我可以在HTML5视频中获取当前帧的编号吗？

Question

我目前正在尝试自定义HTML5视频播放器，以便我可以添加一个返回当前帧编号的按钮。

假设我有一个持续90秒的30fps视频。 当我点击那个按钮时，我想让它打印出当前帧的编号。 那可能吗？

Answer 1

我认为您可以使用以下API用于基于Webkit / Mozilla的浏览器：

Mozilla已经在Firefox中实现了以下统计数据：

mozParsedFrames - number of frames that have been demuxed and extracted out of the media.
mozDecodedFrames - number of frames that have been decoded - converted into YCbCr.
mozPresentedFrames - number of frames that have been presented to the rendering pipeline for rendering - were "set as the current image".
mozPaintedFrames - number of frames which were presented to the rendering pipeline and ended up being painted on the screen. Note that if the video is not on screen (e.g. in another tab or scrolled off screen), this counter will not increase.
mozFrameDelay - the time delay between presenting the last frame and it being painted on screen (approximately). 

Mozilla也正在研究这里列出的一些统计数据。

Webkit实现了这些：

webkitAudioBytesDecoded - number of audio bytes that have been decoded.
webkitVideoBytesDecoded - number of video bytes that have been decoded.
webkitDecodedFrames - number of frames that have been demuxed and extracted out of the media.
webkitDroppedFrames - number of frames that were decoded but not displayed due to performance issues. 

我还在调查关于IE9的决议......

参考文献：http：//wiki.whatwg.org/wiki/Video_Metrics

Answer 2

我不认为跨浏览器设置标准帧率，或者用html5视频开箱即用访问当前帧的任何方式。 你可以做的是使用每秒29.97帧的电视标准帧速率，然后将其乘以视频的当前时间，如： (vid.currentTime * 29.97).toPrecision(6) 。

这是我设置的小提琴演示如何将其绑定到按钮以获取当前帧： http ： //jsfiddle.net/893aM/1/

Answer 3

有一个像样的Video Frame JS lib可以使用框架https://github.com/X3TechnologyGroup/VideoFrame

这是一个非常古老的问题，但这可能对新读者有用。

参考： 在HTML5视频中获取帧编号