[AG-TECH] Re: AG video node using berkley mjpeg work

Lloyd Lim lim at bmrc.berkeley.edu
Thu Nov 15 09:59:47 CST 2001

On Thursday 15 November 2001 05:18 am, Bob Riddle wrote:
>I'm using v5.1.6 - is there a "better" version I should get?  I'm
>guessing I'll need to use CVS & pull down & build the code.

5.1.5 is the last released version.  5.1.6 is the version in 
development, which will probably be released in a week or two.

Please understand that if you use CVS, you should update the source on 
a semi-regular basis.  The current source is always a moving target.  
Occasionally, you'll also be required to check out a whole new source 
code tree from scratch.  (I let everyone know when this is necessary.)

I'm saying this for the benefit of both internal and external 
developers.  Some of our internal developers are not so good about 
keeping up to date.

>Andrew Swan wrote:
>> Bob Riddle writes:
>> > If I set the mjpeg capture rate greater than 10 mbps the display
>> > machine never saw the mjpeg stream.  I don't understand why this
>> > is true.
>> we've done a fair amount of work recently on the mjpeg decode
>> and render path.  the problems that we've been working on are
>> mostly in the handling of large jpeg images (i.e., the images
>> in a high bandwidth stream).  you didn't mention which version
>> of mash you were running although i'd be interested to hear if
>> you saw any improvement with the latest version from the mash
>> cvs repository.
>> it could be that the frames are simply too large for the
>> static sized buffers in the jpeg reassembly code -- you can
>> check this by clicking on "info..." next to the thumbnail in
>> the main vic window, then choosing "decoder stats" and looking
>> a the "huge frame" statistic.  again though, our changes from
>> the last few weeks should address many of these problems.

I doubt that Bob's problems are related to what Andrew's working on.  
RTPtv worked fine for us before, receiving 20+ Mbps streams on Windows 
2000.  There shouldn't be any problems with NTSC 601 frame sizes 
because we've used them extensively with Matt's stuff in the past.

It's either some other problem or something broke recently.

>> > On the Display machine (Win2K), when I expanded the mjpeg vic
>> > window, the reported frame rate dropped from 30 fps to about 15-17
>> > fps.  The data rate reported also dropped from 10 mbps to about
>> > 6-7 mbps. However, the picture was great looking.  I checked the
>> > CPU with task manager & one processor was tapped out completely. 
>> > My belief is if I had a faster processor, I could have sustained
>> > higher frame rates.

A couple notes:

A faster processor will certainly help, but multiple processors won't 
help unless you're also running other stuff on the machine.  vic is 
just a single process.

Performance is much better on Linux than on Windows (any version).  
Linux is just much better at managing the processor.  You won't 
necessarily get better frame rates, but you'll be able to manipulate 
vic much easier.  This includes things like moving vic windows, 
changing the vic controls, and most importantly...  quitting vic!


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