Page 1 of 1

MPG "terminal lag", "black frames"

Posted: Mon Jul 13, 2009 10:21 am
by JeffBTX
No matter how I set it up, MPGs created with Multiquence seem to have a very pronounced lag at the end of the animation. I am generating animations from a sequence of BMP still images. It is of course most noticeable with animations that were meant to "loop".

Watching the Media Player progress bar, it almost seems as if the last frame appears, but is "held" in the stream, and Media Player plays an additional fraction of a second with that last frame "frozen". This happens with and without a sound track.

This happens ONLY A LITTLE BIT with AVI/Cinepak and WMV; barely noticeable, and I assume that is just a characteristic of Vista / Windows Media Player. Back in the days of W98, animations could actually be created that looped perfectly in those older versions of Windows Media Player. AVI/Cinepak seems to be the best way to code these raytracing animations; the best quality, and they "loop" the best with barely noticeable lag at the end.

It is almost as if Multiquence is "padding" in a couple or three frames at the end, using the last BMP, when creating MPG animations.

So when creating MPGs, is there a setting I need to tweak?

During long animations (relatively long... for raytracing... 500 frames created from 500 640x480 BMPs); occasionally there is an almost subliminal "black frame" thrown in. Almost as if Media Player "cuts out"... for maybe 1/10 of a second or thereabouts. The *impression* I have is that these "black cutouts" are approximately equal to one frame in length. Counting "one onethousand, two onethousand", these "black frames" occur regularly about every 8-10 seconds, and always occur in the same locations in a particular animation.

Can anyone explain this, and hopefully offer a solution?

Re: MPG "terminal lag", "black frames"

Posted: Thu Jul 23, 2009 9:12 pm
by GoldWave Inc.
That may be related to the frame rate setting. The frame rate that Multiquence uses needs to be the same frame rate that the video encoder expects. Sometimes that can vary very slightly (29.97 vs 30.00).


Posted: Wed Jul 29, 2009 10:05 pm
by JeffBTX

Thanks; I've made a note of that pasted it into my "home made video tutorials for animating from the Ray Tracer".

I will experiment later.

Posted: Fri Jul 31, 2009 1:40 am
by JeffBTX
Chris... thanks, that DID alleviate the problem.

I re-did a lot of animations that I was doing from the Ray-Tracer... to various formats (MPG, WMV, AVI)... THIS time, I used your suggestion and also experimented quite a bit with the framerate.

Now I can make an MPG that "loops well" (or rather, "repeats seamlessly")... the first time through, there is usually a noticible "lag" / "black frame" at the end (but NOT as noticible as before), but then it starts to loop with the "effect" * barely notible*. I suspect that is just Windows Media Player (Vista 64). I can remember doing this kind of thing back in W98 FE, things looped in Media Player were very seamless... then with W98SE / WinME, the Media Player got "bloated" or something... has a built-in "lag".

Of course, MOST animations aren't "looped", but its nice to do sometimes.

I wish they would open up the International Raytracing Competition to a format other than 320x240 MPG (that has been a strict standard for years). I've suggested / complained again, maybe the Powers That Be are looking into it.

Its most acceptable now after experimenting with the framerate. I seem to get the "Most Consistant Best Results All The Time In General, AND the Best Loop-ability", with AVI / Cinepak.