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[whatwg] HTML5 video: frame accuracy / SMPTE

From: Rob Coenen <coenen.rob@gmail.com>
Date: Sun, 9 Jan 2011 19:14:25 +0000
Message-ID: <AANLkTi=nNe1F3yatrnGMVTOVqU0+8YamSCktsPcGLiaQ@mail.gmail.com>
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?

-Rob


On Fri, Jan 7, 2011 at 5:02 PM, Eric Carlson <eric.carlson at apple.com> wrote:

>
> On Jan 7, 2011, at 8:22 AM, Rob Coenen wrote:
>
> >
> > are there any plans on adding frame accuracy and/or SMPTE support to
> HTML5
> > video?
> >
> > As far as I know it's currently impossible to play HTML5 video
> > frame-by-frame, or seek to a SMPTE compliant (frame accurate) time-code.
> > The nearest seek seems to be precise to roughly 1-second (or nearest
> > keyframe perhaps, can't tell).
> >
> > Flash seems to be the only solution that I'm aware of that can access
> video
> > on a frame-by-frame basis (even though you the Flash Media Server to make
> it
> > work).
> > Seeking to a SMPTE time-code is completely impossible with any solution I
> > have looked at.
> >
> > Very interested to learn what the community POV is, and why it isn't
> already
> > implemented.
> >
>   'currentTime' is a double so you should be able to seek more accurately
> than one second - modulo the timescale of the video file and how the UA
> supports seeking to inter-frame times.
>
> eric
>
>
Received on Sunday, 9 January 2011 11:14:25 UTC

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