问大型视频的慢速加载
EN

Stack Overflow用户

提问于 2022-01-06 20:28:23

回答 1查看 276关注 0票数 3

我有一个AVPlayer正在播放一个中等大的视频(~150 is )。当最初加载视频时，我发现播放机在AVPlayerWaitingWhileEvaluatingBufferingRateReason状态下的空闲时间超过10-15秒。我的问题很简单:我怎样才能防止AVPlayer在这么长时间内“评估缓冲速率的原因”而转而立即播放视频呢？

我使用的是自定义资源加载器(尽管这种行为是在不使用自定义资源加载器的情况下显示的)。下面是创建AVPlayer (所有标准样板)的相关代码：

AVURLAsset * const playerAsset = [[AVURLAsset alloc] initWithURL:videoURL options:nil];
[[playerAsset resourceLoader] setDelegate:self queue:dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0)];

AVPlayerItem * const playerItem = [[AVPlayerItem alloc] initWithAsset:playerAsset];

AVPlayer * const player = [[AVPlayer alloc] initWithPlayerItem:playerItem];
[player play];
_player = player;

然后，我有了一种处理数据请求的方法，可以使用该方法获取有关AVPlayer试图加载的内容的更多信息：

-(void)handleDataRequest:(AVAssetResourceLoadingDataRequest *)dataRequest loadingRequest:(AVAssetResourceLoadingRequest *)loadingRequest {

    NSLog(@"handleDataRequest: %lld-%lld (%@)",[dataRequest requestedOffset],[dataRequest requestedOffset] + [dataRequest requestedLength],[[self player] reasonForWaitingToPlay]);

    NSMutableURLRequest * const request = ... // construct the request
    [request setValue:[NSString stringWithFormat:@"bytes=%lld-%lld",[dataRequest requestedOffset],[dataRequest requestedOffset] + [dataRequest requestedLength]] forHTTPHeaderField:@"Range"];

    NSURLSession * const downloadURLSession = ... // get the session
    NSURLSessionDataTask * const dataTask = [downloadURLSession dataTaskWithRequest:request];
    [dataTask resume];

}

现在，谈这个问题。假设视频长度为~100 in，下面是上述方法中的handleDataRequest日志的结果：

handleDataRequest: 0-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 3080192-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 5570560-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 7143424-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 9699328-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 12713984-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 14811136-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 17235968-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 20054016-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 22675456-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 25427968-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 28311552-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 30932992-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 32374784-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 35192832-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 37224448-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 39780352-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 41549824-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 43778048-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 46465024-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 49414144-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 52166656-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 54984704-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 57802752-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 60293120-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 62783488-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 65732608-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 68550656-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 70975488-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 73531392-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 76480512-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 79495168-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 82313216-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 83951616-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 86573056-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 88866816-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 91422720-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 92667904-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 95289344-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 98172928-100000000 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 32768-5570560 (AVPlayerWaitingWhileEvaluatingBufferingRateReason)
handleDataRequest: 2032769-5570560 (AVPlayerWaitingToMinimizeStallsReason)
handleDataRequest: 4032770-5570560 (AVPlayerWaitingToMinimizeStallsReason)
handleDataRequest: 5668864-22675456 ((null))
handleDataRequest: 7668865-22675456 ((null))
handleDataRequest: 9668866-22675456 ((null))
handleDataRequest: 11668867-22675456 ((null))
handleDataRequest: 13668868-22675456 ((null))