from 1920x1080i/50 to 1280x540(4)p/25?

[quandore]

Hi everybody, i am new in this forum

This is probably a simple question for most of you, but i'm struggling a bit to find an answer myself.
Is it technically possible to switch a video resolution from a 1920x1080 interlaced source to a 540 (better 544) progressive source keeping the horizontal resolution to 1280?
In doing so I could achieve giving my videos a Blu-ray look-alike format (544p) taking advantage from the 1080i/50 resolution that should (theoretically) give me 25 progressive frames with 540 of vertical resolution.
If this is possible, what software would you use?

Sorry if you find this to be a stupid guess, I'm just a beginner.

PS
Hope this is the right section.

[Alex_ander]

You evidently mean the simple way of conversion by removing each other field. It is easy to do with a couple of lines in AviSynth script. Unfortunately, it will not work well in case the video is as sharp as the HD standards provide it. In theory, an image with upper spatial frequency F must be sampled with more than 2F sample frequency (counts per length unit). Those samples are represented in vertical dimension by the standard number of TV lines. By throwing away half of them you violate the theoretical limits and get specific artifacts. Correct ways of resizing are based on deinterlacing methods using both fields and they vary in speed and quality. However in case you deal with an upscaled video or with one slightly out of focus, it's OK to remove even or odd fields.

[edDV]

Hi everybody, i am new in this forum

This is probably a simple question for most of you, but i'm struggling a bit to find an answer myself.
Is it technically possible to switch a video resolution from a 1920x1080 interlaced source to a 540 (better 544) progressive source keeping the horizontal resolution to 1280?
In doing so I could achieve giving my videos a Blu-ray look-alike format (544p) taking advantage from the 1080i/50 resolution that should (theoretically) give me 25 progressive frames with 540 of vertical resolution.
If this is possible, what software would you use?

Sorry if you find this to be a stupid guess, I'm just a beginner.

PS
Hope this is the right section.

Why are you doing this? To shrink files? 1920x1080i/25 (50 fields per sec) is Blu-Ray compatible in full quality.

A quality conversion to 720p or 540p/544p would be at 50 frames per second to preserve motion sampling. 25p would lose half the motion samples.

In the PAL world, this wouldn't be an issue for film source programming which is 24p sped up to 25 fps, then both fields are sampled from the same 25p frame. In that case, you can de-weave 1080i/25 to 1080p/25 then resize to what you want.

[poisondeathray]

I think what he might be asking to make the 1080i50 source appear as if it were like a "blu-ray" rip, inluding changing the aspect ratio wider from 16:9 to ~2.35:1 , and the "choppy" 25p-almost-24p look . But the 1080i50 source has to be shot in a manner that had this in mind, otherwise fast pans, poorly stabilized handheld footage will look really bad....it won't look anywhere near a professionally shot blu-ray

If this is what you wanted, it is possible, you would single rate deinterlace to 1080p25 => resize to 1280x720p25 => crop top & bottom (you will lose active image area) to 1280x544p25 . You could use avisynth for the manipulations and x264 to encode. A gui like avidemux or ripbot264 should make it easier to do, but the avs script is quite easy (a few lines) for this manipulation

[quandore]

Thank you guys for your replies.

I'm from Italy, the "PAL world", so I guess I can deinterlace to 1080p/25 as edDV suggested? I think I did it before with AME after editing a video with Premiere Pro, and the result wasn't that good mainly due to the fact that my dad messed up with the camera. Then i got this jerky effect, which was very annoying. I'm guessing I can do a better job with my camera, trying to avoid fast pans and stuff but, from what you guys said, I begin to suspect that deinterlacing a 50ì source to 25p always creates problems with the motion samples or w/e. Is that what you're saying?
Anyway poisondeathray is right, i wanted to switch the aspect ratio from 16:9 to 2.35:1. Why, do I like black borders? No sir. It's mainly because I thought (in my deep noobness) that, by switching from 1080 to 540, those 50 interlaced fields would give me 25 "fresh and pure" frames without any artifacts and stuff.
I probably need to study a little more about the interlacing method.

So trying to summarize a little bit, what you suggest me to do in AME? what settings? Should I just deinterlace to 1080p/25 MP4 (or 720p/25)? Or maybe I should export my video as interlaced sources and let other SW's (avisynth, yamb) do the dirty job? I heard AME isn't that good for deinterlacing.
What is the best deinterlacing method (better: what would you do to deinterlace) with my Sony Sr12 1080i/50 sources?

Thank you again

[jagabo]

I would deinterlace and resize with AviSynth. Then encode with whatever software is appropriate for the output file type, VirtualDub, x264, MeGUI, etc.

There are many deinterlacing algorithms ranging poor to very good, never perfect. At the poor end you have deinterlacers that simply discard one field (leaving jagged edges), blending (blurring) the two fields together (leaving blurry, double exposure-like frames). In the middle you have algorithms that look at motion in the frame and retain both fields when/where there is no motion, then deinterlace the areas with motion (with one of the above methods). Then you have the smartest deinterlacers which will analyze motion between the two (possibly more) fields and use the second field to fill in (for example, in a horizontal panning shot the second field could be shifted sideways to fill in the missing lines of the first field). The deinterlacers in most commercial packages are at the poor end of the spectrum.

AviSynth poor:
Bob().SelectEven() #throw away one field
Blur(0,1.0) #blend/blur two fields together

AviSynth middle:
TDeint()
Yadif()
Nnedi2()
Eedi2()

AviSynth best (but very slow):
MCBob().SelectEven()
TempGaussMC().SelectEven()

[quandore]

Alright, I know Avisynth is a powerful tool for almost everything video-related. Unfortunately I have no idea how to make it work using those scripts you posted above. Any suggestion would be appreciated.
Would Adobe Media Encoder do a decent job in deinterlacing videos to 1280x720p/50?

[poisondeathray]

Would Adobe Media Encoder do a decent job in deinterlacing videos to 1280x720p/50?

not really , and it's resize is soft as well, and it's avc encoder is average .

I've posted comparisons before if you search, it's quite rediculous for such an expensive product

It's ironic, but freeware deinterlacing & resizing (through avisynth ) and encoding (with x264) beat it soundly . But Premiere excels at the actual editing task, and no freeware package can compete with it in that regard

If you want better than mediocre quality I would start learning the avisynth basics ; it's not that hard for simple scripts

http://avisynth.org/mediawiki/Main_Page
http://avisynth.org/mediawiki/First_script
http://avisynth.org/mediawiki/Getting_started

[edDV]

I'm from Italy, the "PAL world", so I guess I can deinterlace to 1080p/25 as edDV suggested? I think I did it before with AME after editing a video with Premiere Pro, and the result wasn't that good mainly due to the fact that my dad messed up with the camera. Then i got this jerky effect, which was very annoying. I'm guessing I can do a better job with my camera, trying to avoid fast pans and stuff but, from what you guys said, I begin to suspect that deinterlacing a 50ì source to 25p always creates problems with the motion samples or w/e. Is that what you're saying?

OK so your source is a consumer camcorder. Which model and settings? Should I assume 1080i/25 (aka 50i) AVCHD? [edit I see you later said Sony Sr12]

Why do you want to deinterlace to 25p? If you just plug the camcorder into a good 1080p HDTV, it will deinterlace 50i to 50p and should show minimal jerkiness. Camera technique will solve the remaining motion issues.

If 25p is the goal, you will need to use a tripod or other camera stabilization, plus minimal zooms and pans. If you want a 24p TV series look, you need to shoot like they do.

Anyway poisondeathray is right, i wanted to switch the aspect ratio from 16:9 to 2.35:1. Why, do I like black borders? No sir. It's mainly because I thought (in my deep noobness) that, by switching from 1080 to 540, those 50 interlaced fields would give me 25 "fresh and pure" frames without any artifacts and stuff.
I probably need to study a little more about the interlacing method.

Better to solve this with camera technique. Simply deleting a field will cause jerkiness. A proper deinterlace can be done without affecting aspect ratio. No need to go to 2.35 to 1 (letterbox) unless that is your goal. Follow other's advice above for deinterlace.

I'd keep it interlace, edit interlace and let the HDTV do the deinterlace.

[quandore]

@poisondeathray: thank you for the links, i'll have a look.

@edDV: you are right. whenever i connect my camera to my HDTV via HDMI the quality is excellent and it also plays extremely smoothly. thing is, sometimes because of my work, i need to send video previews and stuff so I have to make sure that the receiver will be able to play it.
sometimes i'm dealing with people who don't really like technology. if they play an interlaced mp4 with Windows Media Player the result will be very bad. I could shoot my video in 576p since my camera supports that, but i'd like to keep it HD, possibly 720p.

Anyway you guys are helping me out a lot and i appreciate. my last question would be: what format with AME? i will have to export with that, no choice for me, unless i change SW, but i'd rather not...
Maybe "Uncompressed AVI" i suspect that it may require a terabyte or something

[jagabo]

Uncomrpessed AVI will be enormous -- about 40 MB/second for 1280x720 YV12 at 30p.