[whatwg] HTML5 video: frame accuracy / SMPTE

Dirk-Willem van Gulik Dirk-Willem.van.Gulik at BBC.co.uk
Tue Jan 11 16:48:15 PST 2011

On 11 Jan 2011, at 23:57, Glenn Maynard wrote:

> On Tue, Jan 11, 2011 at 5:40 PM, Rob Coenen <coenen.rob at gmail.com> wrote:
>> Hi David- that is b/c in an ideal world I'd want to seek to a time expressed
>> as a SMPTE timecode (think web apps that let users step x frames back, seek
>> y frames forward etc.). In order to convert SMPTE to the floating point
>> value for video.seekTime I need to know the frame rate.
> I'd suggest that you don't want to know the "framerate"; rather, you
> want a separate seek call to seek using timecodes directly.

Correct - or know what the coordinate is in time space of the 'now' shown -AND- when the next seminal event is going to happen (i.e. 'change' - which marks the passage of time in the sense of detectable change) - AND- the clock relative to shutter/gating to the end user - as this is what you need to avoid flicker, interlace issues, half the frame showing the next scene, etc.

> Please don't dismiss video formats with variable framerates under
> assumptions like "nobody's using them in webpages right now".  That's
> shortsighted, and can only lead to an API that will fall apart in a
> couple years.

I do not think any one does - and the world is already using them on a small scale.

> (Being able to seek to "the next frame" is by itself obviously useful,
> even outside of editing applications, to allow users to single-step
> videos as you can in any native video player.)

Aye - could not agree more !

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