More field order woes

[keithm]

I am getting really confused with the whole field order thing for pal. If I use my Matrox Marvel to grab analogue video i keep everything in field order B and everything is fine. The video can be converted to mpeg 2 for use on an svcd. Fine.

But: when I grab Digital Video (DV) with a firewire 1394 card the field order is A. I don't know what to do with it to use it for pal TV. Do I render the mpeg as a field order A, or convert it to field order B; or ignore the whole thing and do it frame based...

Extremely confused because tests are inconclusive, some times I get odd artifacts which I am putting down to the field order being wrong...Things get even worse ifI have to mix analogue and DV footage!

[Flying dutchman]

It depends. If you want to process the DV video for SVCD etcetera, no further tweaking is necessary. Keep the field order the way it is.

If you want to output it through your Marvel's composite or S-Video connector, you'll have to convert it so the field order matches that of your Marvel.

The Marvel uses bottom-field-first, DV uses top-field-first.

NOTE:
the well-known mpeg encoder tMpeg, version 2.5 and higher, interprets the meaning of "field order" differently depending if the material is PAL or NTSC. If I try to encode analog PAL material that was captured through my Marvel, tMpeg says that it has field order "A" (top field first). And PAL DV alledgedly is "B" (bottom field first). I know it's not true in both cases, but I have to leave the settings this way or else it gets the field order wrong.

[keithm]

I knew it wouldn't be simple..I need to render for an svcd and then render a higher quality mpeg2 to output via the marvel to svhs. Ah well, looks like I'll have to change the field order.

[Snake-Eyes]

Field order is something else I was never too sure about, and since this topic's about that, I might as well include my question here-

I want to take a DV movie (from my NTSC Sony miniDV camera), import it to the PC (using a firewire card), then output it to (x)(S)VCD format (I'm going to be playing around with several, using some tips you gave in another topic, FlyingDutchman). I've never been quite certain what to do about field order. Note that these VCD discs will be for playback in a stand-alone DVD player, and not on a PC (I'm guessing I need to keep them interlaced..).

Any tips on field order for this scenario (and anything else useful you can tell me about the process as far as other settings and filters go would be appreciated)?

[colinbr]

I have just been rumaging around on the net and newsgroups to try to find something definative about DV field order.

Unfortunately there are a lot of differences of opinion.

For example this article has a bold emphatic banner half way down which says "DV footage, PAL or NTSC is always lower field first"

http://www.creativecow.net/articles/onneweer_barend/deinterlacing/

Also TMPGEnc version 2.56 notes appear to agree with this as they say "if source file is DV forma, always bottom-field-first is applied, and no field order detection is applied any more". So Hiroyuki Hori has apparently decided that all DV must be bottom-field-first.

Flying Dutchman, you apparently agree that TMPGEnc selects lower field first for DV, but you say that this is wrong. I don't have any captured DV files to examine, so can I ask how you determine the field order of your DV files?

I wonder where field order is defined in DV? If the DV data stream arrives through the firewire port as a stream of (digital) frames, then presumably we in a similar position to analog video capture where the actual field order in the captured AVI file is dependent on the drivers and codec. So what/where is it that is supposed to enforce a definite field order for DV? Having said that, from what I've read some people seem to be getting different filed orders anyway.

[Snake-Eyes]

I posted this once already in another related topic, but since it partly concerns some experimentation with field order..

First of all, let me thank you again (Flying Dutchman- see other topic). The resulting SVCD videos that I used during my testing showed much better quality than prior attempts I have made.

Now on to the actual tests, mainly concerning NTSC DV to VCD and field order questions.

I spent probably the better part of two hours installing the software for this work on my system (I haven't had any capture / editing / conversion software installed since the last rebuild). For these tests I used Pinnacle Studio DV 7 as the capture program, VirtualDub to do the editing (er, well, filtering, since I didn't do anything else with it), and TMpegEnc for the final conversion to SVCD format, as well as reinstalling my Nero Burning ROM software and applying the latest software update (5590) so that I could actually produce the test disc.

After installation of all the software and patches, I took the latest miniDV tape that we'd shot while back visiting my parents last month, captured it using the standard DV codec (Full Quality DV chosen from Studio DV's capture options), then selected an ~2 minute segment of my children and wife having fun in a wading pool. This segment was then output (using SDV7) to an AVI file, again using the DV codec, so that the resulting footage would be unchanged from what was on tape.

After finding out that the latest VirtualDub doesn't come with the DNR filter, I did some searching on the web, and then installed that. At this point I followed your advice for settings, along with the basic frameserving instructions from vcdhelper.com, and frameserved the short clip to TMpegEnc.

More fun. I tried to dismiss the wizard and select the settings I needed for the output SVCD from the Settings button for the output file, and for some reason, every time I tried, I got nonstandard SVCD warnings from Nero for the resulting MPEG, specifically stating that there was streaming data.. After three unsuccessful attempts (and still scratching my head about WHERE to change anything in TMpegEnc concerning streaming output..), I went back to using the wizard mode.

From the wizard I selected 'Super Video-CD NTSC', and produced my first MPEG2 using the standard settings except for one change- I selected Interlaced (Field Order B, Bottom Field First). I then proceeded to restart the frameserver, repeating the encoding process twice more from TMpegEnc, using Field Order A for the second video, and the default Non-Interlace setting (in other words, all wizard defaults) for the last video. Then I made my test SVCD from Nero.

Nero gladly accepted all three MPEG2 videos as being SVCD compliant (*scratches head again*), so I burned my disc. I already knew that neither my Sony DVP-NS400D single DVD player or my Sony DVP-CX870D 300 disc changer would play SVCDs, but for kicks I inserted the disc in each. I got what I expected with those two players- basically, nothing but an error message. Heading on back to the master bedroom, I inserted the same disc into my Magnavox DVD825AT, where I also got what I expected, at least partially. I expected it to play the disc, and it did. What I didn't expect was the major improvement over past attempts at producing VHS or near-VHS quality SVCD CD output.

Thankfully I had that thought when making the test disc of checking each of the interlaced field orders / noninterlaced possibilities, because I was able to watch all three videos back-to-back. The first movie I made (Field order B, Bottom Field First)was nearly perfect, except for some minor blurring of the output (maybe lowering the DNR is in order?). The second movie (Field order A, Top Field First) was extremely jittery when any sort of rapid motion occured, and the third was jittery too, but not to the extreme of the second.

My verdict overall- your settings are great, though I probably need to tweak a bit for each segment of video I plan to put on disc. Second, at least for Sony NTSC miniDV camcorders, the footage is interlaced, with the bottom field first (unless it's something with the codec itself..).

Thanks again!

[Snake-Eyes]

BTW, I didn't change any settings concerning interlacing / field order in any program besides TMpegEnc for those tests. As far as I can tell, the video being passed through SDV7 and VirtualDub was still in whatever format it was in on tape.. (and based on the results above, that would mean bottom field first)

[Flying dutchman]

I can confirm it now - tMpeg treats field order "A" as "B" and vice versa on PAL systems.

I captured a clip from DV using AVI_IO and loaded it into VirtualDub. Resized it to 480x576 bilinear without changing anything else. I then started the frame server and Presto!
tMpeg analyzed the clip and said it was field order "B".

I did the same thing using Videostudio 5. Kept all settings to field order "A" in VS5. Exported it to 480x576 HuffYuv and loaded it into tMpeg. Turned out to be field order B again!

BTW, VS5's audio conversion from 48 to 44 KHz sucks incredibly. Haven't tried that in VirtualDub yet.

[colinbr]

> I captured a clip from DV ... and Presto! tMpeg analyzed the clip
> and said it was field order "B".

Sounds right for DV.

> I did the same thing using Videostudio 5. Kept all settings to
> field order "A" in VS5. Exported it to 480x576 HuffYuv and
> loaded it into tMpeg. Turned out to be field order B again!

That sounds correct too.

The "problem" seems to be that Ulead defines "Field order A" as LOWER field first, while others including TMPGEnc seem to define (or assume) that Field Order A is UPPER field first. Confusion reigns.

I wish everyone would standardise on an unequivocal term. You can't go far wrong with "upper" and "lower" field first.

Have you been able to do this same test with NTSC DV source? I would have expected the same results with NTSC.

> concerning NTSC DV to SVCD and field order questions. ... The
> first movie I made (Field order B, Bottom Field First)was nearly
> perfect ... The second movie (Field order A, Top Field First) was
> extremely jittery when any sort of rapid motion occured. ...
> For Sony NTSC miniDV camcorders, the footage is interlaced,
> with the bottom field first.

That's correct for DV.

[Flying dutchman]

I disagree: tmpeg calls it "Field order B (Bottom field first)" when the clip is really top field first.

[colinbr]

> I disagree: tmpeg calls it "Field order B (Bottom field first)"
> when the clip is really top field first.

That's very strange.

I've just re-checked some captured PAL footage from my G450eTV.

I put the avi file through the following AVISYNTH filter which splits the fields from their frames and outputs them upper field first

DirectShowSource("K:\test.avi")
AssumeFrameBased
ComplementParity
SeparateFields

and served this into Virtual Dub. Examining this field by field showed that motion was smooth which confirms that my avi file is upper field first. I double-checked this by loading the file directly into Virtual Dub, zooming in and examining the differences between the alternate lines.

So, confident that this avi file was upper-field-first, I started up TMPGEnc (version 2.54), selected the PAL SVCD template and then Browse-d to the avi file. It examined it and reported:

Top Field First (Field A)
4:3 625 line (PAL, 704x576)

So it correctly reports that the file is upper-field first.

I then attempted to fake an NTSC avi file by cropping (not resizing) the avi file down to 480 lines and changing the frame-rate to 30. I fed this into TMPGEnc and it reported:

Top Field First (Field A)
4:3 525 line (NTSC, 704x480)

So here it correctly reports upper-field-first for both PAL and NTSC files.

I can't understand why you are getting opposite results. How are you checking the field order?

[Flying dutchman]

I have no experience with the Marvel G450 Etv, so I can't verify that it uses the same field order as the G200/G400. But I can definitely assure you that the G200 only supports lower-field first.
No doubt possible, I'm afraid:

I happen to own some tapes on VHS (cinema movies in PAL format) with frame counters on them. These tapes were made from progressive material originally, with each frame numbered sequentially for press preview purposes. If I capture them on my Marvel, they don't come out progressive right away. The upper field displays a frame counter like 01:25:00:01 and the lower field lags behind one digit like 01:25:00:00. Thus the lower field is part of the previous frame.

If I feed this into tMpeg 2.56 it tells me it's field order A and the result looks fine. If I set it to B it looks terrible.
If I apply a PAL deinterlace in VirtuaDub first, the field order doesn't matter, it always comes out OK.