NetNews Offline 2/NetNews Offline Volume 2.iso/news/comp/sys/amiga/graphics/2334

Internet Message Format | 1996-08-05 | 3.5 KB

Path: news.mel.aone.net.au!usenet
From: [e-mail] (Mark P Allen)
Newsgroups: comp.sys.amiga.graphics
Subject: Re: VLAB Motion/MovieShop "Data Transfer Phase Error"?
Date: 23 Mar 1996 15:25:37 GMT
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On 22-Mar-96 13:29:01, Jose Alvarez wrote:

>> 1) Does anyone know what aspect of the data transfer phase produces the
>> "Data Transfer Phase Error" of MovieShop's vmotion.library?

 JA>    With out having any technical data to support my theory, I'm almost
 JA> 100% sure you are simply experiensing the terrible "bottleneck" problems
 JA> of Zorro II. I have seen this error my self on my VLAB system
 JA> (A4000T/060/VLAB/Toccata), and it always disapear when I change to a
 JA> lower JPEG quality to edit my work.

Hmmmm. My own experiences have led me to believe that the FiFO Underflow
error indicates a choked bus. It is usually also accompanied by corrupt
fields, which the manual also describes as a symptom of a choked bus (I
also think that sometimes an odd corrupt field will initiate the "FiFo
Underflow" error as well). Also, the "data transfer phase error" was
happening at times when the data rate was well below the card's
capability.

I have certainly found that using separate disks for the video and audio
partitions has drastically reduced the number of "data transfer phase
error"s. I still can't fathom why adding a soundtrack to existing video
and audio can make video playback unstable.

Now for some experiments with the Level Indicator, since I DO leave that
window open, though zoomed down to it's titlebar when not in use. I did
think, though, that MovieShop automatically catered for the Indicator if
it found it open, by freezing it (I think there was some reference to this
in the 2.1 manual).

 JA>    I do all "off-line" work with the card so I don't care much if I have
 JA> to lower my quality for consistent playback. If you are doing finishing
 JA> work with the VLAB, I can't think of too many things that can be done.

By offline, do you mean that you are creating EDL's from the VLAB?

 JA>    The card itself is very flaky. I doesn't like to work above 90% no
 JA> matter how small the screen resolution is. I transfered some Lightwave
 JA> animations at 1/8 screen size (100% quality) and even though it would
 JA> play back with out stopping, all kinds of garbage and artifacting would
 JA> show up on the picture.

I know for a fact that the time base and proc amp circuitry of the card
are nowhere near as good as the GVP TBCPlus'.

 JA>    Remember that hard drives have variying rates of throughput depending
 JA> what sector of the HD is being read. The edges of a hard drive read/write
 JA> much slower that the center of the hard drive. I actualy have my
 JA> harddrive partitioned in three. This way I can:

 JA> - Have three different projects poing at once (different JPEG quality)
 JA> - I use partition 1 & 3 to put all my low resolution (bulk video)
 JA> - Use partition 2 (fastest) to finish my job if I need good output from
 JA> the VLAB.

This is a good point (which I think is mentioned in the v2.1 manual).
However, I suspect every sector and track of my HDs outperform the VLAB/Z2
bus.

Thanks for your comments.

Regards,

         Mark

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