Questions about interlacing/deinterlacing - TMPGenc users

[yukon33]

I'm taking a crash course in TMPGenc Xpress 4.0 and DVD Lab Pro 2. After several years of happy DVD-conversion within Avid Liquid, an apparently unavoidable problem with Liquid's conversion process (burst of white macro-blocks during photographer flashes, present at the max recommended bitrate of 8000CBR) has forced me to seek out an external DVD encoder. TMPGenc seems to have solved the visual glitches I was getting from Liquid's DVD conversion process.


My questions relate to interlacing/deinterlacing. As far as I understand it:-


1] Camera (Canon XH-A1s) records in 50i - interlaced
2] Liquid edits received footage - still interlaced
3] Liquid exports to DVD - deinterlacing in the process


However I am a little unclear about things, as I thought TVs were predominantly 'interlaced' displays? Computer monitors I understand are 'progressive'. Could someone clarify: the deinterlacing process becomes necessary (by removing odd or even fields) to play interlaced footage smoothly on an interlaced display (i.e. TV)?


Secondly, this is my new workflow:-


Edit PAL SD 50i material in Liquid > export AVI > import AVI into TMPGenc > convert to MPEG > import MPEG into DVD Lab Pro 2 > burn VIDEO_TS with ImgBurn


Loading my AVI into TMPGenc, there are several options regarding interlacing/deinterlacing. The first is 'Clip Settings'/'Display Mode'. This defaults at 'interlace' - I believe this refers to the AVI file being made from, and currently remaining, interlaced material. Correct to leave this on 'interlace' I assume. 'Field Order' defaults at 'Bottom Field First'. However when I look at the settings in Liquid's Burn to Disc, Liquid defaults at 'Top Field First'. Because I'd made generally successful DVDs from Liquid without altering any interlace/deinerlace settings, I changed TMPGenc here to 'Top Field First'. This resulted in 'ghosting' on the DVD. Changing TMPGenc back to 'Bottom Field First' seemed to fix this - even though it is opposite to my tried and trusted burns with Liquid.


Why does Liquid state TFF and TMPGenc BFF, giving apparently the same results on DVD, or glitching if these apparently opposite settings are interchanged?


Next options in TMPGenc are 'Display Mode' - defaulting again at 'Interlaced'. What is the difference between this setting under 'Display Mode' and 'Clip Settings'? Apparently I can set one to interlaced and the other to progressive, and vice-versa. I've kept 'Display Mode' on interlaced.


Now the point of all this is when I watch my TMPGenc-converted DVD on my CRT television, everything appears fine. However when I view the MPEG files from TMPGenc on various media players on my computer before burning, I can see small horizontal 'jags' which must be do to with the MPEG deinterlacing process. The monitor is progressive, so it is correct to see these picture jags on deinterlaced material?


What concerns me is that while I seem to have made a nice jag-free DVD using the TMPGenc workflow, I am only able to view this my CRT television. But aren't some of the newer LCD/Plasma screens everyone now has 'progressive' displays (i.e. like computer monitors)? Will the jags return on these screens? Or is there a 'detection' process for non-progressive material?


Sorry I'm not well versed in the de/interlacing minefield - appreciate some insight and clarification on the above !

[manono]

You don't need to deinterlace for any kind of display. Progressive HDTVs will deinterlace it. Software players for computer monitors can deinterlace it. CRT TV sets play fields.

If you're exporting any kind of AVI out of Liquid other than lossless, your workflow is no good.

I don't and won't use TMPGEnc, so someone else can answer the questions specific to it.

[yukon33]

If I don't deinterlace (i.e. select Progressive) then there are playback issues on my CRT display (ghosting) - therefore it seems deinterlacing is necessary. Some of my clients may still have CRT TVs.

TMPGenc converts my AVI (created from an uncompressed 2VUY timeline in Liquid) to MPEG. Liquid does the same, but converts from its uncompressed 2VUY codec to a somewhat glitchy MPEG. I cannot import the uncompressed file into TMPGenc as it is a Liquid-only recognised format. The quality difference between the fused AVI and uncompressed 2VUY is minimal and barely noticable, so I'm not sure why you are saying this workflow is 'no good'?

[manono]

I said if it was something other than lossless then it's no good. Uncompressed is lossless, although with an unnecessarily large filesize. I have no idea what a 'fused AVI' is.

If I don't deinterlace (i.e. select Progressive) then there are playback issues on my CRT display (ghosting) - therefore it seems deinterlacing is necessary.

Then you're doing something wrong somewhere along the line. You aren't resizing anywhere by chance, are you? Have you never seen interlaced video on a DVD? At what resolution are the videos this Canon camera creates?

[yukon33]

I understand uncompressed = lossless. However the only format of 'uncompressed/lossless' I can seem to export from Liquid is with the .2VUY suffix that seems to be Liquid-recognised only. At the moment the best TMPGenc-recognisable format I can make is an .AVI from my uncompressed 2VUY timeline, but this is a fraction of the size of the uncompressed file. By 'fused .AVI' I mean the fusing together Liquid does of the clips on the timeline - this can be achieved as uncompressed 2VUY (but Liquid only) or I guess lossy .AVI.

Using TMGPenc has solved the artifacts problems I had during Liquid's own DVD conversion tool. If the sacrifice at the moment is converting to MPEG from a compressed .AVI instead of an uncompressed 2VUY then I can live with that for now (until figuring out how to import true lossless from Liquid into TMPGenc).

I have done no resizing. The Canon footage is and remains 720 x 576 PAL SD.

I made a mistake in how I reported the ghosting effect I was seeing on my CRT TV - it was actually changing the field order in TMPGenc (from default BFF to TFF) that caused it. However I have run further tests today all on the exact same clips and this is what I have found:-

From .AVI exported out of Liquid - clip features some left to right movement and panning

TMPGenc: [Clip Settings] Display Mode = Interlace (BFF) / Aspect Ratio = Display 16:9
[File Output/Format] Display Mode = Interlace

Results on CRT: Good, no apparent ghosting

TMPGenc: [Clip Settings] Display Mode = Interlace (BFF) / Aspect Ratio = Display 16:9
[File Output/Format] Display Mode = Progressive

Results on CRT: Reasonable, but a little ghosting

TMPGenc: [Clip Settings] Display Mode = Progressive / Aspect Ratio = Display 16:9
[File Output/Format] Display Mode = Progressive

Results on CRT: Best results, no ghosting apparent at all

TMPGenc: [Clip Settings] Display Mode = Progressive / Aspect Ratio = Display 16:9
[File Output/Format] Display Mode = Interlace

Results on CRT: Poor, heavy ghosting


So it seems that keeping settings the same between Clip Settings and Display Mode - either both interlaced or both progressive - yields best results. I'll follow your advice that I should not deinterlace then, since it seems I will lose a degree of quality (?) and that both CRT and HDTVs will process the interlacing themselves and display correctly.

It isn't clear to me at the moment but I am assuming that Clip Settings in TMPGenc refers to the nature of the clip imported into TMPGenc, and Display Mode refers to the destination screen?

Yet with my interlaced .AVI from Liquid, Clip Settings at 'interlaced' and Display Mode at 'progressive' does not yield the best results (some ghosting) on my CRT. How would this be, if Clip Settings are apparently appropriate to the clip?

I have a suspicion I could be confusing 'interlacing' with 'deinterlacing' perhaps - is the 'interlace/progressive' option in Clip Settings asking for the nature of the imported clip, or asking what I want to do with it?

Thanks for any further help.

[manono]

Sorry, but I don't use TMPGEnc so someone else will have to help. In addition I find the terms it uses to be non-intuitive and confusing. I can only judge your output to see if it was done correctly. I can't tell you what settings to use (although on the face of it, any setting using the word 'Progressive' on an interlaced source can't be good. While it might look good on an interlaced CRT set, on an HDTV it might be ruined).The main drawback to deinterlacing an interlaced source is loss of fluidity of movement because what was effectively 60 frames per second (2 fields per frame times 30 frames per second) becomes 30 frames per second. In addition, the quality of the deinterlacing may not be so good (and since you mentioned dropping fields earlier, I know what you were doing wasn't so good).

[nic2k4]

Maybe it's just time to replace Liquid, it's been out of prduction since 2007. A little package like Premiere Element, Vegas Movie Studio or Magix Movie Edit Pro could surely do the same things it does and more.

[yukon33]

Thanks for the recommendation, but most NLEs seem to have their own quirks and Liquid 7.2 is a still powerful and pretty stable system for HD editing. Liquid's CBR encoder is generally very good, it's just unfortunate that some artifacts have appeared in the last of my SD edits. I need the project out quick but clean so have looked to another MPEG encoder for a solution. From tests it looks like my new HD work is not affected by the artifacts in Liquid.

Back to the topic, I have experimented with the interlacing/progressive settings in TMPGenc on 2 TVs and a summary follows:-

Have obtained Phillips HDTV for tests (a fairly old cheap one I think - model no. 26pfL5522D/05)

From interlaced .AVI exported out of Liquid - clip features some left to right movement and panning, ideal for 'movement' quality testing

TMPGenc: [Clip Settings] Display Mode = Interlace (BFF) / Aspect Ratio = Display 16:9
[File Output/Format] Display Mode = Interlace

Results on CRT: Good, no apparent ghosting
Results on HDTV: Decent but some jags - checking DVD frame by frame jags not visible

TMPGenc: [Clip Settings] Display Mode = Interlace (BFF) / Aspect Ratio = Display 16:9
[File Output/Format] Display Mode = Progressive

Results on CRT: Reasonable, but a little ghosting
Results on HDTV: A little ghosting, but no jags at all

TMPGenc: [Clip Settings] Display Mode = Progressive / Aspect Ratio = Display 16:9
[File Output/Format] Display Mode = Progressive

Results on CRT: Best results, no ghosting apparent at all
Results on HDTV: Decent but some jags - checking DVD frame by frame jags also visible

TMPGenc: [Clip Settings] Display Mode = Progressive / Aspect Ratio = Display 16:9
[File Output/Format] Display Mode = Interlace

Results on CRT: Poor, heavy ghosting
Results on HDTV: Bad with ghosting and jags - checking DVD frame by frame jags not visible


My goal is to produce the best quality on HDTV, being that is what most of my clients will be viewing on. From my test burns viewed on HDTV I can see jags (i.e. 'combing' I think) on every TMPGenc configuration (note that sometimes only in normal speed playback and not when using DVD remote to go 'frame by frame'!) except for Clip Settings at Interlace and Display Mode at Progressive. Unfortunately my eyes can still see a little 'ghosting' around the movement, but it is possible that this is over-scrutiny and a quirk of the television set. Adjusting from CRT to HDTV viewing can be quite a jolt as many will have experienced.

'I can't tell you what settings to use (although on the face of it, any setting using the word 'Progressive' on an interlaced source can't be good. While it might look good on an interlaced CRT set, on an HDTV it might be ruined).The main drawback to deinterlacing an interlaced source is loss of fluidity of movement because what was effectively 60 frames per second (2 fields per frame times 30 frames per second) becomes 30 frames per second. In addition, the quality of the deinterlacing may not be so good (and since you mentioned dropping fields earlier, I know what you were doing wasn't so good)'

I guess I need a TMPGenc expert to tell me if I am deinterlacing my footage at all with any of the above settings. I agree the terms used may be confusing.

Thanks for any further insight from anyone.

[davexnet]

If the source in interlaced, the clip properties and the encode type should both be interlaced.
I don't think any of the options actually de-interlace the mpeg. You could probably verify this by looking at
the frames in Virtualdub and using view fields, or similar. In Virtualdub, if you see a frame on the left with the interlaced
combing pattern, then on the right side, the two separate fields (generally) looking clean, the file is not deinterlaced.

See this post. There's a discussion about what happens with the difference permutation.
https://www.videohelp.com/forum/archive/converting-videos-to-ntsc-mpeg-2-using-tmpgenc-...s-t372848.html
They're talking about NTSC, but some of it still applies.

[lordsmurf]

Did you try to rename the .2vuy to .avi file name? It might be that easy.

Generally, renaming video extensions is a bad idea. But this one is okay.