This might be speced but the reality isn’t really matched by this:
- I do get this on Chrome “Error in undefined: NotSupportedError: Failed to set the ‘playbackRate’ property on ‘HTMLMediaElement’: The provided playback rate (-1) is not in the supported playback range.”
- But even if that can be solved in some browsers most online video formats are based around progressive codecs … giving them a beneficial play direction as full key frames are spaced out and in between are progressively added fragments in a frame by frame (diff) manner until the next full key frame is displayed. Hence, there should be a buffer (and performance) issue while running backwards through stream optimized footage.
If you find a way to demonstrate a well performing negative playback I’d love to update my mind about it! Honestly, I am eager to find a better solution as this approach doubles the video length.