iOS html5 video on mobile safari

I have a video I'm playing on iOS 4.2 where I'm listening in the timeupdate events and pausing video at certain times. This is fairly accurate. However, I also have player controls that seek to certain parts of the video using current time.

There appears to be a bug where the time seeked is never accurate - not accurate enough for what I need to do with it. The problem gets worse as the length of the video increases and I've also noticed that at the beginning of the video the seek time would be around 0.5 miliseconds off the time I specify but as I try to seek further along in the video this increases. Seeking 2 minutes into a video 开发者_运维问答files is off by around 2 seconds.

I don't think this is a probloem with my code as I've replicated the same behaviour using the opensource Jplayer.

http://www.jplayer.org/HTML5.Media.Event.Inspector/

currentTime has caused me nothing but problems on iOS. It didn't even work on 3.2.

Is the problem I'm having now a known bug and is there a workaround for this?

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I ran a test to see if I could confirm the same behavior on my emulated build of iOS 4.1.

I definitely experienced similar problems on both the iPhone and iPad. But I didn't notice the offset growing proportionately as the video got longer - it seemed more random. If I had to guess, I'd say the video is seeking to the keyframe prior to to your requested time rather than to the correct position.

The iOS devices seem to be reporting currentTime accurately... You are able to pause the video in the correct place and it looks like the timecode on the iPhone matches that on the desktop. It just won't queue up in the correct place.

What kind of video are you using? I tested h264 video encoded with ffmpeg.

It might be worth adding more keyframes to your video or looking for a switch in your encoder that makes the content more easily seekable. I know ogg video has support for indexing (see this post). That won't help this issue, but we might be able to find a parallel solution that works here.

This is going to be a problem for me very soon, so I'm very interested to see if you found a fix. Please post back if you have.