Shane Walton wrote:
I have seen mention of MPEG as a pixel encoder for VNC, but
have not found any implementations.
It would seem that MPEG type encoding would be more
efficient than JPEG as MPEG counts for unchanged areas
where JPEG doesn't maintain any history of the previous
frame.
Does anybody see or know of a reason why MPEG encoding
hasn't been used by VNC implementations?
As far as I know, both mpeg and jpeg have no advantage for vnc as long as the
grapics are all computer graphics and no pictures or photographs or such.
The compression of mpeg and jpeg is verry good on pictures and photographs, at
the cost of some cpu-power. However, for computer graphics like windows and
such, the compression is verry poor. Not to mention the extreme loss of quality.
You can test this yourself by taking a screen-dump of this window (the one you
use to read this mail) and store it as a bitmap (*.bmp), a gif and a jpeg. Now
compare the file-size and view them. I bet the gif is smaller than the jpeg and
the readability of the jpeg is not that good...
The advantage of mpeg over jpeg is that it only sends the update of the screen
with every frame, just as vnc does by default. Hence no advantage for mpeg
there. The disadvantage for mpeg is that it must send a continuous streem (with
an entire picture once in a while!), where vnc only sends updates if ther are
updates.
Hence, except for handling pictures and photographs, jpeg is not usable for vnc.
Due to the continuous data stream, mpeg has no advantage for vnc either.
HOWEVER: If you like to make a demonstration, vnc can be an aid and it would be
nice if a session can be recorded and stored in some default video format. I
know there is such a thing around but I donnot have any ponters at hand. With
this tool, you can record a session and creat a video-stream out of it. As far
as I have peeked into this in the past, It acts as a vncviewer that records
everything it gets.
CBee
_______________________________________________
VNC-List mailing list
[email protected]
To remove yourself from the list visit:
http://www.realvnc.com/mailman/listinfo/vnc-list
