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RE: Do we need a powerNetworkFrequency constraint?

From: Mandyam, Giridhar <mandyam@qti.qualcomm.com>
Date: Tue, 25 Aug 2015 16:25:53 +0000
To: Harald Alvestrand <harald@alvestrand.no>, "public-media-capture@w3.org" <public-media-capture@w3.org>
Message-ID: <51eaced00da04137982264112ce87f22@NASANEXM01C.na.qualcomm.com>
I would not call this constraint powerNetworkFrequency – I would call it antiFlicker.

Otherwise I don’t see a problem with adding this constraint.


From: Harald Alvestrand [mailto:harald@alvestrand.no]
Sent: Tuesday, August 25, 2015 7:41 AM
To: Mandyam, Giridhar; public-media-capture@w3.org
Subject: RE: Do we need a powerNetworkFrequency constraint?

No, we are raising this issuevbased on users reporting a problem in deployed services.
Den 25. august 2015 16:25:29 CEST, skrev "Mandyam, Giridhar" <mandyam@qti.qualcomm.com<mailto:mandyam@qti.qualcomm.com>>:

Are we re-opening the camera constraints discussion based on what "most cameras seem to have"?  Because if so, there are probably other constraints that could be considered as well.

-Giri Mandyam

-----Original Message-----
From: Harald Alvestrand [mailto:harald@alvestrand.no]
Sent: Monday, August 24, 2015 10:47 PM
To: public-media-capture@w3.org<mailto:public-media-capture@w3.org>
Subject: Do we need a powerNetworkFrequency constraint?

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)


Surveillance is pervasive. Go Dark.

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Received on Tuesday, 25 August 2015 16:26:26 UTC

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