| 24p v. 23.98p
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 | 24p v. 23.98p
by Eric Susch on May 6, 2003 at 3:24:49 am |
We have our first HD shoot on Wednesday. It's for eventual US broadcast on the Discovery channel and as the post supervisor I'm recommending shooting at 23.98p instead of 24p. We are using the Sony HDW-F900. (I'm not even sure if this is a choice on the camera. The specs on the Sony site seem to have everything about the camera except the different frame rates!)
Just thought I'd ask the knowledgeable people here if I'm recommending the right thing...
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• | | | |  | Re: 24p v. 23.98p
by David Mullen on May 6, 2003 at 5:01:34 am |
I'm surprised that Discovery Channel is letting you shoot in 24P / 23.98P -- I thought they wanted everything to be shot in HD to be 59.94i / 60i for that "hyper-real" video look, not the traditional strobey film-look. What HD material I've seen done for Discovery Channel has all been 59.94i / 60i.
As for the difference between 23.98P or 24P, it all depends on if any picture editing or sound editing will be done using NTSC (59.94i) downconversions - if so, use 23.98P.
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• | | | |  | I'd love to post this for you- Cinewave HD Post in NYC
by deadhead on May 7, 2003 at 5:25:31 pm |
Hey Eric,
In case you ever need reasonably priced HD post in NYC, please give me a shout at 212-772-0860.
Richard
Triode Pictures
http://www.edit-video.com
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• | | | | | Re: I'd love to post this for you- Cinewave HD Post in NYC
by Peter Wellington on May 7, 2003 at 11:31:31 pm |
If you plan to offline in ntsc 29.97, make sure to shoot at 23.976. Pure 24p can't be downconvert to 29.97...
Discovery will accept 59.94i, resulting of a 23.976 sequence with 3:2 pulldown.
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• | | | |  | Re: 24p v. 23.98p
by tony salgado on May 11, 2003 at 7:17:07 pm |
Eric,
Shooting in 23.98 or 24.00 psf will present no problem for downconverting to 29.97. However to make life easier in post I would advise shooting in 23.98 which is the more common frame rate used for programs that will release or edit in 29.97.
One of the most important items to be on the lookout for when shooting double system sound (eg DAT or Nagra in addition to the onboard camera sound recording) is the relationship between the camera frame rate and the audio frame rate.
Write the following formula down and remember it by heart.
When shooting at 23.98 psf the DAT or NAGRA must be at 29.97 NDF
When shooting at 24.00 psf the DAT or NAGRA must be at 30.00 NDF
DO NOT MIX UP 23.98 AND 30.00 AUDIO OR VICE VERSA UNLESS YOU WANT TO SPEND THE TIME PULLING UP OR PULLING DOWN THE AUDIO.
The F-900 camera currently only records in NDF when in 23.98 or 24.00 mode.
When would I shoot at 24.00 well if I had a 35mm camera side by side and we wanted common sound at 30.00 then this would be one case or if the material was for 24 frame HD projection where a 35mm camera would be rephotographing the material then this would be another case for shooting at 24.00
The HDW-F500 vtr can be programming to playback a 24.00 psf recording at 23.98 which means it is playing back a tenth of a percent slower. This is exactly what happens when you shoot film at 24 fps and in telecine xfer to 29.97.
The rumors that shooting at 24.00 psf will not allow for downconversion to 525/29.97SD or cross conversion to 1080i/29.97 HD are grossly incorrect.
If you like I have a chart of the HDW-F500 record/playback compatibilty for video/audio and downconvert which clearly outlines what is possible. Provide me with your fax number and I can sent it to you.
Good luck,
Tony
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[tony salgado] "Write the following formula down and remember it by heart"
That is one juicy post. Thaks Tony.
.k.
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"The rumors that shooting at 24.00 psf will not allow for downconversion to 525/29.97SD or cross conversion to 1080i/29.97 HD are grossly incorrect"
Did you ever try?
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• | | | | | Re: 24p v. 23.98p
by tony salgado on May 13, 2003 at 6:49:41 pm |
Peter,
Yes not only have I tried it I have done it successfully on numerous jobs.
The last job I did this was for a HD digital projection where we had to cross convert from 24Psf to 1080/59.94i
The whole concept of shooting at 24 fps and slowing down a tenth of a percent is not a foreign concept as it has been a long standing post production technique used for film to tape telecine xfer's. The fact that shooting in 24Psf and playing back at 23.98Psf 1/10 slower is not a major problem with the HDW-F500 vtr.
Here is another great tidbit of information that everyone should take note of. It is a small portion of the HDW-F500 record/playback compatibilty chart I mentioned in an earlier post.
The point is that if you shoot 23.976Psf and playback at 23.976Psf you can downconvert to 525/59.94i or you can shoot at 24Psf and playback at 23.976Psf and will also be able to downconvert to 525/59.94i. The problem will occur if you shoot at 23.976Psf and playback at 24Psf or shoot at 24Psf and playback at 24Psf in either case downconversion to 525/59.94i will not be possible.
Record Frequency Playback
23.976Psf 23.976Psf 24 Psf
main 2:3PD downconvert main 2:3PD downconvert
output output 525/59.94i output output 525/59.94i
video video video video video muted
audio audio audio audio audio muted
24Psf video video video video video muted
audio audio audio audio audio muted
I hope this will clear up the confusion regarding 23.976Psf and 24Psf.
Tony Salgado
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• | | | | | Re: 24p v. 23.98p
by tony salgado on May 14, 2003 at 3:24:22 am |
Opps,
The chart did not post the way I formatted it in the cow email box.
I will have to try again.
Sorry,
Tony
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• | | | | | Re: 24p v. 23.98p
by Eric Susch on May 13, 2003 at 1:10:09 am |
Tony,
Thanks for the complete and concise explanation…
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• | | | |  | Re: 24p v. 23.98p
by Chi-Ho Lee on May 13, 2003 at 4:22:22 am |
Tony,
I am in a situation where I have most of my sound on DAT at 29.97 and one at 24. What would you recommed?
Most of the sound were recorded straight into the camera (F900) and I plan to use the sound on the HD Master for the online since the quality should be just as good as the original DAT sources...would you agree with this?
A few tapes did not have sound fed into the camera and will have to be synched manually during the offline. How would you recommend getting the DAT sources into the offline edit system without SpDif or AES/EBU? It is a FW only system.
Someone recommended getting the DAT sources onto CDs and use the CDs as the new masters....this sounds like a good plan - would the audio files on the CD retain their original TC?
Thanks,
CHL
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• | | | | | Re: 24p v. 23.98p
by tony salgado on May 13, 2003 at 7:05:10 pm |
Chi,
First question what was the frame rate on the HDCAM camera master's? 23.976Psf or 24Psf???
If the F900 was set to 23.976Psf then all the DAT's at 29.97 will have no issue with pulling up or down.
However if the camera was set to 24Psf then you have the pullup/down issue to deal with.
Did you shoot a smart timecode slate with timecode reflecting the DAT timecode prior to each take?
Regarding the audio quality difference of the onboard vtr audio recording versus the DAT I would say that yes indeed the quality should be as good or better than the DAT. However depending on how your audio post production workflow will be handled using the DAT's may or may not be a better method. I would have to also say that depending on how the sound mixer monitored the camera audio in the field (did he have a return audio feed from the camera to verify the quality of the audio recordings) this would reflect which audio recording would be the best to use DAT or HDCAM. I have found that some audio mixers will consider the DAT's as primary and the camera audio as secondary so they don't monitor the camera audio once the cables are hooked up. In the world of EFP betacam the practice of recording to camera is taken for granted so using a "betasnake" cable which has the return audio feed makes life alot easier to confirm the camera audio recording. This same cable could be used for HD but the concept of using the camera audio as primary requires informing the audio mixer to this fact and making sure he has a return audio feed from the camera in addition to the "confidence" return from the DAT.
I do not know if the DAT to CD xfer will retain the timecode however in anycase depending on what the frame rate of the HDCAM tape's were you still have to deal with pulling up or down the audio to match.
I recommend calling an audio post facility and asking them the best method for pulling up or down the audio to match the HDCAM camera master's.
Good luck,
Tony Salgado
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A quick question on 23.98 drop frame vs non-drop. Is the formula for 23.98 drop frame the same as for NTSC? Namely, drop two counts at every minute except the tens (10, 20, 30 etc)? I would think it would be but I just want to make sure. Thanks
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• | | | | | Re: 23.98 Drop Frame
by tony salgado on May 17, 2003 at 12:24:06 am |
Well that might be the case if Drop frame tc existed in 23.98 and 24Psf. Currently drop frame timecode is not possible in 23.98 or 24psf strictly only non drop frame.
Tony Salgado
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