Frame rate change

[Michael Sacci]

[Todd Udall] “Also, I believe frame rate conversion can happen on the fly when mastering to D5 or digibeta (depending on format). Is this true?”
Yes that is true and this is the best way to do this. I have done this a bunch of times with either the AJA Kona3 and IoHD. It also handles the letterboxing also.

This will give you the highest quality downconvert. Going from 60p to 60i is super clean also.

[Todd Udall]

So, frame rate isn’t an issue either way? I know we’re doubling or halving it.

Thanks!

Todd

[Jeremy Garchow]

[Dave LaRonde] “SD video is interlaced. A 29.97 frame rate means 59.94 fields. The AJA card simply uses one of the 59.94 frames to create a field. Very neat.”

Actually, 720p29.97 will turn in to SD 29.97 psf. 720p60 will turn in to traditionally interlaced video in SD.

[Michael Sacci]

Edit at 59. if that is what the footage was shot at. Going from 60p to 60i is super smooth. You are really not changing the frame rate.

Each of the 60p frames gets converted into one of the interlaced fields. Since both are timed the same the footage is actually interlaced, just as if you shot it that way.

[Jeremy Garchow]

[Michael Sacci] “Each of the 60p frames gets converted into one of the interlaced fields. Since both are timed the same the footage is actually interlaced, just as if you shot it that way.”

Not if you shot 720p29.97 (either pN30 or 30p over 60p). You will end up with a 29.97 psf Sd movie.

[Jeremy Garchow]

[Dave LaRonde] “I suppose there IS a difference between a “frame segment” and a “field”, but it beats the heck out of me what that difference would be.”

Aesthetics. Think about it.

If you shoot 60p, true 60p, you end up with each frame becoming a field, that will be 60i is SD.

Frames ABCD (each letter being a frame) becomes fields AB CD, etc (each letter being a field).

If you shoot 30p over 60p (that’s 30p with 2:2 pulldown) that means that every frame gets made a field, and since it’s 2:2 pulldown, each frame is doubled in the 60p stream, so that means each field is doubled which will become 30psf instead of 60i. It will be the difference between shooting 60i or 30p on your dv camera (if you still have one).

Frames AABB becomes fields AA BB, that is 30psf.

When shooting 24p over 60p (progressive 3:2 pulldown), you will get interlaced 3:2 pulldown in SD

Frames AABBBCCDDD become fields AA BB BC CD DD. That is 24p with pulldown.

I have heard you say you aren’t a big fan of 720p, but I am a huge fan of it. Don’t you think it’s odd that most US broadcasters choose to broadcast @ 720p instead of 1080i? It’s not to save bandwidth as it’s the same. Don’t you think there’s a bit of motivation behind it?

Jeremy

[Todd Udall]

Apparently there is more than one way to de-interlace a cat..

Since the majority of the footage was shot 720p at 29.97, I will edit my HD show at that rate, output via AJA IO to create the letterboxed SD version, then output the HD version at 59.94.

I appreciate everyone’s feedback.

Thanks!

Todd

[Jeremy Garchow]

[Todd Udall] “Apparently there is more than one way to de-interlace a cat..”

Actually, you are reinterlacing when going from 720p to 1080i.

[Todd Udall] “Since the majority of the footage was shot 720p at 29.97, I will edit my HD show at that rate, output via AJA IO to create the letterboxed SD version, then output the HD version at 59.94.”

That will work. Just know your SD footage will appear progressive. There’s a difference!

Jeremy

[Jeremy Garchow]

[Dave LaRonde] “But I’m not holding my breath that affordable 1080 59.94p is coming any time soon.”

Me neither, it will be sweet when it does, though.

Everyone will have to buy a new tv….again.

[Michael Sacci]

I guess I’m assuming I’m clearer then I was. I’m talking about 60 unique frames going into 60 fields. And not 60 with a pull down added.