Newsletter #97 - April 1, 2006
Tags in DVD
Movie files can be of most
any video size, as measured in pixels. There are some standard sizes,
and then there's the ability to make and use a custom profile for others.
A DVD needs to be made of standard
formatted and sized movies. MPEG-2 is the format, and one of the standard sizes
for NTSC TV systems is 720x480 pixels. For this newsletter I
made 4 discs, 2 in the new Vista Windows DVD Maker and 2 in
MyDVD8 on my Windows XP laptop. Each disc has 9 movies.
All 36 of the movies are of the
standard size of 720x480 pixels....
... but 12 of them were made from files of lower
visual quality than standard DVDs. Another 12 are from files on a par with
DVD quality. And the remaining 12 were made from the High Definition movie
options in Vista's Movie Maker.
... and somehow each with 720x480 pixels can
look different when played... why? It has to do with some tags in
the files that tell the players how to display the movie, and how
the players interpret those tags.
The tags are things that I'm still trying to understand.
You don't add them directly, and you don't know what they say, and there
isn't a utility that will let you read them.
This issue won't have a definitive conclusion.
All I hope to share is an awareness of the tags and how important they are
to what you see when watching your DVDs.
Here's an example of tags in action. One DV-AVI file
saved from a widescreen Movie Maker project, and another DV-AVI
file from a standard aspect ratio project.
Looking at the properties of each
in WMP10, see what the player is getting from the tags. It's saying the
widescreen movie has an actual aspect ratio of 4:3 but it'll
display it at a widescreen 16:9.
And the standard one has an aspect ratio of 4:3.
720x480 isn't 4:3 or 16:9... it's someplace
in the middle. if you check the math, it takes 640x480 to be 4:3 and
852x480 to be 16:9. The tags are telling the player to squeeze the pixels
in a bit to show the standard file at 4:3, and stretch them out as needed
to show the widescreen one appropriately. If the player does it right,
the movies will look as you want.
... before getting into it
further, here's a
Vista Corner... I've been busy this week with
Vista's Movie Maker and Windows DVD Maker. In addition to this
newsletter, the Setup Movie Maker > Vista Preview > DVD Maker page of
my website is pretty well fleshed out with new screen shots and more
added 1/2 GB of RAM to my Vista system, doubling the RAM to 1 GB... the max for
the system. It runs peppier, as expected.
project file in Vista has the same .MSWMM extension that we're familiar with...
but if you try to open it in MM2, you'll get
... but all the movies and discs made in Vista work in
XP... that's more important.
.... back to the main
Making and Viewing
I imported some standard
and widescreen camcorder footage into my Vista system, and made two sets
of 1 minute test movies... one set at the standard 4:3 aspect
ratio, and another at widescreen 16:9.
Each set has 9 files, the same project file rendered to each
of Movie Maker's built-in publishing choices.
The standard set was used as
the input files for a standard DVD, and the widescreen set for a
That gave me some files to
play with... to compare file sizes, quality, playback in various players, etc.
What were the tags saying and how were the players interpreting
publishing choices in Vista's Movie Maker are a good mix... with
standard DVD quality right in the middle.
3 less than DVD quality (Portable
Device, Low Bandwidth, and VHS
3 standard or aligned with DVD
quality (DV-AVI, DVD Quality, and DVD Widescreen)
3 higher than standard DVD
quality (HD 720p, HD 1080, and HD 1080 VC-1)
Positive Side Note: as low-end a system that I'm using
for Vista, and as much as it's pre-beta, the captures never drop frames, and
I've yet to make a coaster instead of a DVD that plays well.
All of the MPEG-2 files on
the discs have video sizes of 720x480, but
they play differently. Rather than using words to explain the
similarities and differences, I did a lot of picture-taking so you could see for
Here are 1/4 size snapshots of
the DVDs playing on my Windows XP laptop in InterVideo's WinDVD, which
has a neat frame snapshot feature. The pictures at the left are from the
standard disc, and those on the right from the widescreen.
9 have black borders at the
top/bottom, left/right, or all around... and 9 don't. Some are appropriately shaped to align with 4:3 or 16:9 aspect
ratios, and some are not.
Here are typical frames from each
movie, and some comments. The pixel dimensions that I note are the movies
as saved by Movie Maker and used as inputs to Windows DVD Maker... not the
transcoded MPEG-2 files on the discs, which are all the same
DV-AVI >> Widescreen
The only one of the 9 choices that
looks right in both standard or widescreen mode... they display in
the appropriate aspect ratio and have no black borders.
On a TV, one would have black
borders... InterVideo WinDV on my computer has more than enough room on the
screen to play the movies in a changeable window size. Snapshots of them on a TV
would be different.
Pixel dimensions of
Standard << DVD
Quality >> Widescreen
The aspect ratios are correct... but
the widescreen mode uses a 4:3 overall size with a letter-boxed widescreen video
DVD-Widescreen >> Widescreen
A DVD widescreen movie doesn't
belong in a standard aspect ratio DVD... where it displays as 1:1. And it's just
a bit better in a widescreen DVD, showing as 4:3. In neither case is it showing
the desired widescreen 16:9.
Standard << HD
1080 VC-1 >> Widescreen
Displays the same as
DVD-Widescreen... 1:1 within a 4:4 overall window, with black borders... and 4:3
aspect ratio in a widescreen DVD.
Pixel dimensions of 1440x1080,
a 4:3 ratio.
Standard << HD
1080 >> Widescreen
Displays the same as HD 1080 VC-1...
and both files have the same pixel dimensions of
Standard << HD
720p >> Widescreen
This one stands out in the crowd...
appropriately shaped at 16:9 when in a standard DVD, but with black borders all
around. And wider than widescreen when viewed in a widescreen DVD....
measuring 21+:9 instead of 16:9...
Pixel dimensions of 1280x720, a
ratio of 16:9.
Standard << Low
Bandwidth >> Widescreen
Normal looking at both regular
aspect ratio and widescreen, but letterboxed in widescreen.
320x240 pixel dimensions, a ratio of
Portable Device >> Widescreen
Appropriate for portable players
that have a standard 4:3 aspect ratio screen, with the widescreen mode
letterboxed to be viewed right.
640x480 pixel dimensions, a ratio of
Standard << VHS
Quality >> Widescreen
The 3rd of 3 lower quality options
also views in appropriate aspect ratios, using the letterbox approach for the
widescreen DVD option.
640x480 pixel dimensions, a ratio of
Let's finish this section with a
look at the set of thumbnails for the widescreen DVD. They look
the same as the regular aspect ratio set... at 4:3.
Viewing the DVDs with Windows
Media Player 10 in Windows XP shows the same results... so it's not the viewer,
but the tags in the disc files that account for the differences.
For a cross-check... I used the
same movie sets of input files to make DVDs with MyDVD
Premier 8, running on Windows XP... a standard DVD and a widescreen
Here's the results, using the same
InterVideo WinDVD app to view the discs and take frame snapshots. The
snapshots of the standard disc are at the left, and the
widescreen one at the right.
Most noticeable are how much better
the High Definition widescreen files are displayed than those on
the disc made by Vista's DVD Maker.
Conclusions and Closing
Widescreen and standard mode
video starts with your camcorder, flows through the editing phase, then
into the saved movies, the transcoding for discs, and then the
display by the players. Most of the alignment needed is handled
by the software behind the scenes. You'll accept things that look right and perk
up when it doesn't, and then wonder why not.
This newsletter is about an
increased awareness about the role of the tags in the files, and about how
various files can play back differently than you expect.
For me, the standard versus
widescreen footage sometimes starts with the camcorder... my Sony TRV-80
mini-DV uses a letterbox approach when recording in widescreen. It's the
camcorder I used for the footage in this newsletter. That sets the stage for how
the video stream is processed during editing.
My older Hi8 model TRV-615 gives me
the option of letterboxing when recording as widescreen, or of using the
full recording area of the chip.
DVD making options vary with the
Vista's DVD Maker gives you a
choice of 4:3 or 16:9 aspect ratio for the DVD... its
help file says to pick it based on what you or your audience
will be watching it on.
MyDVD 6.1 doesn't provide an
option of making a widescreen versus standard DVD.
MyDVD 8 has a project setting
option of either 4:3 or 16:9 for the menu aspect ratio. Its help file
says like Vista's... make it shaped like the TV
There's more to learn about tags and the effects they
have... it's best to test your process with a little pilot file and
learn how your systems work... burn a test disc and look at it before doing
your big projects... adapt as needed.
Have a great week...