C100: C100 event shootings, 60I or 24p?

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Shawnvfx

Well-known member
since interlace issue can be fixed without a big visual difference using after effects, I was wondering is it ok to shoot entire project with just 60i and deliver in blu-ray 1080p ?

big difference in terms of image quality compared to 24p?

and difference between PF30 and 60i ?
 
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To be honest, I'm very leery of interlacing - in the world of progressive displays (web, computer playback) interlace leads to tears before bedtime: scaling issues, bandwidth-robbing compression issues, and the sad fact that interlacing was a clever trick from the days of cathode ray tubes that has little place in today's world other than to prepare for 1080p60.

To de-interlace an image requires a resolution drop of 25% when done 'best' - or 50% if done cheaply and quickly. Assuming that we go the 25% reduction route, that brings 1080i down to around 768 TV lines - interestingly close to the 720p60 rate. Hmmm.

If left as interlace, some TVs spot this and treat it well. Others don't and it looks nasty. Or you get field order problems where any motion suddenly becomes super-juddery on some sets. Which is irritating as it's almost impossible to spot field order issues on most LCD monitors/video cards I've looked at for edit suite use. Of course, if your 1080i goes onto a 720p set, then moving edges can get a little Lego-like, and YouTube/Vimeo versions can be fugly too.

So, I'm a strong proponent of Progressive. As a PAL based shooter, I'm aware of the issues with 25/24p in terms of panning, but I preferred this look over 50i because the traditional 'video' look got so devalued. However, 25p has interesting issues with the 60Hz of computer screens (my chosen delivery medium), so have been playing with 29.97/30p over 24/25p as a compromise between the two extremes. I've shot 1080p50/60, and although the clients liked it, I didn't. It definitely needs a modified shooting style.

As this is a Canon C100/C300 forum, we've got to bear in mind that we're using PSF to get a progressive look from an interlaced stream, which requires an extra step or two in the NLEs I use, and I *think* I see some oddities in the C100's AVCHD image - a little bit of hooking or distortion in high motion where the C100's PSF nature seems to hint towards a more interlaced acquisition. However, I'm avoiding any form of interlace and will continue to do so.

But of course your mileage may vary.
 
Matt. I'm currently trying to figure out which might be best for me. Since i'm from Portugal, i'm also in a Pal Zone, so shooting with the C100 in PSF50i and then using clipwrap to turn the footage into .mov progressive files is a solution. But i'm experimenting in shooting at 24p. My main output will be the web and DVD (yeah i know it sucks). So do you think if i shoot 24p edit it on 24p and then convert it to a pal dvd 720x576i i'll have any sort of problem?

Have you tried it out?

Thanks
 
MattDavis said:
However, I'm avoiding any form of interlace and will continue to do so.
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Does that mean 24P only? I've been shooting 30PSF and (once interpreted as 29.97P by CS6) haven't noticed any IQ problems. I've been wondering about 24P though.
 
I'm just avoiding interlace - 24, 25, 29.97, 50 and 60 are all fine. PSF is fine. Just not interlace.

I'd love to dig out a frame to show the odd 'quasi-interlace' artifact that the C100 does in PSF mode on its internal codec when it's under motion stress. I don't think that's on the HDMI output, but I've not tested that yet. OTOH, I have read somewhere here that this may be an issue with the way FCPX ingests C100 footage (and there's deffo something screwy in my setup).
 
Pteraser said:
My main output will be the web and DVD (yeah i know it sucks). So do you think if i shoot 24p edit it on 24p and then convert it to a pal dvd 720x576i i'll have any sort of problem?

Have you tried it out?
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Crumbs, this means going back in history a bit, as DVDs aren't as popular as they once were in my industry niche (it's all WMV and YouTube 720p now).

DVDs: NTSC DVD players don't tend to play PAL DVDs, but PAL DVDs can play NTSC DVDs. If your DVD is for worldwide distribution - i.e. USA and 'the rest of the world' - you have a choice: make two DVDs (yuk), or make it NTSC.

Assuming you are making an NTSC title, you can do a 24p title and this is the easiest flick between 25p and 24p. So, you could make all your assets in 25p, carefully scale them to an NTSC frame size and change the playback rate to 24p, putting up with the time difference and perhaps a pitch shift, and away you go. Or you can shoot in 24p from the get-go, but then you have all this crazy American 24p in 60i 2:3 pulldown stuff to contend with.

Scaling down: there's too much information in a 1920x1080 HD image to scale down to SD without doing some sort of pre-blur stuff. Back in the day, the rule was 'shoot 720p50 for lovely interlaced PAL DVDs' and shoot 720p30 or 720p24 for NTSC titles. This helped in odd ways because we got a nicer picture from HD cameras scrunched down, than from SD.

These days, I'm tempted to shoot 29.97 progressive for web, and let the DVD player make the TV switch to NTSC for DVD, keep it simple all the way. Except now you're going to have to check for issues with shutter speeds (most allow 1/50th on a 60i/29.97 rate) and ambient lighting (beating fluorescents, street lights, Sodium Vapour architectural lighting, LEDs) and that also needs to be checked on a native resolution monitor if you really are paranoid.

The 29.97p frame rate helps just a little bit with motion, and is as close as dammit to the 60Hz computer monitor refresh rate. Things just seem to be smoother in my tests.

This is for corporate, rather than Narrative, where I could understand the desire for 24p motion, though.
 
MattDavis said:
This is for corporate, rather than Narrative, where I could understand the desire for 24p motion, though.
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Yeah, 30PSF on the C100 is with 2:2 Pulldown, so make sure you remove that for clean, artifact free, 30p. I would look into FieldsKit for converting 60i to 60p as it seems to do a great job, though I need to find something where slow-mo is needed to test it out.
 
Matt. thanks for your input. I'm not going to do a NTSC DVD, probably my better solution is using clipwrap and keep the 25p. Those workarounds seem to cause more problems than using only clipwrap.
 
It's kind of interesting that canon gave us these options of 60i framerates while nobody has anything good o say about converting the 60i footage. Does anyone have a tried and true method of dealing with 60i footage with little quality loss? Just curious as I haven't dealt with 60i footage since owning my xha1
 
I think 50i/60i is there as a legacy compatibility thing with AVCHD. In other words, back when AVCHD (and even HDV before that) were ratified, there simply wasn't the bandwidth for full on 1080p - hence the first few HDV steps into PSF.

Then there's the curious situation where the SD 'digital' services that have replaced analogue transmission (certainly here in the UK) were originally designed for the world of CRT as at the time a 640x480 LCD panel was all there was. IIRC, there's a little cheat in the current UK broadcast system that allows numbers to be labeled as negative which makes for lovely results on CRTs but a high degree of crapness on LCD/LED which explains why SD digital broadcasts look horrible if you get too close to the screen. It's silly things like this that seem to easily explain why we still have interlace today.

OTOH, in conversation with hallowed doyens such as Alan Roberts, the 1080i with PSF has been a way of getting things started with 1080 rather than step through 720. UK BBC HD broadcasts are transmitted 1080i but filmed progressive, and their encoders can switch between interlace and PSF on the fly (within the 16 frame GOP structure at least) - so that credit rolls happen at interlaced frame rates but programmes go out as PSF. The whole point being that at some stage the whole system switches to 50p and all back catalogue material remains compatible.

So... Yeah... Interlace. Pfft. :)
 
MattDavis said:
I think 50i/60i is there as a legacy compatibility thing with AVCHD. In other words, back when AVCHD (and even HDV before that) were ratified, there simply wasn't the bandwidth for full on 1080p - hence the first few HDV steps into PSF.
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I think that is for consumer devices that can play AVCHD natively...like Blu-ray players.
 
but PF30 and PF24 confuses me , progressive in a 60i container ? what is this? difference between PF30 and 60i?
 
Shawnvfx said:
but PF30 and PF24 confuses me , progressive in a 60i container ? what is this? difference between PF30 and 60i?
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The PF modes shoots true progressive. That is, for pf25 you get 25 'real' frames per second. Just like progressive. But each of those frames are then split in half into two 'fields' (even/odd lines) and those fields are stored in a 50i container.

The difference to interlaced is that with PF-formats the two fields belong to one solid frame, both fields represent the same point in time. Combine the two fields together and you get the original progressive frame without any quality loss whatsoever.

If you shoot interlaced, the camera isn't shooting frames. Instead it shoots to 'fields' directly. In the case of 50i, it shoots 50 fields per second. The problem is that there is a time difference between each of the recorded fields, so even if you combine them (deinterlace), you're never going to get true frames. This is how the resolution loss happens.

If your camera is on a tripod and nothing in the scene moves, then interlaced would produce perfect frames, but that is rarely the case.
 
so whats the advantage of shooting with PF 24 than 24p? on the on hand I get tru progressive , on the other hand i can do slow motion for a 50i quality ?
 
Shawnvfx said:
so whats the advantage of shooting with PF 24 than 24p? on the on hand I get tru progressive , on the other hand i can do slow motion for a 50i quality ?
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No, on the one hand you get native 24p in AVCHD, and on the other you have 24p in a 60i container in AVCHD for some crazy-ass reason.
 
Gary Huff said:
you have 24p in a 60i container in AVCHD for some crazy-ass reason.
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For the crazy-ass reason of 'compatibility' - hey, you brilliant Americans invented it! :grin:

AFAIK (and believe me this takes time to understand) whilst there are some issues with inter-frame futzing on transmission of 24PF in a 60i system, you can pull 24P out of 24PF so the end result is indistinguishable from original 24p - unless one gets the workflow wrong. This makes 24p work on DVD and on broadcast (sorta). I believe there is a special 24p mode on US DVD players that does the special mad-donkey thing so you do view true 24p. 25p is so much easier to understand...
 
Yeah, and the workflow for pulling out 3:2 pulldown 24p is so easy to get wrong unfortunately. Pretty much the only way is to use After Effects.
 
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