W3C home > Mailing lists > Public > public-media-capture@w3.org > August 2015

Re: Do we need a powerNetworkFrequency constraint?

From: Harald Alvestrand <harald@alvestrand.no>
Date: Tue, 25 Aug 2015 20:47:29 +0200
Message-ID: <55DCB841.9010007@alvestrand.no>
To: public-media-capture@w3.org
Den 25. aug. 2015 17:13, skrev Martin Thomson:
> Is there any sense in distinguishing between "guess for me" and "don't
> try to suppress flicker"?

I can imagine usages where the app wants to do all processing at
receiver side, including antiflicker (the app's business may involve
measuring flicker...). I don't know if they're common enough to warrant
a special constraint value.


> 
> On Aug 24, 2015 10:48 PM, "Harald Alvestrand" <harald@alvestrand.no
> <mailto:harald@alvestrand.no>> wrote:
> 
>     Most cameras seem to have some place in their API where you set the line
>     power frequency of the area you live in; this is used to suppress
>     flicker from fluorescent or LED-based lighting fixtures.
> 
>     Many times, the OS or the browser can make a guess at the right power
>     frequency based on environment factors like timezone or location, and
>     everything's OK.
> 
>     But sometimes it's wrong. And it makes people unhappy.
> 
>     One option is to have a way to override the setting from the application
>     if needed; we can, for instance, have a tri-state constraint, mirroring
>     the camera APIs:
> 
>     powerNetworkFrequency = "50Hz", "60Hz", "default"
> 
>     (I don't see a case for allowing "powerNetworkFrequency=200", which
>     would be the case if we made it a number.... even though there are
>     railway power grids at 16 2/3 Hz, they're rare enough that we should
>     ignore them for simplicity's case).
> 
>     What do people think?
> 
>     (Also filed as https://github.com/w3c/mediacapture-main/issues/234)
> 
>     Harald
> 
>     --
>     Surveillance is pervasive. Go Dark.
> 
> 
> 
Received on Tuesday, 25 August 2015 18:47:59 UTC

This archive was generated by hypermail 2.4.0 : Friday, 17 January 2020 16:26:33 UTC