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AVAssetExportSession-如何从视频持续时间中修剪毫秒

avfoundation swift ios

Lance Samaria · 技术社区 · 4 年前

可变成分:

let mixComposition = AVMutableComposition()
        
let compositionVideoTrack = mixComposition.addMutableTrack(withMediaType: .video, preferredTrackID: Int32(kCMPersistentTrackID_Invalid))

let soundtrackTrack = mixComposition.addMutableTrack(withMediaType: .audio, preferredTrackID: Int32(kCMPersistentTrackID_Invalid))

var insertTime = CMTime.zero
for videoAsset in videoAssets {
    do {

        let videoTrack = videoAsset.tracks(withMediaType: .video)
        try compositionVideoTrack?.insertTimeRange(CMTimeRangeMake(start: CMTime.zero, duration: videoAsset.duration), videoAsset.tracks(withMediaType: .video)[0], at: insertTime)

        let audioTrack = videoAsset.tracks(withMediaType: .audio)
        try soundtrackTrack?.insertTimeRange(CMTimeRangeMake(start: CMTime.zero, duration: videoAsset.duration), videoAsset.tracks(withMediaType: .audio)[0], at: insertTime)

        insertTime = CMTimeAdd(insertTime, videoAsset.duration)

    } catch {

    }
}

AvassetExport会话:

guard let exporter = AVAssetExportSession(asset: mixComposition, presetName: AVAssetExportPresetHighestQuality) else { return }

let start = CMTimeMakeWithSeconds(.zero, preferredTimescale: 600)
let videoDuration = CMTimeMakeWithSeconds(mixComposition.duration, preferredTimescale: 600)
let range = CMTimeRangeMake(start: start, duration: videoDuration)
exporter.timeRange = range

// ...

0 回复 | 直到 4 年前

Lance Samaria 4 年前

trunc() 它截断任何余数,只留下一个整数。

如果使用 AVMutableComposition()

let mixComposition = AVMutableComposition()
// ...

let videoDuration = CMTimeGetSeconds(mixComposition.duration)
let dub = Double(videoDuration)

let durationTruncated = trunc(dub)
print(".......truncate: ", durationTruncated)

let duration = CMTimeMakeWithSeconds(durationTruncated, preferredTimescale: 600)
let start = CMTimeMakeWithSeconds(.zero, preferredTimescale: 600)
let range = CMTimeRangeMake(start: start, duration: duration)
exporter.timeRange = range

如果使用照片库中的url:

let asset = AVURLAsset(url: yourLibraryUrl) // if this isn't a libraryUrl you will need to run it through asset.loadValuesAsynchronously and use the "duration" asset key to get the duration first
let videoDuration = CMTimeGetSeconds(asset.duration)

let dub = Double(videoDuration)
let durationTruncated = trunc(dub)
print(".......truncate: ", durationTruncated)

let duration = CMTimeMakeWithSeconds(durationTruncated, preferredTimescale: 600)
let start = CMTimeMakeWithSeconds(.zero, preferredTimescale: 600)
let range = CMTimeRangeMake(start: start, duration: duration)
exporter.timeRange = range

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