您好,我一直在尝试弄清楚如何在 GPUImage2 中实现电影循环,但到目前为止还没有成功。 GPUImage2 中的 MovieInput 类使用 AVAssetReader 播放电影文件,所以我研究了循环 AVAssetReader 的方法。我在处理这个主题的 StackOverFlow 上发现了这个问题。 AVFoundation to reproduce a video loop
最佳答案是 “AVAssetReader 不支持查找或重启,它本质上是一个顺序解码器。您必须创建一个新的 AVAssetReader 对象才能再次读取相同的样本。”
我试图弄清楚如何将旧的 assetReader 连接到新的,但我不是很成功,而且每次都崩溃。
有人建议我尝试这样的操作,但我不确定如何编写函数 generateAssetReader。
public func start() {
self.assetReader = generateAssetReader(asset: asset, readAudio: readAudio, videoOutputSettings: videoOutputSettings, audioOutputSettings: audioOutputSettings)
asset.loadValuesAsynchronously(forKeys:["tracks"], completionHandler:{
DispatchQueue.global(priority:DispatchQueue.GlobalQueuePriority.default).async(execute: {
guard (self.asset.statusOfValue(forKey: "tracks", error:nil) == .loaded) else { return }
guard self.assetReader.startReading() else {
print("Couldn't start reading")
return
}
var readerVideoTrackOutput:AVAssetReaderOutput? = nil;
for output in self.assetReader.outputs {
if(output.mediaType == AVMediaTypeVideo) {
readerVideoTrackOutput = output;
}
}
while (self.assetReader.status == .reading) {
self.readNextVideoFrame(from:readerVideoTrackOutput!)
}
if assetReader.status == .completed {
assetReader.cancelReading()
self.assetReader = nil
if self.loop {
self.start()
} else {
self.endProcessing()
}
}
}
有人知道解决这个循环问题的线索吗?这是 MovieInput 类的完整代码的链接。 https://github.com/BradLarson/GPUImage2/blob/master/framework/Source/iOS/MovieInput.swift
最佳答案
我找到了答案,以防有人疑惑。
public func createReader() -> AVAssetReader
{
var assetRead:AVAssetReader!
do{
assetRead = try AVAssetReader.init(asset: self.asset)
let outputSettings:[String:AnyObject] = [(kCVPixelBufferPixelFormatTypeKey as String):NSNumber(value:Int32(kCVPixelFormatType_420YpCbCr8BiPlanarFullRange))]
let readerVideoTrackOutput = AVAssetReaderTrackOutput(track:self.asset.tracks(withMediaType: AVMediaTypeVideo)[0], outputSettings:outputSettings)
readerVideoTrackOutput.alwaysCopiesSampleData = false
assetRead.add(readerVideoTrackOutput)
}catch{
}
return assetRead
}
public func start() {
self.assetReader = createReader()
asset.loadValuesAsynchronously(forKeys:["tracks"], completionHandler:{
DispatchQueue.global(priority:DispatchQueue.GlobalQueuePriority.default).async(execute: {
guard (self.asset.statusOfValue(forKey: "tracks", error:nil) == .loaded) else { return }
guard self.assetReader.startReading() else {
print("Couldn't start reading")
return
}
var readerVideoTrackOutput:AVAssetReaderOutput? = nil;
for output in self.assetReader.outputs {
if(output.mediaType == AVMediaTypeVideo) {
readerVideoTrackOutput = output;
}
}
while (self.assetReader.status == .reading) {
self.readNextVideoFrame(from:readerVideoTrackOutput!)
}
if (self.assetReader.status == .completed) {
self.assetReader.cancelReading()
if (self.loop) {
// TODO: Restart movie processing
self.start()
} else {
self.endProcessing()
}
}
})
})
}
关于ios - 如何让 AVAssetReader 循环?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/42309905/