Exporting to HDCam framerate

[Tim Kolb]

The decimal isn’t a “half” or fractional frame…it’s a fraction of time.

I’m not really sure how Matrox handles these things as I don’t have any Matrox gear, but here’s how I’d do it…

Start PPro and create a custom project setting.

Under editing mode, set it for “Desktop”

Set the timebase to 24 if the audio is tied to that framerate, if you’re laying in the audio, set it for 23.976

Set the frame size for whatever the frame size is (I’ll assume it’s 1920×1080)

Fields: No Fields (Progressive)

Import your frame sequences and edit the piece. Export it as Microsoft AVI, compression: NONE…don’t use the matrox codec for now…

Once that is exported…check the sound sync in a media player, or create a NEW project with a 23.976 timeline if you edited at 24 fps. When you import the rendered clip, if it’s 24 fps, right click on it and select “Interpret footage” and set the framerate to 23.976.

I can’t remember what happens to the audio in these circumstances in v1.5, it’s been a while, but if the clip is synced properly on the way out, you should be able to keep it synced.

The weird length thing could just be from editing at 24, exporting at 23.976 and bringing it back in and setting it into a 24 fps project…23.976 isn’t 24 and it might act strangely (though it SHOULD be somewhat longer on the timeline.)

Try this and report back…

TimK,
Director, Consultant
Kolb Productions,

CPO, Digieffects

[Alyssa Barber]

Hi, Tim,

Thank you so much for answering my post. I tried what you said and did the following:
1) Render an .avi from the 24 fps (synced) composition, at 24 fps, no codec.
2) I imported it into a composition set for 23.976 fps, “Video for Windows” editing mode (I only get that or DV mode, no “Desktop”).
3) Then, I interpreted the 24 fps movie as 23.976 and dropped it into the comp window.
4) Now, the picture was indeed longer, longer than the original soundtrack, but my mixer provided me with a mix that was stretched by 8 frames. That one fit.
5) There were only two small areas where the sound was off by two and one frame respectively. I added/subtracted a couple frames in those areas without affecting the overall length.
6) I re-rendered the 24 fps .avi with edits–at 23.976 fps, using the codec. After importing that one into the comp, though, I found it to be three frames shorter than the edited 24 fps .avi. This 3-frame discrepancy is consistent with what I have been seeing all along–the 23.976 .avi is always 3 frames shorter than its 24-fps counterpart, with or without codec. Right now, I am going to import some other sound mixes with slight length variations to test them against this new .avi. But I’m not really confident this is going to work. Have I done everything you said correctly?
Thanks again! If you have any other suggestions, please don’t hesitate to write.
Sincerely,
Alyssa

[Jeff Brown]

Tim has a lot more experience with this sort of thing, so defer to him, but my approach would be:
Load in your video to a 23.97 project. Interpret as 23.97.
Create a version of the audio that is re-rendered (audio only) for 23.97. Add that to the Premiere project. Check for sync.
The thinking behind this is that the visuals need a frame-to-frame correspondence to work; the audio is not frame-based. You can consider the audio “continuous”, so you have to actually convert the data to a new frame rate, commonly by a “rate conversion” or a “fit time” tool. And these are best done in dedicated audio software.

Not that it helps at this point, but if you are doing a video master, you can “think” at 24 FPS, but you have to “work” at 23.97. Which you probably have realized!

Also, I’m assuming you are looking at the actual clips on the timeline when referring to the 3-frame discrepancy, and not judging by timecode, which if drop-frame, can add another level of confusion. Sidebar: unless you have to meet broadcast timing, it won’t matter if you use drop or non-drop. You’d probably rather work in frames anyway.;>).

-jeff

[Tim Kolb]

[Jeff Brown] “Tim has a lot more experience with this sort of thing, so defer to him, but my approach would be:
Load in your video to a 23.97 project. Interpret as 23.97.”

Nothing wrong with Jeff’s approach…scale the audio to the framerate right away on a 23.97 timeline. Actually my thinking was just to verify that all synced at 24, but as Jeff points out, the audio needs to be scaled anyway.

The key is how all this drops in to the Matrox codec. Matrox makes a great and fast system, but it isn’t necessarily optimized for importing files from not-tape/video workflows in my personal experience as the whole RT engine is set up to crank through typical video and to accelerate ‘typical’ SD/HD video post.

TimK,
Director, Consultant
Kolb Productions,

CPO, Digieffects

[Alyssa Barber]

Dear Tim and Jeff,

I’ve been talking to a couple of people who work at Adobe, and I’ve tried what they suggested as well. They were of a different mind on interpreting the footage, for instance. Nothing seemed to help. Even in the tests I ran, with blank frames added to the sound, it still ended up mis-timed. In the end, they suggested that I might have discovered a bug in the program, and that I try the upgrade. They also think it might be the codec. I did not tell them that I had run the render at 23… both with and without the codec, and the sync/length came up the same both times.
Undoubtedly you’re using a more advanced version than I am. Is the functionality with regard to frame conversion to HD and sync any better in CS4?
Thanks again for giving my problem so much of your time.
Sincerely,
Alyssa

[Tim Kolb]

[Alyssa Barber] “Even in the tests I ran, with blank frames added to the sound, it still ended up mis-timed”

As Jeff mentioned, the audio really doesn’t run in frames…it’s continuous. If the video is a bicycle chain, the audio is a rubber band…can’t add links to a rubber band, just stretch it.

An interesting issue on the PPro timeline ever since it has become PPro is the “audio units” feature on the timeline does dictate that the timeline “think” in audio units, even if we have it switched to show us in video frame-time increments. This has been a bit of a hang up for me in the past, particularly in 24/23.976 media situations. I’ve had situations with older versions (version 4 was released today) where the timeline gave me a “partial” video frame on the timeline and simply wouldn’t playback, the play head would simply ‘snap’ to the end and that was that.

It sounds like you’ve effectively eliminated the Matrox codec from participation at the moment.

You can always upgrade of course…I’m wondering if you can achieve sync at any framerate…if you could take that clip back to AE and output it?

TimK,
Director, Consultant
Kolb Productions,

CPO, Digieffects

[Jon Barrie]

I have to extend my opinions here with Tim. I think you should have the 24fps timeline in a Comp inside AE. Run some tests in exporting out the head (30 Seconds), and then at the tail (last 30 sec) with the audio embedded into the same 24fps based Comp so you can see that it all syncs up ends to ends.
Exporting the top and tail tests with a 23.976 frame rate should show the sync slip if its occurring in the AE comp. You could nest the original 24fps comp into a 23.976 comp. Then do another test export of the top and tail 30 sec.
It seems there is a slight squashing of time in the vision frame rate which is easier to work with than trying expand and invent new frame information. I’d play with confirming the sync and then exporting in AE to an uncompressed format (huge file sizes, but only way to be sure you are going to get to matrox without loss). Once you have the uncompressed format version that is a 23.976 fps clip it should be a matter of exporting that to the matrox based codec.
These are just theories and not practiced methods. AE would be your best chance to convert the frame rates. I noticed you are using PPro1.5 that’s a very old app now, newer versions might not share the same problems?
– Good Luck

Jon Barrie
aJBprods
http://www.jonbarrie.net