I got into this newsletter subject in a Support Space session a week ago with Mark, about how Movie Maker handles interlaced
files... TFF versus BFF. He was seeing it converting TFF files to BFF, something I had only read about but not tested.
- TFF is 'top field first' in an interlaced video file
- BFF is 'bottom field first'
What happens when you have the wrong field first during playback. From what I read, the official word is visual 'jittering'.
Each frame of an interlaced file is made of two 'half-frames', half the lines on the first part and the other half on the second.
The 30 frames per second of an NTSC video are made of 60 half frames. Similarly the 25 fps of PAL video are 50 half frames per
When it comes to Movie Maker and interlacing, my notes boil down to this short paragraph...
If you edit in DV-AVI and save to DV-AVI, WMM2 will preserve the interlace present in your original video (and publish
will be much slower as it works in a field-based mode instead of a frame-based mode). In all other cases it de-interlaces
using an adaptive de-interlacing filter that will preserve vertical resolution for still and slow moving images but for fast
moving images will be closer to `bob'
That may be so, but what it doesn't tell you is that if your source file is an MPEG-2 file with TFF, and you save it to a DV-AVI
file, it'll come out BFF, not preserving the interlacing. When it switches the fields without your involvement... you'll end up
with some jittering.
One of the filters in VirtualDub is named 'field bob'... which compensates for field jumping in field-split video by applying
bob-deinterlacing techniques . How it does it is on page 148 of 'Learning VirtualDub' by Georgios Diamantopoulos, Sohail
Salehi, and PapaJohn.
Here's a screen grab of part of a clip in VirtualDub, magnified 4x. At the left is how it looks in the interlaced DV-AVI file
captured from my mini-DV camcorder. The adjusted one at the right is after applying VirtualDub's field bob filter (with Smoothing).
It gets rid of the 'jaggies' but leaves the 'ghosting'.
If you work with DV-AVI or other interlaced files, the 'jaggies' will stay until you save the movie to a wmv which de-de-interlaces
it, or view it on a TV where the hardware does the same. Saving to a WMV file will be similar to using the field bob filter of
Enough background. What does it all mean and what options do you have if you see a video clip that you think could be handled
better when it comes to?
As I mostly work with and distribute wmv files that are not interlaced, I'm not ready yet to see and show you what happens
when you input a TFF file and get a BFF one back. This week's newsletter is more about interlaced or not, and takes a look at
how the different files effect bluescreening in XP and Vista. I'm really doing a jump-shift from the TFF/BFF subject.
Before doing it, here are...
a couple notes...
Support Space entered the next phase of starting up...
charging a standard $25 fee for a session... with the first one free to new customers. The expert gets $20 and the house gets
Customers I know have been extremely pleased with the service when it was a free ride though the early beta phase. We'll see
how many keep going when they have to ante up a modest fee.
Over at my other startup, my 11 software reviews are now online at
BrightHub and I'll be attending the first writers' conference call next week with Bill Phelan, the CEO.
.... back to the main topic...
Interlaced - TFF or BFF
Mark and I were checking video files all week... are they TFF or BFF?
Here's a picture showing GSpot looking at the file that started Mark's quest.
It's a Tivo file, an MPEG-2 one that GSpot says is a SVCD (Super VCD). I marked it to show where GSpot says it's an interlaced
TFF file... which seems to be the 'normal' for MPEG files.
I used MM2.1 to convert it to DV-AVI and saw the same thing Mark had. It goes in as TFF and comes out BFF. As Mark suspected
when he contacted me, Movie Maker and the Microsoft DV codec are changing the field order.
We haven't found a DV-AVI file that is TFF, so it seems the standard for the file type is BFF. So it wouldn't be Movie Maker
doing the changing as much as it would be the codec applying the standard, something we need to be aware of and live with.
Here's a sampling of files I've checked.
Files that are TFF...
- Tivo MPEG-2
- MPEG-2 files recorded by a Sony DCR-SR42 HDD (hard drive) camcorder
- Sony Mini-DVD camcorder files - VOB (MPEG-2)
- M2V files extracted from the Sony mini-DVD camcorder files by TMPGEnc... preserving the TFF
- VOB files on DVDs made by Vista's DVD Maker... by the quick automatic process from tape to disc.
Files that are BFF...
- DV-AVI files, NTSC and PAL, made by Movie Maker 2.1 and 6
- DV-AVI files made by VirtualDubMod when using the Panasonic DV codec for compression... even if the input file is a TFF
- Pinnacle Studio MPEG-2 files heading to DVDs
- SVCD files made by TMPGEnc
- VOB files on a DVD made by MyDVD
- VOB files on a DVD made by Premiere Elements
Anything with a mix of TFF and BFF?... yes, the VOB files on a DVD made by Vista's DVD Maker from recorded TV files.
When going online to check the DV standard, I got as far as finding a website that sells you a copy of the DV-AVI spec for
50,000 yen... a bit too steep for my needs, whatever the exchange rate.
Changing the Field Order
Some video apps let you select the field order, and others take care of it for you.
TMPGEnc lets you set the field order of saved MPEG files as TFF or BFF... if you bring in a BFF DV-AVI file made by Movie Maker,
you can make the MPEG-2 files needed for a disc as either BFF or TFF.
A bit more checking indicates that MPEG files are TFF by default, unless changed by the user... while DV-AVI files are always
Collecting Sample Clips
As anything I shot with my camcorder or ran through Movie Maker to DV-AVI files was automatically made BFF to align with the
DV spec, I had to satisfy my quest to do some testing by checking interlaced versus non-interlaced clips.
I turned to my camcorder and digicam, and had Aeromouse walk around in front of a blue screen (RGB of 0,0,255 in Paint)...
I did green and red ones too, but the blue ones give the best results, so the rest of this newsletter is about bluescreening.
My Sony TRV80 mini-DV camcorder can shoot in the usual interlaced mode or in progressive. But when connecting
with firewire to the computer, the only thing I can capture is an interlaced DV-AVI files. I tried both modes anyway.
My Canon PowerShot SD 750 shoots video in Motion JPEG format and when connecting by USB to the computer,
there's no conversion. The file is a series of JPG images, not interlaced.
I put the cameras on a tripod and shot my laptop's LCD screen. That puts some sort of analog encoding processes between the
pure blueness of the Paint screen and the digital file on the tape or card... actually I kind of like the added complexity of
the analog steps.
Here's what the pure blueness of the screen in Paint looks like... to compare to the different background patterns you'll see
below. The differences didn't effect things as much as I expected.
Bluescreening in XP and Vista
The custom XML code for bluescreening in MM2.1 is on my website (the Persian Gal's code) and in the forum library of custom
transitions (Blaine's code). Both of them use the same settings.
The code for bluescreen transitions in Vista isn't in the forum library yet, but Rehan's Shader TFX package includes 10 different
bluescreen transitions. I used two of the five Chroma blue B ones for these samples.
I packaged the results in a couple 2-1/2 minute clips. Each is of the same series of clips, the only real differences being
the making of one in MM2.1 and the other in MM6, so the bluescreening technology is different.
These images show you a bit of what's happening in the videos. There are pairs of clips, the first of which shows the bluescreen
clip before it's used as an overlay... with Aeromouse over the blue background. The next clip shows what you see when you put
the video clip over a black still picture. The blackness could be any picture or video clip, still or moving. I usually use pictures
or video clips as backgrounds, but it's easier to see what you get of Aeromouse when it's over a solid colored background.
The Motion JPEG clips easily win over the mini-DV interlaced or progressive ones. In XP you can hardly see anything from the
progressive clip. Vista is considerably better but falls short of the MJPEG files.
Inerlaced DV-AVI clips work better than progressive... I don't know why.
Thinking that Vista was doing a better job of bluescreeing than XP, and Movie Maker automatically de-interlaces when making
WMV files, I decided to make a test file in Vista, letting it do the de-interlacing. I used Vista's profile of 3 Mbps, and then
used it in XP and Vista to get some more to ponder when watching the bluescreening clips.
That series of clips starts half way through the sample videos, and shows...
- the wmv clip made from an interlaced DV-AVI one
- one made from a DV-AVI clip de-interlaced and 'enhanced' using VirtualDub (there's an editorial
error in the wording of the clip... where it says 'interlaced...' it should say 'de-interlaced' by VirtualDub
- a wmv clip made from a progressive DV-AVI clip
- one made from the MJPEG clip
Conclusion and Closing... and What's Next?
My quest of the week started with Mark's email asking about Movie Maker converting TFF source files into BFF, and ended with
more of a study of bluescreening using various interlaced and non-interlaced files.
There's the technology of compression, and interlacing TFF and BFF fit into it. I've always wanted a copy of the book Digital
Video Compression by Peter Symes. I ordered it in the middle of writing this newsletter... it's in the mail.
Then there's the application of the technology. If you're putting low quality on YouTube, I'm sure you won't care about which
field is first in a video. But if you're looking at your new Hi-Def 60 inch screen and playing a DVD, you might get better results
by aligning the fields all the way through the process. If you start with BFF files from your mini-DV camcorder, and don't take
steps to change it, you might have TFF files on your discs and wondering what's causing the flickering. Maybe your flickering
is 'jittering' and you can fix it.
Have a great week!!
I look forward to comments and discussion about this and other newsletters on the forums at:
Movie Maker, Photo Story 3, DVD Maker, Expression Media -
Photo Story 2 - www.papajohn.org/PhotoStory2/PS.html
I'm involved in anything and everything that supports the users of Movie Maker and Photo Story, and adding more regularly.
Some are free and others reasonably priced.
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About John 'PapaJohn' Buechler from Microsoft.com
||John "PapaJohn" Buechler, of Kalamazoo, Mich., goes by PapaJohn online. An avid user of Movie
Maker since its first release, and a regular supporter of the community of Movie Maker users,
John received a 2003 MVP award from Microsoft for that support. In March 2003, he started a comprehensive
website about Movie Maker 2 at www.PapaJohn.org.
He maintains the website, writes books and articles, teaches, and provides support services -
all for the community of Movie Maker 2 users. An engineer by formal education, John is a computer
database and multimedia expert by business and personal experience. He co-authored the first book
about Movie Maker 2 and is actively working on a second one. You can find his advice in the
Windows XP Movie Maker newsgroup and in the Windows Movie Makers Forums.
newsletter is republished with permission of John "PapaJohn" Buechler.
Please note that this is an archive of newsletters and some information may become outdated. PapaJohn,
and the webmaster of this site, provides this information "AS IS" with no warranties.
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