Field order

[pedro26]

With my Sony mini DV transferred via firewire, I have project settings set same as the first clip inserted into the time line. I always make sure that I capture as DV1, not sure what I used to do about the audio, but my re-reading of old forum posts suggests that I capture as Dolby. AC3. Anyway I use that preferences project setting re insert clip match project settings to those of the first clip as a way to check on the clip's attributes.

When I inserted the mini DVD clips into the time line (as a first clip of the project) they said it was upper field first, I have stuck with this as a the project settings. Eventually these will be viewed on UK PAL tvs.

Will the interlacing of the clips comprising the DVD cause interlacing viewing issues on TV play back?

These video clips were not recorded on HD camcorders, i.e. they are SD.

Should I re-render the total project (i.e. based on the original input files) but set the project properties as lower field ?

BTW My Reading of Lata's tips is that he captures with an eye to matching that initial capture, so that the input footage wil fit on one DVD disc, so he sets accordingly at the capture stage.

Is this a case of there is more than one way of skinning a cat ? Or is there a best way ?

Clear as mud.

I also note that mini DV ccapture is actually more akin to file transfer, but for my current job 95% of the input is miniDVD which is some form of mpg.

I've seen advice on video and audio bit rates and if following the recommended work flow this should be set as a project property, prior to the share create video file route (which is the recommended work flow).

Yes clear as mud

[Ken Berry]

DV/AVI is ALWAYS lower field first. By default, however, recent versions of VS use Upper Field First in Project Properties. So if you are rendering DV to DVD-compatible mpeg-2, it MUST be changed to Lower Field First, or else you will have problems in playback on your TV, including jagged edges on vertical lines and flickering particularly in fast moving or panning shots.

Your main problem, though, will be with the video from your mini DVD camera as this uses Upper Field First. In another related thread, lata told you that if 95% of your project is from the mini DVD and only 5% DV, then you would need to use Upper Field First, and just accept the consequences for the DV sections.

[pedro26]

Thanks Ken,

Can I take that the mini DVD input files which were recorded upper field first (and my project properties match that) will be ok with respect to eventual DVD/TV playback, and it is just the portion created from the 5% mini DV input file which will suffer the jagged edges ?

(I read somewhere that PAL is lower field first, and that confused me as to what is the optimal way to proceed.)

BTW on their mini DVD camcorder (its either a Sony or a Panasonic) could they have chosen to record lower field first, or is that unchangeable ?

[lata]

Hi
Yes retain Upper Field First.
If you do have problems with jagged edges on the DV-Avi section you could try converting the DV-Avi to use Frame Based, then use them in the project along with the DVD.
But I would check the final output to see if that option is worth the effort, with no guarantee of success, a bit of trial and error.

I assume your next project will contain the one type, mini DVD.

Pal video is just the TV standard as is NTSC and has nothing to do with interlacing.

Lower Field Order is used from all Mini-DV type video, produces DV-Avi files.
All other video (Analogue video – DVD--HD video) uses Upper Field or in some cases for Frame Based-Progressive
Video for the internet will use Frame Based.

The field order is fixed by the camera, or recording device and cannot be changed.
Capturing from an analogue device, Video Studio, older versions may give the option to choose the field order, but would default to Upper Field. But Capturing is converting the video on the fly, you choose the capture settings.

MiniDV and miniDVD transfer the video from the camera without changes no re-coding, Just like copy and paste from a memory card.

[skier-hughes]

I would convert the lower field first to upper field first and use that rather than converting to frame based.
You can run it through VS and produce an mpeg2 UFF and then edit with all of the other mpeg files, or put it in the timeline as it is LFF, edit it and convert it at the end of the process.

[pedro26]

Trevor, Skier Hughes,

Thanks for the advice. I have read a few articles and I think I understand (at the moment anyway). Sio I'll put here for when I might need a refresher.

We need 50 fps so that motion appears fluid to the eye.

BUT to record 50 fps was a problem for early equipment and transmisson bandwidth, but if you slice the scene horizontally into lines/narrow bands.

(Here I will start numbering them from 1, then the systems could record those odd lines (say) in 1/50 of a second (lets call this the first field, or upper field), then in the next 1/50 of a second it would record the even lines (this is called the second field, or lower field). These two fields are combined to give one frame for each 1/25 of a second. Lets call this case A.

Now if the subject is moving say Left to Right in fact the two fields comprising the frame are slightly different, because they have an inbuilt time difference.

No matter that is not a problem because at the other end the dispaly equipment de-interlaces each frame, playing field one then field two, etc. Lets call this A UFF

The problem arises when your recording equipment actually captures the even lines in the first 1/50 of each second and the odd lines in the next 1/50 of a second and so on case B LFF, but the de-interlacing instructions remain as for the first case.

Now here is what I was missing from the explanations I have seen. I assume that in fact PAL TV does not read if your signal (videofile, DVD etc.) needs to be de-interlaced for type A UFF, or de-interlacing for type B LFF.

Instead it is fixed and whatever kit you use to make the PAL-DVD file has to create the same field order that PAL DVD plays for each frame, (possibly LFF ?).

So that render to PAL DVD videostudio uses your file properties recording info (that why it must be set correctly/the same as the input file in the project properties) and knows "oh this camera used UFF which was (1,2) (3,4) (5,6) etc, so time-wise it probably discards the first field and changes the field order to, in frame packets (2,3) (4,5) (6,7) the numbers indicate increasing temporal 1/50s of a second.

Here (x,y) represents a 1/25 of a second frame and x and y are the 1/50ths of a second fields in increasing time-wise numerical order.

If the field order get mixed up then you get (2,1) (4,3) (6,5) etc. or the other mix up (3,2) (5,4).

At least that's the picture I have in head about how it works.

Is it correct more or less ?

Trevor/Ken

[skier-hughes]

You have the theory right, but a good programme will reverse the field order and play them in the right order, so you get less problems

[erdna]

You have the theory right, but a good programme will reverse the field order and play them in the right order, so you get less problems

Yes.In fact hardware players (stand alone DVD, mmplayers) interpret the video info header in digital media and should playback in right field order.