24p vs. 25 - can anyone tell me the TRUTH?

[custerc]

So, I'm looking to buy an HMC 150. I'm an American currently living in a PAL region, thus, the most easily accessible one is the HMC153, which does 50p and 25p instead of 60p and 24p.

Now, I've been trying to figure out how much this difference really matters. I've spent days reading threads on this site, and other discussions I found via Google, and have found tons of confusing, conflicting information. Some ideas I've heard:

- To convert 25p to 24p you just slow the footage down by 45; however, this messes up the audio
-That actually isn't true, there are software converters that can make the conversion easily without affecting audio
-It is possible to convert via software and not mess up the audio but it is difficult and time consuming
-There's no reason to convert to 24p unless you want to output to 35mm
-There are lots of reasons to convert to 24p beyond just film, 25p is a bad choice to shoot in if you want your project shown in NTSC countries
-Shooting in 25p can create issues with dropped frames when played back on vimeo and other web video sites
-25p is supported on vimeo and other web video sites.

Etc. etc. etc. At this point, I have no idea what to believe. It will be easier (and cheaper) for me to go with the 153, but I don't want to close any doors in terms of what can be done with this project when it's finished. I'm not planning to output to 35mm film, but I would like that to be possible if my project were to get picked up and the distributors wanted that. And I want to still be able to use this camera if/when I return to the US.

So, here are what I see as my three options. Could someone please help me evaluate how much the 24p vs 25p stuff really matters? As you can see, I have already read many of the DVXuser threads on this issue, but many of them are a couple years old and also full of conflicting info.

My choices:

HMC 153MC: pros: convenient to purchase cons: can't do 24p
HMC 151/2/4: pros: PAL/NTSC switchable cons: can't buy in China, would have to import (expensive, plus you never know what customs is going to do with it)
HMC 150: pros: native 24p cons: can't buy in China, would have to import (expensive, plus you never know what customs is going to do with it)

Thoughts? The only way I can avoid this question is if I can find someone going to Europe for Christmas who can bring me back an HMC150 (that would likely make customs a non-issue and would make me slightly less nervous than having it shipped, which would make me really nervous...)

 

[Exact]

The problem is you are asking for a definitive 'do this' answer and there simply isn't one. Why?

Let's look at several of the options you mentioned above.

To convert 25p to 24p you just slow the footage down by 4%; however, this messes up the audio

Converting from 25p to 25p is a couple of button clicks in Apple Cinema tools, so I assume it can also be done this easy in Windows too. Does it mess with the audio? That depends what you mean by 'mess'. Conforming to 24p simply means playing the same 25 frames (i.e. no loss) but at 24fps. However, when ever you play audio slightly slow the pitch will change slightly. To most people this is completely unnoticeable, especially if they don't have the original to compare it with side by side. So, does it mess with the audio? Yes, the pitch has a marginal change, but it's still played back in sync with the video.

It is possible to convert via software and not mess up the audio but it is difficult and time consuming

Correct, but this method is also not lossless in so far as going from 25p to 24p and maintaining the same audio pitch would mean dropping 1 in every 25 frames of video and scrunching up the audio t match. There are several different algorithms for this, but essentially you will have to throw away 1/25 of the footage. It's also possible to take 25p footage and convert to 29.97p (30p drop frame) using the same interpolation theories. In this case the computer has to repeat frames every so often. The calculations are easier from 24p than 25p but the problem still exists.

When I shoot at 25p and need to distribute both PAL and NTSC DVDs I usually let the DVD encoder handle the change. It's not the absolute best solution, but very few people can tell the difference between them without looking VERY closely indeed. The majority of viewers will neither know it's been done nor care.

There's no reason to convert to 24p unless you want to output to 35mm

Again, this depends on what you were hoping to do. For instance some (but not all) DVD players will play 24p, as will Blu-ray players, even in PAL countries. However, the question you have to ask yourself is why are YOU doing it? What media are you really targeting?

There are lots of reasons to convert to 24p beyond just film, 25p is a bad choice to shoot in if you want your project shown in NTSC countries

25p is a bad choice for NTSC countries for any type of playback other than by a computer if you actually want to play it at 25p. NTSC countries prefer 24/29.97/59.98 so some conversion will be required for anything other than computer playback via vimeo/youtube etc.

Shooting in 25p can create issues with dropped frames when played back on vimeo and other web video sites

This is news to me. I shoot almost exclusively at PAL rates (25p/50p) and upload to vimeo all the time at 25p. I've never seen any problems on my own footage. Never.

25p is supported on vimeo and other web video sites

Correct

EDIT: I saw your other post here [ http://www.dvxuser.com/V6/showthread.php?230138-A-few-HMC-150-questions ] about the long term documentary. Looks like you got your funding - congratulations ).

Vimeo and YouTube and most (if not all) the other sites use players that play 25p just fine. If they didn't, the MAJORITY of the world would be complaining because the MAJORITY of the world watches TV at 25p / 50i frame rates. The USA and Japan are actually in the minority here, contrary to what many people in the US assume.

It really doesn't matter which frame rate you shoot at, you are going to have to convert it for 'someone', even if you shoot at 24p! People local to you, all the people in Asia, Australia, most of Africa, India, Europe etc will want to view at 25p / 50i where as the US will want to view at 29.97p. You can't please all people all of the time, so 'someone' is always going to be looking at converted footage no matter what you shot at.

Most broadcasters have ways of converting footage in-house, so again, I would not worry about the frame rate too much if your intended target is broadcasters, i'd be more concerned about whether they will accept footage source exclusively from an HMC. Some will, many won't.

Ultimately, a world camera would be the most flexible solution, e.g. the HMC 151, or one of the Sony models, allowing you to shoot different material at different frame rates as required (e.g. documentaries aimed at different audiences), but think very hard about how the video you shoot will really be seen before getting too tied up about frame rates.

Once you know the areas of distribution and the type of media most of your viewers will need, your questions will pretty much answer themselves.

 

[custerc]

Exact, thanks for the breakdown! My issue is that I'm guessing the primary audience will be web (probably not an issue either way) and via DVD, primarily in China and the US. So there's the conundrum, I suppose. I guess I'll have to convert it for someone either way, but which way do you think is going to be easier?

Also, why wouldn't broadcasters accept footage from an HMC 150?

 

[PaulWM]

"Also, why wouldn't broadcasters accept footage from an HMC 150? "

Interesting. Could a HMC project be delivered on the broadcasters' chosen format - without them knowing what it was originally captured with?

Sneaky but I'm sure I've read somewhere that this has worked in the past for people using older format cams.

 

[custerc]

Seriously, are there rules about what broadcast stuff has to be shot with? Because I think I can make something that looks damn good with an HMC and a 7D, and since people have used DVXes and other SD video cameras for film transfers and the like, I can't imagine it's a IQ issue...I mean, there are plenty of TV shows that use those cameras; the HMC is a decent codec and can shoot 1080p, why wouldn't that be good enough for TV (or film)?

And what's the deal with using 25p footage to create a DVD for NTSC regions? Is that easy (for example, can I covert up to 30p with duplicated frames to retain the 25p "look" and not mess with the sound at all)?

 

[custerc]

what's the deal with using 25p footage to create a DVD for NTSC regions? Is that easy (for example, can I covert up to 30p with duplicated frames to retain the 25p "look" and not mess with the sound at all)?

If someone could please just answer this question, I promise I will shut up.

 

[jchristie]

If you want to create a DVD for NTSC countries, you need to convert your 25 fps to 24 fps. You can use a program like soundtrack pro to pitch shift the sound or just keep it the way it is, most people won't notice the difference. Your music composer will notice the change in pitch, but that's about it. NTSC DVD players add pulldown to convert 24 frame to 30. (There's no decent way to convert 25 fps to 24 Fps without running your material through an expensive converter like a Terranex or Schnell and Willcox) If your on a mac, try a quick test. Record something at 25 fps, preferably with some music playing in the BG. Use cinema tools to convert the 25 to 24 (it doesn't recompress, just tells quicktime to play back the file at the new rate) Every European film that makes it's way to North America has been handled this way, sometimes with accompanying pitch shift, and sometimes without.

 

[Exact]

As jchristie says, use Cinema tools to modify the header on the 25p movie to tell it to be played back at 24p. Job done. As I said above, and jchristie also mentioned, there will be a very slight change in pitch but most people won't notice. You will retain your 24p/25p look.

To answer your question about broadcasters and cameras, some broadcasters have set minimum bitrates for cameras that 'they' consider suitable for outside (or even inside) broadcast quality material. As an example the BBC have set 50mbps which is supported by the likes of the Canon XF-305. Most will accept a certain percentage of footage for lesser bitrates while others will accept most bitrates.

I've seen some awesome TV sows on the BBC recorded almost entirely on HDV and unless you were looking for it, you would never have known, so there are times when the rules change because of the content and the way it had to be captured.

There is a universal argument about what it or is not broadcast quality, and as usual it comes down to several factors, including how much they want the content. If there is a train wreck and the only footage they have is from a mobile phone they don't refuse it based on it's codec, they broadcast it!

If you are expecting your program to be watched primarily on the web then all such bitrate rules fly out the window because it's going to get even more heavily compressed for web distribution. No one is going to want to download 60GB of footage, then want it real time. With this in mind the HMC is plenty good enough.

If you are targeting DVDs then again, the HMC is plenty good enough.