMTimeRange(start: .zero, duration: CMTime(seconds: 5, preferredTimescale: 1000))
             let audioResource = AVAssetResource(
-                asset: loadAsset(named: "audio1", withExtension: "mp3")!,
-                selectedTimeRange: timeRange
+                asset: loadAsset(named: "audio1_trimmed", withExtension: "mp3")!
             )
             return Clip(resource: audioResource)
         }()

diff --git a/Pods/Pods.xcodeproj/project.pbxproj b/Pods/Pods.xcodeproj/project.pbxproj
diff --git a/Source/Model/Clip.swift b/Source/Model/Clip.swift
@@ -189,4 +189,24 @@ extension AVMutableComposition {
         try compositionTrack.insertTimeRange(selectedTimeRange, of: resourceTrackInfo.track, at: time)
     }
 
+    func addResource(trackID: Int32, with resourceTrackInfo: ResourceTrackInfo, at: CMTime, timeRange: CMTimeRange, until: CMTime) throws {
+        let assetTrack = resourceTrackInfo.track
+
+        let compositionTrack: AVMutableCompositionTrack? = {
+            if let track = track(withTrackID: trackID) {
+                return track
+            }
+            return addMutableTrack(withMediaType: assetTrack.mediaType, preferredTrackID: trackID)
+        }()
+
+        guard let compositionTrack = compositionTrack else {
+            throw MTTimelineCompositionError.noCompositionTrack
+        }
+
+        let times = CMTime.makeLoopTime(timeRange: timeRange, at: at, until: until)
+        for time in times {
+            print("at: \(time.at), range: \(time.timeRange)")
+            try compositionTrack.insertTimeRange(time.timeRange, of: resourceTrackInfo.track, at: time.at)
+        }
+    }
 }
diff --git a/Source/Model/MTTimelineComposition.swift b/Source/Model/MTTimelineComposition.swift
@@ -118,9 +118,9 @@ public class MTTimelineComposition {
                     try composition.addResource(trackID: trackID, with: resourceInfo, at: time)
                 case .backgroundAudio:
                     let resourceInfo = clip.resource.trackInfo(for: .audio, at: trackInfo.index)
-                    try composition.addResource(trackID: trackID, with: resourceInfo, at: time, duration: trackInfo.timeRange.duration)
-
-                    let endTime = time + trackInfo.timeRange.duration
+                    let endTime = trackInfo.timeRange.end
+                    try composition.addResource(trackID: trackID, with: resourceInfo,
+                                                at: time, timeRange: resourceInfo.selectedTimeRange, until: endTime)
 
                     let track = composition.track(withTrackID: trackID)
                     let inputParameter = AVMutableAudioMixInputParameters(track: track)

diff --git a/Source/Model/Timeline.swift b/Source/Model/Timeline.swift
@@ -207,7 +207,7 @@ public class Timeline {
         if let backgroundAudioClip = backgroundAudioClip {
             let start = clipTimeRanges.first!.start
             let end = clipTimeRanges.last!
-            let timeRange = CMTimeRange(start: .zero, duration: end.end)
+            let timeRange = CMTimeRange(start: start, duration: end.end)
 
             for index in 0..<backgroundAudioClip.numberOfAudioTracks() {
                 let trackID = makeTrackID(trackIndex: index, clipIndex: 0, mediaType: .backgroundAudio)