Encoding interlaced video as progessive = better video?

[racer-x]

Just when I thought I knew almost everything there is to know about Interlaced and Progressive encoding, I come across something that doesn’t make cense. I have a Panasonic DV-953 Camcorder. It shoots great video. I know that all mini-dv is Interlaced. When it is transferred to the PC in DV-AVI, it is Interlaced. The thing is, that this camera shoots such great resolution, that there is virtually no interlaced artifacts. Only in high motion objects, even then there is very little.

I decided to try a test. The test was a video of my son’s Pinewood Derby Race. The video was edited in Premiere 6.5 with lots of special effects. The Timeline was Frameserved to MainConcept Encoder v1.4. I encoded 2 versions of the same Timeline and at the same settings except one was Interlaced and one was Progressive. * Note that the video was not De-Interlaced in any way, it was encoded straight from source! I then Authored both versions on a DVD+RW to test them on TV.

The results were interesting. On my standard 27” TV, the Progressive encoded video looked better in every way. On my PC, the Progressive encoded video looked better in every way. Then I decided to go down to the local Best Buy and try it on one of their Widescreen HDD TVs. The results were the same, the Progressive encoded video looked best.

I always thought that if a video is Interlaced, then it has to be encoded as Interlaced. Now I’m not so sure anymore, at least not with this camera. I wouldn't dare try this with my old camera. If anyone can explain this, I’d like to know why my Interlaced video looks better when I encode as Progessive.

[SLK001]

I'm not sure if Premiere is not affecting your results.

Interlaced video is field based, so you need to encode as field based (or ALTERNATE SCAN). Progressive video is frame based, so you use ZIG ZAG SCAN when you encode.

I've seen true 29.97 interlaced video that you had to struggle to see the interlacing lines. So much so, that I originally thought that it was true progressive. You may have lucked out and had a video that was enough like a progressive video to not suffer too much from a progressive encode.

Try the same test with just the raw video.

[racer-x]

Even in the sections of the video that had no special effects looked better. The progressive version had better and sharper detail than the interlaced version. When you hit the pause button, the difference is much more.

Here are some screen capture of the finnished Mpegs. The captures were done in Vdub, so no bob filters were used.

Interlaced Version


Progressive Version


You can see the difference in the flaming text.

[SLK001]

Your text is PROGRESSIVE overlayed on INTERLACED video. This is what your problem is. The rest of the pictures look virtually the same (to my eyes).

Can the text be converted to INTERLACED? Don't use P6.5, so I don't know about this. If not, just encode as progressive. The only places where you might have problems is at scene changes.

[racer-x]

Actually the text is animated 3-D that I created in Ulead Cool 3D then saved as AVI video(not sure if it is progressive) uncompressed RGB. I then overlayed it over the video and matte, then set transparency. If you see that scene on a TV and pause it, you will see well defined jagged edges in the oval cutout of the black matte on the Iterlaced video. The progressive video looks perfect when paused an the TV.

It's just funny that a interlaced source looks better when encoded in progressive format.

[SaSi]

The PC generated video is bound to be progressive. The issue you bring up is really interesting. Take interlaced camcorder footage, overlay it with progressive material and you got a problem.

Now that you brought the issue up, aren't the subpictures of a DVD progressive frames? They are overlayed over the video in real time. Could it be that some of the subpictures that I notice to flicker a bit, are because of the same reason?

Just a thought.

[Bstansbury]

Try a simpe test in your DVD player. Run your DVD to a action scene and view it. Then stop it and take it back and put it in slow motion, and zoom it to 2x or 4x and look at it again. Now do that to both the interlace DVD and the Progressive DVD.

I'm not sure, since I'm not an expert on MPEG or DVD, but I thought that DVD MPEG is Frame based and is recorded that way. When the DVD player reads the data, it converts it to interlace just before the output of the card,... just after the MPEG decoder, there is an NTSC conversion chip. At least this was the design on the last MPEG decode card I designed. Of course that was 8 years ago and a lot has happened since I retired.

I remember how funny is was back then to get 10 experts in a conference room to work on Digital quality TV, HDTV, broadcast TV, MPEG technologist, computer geeks, etc. They could argue for hours and never agree on anything. Things havn't change much. Just when you think you have it figured out, you learn something new.

[proxyx99]

Are your results (better progressive mode) the same without text (raw AVI video straight from cam without any modification)?

[racer-x]

I would say yes. The video is a little sharper, but not much. The real difference is when you hit the pause button. The progressive version displays a much better picture.

I came across this idea when I started encoding my slideshows as progressive. My slideshows looked much better progressive than Interlaced, but then the images were progressive source.

Then when I started editing this video, I extracted many frames so that I could use them to make my effects. I noticed there was virtually no interlace artifacts in the video frames. So I thought to myself, maybe there's enough image information to make the video progressive even though it is really interlaced. So, I decided to encode the two versions and compare them back to back. I really didn't expect it to work, but when I saw the results, I was quite impressed.

I wouldn't recomend anybody else try this, unless the have a very good camcorder that shoots clean video with no or very little interlace lines.

[proxyx99]

I wonder how proper deinterlacing and encoding as progressive would compare. I may be tempted to try it during the weekend. I recall my friend did what you did once from VX2000 footage that I was later transferring to PAL for him. Very good picture indeed by I did not pay attention to postpro as I assumed cam was responsible for that. Interesting that you brought this up. It is quite unorthodox but hey... may deliver something interesting.

[racer-x]

My camera can shoot in frame mode. If I use frame mode, the fields are blended together and there or no interlaced lines whatsoever. The frame captures look like they've been run through a de-interlaced filter. I've encoded some videos that I shot in frame mode as progressive. But I think they lost a little bit of resolution in that mode. Also the movement didn't look quite natural.

This last video was in Normal Mode with Progessive turned on. The camera has lots of settings and I'm trying something new with it every time I use it. The manual is next to useless, so I keep experimenting.

[duhmez]

Here is an issue. Encoding progressive makes the top field first everytime. Your DV is probably bottom field first. If you are going to do thi, i atleast suggest to swap the field order, then your results will be perfect. you can use zigzag or not, it's your preference, your eyes etc, either wy will get you a video. I highly recommend if your source really is bottom field first, then make sure to swap the fields. Then encode interlaced or not will have proper playback.

[racer-x]

duhmez,

I'm sure you have a point, but I'm not sure what your point is. Just to clearify, my video plays perfect as is. In either Interlaced version or Progressive version. In low motion scenes, high motion scenes, even in camera pans. There is no jumpy video that is acociated with incorect field order.

Yes my source is Lower field first, just like all DV. To do what you sugest, I would have to encode to another avi in upper field first, then encode that one to mpeg. I doubt it would improve my video, but maybe if I have some time I'll experiment.

I read somewhere that a guy rendered two versions of the same video. One version to the standard lower field first, and one vesion in upper field first. He then imported one on top of the other in the Timeline, synced them, then output to progressive mpeg. It made a perfect progessive video because the fields would overlap each other.

[BJ_M]

the over and under frame interlacing combo is one part of how to get a film look from video -- its covered in depth on creative cow and sundance media web sites

[duhmez]

If you are using cce and have pper field first checked, then it's reversing the field order for you. this may be what is hapening perhaps?