[mythtv] Streaming over network

Stacy D. Coil mythtv-dev@snowman.net
Fri Jan 10 21:19:00 EST 2003


Hello everyone!

I'm new here, but I thought I would add my 2 cents.

Don't most codecs divide the frame into several cells and calculate the 
difference of Cell A(N) to Cell A(N+1) and so one?

Couldn't one then write a codec to have several threads each coding X 
number of cells in parallel?

--Stacy


At 04:02 PM 1/10/2003 -0500, you wrote:
> > Modern video encoding works by calculating the differences between frames.
> > Thus, in order to do any work on frame N+1, frame N must already be 
> encoded.
> > It is a serial process.
>
>Just to throw out a couple ideas....
>
>1) What if you had 2 threads doing the encoding, and each encoded 1/2 of the
>frame (ie, top half and bottom half on the 16-pixel boundary or whatever
>fits best with the codec).
>
>2) If you're using a codec with key frames, what if 2 (or more) threads
>were running and each only encoded a key frame and the succeeding diff
>frames up until the next key.  So if you had 2 threads, they would do
>alternating groups of frames.  As long as they could encode at over
>1/2 speed they should be able to keep up with realtime.  This would take
>a lot of memory though if you used a high key frame rate of 150-250.
>
>Just a couple ideas, was thinking about #2 when #1 hit me all the sudden.
>Don't know if either is feasible just thought I'd throw them out there.
>
>Chris
>
>*****************************************************************************
>** Chris Pinkham                  Linux v2.2.18, Sane v1.0.4, Cajun v3.0-8 **
>** cpinkham@bc2va.org                          http://www.bc2va.org/chris/ **
>*****************************************************************************
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