PapaJohn's Newsletter #48 - April 9, 2005
Maker 2 and Photo Story
Study DV-AVI File
This issue was planned to be about converting MPEG-2 files to
AVI, but the AC/DC converter on the power chord of my Toshiba laptop
stopped working last Thursday, and it's back to the CompUSA repair
center in Texas. Until it returns, I'm back to using my older
minimalist Dell Inspiron 3200... 266 Mhz CPU, 144 MB of RAM, and
an almost full 4 GB hard drive. I needed a topic a bit less
challenging on the laptop so I thought I'd revisit a couple issues about
rendering movies to DV-AVI files.
It'll be two years ago next
month that a couple of us did some testing of the generational losses we saw in
both DV-AVI and WMV files... re-rendering a previously saved video would
lose a frame or so. What frame and why?
During that testing I had
pointed to the visual loss of the 27th frame of each
DV-AVI clip on the timeline... one lost frame per clip when rendering
to a new DV-AVI movie file.
The routine stream
of posts from users noticing audio and visual issues with
saved DV-AVI files continues... so I thought it would be a good
time to revisit the subject, and this time look as closely at the
audio track as the visual.
This will be one of those
newsletters that some readers don't like, can't follow, or get confused about...
rather than not read it at all, skip to the conclusions and closing section at
any time to see what the bottom line is.
I'll start with a
15 second Photo Story... one that diagonally pans a still image
at a constant speed that shows the change in position from one frame
to the next. After studying the visual frames, I'll add a music track
and study the audio in as much detail as the visual. Even this
minimalist laptop can handle a 15 second DV-AVI file.
The lost 27th frame of the
first clip is still there. SP2 and MM2.1 haven't resolved it. With the help
of Photo Story 3, TMPGEnc, Excel, and Audacity, we
can look closer at missing frame locations and dropped audio segments.
When I looked with a magnifying glass a couple years ago, it's more like
being able to check it today with a microscope.
... but before getting into it, here are
some notes about current items...
Ellen, a newsletter subscriber, sent an
email pointing me to a great website... 2,650 downloadable midi-files
of piano tunes free to use as background music in non-commercial
stories and movies. I checked one pack and this piece in it:
That was enough to wet my appetite for the rest. It's midi-music
but sounding 10 times better than the midi-music that I'm
used to hearing. The website is
Remember those old 'player pianos' that automatically play a
tune from a paper roll... Terry Shaw has been
rounding up rolls from around the world, scanning them to get the paper
cutout info converted to digital files, and then creating midi-files from
The midi file format isn't supported by Movie Maker,
but plays fine in the Windows Media Player. My sample WMA file is a
Movie Maker 2 narration file recorded as I played the midi file in
WMP10. It's that easy to use one in a project.
The site also has a downloadable master index to all 2,650
tunes in an Excel spreadsheet. I've downloaded all the tunes and the
I was reading a book about Adobe Premiere
Elements and surprised to see that it can only work with Digital Video
source files... no analog sources with conversion devices... even analog to
DV-AVI conversion devices won't work with it, such as using a digital
camcorder as a pass-through device. Page 47 of the Visual Quick
Start Guide for Premiere Elements says "... you'll have to use another
program... such as Windows Movie Maker... to capture footage using this method
On the other hand, the
software is probably great. Similar to Premiere itself, you can use as many as
99 audio tracks and 99 video. You can do clip speed reversals, freeze a frame,
link audio and video clips to retain sync, do sophisticated motion and
transparency effects, apply 'rubber-band' volume controls to a clip,
When saving a movie, you can opt to burn a DVD (it includes
DVD menuing), save as a DV-AVI, export to a camcorder, export to MPEG
format... or Quick Time (MOV), or WMV. Having used Photoshop/Photoshop
Elements and Premiere for a number of years, I'm sure the package offers a
lot for the cost.
I tried using the Windows Media File
to embed a website address in a video. It worked in
a sample on my website... go to this
, scroll down to the embedded media player, enter
above it (be careful as it's case-sensitive),
tab a couple times to move the focus to the start button... and play the 22
At the end of the video the NASA World Wind website will
automatically open. The website page includes info about how to embed the
.... on to the main topic
To prepare for the
...I did a diagonal pan of a single large picture, using
Photo Story 3 to make a high quality video clip... no audio, no starting
transition, and accepting PS3's duration for the smooth pan - 15 seconds. I
wanted something fairly plain, but with moving pictures and
text, and a linearly smooth pan so I could see any breakdown in the smoothness
from one frame to the next.
MM2 said the story file (WMV) was 14.93 seconds
long. I wanted a DV-AVI file as a starting point, not a Photo Story,
so I used MM2 to save it a DV-AVI file.
I imported the saved DV-AVI file right back into
MM2... where in the collection bin MM2 said it was 14.88 seconds long...
I'd been used to the
routine dropping of the 27th frame when making the DV-AVI
file, so the shorter duration by 0.05 seconds was normal.
I dragged the DV-AVI clip from the collection to the timeline.
The duration of the timeline per the monitor was 14.87 seconds, but
the position of the end of the clip showed as 14.80 seconds.
With Movie Maker's preview
mode being a rough draft 15 frames per second, this difference is probably
not significant... just noted.
I was only getting ready for
the serious studying... let's move on to our quality checking and see what we
First Quality Check -
the Dropped 27th Frame
In this first generation rendering,
using only one clip on the timeline, there should only be
the dropped 27th frame... something to start the detailed
I used TMPGEnc to extract the
first 50 frames to individual JPG files. When it reached the 50th frame in the
saving process, I pressed the Stop button and ended up with 52 extracted
Frame numbers start with 0
(zero), not 1... so the missing 27th would be the picture file #26... I
flipped through the images in IrfanView, like you would
a deck of cards. I didn't see any break
in the visual flow when I flipped past the 27th frame.
Sub-Splitting the Single
Let's go ahead and split the clip on
the timeline into five 3 second sub-clips, do nothing more
to it, and render it to a DV-AVI file... the timeline stayed the same during the
clip splitting in the project... 14.87 seconds of duration showing under the
The newly rendered DV-AVI file
shows as 14.67 seconds... down 1/5 of second
in duration (5 frames at 30 frames per second is about 1/5 of a
second). At this point I'm thinking the generational loss... the 27th frame of
each clip... is doing it.
Splitting each of the sub-clips
again... each into 3 parts... gets the project to 15 clips on
the timeline. The saved DV-AVI file is now 14.53 seconds... going
One more round of splitting each clip
into 3 parts... the project is now 45 clips on the
timeline. Still 14.87 seconds on the timeline before saving, but now all
the way down to 13.57 seconds after saving. We've dropped
almost 1-1/2 seconds by splitting the clip into 45 sub-clips.... 1 frame
per clip... with this approach the 27th frame generational loss issue seems to
be a constant at 1 frame per clip.
But how does it effect
the smoothness of playing? Is it still smooth, with the same beginning and
ending frames, just playing quicker to get through
it? What frames are missing?
I used TMPGEnc
to make sets of images from each frame of the saved
DV-AVI files. There were 446 frames from the full starting clip....
and 411 from the file rendered from 45 sub-clips... 35 fewer
frames... but that wasn't 45 fewer, a chink in my
long-standing point that it was dropping one frame per clip... it's
not, or not unless TMPGEnc somehow sees frames differently than
It's time to study the sets of
frames closer. Believe it or not, time to open
I did a number of passes with the
renderings and frame extractions, and put the lists of
files into an Excel spreadsheet to help evaluate
The baseline file with no audio
was a single 15 second clip, 446 extracted frames. When split into 15 clips on the timeline, there
were 10 fewer extracted frames. I checked the data in Excel and
noticed that the extracted frames each had a different file size, reasonable as
I had opted for JPG images... comparing the files sizes of the two sets of
frame images showed each to be exactly comparable... until... YES!!! the 27th
frame wasn't there. The 28th frame and beyond were aligned to continue the
But I also saw that maybe I lucked out
by seeing the first missing frame as the 27th... by continuing the comparison, and making a close but not exact comparison
of where the missing frames were relative to the clips on the timeline, the
10 dropped frames were located as
27th frame of the first clip (this
was exact... the ones that follow are approximate locations)
last frame of the 2nd clip (because
it's approximate, it could be the first frame of the 3rd clip)
last frame of the 3rd
last frame of the 6th
last frame of the 9th
20th frame of the 10th clip
27th frame of the 12th
last frame of the 13th
last frame of the 14th
last frame of the 15th
The missing ones were mostly not
the 27th frame of each clip... and some clips had no missing
Split into 45 clips on the timeline...
35 dropped frames... checked again in the spreadsheet, but I won't put the
details here. The locations of the dropped frames didn't always align. In fact,
the first dropped frame wasn't the 27th... it was the 29th.
Some users had reported that
adding an effect, any effect, was enough to resolve audio issues, so I tried
adding an effect to see what it did to the dropping frames.
A single clip with the
mirror-horizontal effect applied had 1 dropped frame, the 27th. And
the 15 clips with the mirror-horizontal
effect applied to each of them also had 1 dropped frames, the
27th. Adding the effect to each clip on the timeline had
effectively stopped further frame drops.
This newsletter can only be so long,
and I want to get into the audio track also, so I'm stopping here with the
visual issues... I'd be glad to email you a copy of the spreadsheet if you
Study the Audio
This is my first comparable study of
missing info on the audio track. I started with a new 15 second clip,
this one with music, rendered to what I
call the audio baseline clip of 15 seconds.
I split the baseline clip
into 15 clips... at each of the full 1 second points of the
Here's a picture showing part of the
baseline clip with music, split into 15 one-second clips. On
the audio track below it is a copy of the baseline
audio DV-AVI file. At this point the two audio tracks are in
15 Clip Splitting... and Baseline Audio Track
And now another view.
The same baseline clip is on the Audio/Music track, but I
replaced split 15 sub-clips with the new DV-AVI
file rendered from them, a single clip.
The rendering had resulted in the 10
dropped visual frames; looking at the audio shows that, what starts off
being in sync drifts apart over the duration of the project... and the
drifting apart starts at about the 27th frame.
DV-AVI Clip versus the Baseline Audio
Let's zoom into the first second. I've
marked the figure below to show where the 25th and 30th frames
are. The sync is there exactly thru at least the first 25 frames. I've
circled the spot where they begin to diverge... and, with my bias
toward it going off as the 27th frame is dropped, it appears that's what's
the First Second
In this technical analysis, I'm trying
to determine if it's a sudden shift of audio or a gradual loss of sync... it
appears to be sudden, which correlates with the kinds of clicking or
metallic sounds reported as you hit such points during playback.
The visual showed the loss of
only one frame by the time the 32nd frame is reached. The audio shift
looks more like 2 frames... this assessment is close, but not exact. Each frame of a Movie Maker
project is really a double-frame, so taking a magnifying glass to it can't get
you to the single frame level.
The visual frame
assessments showed a loss of 10 frames over the 15 second clip. The
image at the right shows how much the audio is off by the end of the project...
MM2 reports the new clip as 14:38 and the baseline clip as 14:85, a
shortening of 0.47 seconds... 14 frames. Not exactly 10, but in the same
Do the two files end on the same
note or beat? Yes, they do.... so the shrinkage or loss is between the
opening and closing notes. The audio isn't being trimmed at the
Is it a progressive movement out
of sync? No, it's a sudden shift at certain points. We looked closely at the
first one, at about the 27th frame of the first clip. The next shift occurs
right after the end of the 2nd clip, aligned with the visual loss of the next
frame. The visual then lost another frame right after the start of the 3rd
frame... the next audio shift was in the same place. It's looking like segments
of the audio are suddenly dropped at the points the visual frames are lost...
The audio waves in the Movie Maker
timeline are like using a magnifying glass. Let's get out a microscope and
look even closer.
An Even Closer
Look at the Dropped Audio...
This is probably the most important
part of this analysis... is there a segment of audio being dropped, and if
so, by how much? Let's use the Audacity utility to
check the end of the first second... where the first visual frame
is dropped and some audio with it.
The upper two tracks of the next
figure are the two channels of the stereo track from the baseline
clip, before splitting into 15 smaller clips. The bottom two are the same tracks
from the DV-AVI file rendered from the project which was split into 15
I used TMPGEnc to rip
WAV files from the two DV-AVI files, and then put the imported WAV files
into Audacity for this analysis.
This picture shows both files in
full sync past the mid-point of the first second. I've zoomed into the
Audacity timeline to view it in increments of 10,000ths of a
The next picture shows the beginning
of the departure in wave patterns... with the wave patterns being minimal in
some parts, I had to do a lot of close looking to detect this
The two sets of tracks were
identical in patterns up to this point, at about the 27th
With a sudden departure in patterns,
how much is dropped? This next picture shows it.. a 0.065 second
segment... 2 frames of a 29.97 frames per second video. The segments
of the audio track shown in the upper two tracks are missing from the lower
Just one more picture and we're
finished... showing the shift in the audio tracks due to the dropped 0.65 second
segment. We've now measured the dropped audio pretty precisely... 0.065 seconds
= 2 frames.
At this point in
the timeline, the extracted visual frames show
us dropping one visible frame, but the audio timeline shows the loss
of 2 audio frames... the audio losses may actually be a more precise way of
assessing it than comparing extracted visual frames.
That's enough for this newsletter...
for those who have gotten this far, I hope it's been interesting, even if not
particularly positive or helpful.
Conclusions and Closing
Some users report visual problems with saved DV-AVI files...
others report audio issues. This analysis shows why there can be both. When the
visual and audio tracks of a movie play in real time, the content can
be such that missed information can be noticed or not noticed. It's a problem
only if you can notice the loss of info... or the shifting out of sync ends
up causing alignment issues.
What we can say is that, at the lower level, the rendered DV-AVI
movie is different than the source files... slight or not, it is
We're building a pattern of lost visual frames aligning with
lost audio frames. We can see the visuals in the extracted frame pictures. Can
we hear the audio glitches? After this analysis, I rendered the shortened audio
track to a CD quality WMA file and listened many times. I think I hear
issues but it's hard to tell conclusively... maybe because I don't particularly
care for the music I used.
the Bottom Line when heading toward a
For today it's: save your movies a couple or a few
times: to DV-AVI for the best visual, to a WMV file for the best audio, and
then marry the visual and audio tracks together into a final DV-AVI file
rendered from one long clip. You'll have only one small hiccup at the 27th
frame... within the first second of your opening. If there's blackness
and quiet for the first second, the split-second hiccup won't be a
What about audio/video sync issues? I ran across those
in many places doing the wedding videos... you just have to manage
them during editing. Sync the video and audio where it's most important...
and resync as needed.
This is a small study... which shows the world isn't perfect
yet. But it keeps trending in the right direction. Nothing I've learned
this week detracts from being able to use Movie Maker to achieve amazing
results, and I hope the information helps you learn a bit more about
what's happening. It's certainly helping me.
Have a great week...