Question: Why lower field First for creating DVDs?

[zhang1ning2]

Ulead would set the default settings for creating DVDs to "Lower Field First". And I always followed it.
The other day I used Ulead VideoStudio 10 (TBYB) to open some VOB files from commercial DVDs and to my suprise, all of them are upper field first MPEG files.
The list of DVDs I tried:
Matrix, ET, Lord of the Ring, Sin City

Anyone has any idea?

[Trevor Andrew]

Hi

As the object is to create a dvd then one of the field orders has to be used.
The video has to be interlaced.

Upper or Lower.

Ulead has defaulted to using Lower. They have to choose one or the other.
May be they are assuming that most people will be using a digital source, either now or in the future.

Trevor

[heinz-oz]

If you have a digital MiniDV video camera, the field order of that will be lower field first. Since Ulead expects most users to work from a DV source, the default setting is correct. Easy enough to change if need be.

[mikewillnot]

I have a tivo file that was originally a cable transmission cap. (copyright is not an issue.) I transferred it to my PC, for eventual burning to DVD.
Q: Is this the same sort of "digital" source as DV?
I was unable to determine the field order parameters of the tivo file, but when exporting to mpg I have the full range of options.
Q: lower or upper?

[sjj1805]

Probably not.
It all depends upon the equipment you are using and the method of getting the video into your computer.

If you have a digital camcorder and it is connected to your computer with a firewire cable it is more often than not lower field first.
If you have a TV card it is more often than not upper field first.

These settings are not written in stone and for some users the field settings are the other way round. If you notice that upright things in your video such as lampposts appear jerky when you move across the screen, try the other field setting to see which gives the best results.

[maddrummer3301]

.

[mikewillnot]

Thanks so far. Actually, the sequence of conversions leaves me still uncertain as to what the video properties are at what stage, and because VS8.0 doesn't see .tivo files, I can't verify using that tool. Here's the work flow sequence I'm using at the moment.

GOAL: DVD files for burning and viewing on conventional stand-alone players and TV sets

1. video captured on Tivo, in *.tivo format; I understand it is analog video (from cable) captured in the device in digital format of some kind. It's something like *.mpg, but I have no way of telling field order. It's sure enough a digital file, though not a conventional camcorder DV file type.
2. transfered to PC.
3. converted to *.mpg using Direct Show Dump
--- neither the *.tivo nor the *.mpg produced above can be seen/accessed by VS8.0. The only tool I have that can read the DSD *.mpg file is Nero Vision, and it doesn't indicate field order of files, imported, only has settings for output. I still can't tell the field order.
4. Using Nero Vision, I do a basic edit on the file (trim, etc), combine other video files, etc., and EXPORT as a single *.mpg file, with the full range of settings. I typically use DVD type mpeg settings, low compression (variable, 8,000), and sometimes set for bottom field first, sometimes top.
5. Using VS8.0, I can now see the mpg file. Using the "recommended work flow," I insert the video not in the timeline, but in the "share" stage, and generate a DVD file set. I BELIEVE I'm configuring VS8.0 to use the same settings as the inserted video file, but it always goes through a lengthy rendering process for some reason.

RESULT: DVD w good video, but jittery motion.

Any suggestions or thoughts would be GREATLY appreciated. THANKS.

[jchunter]

Video Studio <sometines> uses the "stopped watch" method of choosing default values (correct twice a day). This makes as much sense as forecasting the weather in desert regions as "hot and dry". Of course, this prediction is right 90% of the time in Phoenix Arizona.

BitRateViewer http://teco.emg.hu/bitratev/BV.EXE does read the field order for many video file formats. Try using this to determine the field order on the tivo file stage - before any transcoding to other formats. Then make sure that every time you transcode, you maintain that field order - all the way to the DVD.

[heinz-oz]

@mikewillnot

I gather your motion is jittery because the field order is upside down. Render a new one from the original source with the field order reversed.

It is not important to have either lower or upper field first to have a good DVD, what is important though, very important, is to have the same field order right through. Your TV is going to show the picture interlaced unless it is a progressive scan HD (should be frame based then rather than field based). The picture will only be good if the correct field order is maintained. If you see the wrong field first, the motion is going to be jittery.

[mikewillnot]

Correct as usual, King Friday. And thanks.

BitRateViewer produced the info below. Indeed, the tivo files are top field first, and I was flipping it somewhere along the way to bottom.

--------------------------
Num. of picture read: 31
Stream type: MPEG-2 MP@ML VBR
Resolution: 480*480
Aspect ratio: 4:3 Generic
Framerate: 29.97
Nom. bitrate: 5800000 Bit/Sec
VBV buffer size: 112
Constrained param. flag: No
Chroma format: 4:2:0
DCT precision: 8
Pic. structure: Frame
Field topfirst: Yes
DCT type: Field
Quantscale: Nonlinear
Scan type: ZigZag
Frame type: Interlaced
Notes:

[heinz-oz]

You are welcome

[jchunter]

You are not out of the woods, yet. Your frame (480x480) is non-standard, yet the aspect ration is listed as 4:3 - but I would stick with this frame through rest of the process and monitor picture quality as you proceed. Be sure to check Keep Aspect Ratio in the Preferences menu.

[maddrummer3301]

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