如何在 iOS 中使用 AVPlayer 实现 4.0 的播放速率？

Question

player.rate = 4.0 对我不起作用。

这是达到 4.0 率的好方法AVPlayer，还是有更好的方法？

Answer 1

使用[AVComposition scaleTimeRange:toDuration:]产生快速运动AVAsset。

float rate = 4.0;
AVAsset *asset = [AVAsset assetWithURL:someURL];
AVMutableComposition *composition = [AVMutableComposition composition];
NSError *error = nil;
[composition insertTimeRange:CMTimeRangeMake(kCMTimeZero, asset.duration)
                     ofAsset:asset
                      atTime:kCMTimeZero error:&error];
[composition scaleTimeRange:CMTimeRangeMake(kCMTimeZero, asset.duration)
                 toDuration:CMTimeMultiplyByFloat64(asset.duration, 1 / rate)];
AVPlayerItem *playerItem = [AVPlayerItem playerItemWithAsset:composition];
AVPlayer *player = [AVPlayer playerWithPlayerItem:playerItem];