[whatwg] HTML5 video: frame accuracy / SMPTE

Rob Coenen coenen.rob at gmail.com
Wed Jan 12 05:05:38 PST 2011

On Wed, Jan 12, 2011 at 10:15 AM, Jeroen Wijering
<jeroen at longtailvideo.com>wrote:

> Alternatively, one could look at a step() function instead of a
> seek(pos,exact) function. The step function can be used for frame-accurate
> controls. e.g. step(2) or step(-1). The advantage over a seek(pos,exact)
> function (and the playback rate controls) is that the viewer really knows
> the video is X frames offset. This is very useful for both artistic/editing
> applications and for video analysis applications (think sports, medical or
> experiments).
glad that you are mentioning these artistic/editing/video analysis type of
applications. I'd like to add video archiving/logging/annotating/subtitling
to the list of potential applications. But also experiments and time-based
Most online ad-agencies have been using Flash to design eg. highly
interactive mini-sites where banners, etc. are shown or hidden based up on
the exact timing of the video. Also think projects such as

> The downside of a step() to either always accurate seeking or a
> seek(pos,exact) is that it requires two steps in situations like bookmarking
> or chaptering.

I like the idea of a stepping-function, similar to how Flash Media
Server/Flash Player 10.1 does frame-accurate stepping.

> It seems like the framerate / SMPTE proposals done here are all a means to
> end up with frame-accurate seeking. With a step() function in place, there's
> no need for such things. In fact, one could do a step(10) or so and then use
> the difference in position to calculate framerate.
> - Jeroen

The need for SMPTE still remains as I want to be able to do things such as
video.seekTo(smpte_timecode_converted_to_seconds, seek_exact=true); so that
my video goes to exactly the exact frame as indicated
by smpte_timecode_converted_to_seconds. Think chapter bookmarking, scene
indexing, etc.


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