Field Order - PAL playback on NTSC

nugent schrieb am 11.11.2003 um 23:32 Uhr
I live in an NTSC country and have an NTSC TV set. My DVD player can play both PAL and NTSC disks on it.

I have some old PAL videotapes that I have captured at full DVD resolution. VV tells me the avi captures are Upper Field first. However, the VV template for PAL projects and PAL DV rendering have Lower Field as default.

To test the difference, I have burned two DVDs. The Upper Field result is definitely better (when viewed on an NTSC set). This is confusing to me, as I have seen other posts that say DVD is always Lower, for both PAL and NTSC. Can someone explain?

Would it make a difference if I viewed them on a PAL set?

Also, I am making NTSC DVDs to be sent to relatives in PAL land. These are Lower Field and look great to me. Will they be ok when viewed on PAL?

Kommentare

farss schrieb am 11.11.2003 um 23:48 Uhr
1) I don't think VV has anyway of knowing what the field order is on capture, it just captures which ever way its told.
2) You're right, as far as I know both PAL and NTSC is lower field first. at least we agreed on that.

Don't quite know why you even get a choice, is there anything that works the wrong way around, although I think I saw something about Media 100 systems doing it the other way around. I really don't understand why anything would do it the other way around, I'd like to understand this a bit better too.

Was the footage capture from DV or analogue?


Maybe what's happened is for some reason VV captured the footage the wrong way around, it'll certainly look bad if you then display it with the wrong field order.
vonhosen schrieb am 11.11.2003 um 23:49 Uhr
You can render MPEG for DVD as upper or lower field first & it is not going to be NTSC or PAL specific.

The important thing with this is that the encoder is informed correctly if the source file is upper or lower field first.

DV source will be captured as lower field first & analog will be dependant on the capture card.

If your PAL videotapes have been captured & edited as upper first , look best encoded as upper first, then trust what your eyes tell you & keep to that. It will not matter whether it is for PAL or NTSC . (The actual NTSC to PAL conversion side of things is a different topic & the field order doesn't come into it)

My workflow is typically to capture PAL DV as lower field first. Edit as such in Vegas. Encode the MPEG as upper field first (because that is the default on my encoder & as long as the encoder correctly knows the source is lower it makes no difference outputting upper first from it) & author/burn that to DVD.

Wrong field order displayed on an interlaced TV will be very obvious with any motion & as I say this will have come about because source has been incorrectly recognised as opposed to what you render it out as.

That said I don't use the MPEG encoder in Vegas & I'm not sure whether the field order selection on the video tab of the render template is for indentifying the source or what you would like the ouput to be. If you are doing it all in Vegas best to stick with whatever your original source's field order was all the way through. IMHO :-)
RBartlett schrieb am 12.11.2003 um 11:56 Uhr
As long as each element that touches your video on the way to the target DVD knows which field dominance has been used, you'll be OK on the final PAL playback. The playback you see on your equipment that is capable of playing the PAL discs is going to be representative of the client/recipient playback on PAL, IMHO.

DV, the 25Mbps, standard play, standard track width, 4:1:1 NTSC, 4:2:0 PAL stuff you capture over firewire, is when taken from the lens to the tape, lower field first. (phew!)

720x480 and 720x486 NTSC are different, PAL via many analogue capture cards is upper (odd) first. When I capture with PICvideo MJPEG I can select in this codec which order it presents the data to the codec's clients. I choose to make it all the same as plain-DV, lower first.

Where the codec can convey this information to say DVDA, then all is well. It seems like knowing too much information to know if the DVD format can identify or expect a certain order. If you encode in TMPGEnc, you can determine the right order from your AVI or MPG2 by going to settings -> Advanced and double click on the "Deinterlace" to check the field order. Click the combo "Method" and select "Even-Odd field (field)", and go to some area with action. Advance a few fields manually, and if it appears to bounce a bit back and forth, the field setting is incorrect. This method works for just about anything that doesn't switch field orders mid file. Don't forget to uncheck "Deinterlace" when done. (thanks to my friend Eugene for teaching me this).


As I said earlier, this is of no consequence if you build MPEG-2 with a DVD profile or app that is completely aware of your source file format and the DVD forum specs. DVD MPEG-2 uses the temporal compression option, which can repeat fields, making identification and comments on field order slightly moot:

I wouldn't be surprised if the DVD format resolves on the DVD with upper field first in PAL mode, which is fine if this is played out by your PAL capable kit that recognises this fact and puts out the lines in the right spot relating to the first scan line of the electrical output. NTSC would probably be the other way about, unless there was such a thing as a 720x486 NTSC DVD-Video type, which there isn't. Essentially this is an internal quandary for the DVD player (be it software or hardware) to sort out. Where a set-top player has a DV connection to the TV/broadcast-monitor, it will almost certainly be lower field first in PAL and NTSC....
nugent schrieb am 12.11.2003 um 16:24 Uhr
Thanks to posters for your insights so far - I need to digest and understand them.

Some clarification to my original post: My captures are of regular analog VHS PAL tape, via a TV card (Brookfield 8x8), using AVI_IO capture software. This produces an avi with huffyyuv codec, upper field first, which VV then renders to MPEG-2.

OT note on AVI_IO: It gives me the most reliable captures, with the best handling of dropped frames due to poor quality source. All video/audio is perfectly synchronized. Much superior to VV analog capture!
RBartlett schrieb am 12.11.2003 um 18:22 Uhr
My Conexant/BrookTree Fusion-878 based cards (one from Hauppauge, the other from LeadTek) capture with the upper field (odd) first.

Subsequently I've tuned the compression codec to always deliver the fields the other way about, which by way of the field order not being flagged in the MJPEG AVI header, makes mixing DV in Vegas that much easier. Not sure why Vegas doesn't see the header right, but neither does WMP with my Matrox G450 TV-out "DVDMax" feature, unless I reverse in the codec preferences (control panel, multimedia.....hardware....properties properties video codecs, properties, settings!).

AVI_IO is good. I use ShowShifter which is similar in that it, unlike virtually all NLEs, recognises a Bt878/881 card when detected. The preview bus that uses a PCI overlay surface on your PC adapter (even when the gfx card is in an AGP port) falls back to quarter frame when you capture full frame in the capture settings. This breaks most NLE capture and I've given up caring why they do this all wrong. AVI_IO/ShowShifter can recognise that the capture pin/bus is active and don't mind if the driver then delivers a new switched-over format for the preview pin/bus once the capture has been commanded. Doesn't sound too difficult for a piece of software to handle...!

You might enjoy another thread here that covers multipass sampling of analogue sources and then layering these captures together with a percentage fade weighting that for the number of passes adds up to 100%.

John Meyer's recipe for VHS restoration