a Test Project
I started with an existing wmv file...
the 'XML the Beginning' tutorial made recently by
the Persian Poet Gal... a 2 minute and 10 second, 640x480, 602
Kbps, 7.6 MB file.
I could have started with anything... the goal was
simply to make a project more and more complex, render it to a movie at each
step, and see how much memory was needed.
Over and over, add more complexity after each
successful render, assess the extra memory needed, and render again until I
ran into the upper limit and got the error message.
the computer system
The Dell laptop has a 266 Mhz CPU, a 4 GB hard
drive, and 144 MB of RAM. I bought it new in June 1998 with
Windows 98.
In August 2004 I upgraded it to the Home
edition of Windows XP.
I had no problems doing the upgrade and the
laptop has been running the best it ever has... even though it's far short of
the system considered minimal for XP and Movie Maker 2.
Starting the
Project
Before opening Movie Maker, the Dell was using
116 MB of the 144 MB (80 percent of the installed RAM)... it wasn't going to
take much complexity to use of the rest of the RAM and start digging
into virtual memory...
Memory usage varies... I assessed things as I went
using the Performance tab of the Windows Task Manager. Before
starting a Movie Maker project, there are memory demands on the computer
due to the operating system and other software running.
Opening Movie Maker
2.1 added 8 MB of memory to the total
used... not much. The Windows Messenger service uses over 20 MB when
I'm not even online. Sonic's MyDVD 4.5 uses 58 MB of memory when opened,
before starting a DVD project.
Another 24 MB of memory was needed to create the start of the
project, to get it to the point shown at the left... the single
clip of the starting wmv file was on the timeline and split into 5
sub-clips.
Total memory usage at this point was 148
MB, which was 4 MB over the installed RAM... the project was starting
to use virtual memory. When it does that, there's a
significant slowdown as using the hard drive is much slower than using
RAM.
If you don't mind going that slow, you can
keep going until the combined total of RAM and virtual memory reaches your
established limit.
Virtual Memory
The virtual memory setting gave Windows XP as
much as 432 MB of the hard drive space to use as if it was installed RAM...
adding that to the 144 MB of RAM, the Dell could go as high as 576 MB
of memory before it gets the message from Movie Maker about not being able to
save the movie.
On this system, most or all of the memory available
for rendering is from virtual memory, not installed RAM.
To change the setting, use Start > Control Panel
> Performance and Maintenance > System > Advanced Tab > Performance
Settings > Advanced > Virtual Memory > Change...
If we run out of memory, we can increase the
virtual memory maximum size instead of purchasing more RAM... right?? Yes,
we'll see.
Make a mental note of the Initial size of 432 MB...
we'll mention it below.
Add Complexity and Watch the Effects on
Memory Usage...
Anything added to a project adds complexity... and
more complexity adds more demands on memory. How much?? We'll
look.
Adding complexity happens routinely as you
work on the project... keeping an eye on the effects of the complexity, and
where you are relative to your memory limit by using your Task
Manager...
Task Manager - Processes Tab
The Processes tab of the Task Manager helps you see
what's using your memory, and lets you close down some processes that are not
needed when you render a movie... that's one way to free up some additional
memory if needed.
Movie Maker, with no project open, is using a bit
over 12 MB of memory... the two lines starting with NAVA... are for Norton
Antivirus, things I could close down to gain 6-1/2 MB of memory. I tend to
leave them and other processes running.
Task Manager - Performance
Tab
To track the effect of adding complexity, use the
Performance tab of the Task Manager.
The Commit Charge (Memory Limit) is the
key item to watch. Compare it to the other two numbers in the lower
left block, the Total memory being used, and the Peak memory
level reached since the computer was last started up.
This picture shows the laptop after a fresh
reboot, with Movie Maker running but no project open.
It's telling me that the current memory demands
from all running processes total 142 MB... that the current Limit is 356
MB... and that the highest or Peak demand for memory since the laptop last
started up was 143 MB.
The 432 MB Initial Limit for Virtual Memory, noted
above, shows up here in the 356 MB Limit (144 MB of RAM + 216 Initial Swap File
size = 360 MB).
After checking the running processes and the memory
needed for them, and setting up the Task Manager to watch things... it's time to
add the complexity and note the effects. In doing it, realize that these numbers
are precise, but things change so dynamically on the system that you can only
use the numbers as approximations when trying to draw conclusions.
Rendering the Simple
Project
To see how memory needs change with the choice of
quality, I did some renderings without changing the project.
The memory used just before rendering
was 148 MB. The memory needed to ramp up to the first couple percent
progress points (I didn't spend the time to finish the renderings... the
memory needed ramps up pretty quickly to the maximum level for
the profile selected):
-
1 MB limit - 170MB peak memory needed - very
steady memory usage thru the rendering - it fell instantly to 155MB when
rendering finished
-
2 MB limit - went up to 181MB within a percent or
two... and leveled... cancelled - fell to 160MB
-
4 MB limit - went up to 194MB within 2 percent
and leveled... cancelled - fell to 149MB
-
8 MB limit - went up to 189MB within 2 percent
and leveled... cancelled - fell to 152MB
-
16 MB limit - went up to 251MB within 2 percent
and leveled... cancelled - fell to 149MB
-
32 MB limit (the max for the size setting was 33
MB) - went up to 268MB within 2 percent and leveled... cancelled - fell
to 149MB
-
DV-AVI - went up to 200MB within 2 percent and
leveled... cancelled - fell to 149MB
Here's a 
chart to show these results... quality
(file size) versus peak memory needed to render
it.
The horizontal red line shows 46 MB was needed
to render it to a DV-AVI file... the numbers in the vertical bars are the file
sizes of the compressed WMV files, with the scale at the right showing the
memory used to render them.
Maybe I made a mistake noting the memory needed for
the 8 MB file... or maybe it really was an anomaly... it doesn't change the
overall pattern so I didn't do a retest.
The bottom line is that, for a given
project, rendering higher quality compressed WMV files needs more
memory than rendering a DV-AVI file... and rendering a low quality
compressed file needs less.
With the highest memory demands being for a high
quality WMV file, I did all the remaining tests using the WMV option at the
highest file size choice that Movie Maker offered... the maximum
size allowed moved up as the project timeline got longer. As
complexity increased, the size of the rendered movie went
from the 1 MB limit above to one as large as 331
MB.
Adding Complexity
Here are the steps I used to make the project
larger and more complex... and the effects on the memory needed. I looked
at the changes in memory usage in two places. How much more was used
when having the project open on the timeline, before the rendering? And
then, how much more memory was needed to render the movie.
8 MB were used to open MM2, and
another 24 to get the project started with its 5 clips. The rendering of
the basic no-frills project to a 32 MB WMV file needed 120 MB. These
are the baseline needs; I'll note the changes from there.
1 - added one
random effect to each of the 5 clips... 14 MB more (60% increase) was needed for the project, but nothing
extra needed to render it to a 32 MB movie.
This was the first clue that the addition of
video effects has minimal effects on the memory needed for
rendering.
2 - added a
transition between each clip, 4 transitions total... with
default durations... 24 MB more (60% increase) was needed for the
project, and 17 more (15% increase) for the rendering to a 32 MB
movie.
3 - maximized the
transition durations by overlapping the clips as much as possible,
reducing the total length of the movie. There was no change in the
memory needed for the project, but 27 more was needed to
render it, although the maximum file size choice had gone down from 32 MB to
20.
Steps 2 and 3 combined was the first clue that
the memory needed to render transitions is more
significant.
4 - added 5 more
effects to the 1st, 3rd and 5th clips, to the maximum allowed
of 6 per clip... the increased memory needed to work on the project was 9 MB
and there was a decrease of 9 MB in the memory needed to render it
to a 20 MB file.
5 - added 5 more effects to the 2nd
and 4th clips... only 1 more MB was used when working on the project, and 12
more to render it to the 20 MB movie.
Steps 4 and 5 combined reinforced what I saw
in step 1 about video effects not needing more memory to render the
movie.
6 - rebooted
the computer... which cleared memory to the tune of reducing the total used by
34 MB.
This was the first of a few reboots
during the testing, each one showing significant memory
reductions. Something was happening to clear the air during
reboots.
7 - added a single music
wma file... the sample Beethoven clip. 4 more MB was needed
for the project itself and 15 additional for the rendering to a 20
MB movie.
Adding music added more memory demands than adding
effects, but less than transitions.
8 - added a single text
overlay to the first 40 seconds... using the scroll perspective
animation. 14 more MB was used to work on the project and 48 more to render it
to a 20 MB movie.
Adding a text overlay required significantly more
memory, especially to the rendering step.
This completed the basic project... it was now a 1
minute, 20 second timeline with 5 video clips, packed with special effects
and transitions, and topped with background music and a long text
overlay.
At this point I rebooted and jogged the total memory usage
back down by 45 MB... after the memory usage was cleared with the reboot,
the project open in MM2 was using only 12 MB more than before I started
adding the clips to create the project. The rebooting had saved over 65% of the
memory being used as the project was being built.
This drove home what I had seen of the memory
savings from the first reboot in step 6.
The renderings weren't close to running into my total
available memory limit. I'll change tactics to increase the complexity from
here.
Doubling and Doubling Again... till
it Crashes
9 - copied and pasted all the
clips in the project... doubling the project duration
to 2:40. It used 39 more MB to work on the timeline, but memory
to render it to a 41 MB movie went down by 20 MB.
I was wondering if copying/pasting the same clips
results in some efficiencies over having totally different clips... I don't
know. Even if there are efficiencies, the complexity was going up due to
overall project size increases.
At this point, each doubling of the project also
doubled the file size limit for the saved movie... the same profile was
being used each time.
10
- doubled again to 5:21. Memory used to view the
project went up another 19 MB, and memory needed to render it to an 82 MB movie
rose another 13 MB... very modest increases in memory needs.
11 - doubled
again to 10:41. Only 4 more MB needed to view the timeline, but
an increase of 59 MB in what was used to render it to a 165 MB
movie.
12 - doubled
again to 21:23. 27 more MB to view the timeline... and didn't know yet what
was needed to render it to a 331 MB movie file.
The project had reached the complexity level
needed to two-block the memory of the Dell laptop. It had
The
memory to do the rendering reached
the limit of 576 MB (144MB RAM + 432 MB of virtual memory = 576
MB)...
I got the familiar error message... in this case I was happy to
see it so I could get on with the rest of the newsletter.
Memory usage ramps up pretty quickly in the rendering process,
reaching close to peak levels within the first couple percent of progress...
that saves a lot of wasted rendering time, as you can cancel the process and
think about what to do.
If memory usage is over 95% of the Limit, you might still
reach it at some point later in the rendering. If you have more slack than that,
you should be able to finish.
13 - I was increasing project
complexity to reach this point... but instead of breaking it back down into
parts to render separately, I wanted to go forward by raising the
virtual memory limit.
I changed it to a maximum of 500 MB...
... and rebooted...
... and tried the render again.
The Final
Render
With the new higher virtual memory setting, I
started the final render.
It started at 01:34 am on Sept 5th... and took
almost 30 hours to complete. Obviously I didn't watch it the whole time. Here
are some of the data points I noted:
493 MB of usage at 0% with a projection of 981 more
minutes...
500 MB and still at 0% with 1317 minutes left...
529 MB
at 1% with 1709 minutes to go...
529 MB at 2% with 1950 more minutes
projected
... 3% - 1991 minutes left (the projected time was
still growing to this point)
570 MB at 23% (with a peak of 583 MB so far)
with 1540 minutes to go
541 MB at 24% with 1505 minutes
left
612 MB at 54% with 900 minutes to
go
622 MB at 60% with 790 minutes
left
605 MB at 64% with 708 minutes to go
(with a peak so far of 632,616)
590 MB at 69% with 597 minutes to
go
... 10:30 am on Sept 6th - the rendering
had finished sometime overnight. The peak memory usage
was 641,548, just a few MB less than the higher Limit... I pressed
the Finish button and watched the movie. It played fine...
Cross-Check on Rendering to
DV-AVI
My Toshiba laptop had returned, and I moved the
project over to it... I wanted to confirm that rendering this
complex project to a DV-AVI file used less memory than the high quality WMV
option I'd been using. The chart early on in the newsletter says it should be
less memory intensive.
It confirmed it. Peak memory usage during rendering to a DV-AVI file was 359 MB on the Toshiba, while
rendering the WMV used 400, over 10% more (it probably was higher... I
cancelled the rendering when it was at a few percent complete).
