[whatwg] HTML5 video: frame accuracy / SMPTE

Rob Coenen coenen.rob at gmail.com
Mon Jan 10 11:18:21 PST 2011

Thanks for the update.
I have been testing with WebKit nightly / 75294 on MacOSX 10.6.6 / 13"
Macbook Pro, Core Duo.

Here's a test movie that I created a while back. Nevermind the video
quality- the burned-in timecodes are 100% correct, I have verified this by
exploring each single frame by hand.


Please let me know once you guys have downloaded the file, I like to remove
it from my el-cheapo hosting account ASAP.



On Mon, Jan 10, 2011 at 2:54 PM, Eric Carlson <eric.carlson at apple.com>wrote:

> On Jan 9, 2011, at 11:14 AM, Rob Coenen wrote:
> I have written a simple test using a H264 video with burned-in timecode
> (every frame is visually marked with the actual SMPTE timecode)
> Webkit is unable to seek to the correct timecode using 'currentTime', it's
> always a whole bunch of frames off from the requested position. I reckon it
> simply seeks to the nearest keyframe?
>   WebKit's HTMLMediaElement implementation uses different media engines on
> different platforms (eg. QuickTime, QTKit, GStreamer, etc). Each media
> engine has somewhat different playback characteristics so it is impossible
> to say what you are experiencing without more information. Please file a bug
> report at https://bugs.webkit.org/ with your test page and video file, and
> someone will look into it.
> eric

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