Contradicting advice on workflow for documentary

[Merino]

During May and June I will be recording an ethnographic documentary for my master research at the university (cultural anthropology).
My university has had extensive experience in producing ethnographic documentaries but only in SD production.

This year the university purchased a AG-HMC151 in order to start producting documentaries in High-Def. I will be the first student to make a film using this camera and am therefor the guinee pig who has to find out how to do these productions in HD. Unfortunately not a single professor or employee at the university has any experience or knowledge about recording or editting in HD. They thus put me totally in charge of moving the university from a SD workflow towards a HD workflow.


So I've been reading this forum extensively trying to prepare myself. I went through the full 110 page thread started by Barry Green and this helped me alot in learning about the camera. After reading the full thread I had the idea that I knew what I was talking about and how this camera and HD works in general. However I also managed to make an apointment with an experienced filmmaker who has worked with AVCHD on some of his projects in order to discuss my workflow. The conversation led to radically different answers than the ones that Barry Green provided in his thread.
I feel thus to be stuck in between two contradiction advices on the workflow with this camera. One comming from Barry Green who is clearly experienced with this camera, the other comming from someone who was specifically hired by the university in order to supply me with the necassary advice.
Below I will sketch the detailed situation that I am in:


Project: Ethnographic Documentary (ie, reactive filming style) on hindu disciples (thus not alot of movement and certain scenes will be in low light situations)
Camera: Panasonic AG-HMC151
Country: Netherlands (PAL, 1080i public broadcasting)
NLE: Adobe Premiere CS5 (available 12th of april 2010)
Output: BluRay (1080i50, 720p50) and DVD (576i50)
Shooting Modes: 1080i50, 1080p25, 720p50, 720p25


Reading through Barry Green's comments on this forum I believe it comes down to the following advices:
- Do NOT film in interlaced (1080i50) because of 4:2:0 chroma subsampeling. Also 1080i and 720p are close in image quality. 1080i and 720p are both used for broadcasting however 720p is recommended by the EBU (european broadcasting union).
- Computers, LCD/Plasma TV's and new technology is progressive rather than interlaced (CRT monitors)
- 720p was recommended as being the ""sweet-spot" for this camera.
- 720p was recommended as the best to downconvert back to SD (576i)
- 720p50 is usefull for slow-motion and for reality look (isn't reality look what I should be aiming for in an ethnographic documentary?). I might want to use slow-motion on some shots but it is not necessary and I could do without that option.
- 1080p25 was later recommended by Barry Green as it has a higher chroma resolution than 720p. However Barry Green advices to downconvert this 1080p to 720p in order to get the best image quality. Thus it seems not recommended to output in 1080p25? Also I feel that filming in 25p gives me a stuttering image in pans. As I am filming a documentary in which I might make sudden and unexpected movements with the camera I am scared to film in 25p.


After reading through Barry Green's advices I looked up the speclist for Blu-Ray discs and found out that 1080p25 and 720p25 which are both supported by this camera are not supported by BluRay. Thus, looking at what I will be producing in the end only two of the four recording modes are left if I want to burn my project to BluRay.
BluRay: 1080i50, 720p50
Camera: 1080i50, 1080p25, 720p50, 720p25

It seems rather strange to me that the camera can record in 1080p25 and 720p25 but there is no way to burn this material to a high-definition disc (as Bluray is now standard).


On the base of the information above I had almost fully decided to go and record in 720p50 mode as this seemed the most logical choice (not recording in interlaced, 50p thus fluid motion and reality look, able to burn to Bluray).


Then I had the appointment with the filmmaker who would help me with my workflow. Without barely any thought he immediatly recommended me to film in 1080i50. As reasons for this he cited the following arguments:
- interlaced looks beter to the human eye when displayed on television than progressive which looks like a series of pictures.
- interlaced is the standard in broadcasting (I can confirm this as Dutch public broadcasting is currently done in 1080i)
- 1080i50 will downconvert to 576i50 without any artifacts or problems (though with a large loss in resolution).
- There should be no problem playing back interlaced material on progressive screen. There is a problem playing back progressive material on a interlaced screen.
- He didn't mention anything about having to de-interlace the 1080i50 stream before or after editting. I have no idea if and when this would be necessary when recording in interlaced



Thus basically what it comes down to; listen to Barry Green (record in 720p50) or listen to the advice of the filmmaker I just spoke to (record in 1080i50)?

 

[Smifis]

Listen to Barry but shoot in 1080i50 as this is your broadcast standard

 

[Tim Joy]

If you want it to look and feel more like a movie, then go for 25p.
If you want it to look and feel more like a TV show, then use 50i.

Yes, there are limitations you should be aware of if you shoot in progressive, like panning slower, but to me, anything interlaced looks like home video or a news broadcast.

As for the 720 vs 1080, I can't speak on that, but you could do some tests of the entire workflow and see which seems best.

 

[Desertfox]

Contradictions makes people who haven't bought wanna buy.

Contradictions makes people who have bought, maintain happiness. (They call it customer's burnt pocket psychological support.)

I learnt today that BluRay supports only 1080i50 and 720p50. SO thank you!

 

[Cranky]

I prefer documentaries to look real, hence 50i or 50p. I hate interlaced, hence 50p. If you shot 720p50, you can keep it "live" or you can make it "film-like". You can convert it to 1080i25 or 720p25 without quality loss, or to 1080p25 with slight quality loss, which no one will see anyway.

As for BD, you can convert to 720p25 for "film" look and record as 720p50 with frame repeat (no actual data will be repeated, just repeat flag added). Or you can keep it "live" and record as 720p50.

Compared to 1080p25, you lose practically nothing as the HMC150 is pretty much a 720-line camera. 720p50 simply gives you more options and is easier to edit than interlaced. You can keep it "live" or you can make it "film-like", your choice. If you choose "film" style, you can make very nice slo-mo out of 50p source clips.

"interlaced looks beter to the human eye when displayed on television than progressive which looks like a series of pictures." -- load of crap, unless by progressive they mean 25p and by series of pictures they mean stutter.

"interlaced is the standard in broadcasting" -- 720p50 is standard in broadcasting too, and converting it to 1080i25 is as easy as pie.

"1080i50 will downconvert to 576i50 without any artifacts or problems (though with a large loss in resolution)." -- load of crap. To scale video, it must be deinterlaced first anyway.

"There should be no problem playing back interlaced material on progressive screen. There is a problem playing back progressive material on a interlaced screen." -- load of crap. Interlaced never look perfect on progressive screen, it can look tolerable, with significant image processing. Progressive looks just fine on CRT.

"He didn't mention anything about having to de-interlace the 1080i50 stream before or after editing." -- Hence I suggest to not listen to him. The dude may know about film, but quality of his knowledge of interlaced and progressive video is questionable.

 

[Merino]

Thanks alot for all the advice.

One thing that is not clear to me however is how its possible for 720p50 to be converted to 1080i50 without quality loss or upscaling.

Also if 720p50 is really this flexible and better to work with why would anyone still want to film with this camera in 1080i50. Especially when interlaced is considered ancient and progressive the future?

 

[Postmaster]

1080i50 is your broadcast standard. That´s what they used for the winter Olympics for example.

Your camera shoots progressive native anyway. Everything else is converted internally. So even if you select 1080i50 the 2 fields would be the same and it will be no difference between i and p.

But as I said 50i is the broadcast standard, so if you deliver 25p they will convert it to 50i anyway and the crappy flat screen deinterlacer at home will reconvert it back to 25p (by throwing away half of the vertical resolution) and double every picture.

Ah, it´s a mess.

Bottom line. Today there is no perfect output format anymore - just a bunch of crappy compromises. Record in 1080i and downsample to whatever you need for your target device via software. At least then you have some control.

best, Frank



ff