Re: [Ekiga-list] Video resolution

[Bret Busby <bret busby net>]

On Wed, 23 Dec 2009, yannick wrote:

> Date: Wed, 23 Dec 2009 11:48:42 +0100
> From: yannick <sevmek free fr>
> Reply-To: Ekiga mailing list <ekiga-list gnome org>
> To: Ekiga mailing list <ekiga-list gnome org>
> Subject: Re: [Ekiga-list] Video resolution
>
> Le mardi 22 décembre 2009 à 17:30 +0800, Bret Busby a écrit :
> Hello.
>
> I am wondering what prospect exists, for the video resolution, and thus 
> the displayed video size on screen, to be increased?
>
> I have recently purchased a Logitech C300 webcam, which apparently has 
> video resolution of up to 1.3MP; 1280 x 1024, I think.
>
> The webcam came with access to a Logitech free videocall facility' 
> "Vid", which apparently (on this computer, anyway) allows for video 
> resolution of up to 640 x480, at 30fps.
>
> So, I am wondering whether any intent exists, for Ekiga to provide for 
> image resolution of 640 x 480, or, better, also, 800 x 600, or, even 
> better, also, 1280 x 1024, at 30fps.

> The higher you can get with Ekiga 3.2.x is: 704x576 30fps

> (This is 4CIF, see http://en.wikipedia.org/wiki/4CIF )

Okay, now I understand; the video format used by Ekiga, is apparently 
for television screens, rather than for computers -
("CIF was designed to be easy to convert to PAL or NTSC standards. CIF 
defines a video sequence with a resolution of 352  288 like PAL Source 
Input Format, a framerate of 30000/1001 (roughly 29.97) frames like 
NTSC, with colour encoded using YCbCr 4:2:0."
and
"xCIF pixels are not square, instead having a native aspect ratio of 
~1.222:1. On older television systems, a pixel aspect ratio of 1.2:1 
was the standard for 525-line systems (see CCIR 601). On square-pixel 
displays (computer screens, many modern televisions) xCIF rasters 
should be rescaled horizontally by ~109% to 4:3 in order to avoid a 
"stretched" look: CIF content expanded horizontally by ~109% results 
in a 4:3 raster of 384  288 square pixels.").

I assume that the 4CIF resolution, is what used to be named something 
like High Definition television, in the 4:3 analogue television format 
(now all television screens available in sizes bigger than 14" 
diagonally, are this silly widescreen format, that makes the pictures 
look like someone heavy has sat on them).

So, is the 4CIF format available for Ekiga, and, how can a user select 
that resolution, to be used?

I could not find a means of selecting different resolutions, in the 
facilities for configuring the Ekiga interface.

Does a method or facility exist, whereby a user (one party to a call) 
selects a particular resolution, as a maximum possible resolution to be 
viewed by the user, and the user interface software or carrier software, 
then determines the lower common factor for the resolution selection 
between the parties to a call, and uses that lower common factor 
resolution, for the call, at each end involved in the call, so that, if 
one party to a call, sets the maximum possible resolution at 4CIF and 
another party sets the resolution at CIF, the CIF resolution gets 
used by the call, to optimise bandwidth usage (me sending video at 
4CIF, isn't much use, if a receiver can view only CIF) and the call 
then progresses using the lower common factor resolution?

--
Bret Busby
Armadale
West Australia
..............

"So once you do know what the question actually is,
 you'll know what the answer means."
- Deep Thought,
  Chapter 28 of Book 1 of
  "The Hitchhiker's Guide to the Galaxy:
  A Trilogy In Four Parts",
  written by Douglas Adams,
  published by Pan Books, 1992

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