A tricky HDCAM question for the over-clever folk here

[Michael Gissing]

Speeding 25 up to 29.97 or vice versa is a lot more than 4%. 24 to 25 is 4%. 16.5% approx is 25 to 29.97.

You need to a real time hardware standards conversion from 50i to NTSC DV so there is no time difference and no audio re-pitch.

[Baz Leffler]

Hey Michael – Ah yes, I was confused with my own spock logic – of course – it was 24 to 25 down conversions I was doing previously and the 16.5% difference in sound is too much for the deck to handle although the pictures provide a nice smooth conversion.

I guess its back to Procoder and over night batch conversions!

Baz

What would I do without the ‘UNDO’ button!!!!

[Thompson Coles]

I’m just going to consider this “thinking out loud”
Would it be possible to make this a two step playout, the first time record to a 24p setup on HDCAM. this makes the whole 25 -> 24 process and audio a little easier. then you could transfer again from 24 -> 29.97 with the pull down inside the deck. I’m not sure if the audio transfer from 25 to 24 would create the same issues.
Well enough thinking out loud, let us know how you work it out.

Thompson

[Michael Gissing]

I am not sure why it is necessary to change speed at all. A 4% audio pitch change is 3/4 of a semi tone which is just horrible to music and it means the program length changes.

I still think a real time dub through a standards/down converter straight from 50i to 29.97 is not only the best technically, but a real time saver which must be worth the cost of doing it right.

[John Pale]

You busted your butt making a whole series of shows and now you want to take the finished product and do a makeshift standards conversion….take a deep breath…if you have any way of affording it, get it done right.

[Baz Leffler]

[John Pale] “You busted your butt making a whole series of shows and now you want to take the finished product and do a makeshift standards conversion….take a deep breath…if you have any way of affording it, get it done right.”

Yeah well what was missing from the original post was the purpose of the exercise – it is just for preview purposes – non broadcast and as such didn’t warrant such an expensive exercise. The Procoder conversion will suffice as it has in the past.

Whoever invented ‘batch processing’ should be given an “Obama certificate of merit”!.

And Thompson thanks for thinking out aloud; fortunately I own the decks so it wouldn’t cost me to try your thoughts but I would hate to pay the rental on a theory – risk takers we all are,,,,

BAz

What would I do without the ‘UNDO’ button!!!!

[Gary Adcock]

[Thompson Coles] “Would it be possible to make this a two step playout, the first time record to a 24p setup on HDCAM. this makes the whole 25 -> 24 process and audio a little easier.”

OK guys-
this is done all the time.

conform the 25fps to 23.98 in Cinema Tools- the 4% audio slowdown here is customary and usually accepted.

Let the deck do the 23.98- 29.97 pulldown insertion so there is no additional conversion of the audio.

gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows

Inside look at the IoHD
https://library.creativecow.net/articles/adcock_gary/AJAIOHD.php