Jerky output from WIndows Movie Maker 2


P

prepbgg

We take short movie clips (up to about 2 minutes length) with our Canon
Ixus digital camera. The avi files play very well on our computers. In
order to be able to store as many as possible on my hard disc I store
copies that have been compressed using Windows Media Encoder 9. After
some experimentation, I have settled on using VBR (variable bit rate)
settings for both audio and video with quality 50 for video. This
achieves a high compression ratio and the amount of pixellation or
fuzziness is usually reasonable. With some videos, where the picture is
unusually detailed, I use a higher quality setting to improve the
clarity.

Although pixellation is noticeable with these compressed movies I have
never been bothered by jerkiness. However, I have noticed that when I
use WIndows Movie Maker to trim movies, and sometimes to join sequences
of clips together with transitions, the result can be unpleasantly
jerky, especially when the camera is panning across a view. When an
object moves across a steady background this is not a problem, even if
the object is fast-moving.

I have tried numerous different output settings in WMM. I have made a
custom profile emulating the Windows Media Encoder VBR settings. I have
tried different custom profiles with different quality settings and
with different key frame rates. I have also tried the "DV_AVI (PAL)"
setting. However, the output is equally jerky whatever setting I use.

I don't think the problem is lack of processing power when playing the
movies. The jerkiness seems the same even if no other programs are
running. The movies seem equally jerky played on another, more
powerful, computer.

Interestingly, the files saved by WMM seem to be larger than I would
expect. A test source AVI file is 59MB. Loading it into WMM and simply
saving it as DV-AVI (PAL) with no prior editing produces an output file
of 113MB. Converting the same file with WMP using VBR Quality 50
produces a file of 2.8MB. Outputting from WMM with a VBR Quality 50
custom profile produces a file of 3.5MB. The 2.8MB file is less jerky
and therefore more watchable than the 113MB one!

Since there seems to be a noticeable difference between the quality of
the output produced by WME and even the supposedly highest-quality
output from WMM, there seems to be something wrong in the way I am
using WMM.

Help, please!

(I am using Windows Movie maker version 2.1.4026.0 (I think this came
with XP SP2). I have subsequently downloaded and installed Windows
Media Encoder 9 series Version 9.00.00.2980. I have Windows Media
Player version 10)
 
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P

prepbgg

Thanks for your reply, Graham
Other types of avi, don't work well.

I wasn't aware that there were different kinds of AVI files. Do you
think it should be possible to convert the avi file from the camera
into a form of avi that WMM will find more acceptable?

It occurred to me that VirtualDub might do just that, so I tried
loading the source avi file (59MB) into VirtualDub then simply saving
it as AVI. However, unfortunately this seems to have achieved nothing.
The resulting file is 873MB! After I loaded this into WMM and saved as
DV-AVI (PAL) the resulting file is exactly the same size as the one I
made earlier (using the source file from the camera and saving as
DV-AVI (PAL) from WMM), and it plays just as jerkily.

It then occurred to me that WMM ought to work well with wmv input and
that the problem might therefore be solved by making a wmv copy of the
movie and processing this through WMM, so I've just made a wmv from the
source avi file using WME (quality-based variable bit-rate) then
loading this wmv into WMM and saving as DV-AVI. Although the wmv
created by WME plays perfectly well the DV-AVI from WMM is just as
jerky as all the other versions of this movie saved from WMM.

Incidentally, do you have any idea why WME should produce less jerky
results than WMM? Might this hold the key to solving my problem?

Hugh
 

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