a technical pixel aspect question

[Michael Duff]

Hi again…

“It is 720 wide if it the 16:9 is broadcast as 4:3, center-cut. BUT when the 16:9 is broadcast as pure 16:9, then you will get the full glory of 1024 pixels wide.”

– I just got off the phone to an engineer at one of our national broadcasters (SBS) … and he confirmed that EVERYTHING that is broadcast SD PAL is 720. Whether it is 16×9, 4:3, everything .. there is no such thing as a 1024 transmission. Everything that a broadcaster receives gets ingested as a type of MPEG-2 at 720×576 … it is only the PAR that determines the final aspect ratio.

“The fact that they do in fact broadcast at pure 16:9 should preclude you from wanting to provide anything at 720, unless it’s anamorphic. But from your initial post, they have requested for 1024×576.”
-From the point above I’d now only ever want to provide everything (16:9 or 4:3) at 720 anamorphic as that is how it is going to be ingested.

He also suggested that working at 1024 would result in an incorrect image on your broadcast monitor, because the 1024 is getting down sampled to 720 through your output card(ie for us Blackmagic cards). And that if you send a 1024×576 image to a broadcaster it will lose an every so slight amount of quality in the down sample when it is ingested.

[Roland R. kahlenberg]

[duffbeer911] “- I just got off the phone to an engineer at one of our national broadcasters (SBS) … and he confirmed that EVERYTHING that is broadcast SD PAL is 720. Whether it is 16×9, 4:3, everything .. there is no such thing as a 1024 transmission. Everything that a broadcaster receives gets ingested as a type of MPEG-2 at 720×576 … it is only the PAR that determines the final aspect ratio.”

It is 720 but it is either square PAR or non-square PAR. For non-square PAR, you would have to provide the square-pixel equivalent of non-square 720, which is 1024.

[duffbeer911] “The fact that they do in fact broadcast at pure 16:9 should preclude you from wanting to provide anything at 720, unless it’s anamorphic. But from your initial post, they have requested for 1024×576.”
-From the point above I’d now only ever want to provide everything (16:9 or 4:3) at 720 anamorphic as that is how it is going to be ingested.”

That’s fine. The only question is how you’re going to get to 720×576 for 16:9 or even for 4:3. Are you going to work on your computer’s square PAR or try to kung-fu things out on your computer by working entirely in a non-square worfklow?

[duffbeer911] “He also suggested that working at 1024 would result in an incorrect image on your broadcast monitor, because the 1024 is getting down sampled to 720 through your output card(ie for us Blackmagic cards). And that if you send a 1024×576 image to a broadcaster it will lose an every so slight amount of quality in the down sample when it is ingested.”

I can’t see the incorrect image as being an issue. If your monitor has a 16:9, which most if not all broadcast monitors have, then it is really a non-issue.

The workflow that I suggested, working entirely in square PAR until the render stage, where you nest the square PAR comp into a non-square comp should allow you to view 720 anamorphic on your broadcast monitor prior to rendering. Further it precludes any issues related to plugins or AE’s 3D render engine from having to work with non square PAR.

I think you only need to hit the wall once when working in non-square PAR before you realise that it’s not an ideal work situation. Plugins such as CC Sphere, AE’s Render Engine, Digital Anarchy’s 3D Assistants and a few others tend to have problems with non-square PAR layers and comps.

It’s been quite an interesting discussion. My only Q for now is didn’t you say initially that they requested for 1024×576? And that now this engineer that you’ve spoken to says that anamorphic 720 is preferred?

We should take note that working in a square PAR world, computers, and outputting to a non-square PAR format, results in imperfections, either in the workflow or the final deliverable. At issue is which workflow works best for you and how much of an imperfect image you’re happy to live with.

Cheers
Roland Kahlenberg
https://www.broadcastGEMs.com – Adobe After Effects project files
https://www.myspace.com/rorkrgbspace

[Michael Duff]

“It’s been quite an interesting discussion. My only Q for now is didn’t you say initially that they requested for 1024×576? And that now this engineer that you’ve spoken to says that anamorphic 720 is preferred”
-these are different people/companies … the engineer I contacted is not connected to the initial request for 1024

“The workflow that I suggested, working entirely in square PAR until the render stage, where you nest the square PAR comp into a non-square comp should allow you to view 720 anamorphic on your broadcast monitor prior to rendering.”
– ok … well I think in a round about kind of way we do agree … that working in square pixels is better due to the way plug-ins and render engines approach pixels …. but final output at 720 anamorphic is best because that is how it is ingested at the television station.
And if we already have a 720 16:9 render on our system and need to send it to a broadcaster .. it is best to just leave it as is rather than going through that resizing process.

Thank you so much for your help with this … one more question though 🙂 How are you getting the quotes from my post in? I can’t find any buttons to insert quotes … I’m just cutting and pasting … maybe cause I’m on Firefox?

[Roland R. kahlenberg]

[duffbeer911] “How are you getting the quotes from my post in? I can’t find any buttons to insert quotes”

Just ue your cursor to select the text and with the text still selected, press the letter “Q”. This will automagically copy and then paste what you have selected into the Reply text area.

BTW, what’s the story like with AE training in Australia? I’ve been thinking of linking up with a training provider to offer my AE courses on a quarterly basis. Any ideas on who to get in touch with?

Cheers
Roland Kahlenberg
https://www.broadcastGEMs.com – Adobe After Effects project files
https://www.myspace.com/rorkrgbspace

[Michael Duff]

thanks …

i’m not really sure about AE training … a few years ago I looked for some and there really wasn’t much around (and what was around looked below average) .. since then I haven’t looked … probably a person with better/more information on this would be John Dickinson (former COW leader & motionworks.com.au)

good luck, and let me know how it goes and if you come over here