Weird SD 4:3 and 16:9 Clip - How to display it properly via Avisynth?

[LMotlow]

It kind of depends if 544x576 is the equivalent of 720x576 or 704x576, and also if you're supposed to use ITU resizing or not. I just don't know.

I can tell you what's correct (it's scaled by exactly 4/3, meaning 528=704, and 544 has lots of padding)

I agree there 100%. In ~8 years of capturing DVB-S with lots of 544x576 I can confirm this. Sometimes I had the chance to capture something both from a 544x576 channel and at some point later at 720x576 from another channel so I could compare how those 544 were scaled, and it's always the same: 540 out of the encoded 544 pixels are supposed to be 75% of 720; likewise 528 are 75% of 704 at the same time. The 4 pixel padding (540 -> 544) is necessary because the frame size needs to be mod 16, that's the sole reason. So assuming 544 = 4:3 is in any case not correct, it should be 528 = 4:3 (ITU) or 540 = 4:3 (non-ITU)...

Makes sense to me. Good notes.

[Cornucopia]

...You can't have a 16:9 DAR in 704x576. DVD and BD spec say 16:9 in standard def is valid only at 720x480 (or 720x576 PAL).

Not true. 704x576 16:9 (and 4:3) is perfectly valid for DVD - just looked it up. For BD, you are right, only 720width is valid for SD material (4:3 or 16:9).

Scott

[LMotlow]

So noted.

[VideoFanatic]

The wiki says Spline64Resize gives a sharper picture than Spline36Resize. Just wondering why you guys don't use that on SD footage?

I've also have 1080i videos I want to downscale to 720p. Should I use Spline36Resize on that as well or Lanczos4Resize or something else? I noticed when on SD footage that Spline36Resize gave a cleaner picture with less artifacts so should I also use that when downscaling 1080 to 720p?

[LMotlow]

The wiki says Spline64Resize gives a sharper picture than Spline36Resize. Just wondering why you guys don't use that on SD footage?

I've also have 1080i videos I want to downscale to 720p. Should I use Spline36Resize on that as well or Lanczos4Resize or something else? I noticed when on SD footage that Spline36Resize gave a cleaner picture with less artifacts so should I also use that when downscaling 1080 to 720p?

I think you answered your own question. Sharper isn't always cleaner (who needs "sharp artifacts"?). You can always try the resizers yourself to check which one suits a particular video better than another, but '36' is the one most often seen in use.

[2Bdecided]

The image inside the frame, after all 4 borders are removed, doesn't look like 16:9.

It's 14:9, as has already been said. It was very common in the UK. SD 16:9 widescreen production started in 1998. Most TV 16:9 content was shot "shoot and protect 14:9" meaning the action was always within the centre 14:9 part and the outside edges of the active picture could always be cropped off without losing anything important. On digital SD broadcasts this content was 16:9 FHA; on analogue SD broadcasts the 4:3 signal included the 16:9 version, cropped to 14:9, with small letter box bars added to make it 4:3, as you see here.

Originally only the most popular channels supported 16:9 FHA digital SD broadcasts. Lots of lesser channels stayed with 4:3 SD on digital (i.e. they didn't have the ability to switch the aspect ratio flag!), and used the 14:9 version when broadcasting 16:9 originated content in a 4:3 frame. Apart from some really low budget channels on satellite, I didn't know anyone was still doing this. Obviously the most popular channels are all 16:9 HD, and as almost no content was actually made with a 14:9 active frame, you (I) never see it anymore. It's all 4:3 SD upscaled, 16:9 SD upscaled, 16:9 HD and letterboxed films.

Cheers,
David.

[VideoFanatic]

I don't think anybody does it anymore. This was a series repeat of Series 15 of Bullseye (revival with Dave Spikey) that's currently showing on Challenge. What's ironic is that it's from 2006 and you get that crap 14:9 picture with borders on the sides and bottom yet earlier series from several years ago had a better picture at 4:3.

Can't believe broadcasters get away with actually shrinking a 4:3 picture so it has borders on the top!

[jagabo]

cropped and resized to 16x9:

[Skiller]

Can't believe broadcasters get away with actually shrinking a 4:3 picture so it has borders on the top!

They are not shrinking a 4:3 picture. As 2Bdecided explained, 14:9 broadcasts are usually derived from a 16:9 production with a 14:9 protection in mind, so that the outer left and right sides of the video (the two areas extending beyond 14:9) can be chopped off without losing anything important. That leaves you with 14:9 which is then put into a 4:3 frame by letterboxing it with small letterbox bars at the top and bottom. The earlier 4:3 full screen episodes were probably native 4:3 productions.


I kinda feel like doing the math now , so here is what I would do, assuming ITU-compliant scaling because the BBC itself demands it in it's specifications (available online).

From: 544x576 "4:3" with 14:9 Letterbox
To: 704x576 anamorphic 16:9 with Pillarbox

ITU-PAR of 544x576 is: (12/11) / 0,75 = 16/11

Cropping 84 lines in total, we're left with 492 lines.

New height is 576 of course.

New width is: 576 * (544 * (16/11) / 492) / (16/11) = 636.88

Spline36Resize(636,576, 0,43,0,-41)
AddBorders(34,0,34,0)

Edit: Of course you need bob-deinterlacing before and re-interlacing after scaling. This is just the scaling.


Apart from all of that, do they really transmit AC3 audio at 128 Kbit/s or is this a re-encode by the OP? The video bitrate is extremely low also, even by DVB standards, only 1611 KBit/s average (yes, it's a low-motion sample, but still)?!

[VideoFanatic]

You can give whatever technical explanation you want but the fact is when viewing on your TV you have big borders on the top and bottom of the picture which is "shrinking the picture"! I find it unacceptable that channels broadcast that crap.

Yes that's the video bitrate used in the broadcast. Obviously because the picture is smaller than usual they have used a lower bitrate than normal.

People are just giving different versions of fixes now which I appreciate but it's not needed as the issue was fixed several posts ago.

[_Al_]

Footage from 2006? I'd say it was a winner, considering it could be a full letterbox. It's all part of transforming era going from 4:3 to 16:9. In 2006, what was the percentage of people still using CRT? I'd say quite high , perhaps even more than half of TV's in living rooms.

[Skiller]

You can give whatever technical explanation you want but the fact is when viewing on your TV you have big borders on the top and bottom of the picture which is "shrinking the picture"! I find it unacceptable that channels broadcast that crap.

Well, on a widescreen TV you are supposed to use it's 14:9 zoom feature. That would give you exactly the same picture you get with the scripts we provided – small Pillarboxing on the left and right and no Letterboxing at all on the top and bottom. So no shrinkage. I haven't seen a single widescreen TV that doesn't have a 14:9 zoom option.

Yes that's the video bitrate used in the broadcast.

OK. But that's still very low, even for 544 with 14:9 Letterboxing. I'm curious about the AC3 audio. Do they really not transmit any MP2 audio? The DVB spec requires MP2, AC3 is optional.

[VideoFanatic]

I re-encoded the audio from MP2 to AC3 as Bluray doesn't support MP2. Video is exactly as transmitted. FTP'd it directly from my satellite receiver.

Tried using the aspect ratio button on my remote to get the 14:9 Zoom option, you're correct it works. Didn't occur to me to look for that option.