在IOS 9上使用AVPlayer和Swift反向播放视频 [英] Play video in reverse using AVPlayer and Swift on IOS 9

问题描述

我有一个要反向播放的录制的视频剪辑.

I have a recorded video clip that I want to play in reverse.

向前播放是可以的，但是只要我搜索到视频文件的末尾并将播放速率设置为-1.0，视频剪辑就会搜索到剪辑的末尾(我在视频上方的时间轴栏中看到了这一点)，但不会反向播放.

Playing forward is fine but as soon as I seek to the end of the video file and set the rate of playback to -1.0 the video clip seeks to the end of the clip (I see this in the timeline bar above the video) but does not play in reverse.

展示播放器视图控制器后，我检查它是否可以使用:

After I present the player view controller I check if it is ready to use:

            print("readyForDisplay = \(playerViewController.readyForDisplay)")

这告诉我所有人都准备好比赛了.

This tells me that all is ready to prepare to play.

我检查是否可以进行反向播放:

I check if reverse play is possible:

let reversePlay = playerViewController.player!.currentItem?.canPlayReverse
        print("reversePlay = \(reversePlay)")

这将返回TRUE

然后我寻找剪辑的结尾，然后将播放速率设置为-1.0以进行反向播放.

I then seek to the end of the clip and set the play back rate to -1.0 for reverse play.

playerViewController.player!.seekToTime(playerViewController.player!.currentItem!.asset.duration)
        playerViewController.player!.rate = -1.0

我相信目前已经可以使用了，因为如果添加以下内容:

I believe having got this far it is ready to play because if I add the following:

let status : AVPlayerItemStatus? = playerViewController.player!.currentItem?.status

        if status == AVPlayerItemStatus.ReadyToPlay {
            print("Ready to play")
        }

它向我展示了剪辑已经可以播放了，因此我假设到剪辑结尾(只有2秒长)的搜索已经完成.

It shows me that the clip is ready to play, so I am assuming that seeking to the end of clip (which is only 2 seconds long) has completed.

然后我播放剪辑:

            playerViewController.player!.play()

如果我不尝试到底并尝试更改速率以将其设置为反向播放，则可以正常播放.

It plays fine if I don't seek to the end and attempt to change the rate to set it to reverse play.

我在这里想念什么?

推荐答案

在启动视频后，我决定添加一些日志记录，发现该速率在启动之前为-1，在启动之后立即为1，因此看来速率已重置为1.

I decided to add some logging after launching the video and found that the rate was -1 before launching and 1 immediately after so it seems that the rate is reset to 1.

这可能是错误吗?

无论如何，在请求播放视频后立即设置速率具有预期效果.

Anyway setting the rate immediately after the request to play the video has the desire effect.

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