BFRecordScreenKit/BFRecordScreenKit/Classes/BFVideoThumbImageFetchHelper.swift

//
//  BFVideoThumbImageFetchHelper.swift
//  BFRecordScreenKit
//
//  Created by 胡志强 on 2021/12/3.
//

import AVFoundation
import BFCommonKit
import Foundation

/// 视频分解成帧
/// - parameter fileUrl                 : 视频地址
/// - parameter fps                          : 自定义帧数 每秒内取的帧数
/// - parameter firstImagesCount             : 获取首先N张连续视频帧后先返回给调用方使用作为缓冲
/// - parameter splitCompleteClosure    : 回调
func splitVideoFileUrlFps(urlAsset: AVURLAsset, fps: Double, firstImagesCount:Int = 0, splitCompleteClosure: @escaping ((Bool, [UIImage]) -> Void)) {
    var splitImages = [UIImage]()

    var times = [NSValue]()

    let start = 0
    let end = Int(urlAsset.duration.seconds * Float64(fps))

    for i in start...end {
        let timeValue = NSValue(time: CMTimeMake(value: Int64(i * 1000), timescale: Int32(fps * 1000)))

        times.append(timeValue)
    }

    let imgGenerator = AVAssetImageGenerator(asset: urlAsset)
    imgGenerator.requestedTimeToleranceBefore = CMTime.zero
    imgGenerator.requestedTimeToleranceAfter = CMTime.zero
    imgGenerator.appliesPreferredTrackTransform = true
    let timesCount = times.count
    var cocu = 0
    // 获取每一帧的图片
    imgGenerator.generateCGImagesAsynchronously(forTimes: times) { _, image, _, result, _ in
        cocu += 1
        switch result {
        case AVAssetImageGenerator.Result.cancelled:
            BFLog(1, message: "splitVideo: cancel")

        case AVAssetImageGenerator.Result.failed:
            BFLog(1, message: "splitVideo: failed")

        case AVAssetImageGenerator.Result.succeeded:
            let framImg = UIImage(cgImage: image!)
            splitImages.append(framImg)
//            BFLog(1, message: "aaa: \(requestedTime.seconds) - \(actualTime.seconds)")
        @unknown default:
            break
        }
        
        if cocu == firstImagesCount {
            splitCompleteClosure(false, splitImages)
        }
        
        if cocu == timesCount { // 最后一帧时 回调赋值
            splitCompleteClosure(true, splitImages)
            BFLog(1, message: "splitVideo: complete")
        }
    }
}

/// 视频分解成帧
/// - parameter fileUrl                 : 视频地址
/// - parameter fps                     : 自定义帧数 每秒内取的帧数
/// - parameter splitCompleteClosure    : 回调
func getThumbImageAtTime(urlAsset: AVURLAsset, time: CMTime) -> UIImage? {
    let imgGenerator = AVAssetImageGenerator(asset: urlAsset)
    imgGenerator.requestedTimeToleranceBefore = CMTime.zero
    imgGenerator.requestedTimeToleranceAfter = CMTime.zero

    var cgImg = try? imgGenerator.copyCGImage(at: time, actualTime: nil)
    if cgImg == nil {
        imgGenerator.requestedTimeToleranceBefore = CMTime.positiveInfinity
        imgGenerator.requestedTimeToleranceAfter = CMTime.positiveInfinity
        cgImg = try? imgGenerator.copyCGImage(at: time, actualTime: nil)
    }

    return cgImg == nil ? nil : UIImage(cgImage: cgImg!)
}