23.976 frame rate explained
This post was triggered from this this thread:
http://discussions.apple.com/thread.jspa?messageID=4741388#4741388
I just thought it best to start a new one
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Okay iSchwartz, with the speed of a flying bullet, and with help from my fellow members of the IBS (Institute of Broadcast Sound - in the UK), I think I have some answers...
24P is indeed simply video at 24frames per second with the "P" meaning Progressive scan. Its a video format invented to be compatible with film. It also means that the footage will have more of a "film look" when its converted to TV frame rates for broadcast as it will have the same process applied to it as film footage.
As to where 23.976 fps comes in (with regards to Logic) is rather more vague!
(warning - the following contains some speculation!)
As all will know ⚠ because film is shot at 24fps it needs a special conversion process to be shown on an NTSC TV of 29.97fps. The process could just speed the film up but it would look funny and so they sort of duplicate some of the film's frames instead, to get the frame rate increased. The process used would result in a frame rate of 30fps so to bring it in line with the (cumbersome) NTSC frame rate they have to slow the film down slightly (by 0.1%) before they "scan" in the film's frames to make video.
...and guess what a 0.1% speed reduction of 24fps results in? Yes - 23.976!
so...
23.976 is the frame rate of the telecine machine when playing film to transfer to NTSC tv. The process involves slowing the 24fps film by 0.1% to 23.976 and applying a 2:3 pulldown picture process, resulting in NTSC's frame rate of 29.97fps
Now the question is why would you want Logic to work in 23.976fps?
It is possible (I don't know for sure) that when you shoot with film (ie 24fps), destined for tv that the programme is edited at 23.976, ready for the telecine process, and so this is the frame rate used during the post production process - As it is the time reference used in the edit then we need logic to work at this rate too so we're all in time.
It is also possible that the latest HD video cameras provide a shooting frame rate of 23.976 fps so that the "slow down" process of the past is not required.
Having said that to view the 23.976 fps pictures on telly the video needs to be converted to 30fpsDrop - or you need a display that can work at this unusual frame rate. I am not sure what the implication of all this would be for the musician "working to picture".
One thing I would say, is that musicians are not alone in having much confusion with frame rates and time code, especially now Hi def has arrived. I would strongly advise double checking with "production", particularly the dubbing editor, if that frame rate requested ~really~ is the right one!
I hope I haven't confused the issue even more with all that! Don't take any of this as gospel as I am still learning too. I trust someone will provide corrections and additions.
http://discussions.apple.com/thread.jspa?messageID=4741388#4741388
I just thought it best to start a new one
------
Okay iSchwartz, with the speed of a flying bullet, and with help from my fellow members of the IBS (Institute of Broadcast Sound - in the UK), I think I have some answers...
24P is indeed simply video at 24frames per second with the "P" meaning Progressive scan. Its a video format invented to be compatible with film. It also means that the footage will have more of a "film look" when its converted to TV frame rates for broadcast as it will have the same process applied to it as film footage.
As to where 23.976 fps comes in (with regards to Logic) is rather more vague!
(warning - the following contains some speculation!)
As all will know ⚠ because film is shot at 24fps it needs a special conversion process to be shown on an NTSC TV of 29.97fps. The process could just speed the film up but it would look funny and so they sort of duplicate some of the film's frames instead, to get the frame rate increased. The process used would result in a frame rate of 30fps so to bring it in line with the (cumbersome) NTSC frame rate they have to slow the film down slightly (by 0.1%) before they "scan" in the film's frames to make video.
...and guess what a 0.1% speed reduction of 24fps results in? Yes - 23.976!
so...
23.976 is the frame rate of the telecine machine when playing film to transfer to NTSC tv. The process involves slowing the 24fps film by 0.1% to 23.976 and applying a 2:3 pulldown picture process, resulting in NTSC's frame rate of 29.97fps
Now the question is why would you want Logic to work in 23.976fps?
It is possible (I don't know for sure) that when you shoot with film (ie 24fps), destined for tv that the programme is edited at 23.976, ready for the telecine process, and so this is the frame rate used during the post production process - As it is the time reference used in the edit then we need logic to work at this rate too so we're all in time.
It is also possible that the latest HD video cameras provide a shooting frame rate of 23.976 fps so that the "slow down" process of the past is not required.
Having said that to view the 23.976 fps pictures on telly the video needs to be converted to 30fpsDrop - or you need a display that can work at this unusual frame rate. I am not sure what the implication of all this would be for the musician "working to picture".
One thing I would say, is that musicians are not alone in having much confusion with frame rates and time code, especially now Hi def has arrived. I would strongly advise double checking with "production", particularly the dubbing editor, if that frame rate requested ~really~ is the right one!
I hope I haven't confused the issue even more with all that! Don't take any of this as gospel as I am still learning too. I trust someone will provide corrections and additions.
Mac Pro 2.66GHz 2GBRam, Mac OS X (10.4.8)
