Topic: at the risk of looking like a dipshit, what is "24p"?

[cleantone]

I hate to ask but was wondering if someone could explain it. I want to guess it has to do with 24 frame recording/playback.

[willndmb]

24 frames progressive, not interlaced

[cleantone]

Thanks. I think some do 25p as well. Can you explain the difference perhaps? I only know of progressive and interlaced. Any resource you can aim me to that explains the differences?

[KurtMichaels]

24p is taking 24 full pictures per second, 25p is taking 25 full pictures. PAL countries need 25 fp/s, NTSC countries need 24 fp/s. Of course, the more frames per second you have, the more fluent movement usually looks. It's more then just a slight difference. People from Europe (like me) find the 24 fps a little choppy, but the conversion from 24 to 25 fps creates what people refer to as "cinematic look". Alternatively, you can take Holllywood movie footage (24 fps) and run it on a european 25 fps projection system. The movie is then just 2% faster and you have to sync the audio to that.

The interlaced/progressive thing comes from the TV legacy. Traditional TV sets don't show 25 or 24 full pictures per second, but half ones. For PAL ( 25fps) that means 50 half frames per second or 50 fps interlaced or 50i. People filming movements will usually stick to interlaced mode. But since the "cinematic look" needs progressive footage a true(!) progressive mode on camcorders is a demanded feature - for example the Canon HV20 scores because of that mode.

If a camcorder has to take only 25 or 24 frames per picture instead of 50 fps there is more time to bring the motive on the chip - such (usually) improving low light capabilities.

Now, your TV set or standalone DVD player will transform interlaced footage into progressive footage on the fly. Free software players like VLC will convert footage too. On the computer things are more complicated. There is tons of different software that transforms i to p footage. There is another reason to shoot in progressive mode and that is DVD publication, both for Standard and High Definition. HD Blue-Ray and HD-DVDs need progressive, 24 p footage.

[cleantone]

Really good explanation. Thanks for that. Welcome to the forum.

[Josh P]

wow, that really cleared some things up for me.  thanks and welcome Kurt!

[wilsonedits]

www.dvxuser.com can answer all and any questions...
if you not doing HD a dvx100 is pretty much the standard for 24p shooting/indie films

i really don't shoot in anything other than 24p... i don't like the look of 60i video at all...

www.nattress.com has excellent software (final cut pro filters) that you can use to give a 24p look in post..

[BayTaynt3d]

FWIW, the whole 24p thing gets a little complicated when 3:2 pulldown comes into the mix. For example, the 1080i 24p that is shot on the HV20 is stuffed into a 60i format by using 3:2. So, if you don't remove the pulldown or if you render out footage to 60i, a 24p video can suffer from a rhythmic stuttering of motion. It's subtle, but noticeable, and has nothing to do with the "feel" of 24 fps but is an artificial artifact of 3:2 pulldown. Some devices are smart enough to recognize the 24p signal in the 60i format and automatically remove the pulldown and display a true progressive image on your monitor (if you have a progressive monitor that is). Anyway, there's a little more 24p info for you...

Oh, and one more huge benefit for shooting in 24p (if it's true 24p like the HV20 is) is the fact that you can leave your shutter open just that much longer than at 30 frames per second -- resulting in superior low light performance before needing to add video gain when compared to running in 30p or 60i.

[John Kary]

Oh, and one more huge benefit for shooting in 24p (if it's true 24p like the HV20 is) is the fact that you can leave your shutter open just that much longer than at 30 frames per second -- resulting in superior low light performance before needing to add video gain when compared to running in 30p or 60i.

While 1/24 will give you 1/4 more stop than 1/30, it will give you that much more motion blur as a trade-off for "superior low light performance."  I've seen people (Barry Green, DVX expert over at DVXUser.com) claim that 24p is 1 stop slower than 60i in general, but he didn't comment on if the shutter speed was the same for that claim.  I'll test this for sure when I get home with a Panasonic DVX100b and see the results.

Relative to your shutter speed comment, I'll test this also, since the slowest shutter for 24p = 1/24, while 30p = 1/30 and 60i = 1/60.  While 24p technically gains you 1 1/2 stops of light, it will result in a LOT more motion blur.  I know I've shot some things in 24p and went 1/24 to gain the extra light and the footage was just unsatisfactory with any type of movement.  I wouldn't recommend 1/24 at all unless you're on a tripod and planning on not moving the camera.

[John Kary]

Oh, and one more huge benefit for shooting in 24p (if it's true 24p like the HV20 is) is the fact that you can leave your shutter open just that much longer than at 30 frames per second -- resulting in superior low light performance before needing to add video gain when compared to running in 30p or 60i.

While 1/24 will give you 1/4 more stop than 1/30, it will give you that much more motion blur as a trade-off for "superior low light performance."  I've seen people (Barry Green, DVX expert over at DVXUser.com) claim that 24p is 1 stop slower than 60i in general, but he didn't comment on if the shutter speed was the same for that claim.  I'll test this for sure when I get home with a Panasonic DVX100b and see the results.

Relative to your shutter speed comment, I'll test this also, since the slowest shutter for 24p = 1/24, while 30p = 1/30 and 60i = 1/60.  While 24p technically gains you 1 1/2 stops of light, it will result in a LOT more motion blur.  I know I've shot some things in 24p and went 1/24 to gain the extra light and the footage was just unsatisfactory with any type of movement.  I wouldn't recommend 1/24 at all unless you're on a tripod and planning on not moving the camera.

Just finished with some tests. 
24p @ 1/60.3s was able to achieve 50IRE at [f2.4]
60i @ 1/60.3s was able to achieve 50IRE at [f.4.0]

So 24p is actually 1.5 stops slower than 60i.

If you switch 24p to 1/24 shutter speed, in compoarison to 60i @ 1/60.3, you gain about 1/4 to 1/2 a stop, again, at the price of extreme motion blur.  If that works for you, try it.  But if you're filming an type of action concert, it will look pretty sloppy.

[BayTaynt3d]

Interesting.

So what shutter speed is typically used when shooting 24p? How about film?

BTW, I've been thinking about buying an HV20 soon, the thing looks pretty sweet. Small. Tape. HDV. 24p. 1080i. Not bad for $900. What do you think? 

[wilsonedits]

Interesting.

So what shutter speed is typically used when shooting 24p? How about film?

BTW, I've been thinking about buying an HV20 soon, the thing looks pretty sweet. Small. Tape. HDV. 24p. 1080i. Not bad for $900. What do you think? 

1.48

BTW that HV20 is a 900 dollar camera... it doesn't shot real 24p or HD for that matter... its a good camera for soccer moms... and the low light performance like all canons you will find its very disapointing .... you would be much better off spending another 500 dollars and getting a used dvx100a

panasonic dvx or hvx are the only cameras that are going to give you real 24p unless you spend over 6,000

Posted by: BayTaynt3d
Insert Quote
FWIW, the whole 24p thing gets a little complicated when 3:2 pulldown comes into the mix. For example, the 1080i 24p that is shot on the HV20 is stuffed into a 60i format by using 3:2. So, if you don't remove the pulldown or if you render out footage to 60i, a 24p video can suffer from a rhythmic stuttering of motion. It's subtle, but noticeable, and has nothing to do with the "feel" of 24 fps but is an artificial artifact of 3:2 pulldown. Some devices are smart enough to recognize the 24p signal in the 60i format and automatically remove the pulldown and display a true progressive image on your monitor (if you have a progressive monitor that is). Anyway, there's a little more 24p info for you...

thats all true becuase your using a 900 dollar consumer camera... none of it is if your using a dvx


EDIT:
and your also going to find that 24p HD is pretty much out of reach....  sensors on all HD cameras struggle with low light...  for example... the panasonic dvx is a good three stops lower than the hvx...i have run them side by side and  I have found the hvx really isn't suitable for shooting concerts after dark... kickass during the daytime but not so much after dark....

to shoot 24p 1080i HD you need a 10,000 dollar plus camera like a panasonic HPX

[Josh P]

Interesting.

So what shutter speed is typically used when shooting 24p? How about film?

BTW, I've been thinking about buying an HV20 soon, the thing looks pretty sweet. Small. Tape. HDV. 24p. 1080i. Not bad for $900. What do you think? 

1.48

BTW that HV20 is a 900 dollar camera... it doesn't shot real 24p or HD for that matter... its a good camera for soccer moms... and the low light performance like all canons you will find its very disapointing

panasonic dvx or hvx are the only cameras that are going to give you real 24p unless you spend over 6,000

hmm, the exact opposite is what I've read in all the reviews.  You may be thinking of the HV10.

True 24p and fantastic in low light.  I think I'll be picking up a HV20 after the first of the year.

If anyone is interested, check out http://www.hv20.com, its a message board dedicated to this cam much like dvxuser.com

[BayTaynt3d]

BTW that HV20 is a 900 dollar camera... it doesn't shot real 24p or HD for that matter... its a good camera for soccer moms... and the low light performance like all canons you will find its very disapointing .... you would be much better off spending another 500 dollars and getting a used dvx100a

panasonic dvx or hvx are the only cameras that are going to give you real 24p unless you spend over 6,000

Wow, that was a bit harsh, but more importantly COMPLETELY WRONG.

The HV20 shoots to the HDV codec in 1080i. So, it's every bit as HD as a whole lot of other prosumer HD cameras out there. Now, there's more to HD than the codec, glass for starters, and I'm not saying the HV20 can compete with the HVX200's DVCProHD codec and bitrate, but there's no doubt it shoots HD, at least every much as any other cam that records to HDV:
http://www.bhphotovideo.com/c/shop/12734/HDV_Categories_Professional_Camcorders.html

Next, it DEFINITELY shoots TRUE 24p. And yes, it does it for $900. It has a progressive sensor, and it stuffs the 24p footage into a 60i wrapper using 3:2 pulldown (just like a DVX does). If you remove the pulldown, you get true 24p, period. End of story. The one downside is it doesn't do 24pa (aka 3:2:2:3 pulldown) and it doesn't set flags, so you need to use a smart pulldown removal tool that accurately determines where to remove frames, etc. Cineform's Nero HD can do that no problem, and the result is true 24p footage (not some fake shit like frame mode).

Lastly, I guess you can put me in the soccer mom camp if you want, but the more and more features they slap into these cosumer-grade cams, the closer they come to the edge of the prosumer lineup available. Is the HV20 a prosumer level camera, probably not, but it's not that far behind, and for me, the form factor, size, the fact it shoots to tape, does 24p, does HDV, as an external mic jack, even has line attenuation on the mic in, all point to this being a pretty sweet little consumer camera.

[John Kary]

BTW that HV20 is a 900 dollar camera... it doesn't shot real 24p or HD for that matter... its a good camera for soccer moms... and the low light performance like all canons you will find its very disapointing .... you would be much better off spending another 500 dollars and getting a used dvx100a

panasonic dvx or hvx are the only cameras that are going to give you real 24p unless you spend over 6,000

Wow, that was a bit harsh, but more importantly COMPLETELY WRONG.

Next, it DEFINITELY shoots TRUE 24p. And yes, it does it for $900. It has a progressive sensor, and it stuffs the 24p footage into a 60i wrapper using 3:2 pulldown (just like a DVX does). If you remove the pulldown, you get true 24p, period. End of story. The one downside is it doesn't do 24pa (aka 3:2:2:3 pulldown) and it doesn't set flags, so you need to use a smart pulldown removal tool that accurately determines where to remove frames, etc. Cineform's Nero HD can do that no problem, and the result is true 24p footage (not some fake shit like frame mode).

Lastly, I guess you can put me in the soccer mom camp if you want, but the more and more features they slap into these cosumer-grade cams, the closer they come to the edge of the prosumer lineup available. Is the HV20 a prosumer level camera, probably not, but it's not that far behind, and for me, the form factor, size, the fact it shoots to tape, does 24p, does HDV, as an external mic jack, even has line attenuation on the mic in, all point to this being a pretty sweet little consumer camera.

From what I've read second-hand by people like Stu Maschwitz, the HV20 has a lot of little quirks about it that make it a bit more demanding than working with a camera with more intentional features like a DVX or HVX.  Things you will run into like the rolling shutter and using the camera's photo-button to check exposure make the $900 a bit of a struggle compared to more expensive cameras.

The HV20 shoots to 4:2:0 long GOP MPEG2 HDV at 1440x1080/24p.  I think what wilsonedits is getting at is that the camera is not "true HD" because it doesn't pump out and record 1920x1080 native off its image sensor.  Where this all morphs into a discrepancy is when talking "HD" vs "HDV" resolutions.

One person might argue that anything above above Standard-Definition NTSC resolution of 720x480 is considered HD (excluding PAL's extended vertical resolution of 720x576, of course.)  Then again, another might say that anything that isn't 1920x1080 isn't even "HD."  Then what about all of these cameras and TV's that do 720p?  1080i?  1080p?  It's easy to get confused.  Let's lay out a few resolutions of HD/HDV, disregarding their different frame-rate capabilities:

Sony CineAlta (MSRP $102000) - 1080 @ 1920x1080
Panasonic VariCam (MSRP $45000) - 720 @ 1280x720
Panasonic HVX200 (MSRP $5995) - 1080 @ 1280x1080, 720 @ 960x720
Sony Z1U (MSRP $5946) - 1080 @ 1440x1080
Canon HV20 (MSRP $1099) - 1080 @ 1440x1080

You might see, "oh, the HVX200 has better horizontal resolution than the VariCam, so at $6000 it's a total steal!"  Yet there's much more to producing a good image than strictly resolution.  Differing features, like the recording medium (including color fidelity due to color sampling for compressed storage), codec, frame-rate options, lens-mounts (or lack there of), workflow... the list goes on and on.  The decision on what camera to use often times doesn't rely solely on resolution, and might include:

1. How much you can afford.  Either to buy, or to rent.
2. What workflow options you have available (again, dependent on money or software competency)
3. What quality you need the deliver the final product at (a huge movie theater screen, or broadcast television)

So where do you draw the line between "HD" and "HDV"?  The marketing hype engine of capitalism leads people to believe that a resolution greater than standard-def is "HD," while the method you capture and store your footage from the camera might be what gets it labeled as as "HDV" or "HD."  I might argue that unless it's 1920x1080 at 1:1 full raster, it's not HD, and is rather "HDV."