Re: what happened to this show? (crashes, failing to render, out of memory, etc)

[paulingvarsson(at)mac.com]

Owen,

you imported stills into a graphics effect? And image sequences you 
imported one at a time as separate objects in a graphics effect? Maybe 
i read this wrong?

If you are only scaling your images to the size of your project you 
should always import the stills via the browser (ie right click and 
capture the raw files) this creates new media in DNX for each of the 
stills with alpha channel - and the DS eats this kind of media easily.  
Linking to files in a sequence has always historically 'bloated' 
sequences.  But importing lots of files into graphics would easily kill 
the sequence like you describe.

Even on SD 1 hour shows I still split my project up into 3 or 4 
segments just so I can work quick all the time.  Many people disagree 
with this, but i always find it keeps things very nippy.

If you come across a similar problem again - rather than use quicktimes 
you could use reference sequences to lighten the load on your sequence 
if you do have a lot of 'linked' sources in it.  Also doing a 'Save As' 
regulary is good for backups and helps clean down a sequence.

Paul

On 8 Dec 2005, at 14:24, Owen Williams wrote:

> We recently onlined a show on the DS that was different for us in two 
> ways:
> we used DNxHD for the first time, and it was very graphics-heavy 
> compared
> to what we usually do.  We had about 10-11 minutes of stills and 
> animation
> for the hour-long sequence, which is high for us.  We ran into major 
> problems
> with the DS crashing, not playing down, and eventually failing to 
> render
> properly.  We'd like to know how to avoid these problems in the 
> future, because I had to
> work a lot of extra agonizing hours trying to get this show out the 
> door.  Any
> hunches or advice would be greatly appreciated.
>
> So here's the setup: We have an hour-long 1080i/DNxHD 220 sequence with
> a lot of stills and animations.  The effects in our sequence are not
> particularly difficult, just basic stills with alphas in up to four of
> five layers.
>
> To conform the stills, I opened a graphics effect and imported the
> stills, fitting them to the size of the HD frame.  Some of the stills
> were a couple times the size of the HD frame, but I scaled them to fit.
> One short sequence contained 30 or so stills, each a single frame.  (I 
> called
> this the "seizure clip".)
>
> After we started color correction, we noticed that it was taking a long
> time to save the sequence, about 2 or 3 minutes.  I did some digging,
> and discovered that the sequence had grown to 400 megabytes, whereas 
> the
> conformed sequence had started at 4 megs before I started placing
> stills.
>
> Soon after that we started having playback errors.  I could only play
> back a few seconds of footage before I got an error message saying that
> the nitris had a CRC decoding error, or "the video hardware is having
> difficulty reading images" / "waiting time to get image expired." We
> also got a lot of out-of-memory errors when trying to work with the
> effects.  Just clicking locations in the timeline would generate memory
> errors.
>
> Since the sequence was so huge, I thought that perhaps the problem was
> that the stills were being stored in the sequence (which seems daft),
> and that they were consuming too much memory.  I proceeded to replace
> stills wherever I could with quicktime outputs of the effects.  For
> instance, the seizure clip became a single small quicktime that I
> dropped in to replace the graphics effect.
>
> I also deleted all the media from a previous show and defraged with O&O
> using the "space" method.
>
> Unfortunately this didn't solve the problems.  The sequence was still
> 400 megs and I was still having problems playing the sequence.  At this
> point it also started crashing, and sometimes upon recovery it said it
> had trouble with some of the effects.  It claimed some of the effects
> were not installed correctly.  At this point I was afraid the sequence
> was getting corrupt.  We seeked out all the places where effects trees
> had nodes that said "effect not installed" and fixed them.
>
> I then tried pasting the entire sequence into a new, blank sequence, 
> and
> that reduced the sequence size to 100 megs, which is big but 
> manageable.
> It has since grown back to 200 megs, even though we didn't any more
> stills.
>
> As the online progressed, the playback problems nearly disappeared, but
> soon we had a lot of trouble processing frames.  Usually the render
> would hang, saying "waiting for rendered image...".  When I get that
> message I exit out of DS and reboot the Nitris hardware, but this time
> that didn't fix the problem.  A few times it would say "can't write
> image to disk through node based graph".  I don't know what that means.
> Basically it became impossible to render most effects, even simple
> things like a software-realtime DVE and color correction.
>
> I figured out that we could get it to render most things if we had our
> RP box render them.  Using that method we got all but three small
> sections rendered.  From there we had to rearrange effets or tweak them
> slightly before they would render.  Again this suggests to me a corrupt
> sequence, but why on earth would the RP be able to cope with the 
> problems?
>
> We were able to output the show, but we still can't render effects 
> reliably
> unless we send them to the RP, and that takes a long time, even with 
> 220 media.
>
> Here are my questions:
> * should the nitris be able to store a large number of high-quality
> stills and perform effects on them?
> * If so, why did our sequence get so huge, and why did I keep running 
> out of
> memory operating on stills?
> * did our sequence get corrupt, and is there a way to repair that
> corruption?
> * why did remote processing work, but not local processing?
> * why does remote processing process realtime (green) sections even 
> when I don't
> want it to?
> * why does the RP reload the entire sequence for every single process 
> operation, instead of
> caching the last copy or just copying the relevant section of timeline?
>
>
> thanks,
> Owen Williams
> Online Editor
> Powderhouse Productions
>
>
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Paul Ingvarsson
Freelance Editor
Avid DS / Avid Symphony
+44 (0) 7768 016948

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