拼接后视频中的绿色背景答案

【问题标题】：Green background in video after stitching拼接后视频中的绿色背景
【发布时间】：2019-09-11 15:58:15
【问题描述】：

我正在开发一个应用程序，该应用程序应该录制并粘贴来自相机的录制视频和来自资源的视频。拼接效果很好，最终视频在设备上播放良好。但是，当最终视频上传到 Facebook 或 YouTube 时，在那里播放视频时会出现绿色和灰色背景。此背景出现在录制的视频结束和资源中的视频开始的地方。

This is what it looks like:

我使用 AVFoundation 进行拼接。这是一个示例代码：

let finalMixComposition : AVMutableComposition = AVMutableComposition()

    var videoCompositionTrack : [AVMutableCompositionTrack] = []
    var audioCompositionTrack : [AVMutableCompositionTrack] = []

    let finalVideoCompositionInstruction : AVMutableVideoCompositionInstruction = AVMutableVideoCompositionInstruction()

    let renderSize = CGSize(width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.height)

    var startTime = CMTime.zero

    videoCompositionTrack.append(finalMixComposition.addMutableTrack(withMediaType: .video, preferredTrackID: kCMPersistentTrackID_Invalid)!)
    audioCompositionTrack.append(finalMixComposition.addMutableTrack(withMediaType: .audio, preferredTrackID: kCMPersistentTrackID_Invalid)!)

    let arrayVideos : [URL] = [firstVideo, secondVideo, thirdVideo, fourthVideo…]

    for url in arrayVideos {
        let videoAsset : AVAsset = AVAsset(url: url)

        let aVideoAssetTrack = videoAsset.tracks(withMediaType: AVMediaType.video)[0]

        var aAudioAssetTrack = videoAsset.tracks(withMediaType: AVMediaType.audio)[0]

        do {
            try videoCompositionTrack[0].insertTimeRange(CMTimeRangeMake(start: CMTime.zero, duration: aVideoAssetTrack.timeRange.duration),
                                                         of: aVideoAssetTrack,
                                                         at: startTime)

            try audioCompositionTrack[0].insertTimeRange(CMTimeRangeMake(start: CMTime.zero, duration: aVideoAssetTrack.timeRange.duration),
                                                            of: aAudioAssetTrack,
                                                            at: startTime)
        }
        catch {
            print("error")
        }

        startTime = CMTime(seconds: startTime.seconds + aVideoAssetTrack.timeRange.duration.seconds)
    }

    finalVideoCompositionInstruction.timeRange = CMTimeRangeMake(start: CMTime.zero, duration: startTime)

    let mutableVideoComposition : AVMutableVideoComposition = AVMutableVideoComposition()
    mutableVideoComposition.frameDuration = CMTimeMake(value: 0, timescale: 60)

    mutableVideoComposition.renderSize = renderSize

    let savePathUrl = tempURL()

    let assetExport: AVAssetExportSession = AVAssetExportSession(asset: finalMixComposition,
                                                                 presetName: AVAssetExportPresetHighestQuality)!
    assetExport.outputFileType = AVFileType.mp4
    assetExport.outputURL = savePathUrl
    assetExport.shouldOptimizeForNetworkUse = true

    assetExport.exportAsynchronously {}

怀疑这是由于视频的参数不同造成的。有谁知道如何解决这个问题？感谢您的帮助；）

【问题讨论】：

标签： ios swift video video-editing

【解决方案1】：

解决了视频拼接的问题。需要在视频设置中指定 BitRate、Codec、ProfileLevel。对于解决方案，我找到了一个库：SDAVAssetExportSession

这是一个示例代码：

let encoder = SDAVAssetExportSession(asset: finalMixComposition)
    encoder!.outputFileType = AVFileType.mp4.rawValue
    encoder!.outputURL = savePathUrl
    encoder!.videoSettings = [AVVideoCodecKey: AVVideoCodecType.h264,
                              AVVideoWidthKey: 1024,
                              AVVideoHeightKey: 768,
                              AVVideoCompressionPropertiesKey: [AVVideoAverageBitRateKey: 6000000,
                                                                AVVideoProfileLevelKey: AVVideoProfileLevelH264High40]]

    encoder!.audioSettings = [AVFormatIDKey: kAudioFormatMPEG4AAC,
                              AVNumberOfChannelsKey: 2,
                              AVSampleRateKey: 44100,
                              AVEncoderBitRateKey: 128000]

    encoder!.exportAsynchronously {}

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