DODCAP - Interpolated padded frames

[Dave Anderson]

I see that there is something called "interpolated padded frames" with DODCAP that only becomes an option when I pick a CODEC other than the 'default capture card" CODEC. My project needs to product a file for BOTH television, DVD and web. Would it be recommended that I produce two separate pulldown conversion files (one with, and one without interpolated padded frames)? Seems like that would be a lot of work, especially if I have a lot of post production color correction, editing to do on a file... I'd have to do that stuff twice!?

My thought is to produce for Television using "interpolated padded frames" and then take the final post-production AVI and create MPEG2's from that knowing that there might be some interlace artifacts.

What are you DODCAP user's doing these days?

Thanks

[MovieStuff]

Your best option is to capture without any pulldown at all so that you get one film frame for each video frame. The click on the icon in the upper left hand corner of the DodCap app and a drop down menu will pop up with "Batch Processing" as an option. Drag your folder with all your clips into one set up for what ever speed you want (15, 18, 24fps, etc) and then hit the process button. That will generate a completely new clip or set of clips with the interpolated frames built in.

The interpolate frames allow the film to play back smoother at the new rate. Though DodCap CAN perform pulldown during capture, it is much more resource intensive and is more likely to cause synch issues during capture. Performing the speed change after the fact allows you to use interpolated frames (not possible during capture) AND protects your original transfer so that you can generate a different version for the web or if you happen to guess wrong on the playback speed of the film. That is actually an issue for non-sound 16mm films because there were no silent standards. People could shoot at 12, 16, 18, 20 or 24fps and often did just to economize on film usage. Doing the speed change after the fact, as opposed to during capture, preserves your speed options without having to retransfer.

Roger

[Dave Anderson]

Thanks Roger. I'm still hazy on the "interpolated frame padding" check box in Dodcap. I understand what it does, but what I don't understand is that if you use Batch Process as an option, it automatically applies the frame padding whether you want it or not? Is there a way to turn that off and just have it do the pulldown only?

In other words, right now I'm capturing with the 'default capture card codec' setting and the 'interpolated frame padding' is greyed out. So if I go back later and do the pulldown, I'm assuming that it will not add the padded frames. Correct?

I also wrote to Jeff about some addition issues, however he mentioned that with reg 8mm film since the frame rate is 15fps, having the check box checked makes no difference anyhow since none are added.

Thanks

Dave

[MovieStuff]

Just capture with the default codec with no pulldown/speed change. Then open the Batch Processing function and apply the speed change after transfer. Your original clips will not be affected because DodCap will generate a new set.

Roger

[digvid]

Hey there Mr. Dave -

Just thought I would try and clarify these Dodcap issues.

First, if you apply any type of pulldown, whether you check the "Interpolate" box or not, Dodcap will create a new file that contains all the originally-captured frames plus "padding" frames. These extra frames "pad" the film frame rate out to match what it should be for video (i.e., approximately 30 fps for us folks in the US, and 25 fps for most other people). Dodcap never erases your original capture file when doing pulldown.

The difference between regular pulldown and pulldown with the "Interpolate" box checked is that the interpolated option makes some of the padding frames interlaced. This means that every other scan line of the padding frame is made up of lines from the previous frame, and the other lines come from the next frame. This produces a frame that looks rather odd when viewed on the computer screen, but actually produces smoother-looking motion when played on a camcorder or television.

Note that you can apply normal pulldown without interpolation and the files will look good both on the computer screen (and the web) as well as when played on a television. However, if you are a perfectionist and want your footage to look as smooth as possible on the TV, you can use the interpolated checkbox.

One other thing to note about the interpolated checkbox: it is grayed out unless you specify a compression codec to use during the pulldown post-processing. As I said, the interpolated option sometimes creates padding frames that are made up of scan lines from two different frames. Dodcap can't combine frames in this way if the frames in question are compressed, so it has to decompress them before performing interpolated pulldown. You specify a compression codec so that Dodcap can then (after pulldown) compress the resulting frames again and store them in your AVI file. This decompression is not necessary when doing normal pulldown, so you don't have to specify a compression codec then (i.e., you just choose <Same As File> for your compression option, which really means "don't decompress any frames--just use the original frames as-is").

One note about batch processing also. With batch processing, you are never forced to select the interpolated checkbox. Actually, you aren't forced to select it with "Single-File Pulldown" either. In any case, you can choose just about any combination of options in batch processing. You can apply burn-in timecode without applying pulldown, you can apply normal pulldown only, you can apply interpolated pulldown, interpolated pulldown with mirror image and burn-in timecode, and on and on.

I hope that illuminates things rather than confuses them. After writing long, rambling posts, I sometimes lose sight of whether or not it made much sense. In any case, I have invested too much time in this post to erase it and start over, so I guess I'll let it stand. Later!

- Jeff Dodson