W3C home > Mailing lists > Public > whatwg@whatwg.org > January 2011

[whatwg] HTML5 video: frame accuracy / SMPTE

From: Dirk-Willem van Gulik <Dirk-Willem.van.Gulik@BBC.co.uk>
Date: Wed, 12 Jan 2011 01:22:01 +0000
Message-ID: <943A715B-18D8-429D-BEFF-6AE33B19CC61@BBC.co.uk>

On 12 Jan 2011, at 01:17, Chris Pearce wrote:

> On 12/01/2011 1:37 p.m., Dirk-Willem van Gulik wrote:
>> On 11 Jan 2011, at 23:00, Chris Pearce wrote:
>>>> Even then I'd like the 'virtual' FPS of the WebM file exposed to the
>>>> webbrowser- similar to how my other utilities report a FPS.

>>> If the 'virtual' FPS value isn't provided by the container, and given that the frame durations could potentially have any distribution and that the media may not be fully downloaded, how can this be effectively calculated?

>> I cannot think of a format where this would in fact be the case - but for a few arcane ones like an animated push gif without a loop.
>> 
> WebM can be variable frame rate. At best the WebM container specification [http://www.webmproject.org/code/specs/container/#track] lists the FrameRate block as "Informational only", which presumably means the value stored in the container can't be trusted.

Right - but is there a WebM decoder which is able to hand it off that way ? AFAIK they all use that value or select a default/measured rounded heuristic to solve flicker ?

Dw.
Received on Tuesday, 11 January 2011 17:22:01 UTC

This archive was generated by hypermail 2.4.0 : Wednesday, 22 January 2020 16:59:29 UTC