I shoot regular DV on a Canon XL2. I shoot at 60 fps interlaced. I see in the forum others working at 24 fps, which I could also shoot except I get blurring on panning. However, I wonder if shooting at 24 would render better for dvd recording. What is recommended?
> "perhaps your camera is shooting 24p inside a 60i stream?"That's how many cameras -- in fact most all cameras that record to tape -- encode their 24p. That's why pulldown removal is mandatory when dealing with these cameras.
John, as I said I accept this, but I was asking "how"? How is this done? I am not saying that this DOESN'T happen, I really want to know the "how"? You are telling me that it does - I accept that.
Here is my "camera" setup for 60i. The tape goes over a head and records 60i. What/how is it making the 24p from that? Is there an encode that is laying down a FURTHER layer on top of what was being captured AT 60i? Is the 60i just a method of transportation of the 24p?
Hey Grazie I'm with you on this one. You have to some serious pull the other one to get this right. What's the difference between 24P & 25P? Surley not just one frame.
What I learned is that 24P came about when they converted cine 24 Frames to video. The nightmare started because of the power source difference in the USA NTSC (60 hertz) and UK PAL (50hertz). This is when everything went muddy.
"What's the difference between 24P & 25P? Surley not just one frame"
It is THAT simple, just one frame per second. This means that in PAL land a movie shot at 24fps can be telecined and brodcast at 25fps, well to be precise 50i. The 4% speedup is almost impossible to detect. The 4% pitch shift in the audio is more of a problem.
You're entirely correct, 25fps and 30fps where chosen for television systems because of the related power frequencies. As explained above this made it very easy to broadcast film at 25fps. Speeding up film from 24fps to 30fps would have made motion way too fast to be acceptable so another system had to be devised and that was to add pulldown.
Q) How does a tape being written to at 60 fields per second get 24 frames per second written to it?
A) A "black box" of electronics between the sensor being scanned at 24fps does the pulldown thing and outputs 60 fields per second to be written to the tape.
That's a fairly trite answer. There's already a lot of electronics between the sensor and the tape. Digital video cameras today have a lot of 'digital' stuff between the analog sensor and the digital tape. Much different to the old analog cameras. It was kind of amazing at NAB a few years back to look into the guts of one of the earliest tube cameras. There was a remarkably small number of components campared to the millions of transistors in the cheapest palmcorder of today.
Thanks Johnny. I had known about the shifting of and the "dealing" of Frames, like a crooked blackjack player. It was the answer that Bob, finally, gave that underpins all this for me:"[i]the sensor being scanned at 24fps does the pulldown thing and outputs 60 fields per second" and THAT is what I wanted to hear/read. I couldn't work out, in all that is Logie Baird, just how a 60i camera deals with the 24p. It still tapes at 60 fields per second. Now THIS might have been obvious to all you guys, but from where I was standing I couldn't understand that that, no matter how bleedin' obvious it is/was to others, I couldn't get my mind around.
ahhh..back to the original question...
blurriness at 24p.....the XL2 records an interlaced format in which each field is only half the resolution of the full frame, and temporally acquired at 1/48 sec intervals, and I dont mean shutter speed, but field acquisition speed. If you're recording at a progressive mode, what happens to the two fields in the XL2. Does the camera throw away one field of info when it deinterlaces?, or what algorithm is used to de-interlace the two fields? This is probably the source of the increased blurriness at 24p..it's from the resolution, which gets halved when one field is discarded or interpolated, and the motion effects introduced when acquiring at 1/48 sec and discarding every other field .
More modern cameras, that acquire true 24p and record 60i, record two full frame, identical fields, so that interpolating and inverse telecineing restore a full resolution 24p framerate.