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Compressor's best 23.98 to 29.97 conversion?

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Alan Langdon
Compressor's best 23.98 to 29.97 conversion?
on Mar 21, 2010 at 7:38:44 am

I have HD footage shot in anamorphic 960x720 (in practice becomes 16x9 proportion), and the frame rate is 23.97. So far, I have been having a hard time converting the footage in a way that the 6 added frames don't make pans and movement in general look a little choppy. Observing comercial DVDs, I notice that the repeated/added frames are interlaced, which smoothes out a bit thi jumpyness, making pans look smoother.

Now, my questions are 3:

1- Is there a way to make those added frames interlaced using compressor, achieving a similar smooth motion?

2-But then, since most TVs are now LCD and Plasma, not exactly interlaced, is this a good idea afterall?

3- Another artifact I am getting from Compressor's convertions is a sort of pulsing of the image every 15 frames or so, probbly due to the GOP structure of the VBR of Compressor. Now, I am sure VBR is the best way to go, so how can I liminate this pulsing, which is unacceptable? Others here at the Cow have suggested I use CBR, which I am doing, but is taking a long timt to convert because I incremented the quality of other settings availabl... My 20 minute short film is taking about 30 hours to convert!

The first COmpressor converstion I made with this 23.98 footage didn't even change the framerate (I left it all at automatic, using the 90-minute Best setting), so my DVD player (and NTSC tube television) had to deal with the 23.98 framerate and they seemed to really struggle and make things (pans, etc.) look choppy.


Whee. I know it's a lot to ask, but anybody have some ideas?


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Andrew Saliga
Re: Compressor's best 23.98 to 29.97 conversion?
on Mar 22, 2010 at 3:47:26 pm

By 23.97 I assume you mean 23.98 (23.976). If your'e going to DVD leave it at 23.98. Duplicate an existing Compressor preset or make your own if you're comfortable doing so. In the "Encoder" tab you can select 23.98 as your framerate. Keep it progressive. DVD players will add the pulldown.

30 hours seems long, but it'll go faster if you're keeping it at 23.98 and not having to interpolate the extra frames.

-Andrew Saliga

Steelehouse Productions
http://www.steelehouse.com (undergoing a much-needed redesign)
http://www.vimeo.com/steelehouse


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Mark Spano
Re: Compressor's best 23.98 to 29.97 conversion?
on Mar 23, 2010 at 5:01:52 pm

[Alan Langdon] "1- Is there a way to make those added frames interlaced using compressor, achieving a similar smooth motion?"

Yes, but as previously commented, if you're going to DVD, you should stay at 23.976p. It's in the DVD spec, and all DVD players can add pulldown seamlessly. Plus, having 6 less frames per second means you can spend more bits during compression on quality.

[Alan Langdon] "2-But then, since most TVs are now LCD and Plasma, not exactly interlaced, is this a good idea afterall?"

You have the right idea in theory: if your DVD player outputs progressive frames (most these days do) and it's hooked up via HDMI or component to a progressive display, there will be no interlace/deinterlace processes happening, and the picture will be sharper. If either of those things aren't true, then the DVD player will add interlacing and the display will deinterlace.

[Alan Langdon] "3- Another artifact I am getting from Compressor's convertions is a sort of pulsing of the image every 15 frames or so, probbly due to the GOP structure of the VBR of Compressor. Now, I am sure VBR is the best way to go, so how can I liminate this pulsing, which is unacceptable? Others here at the Cow have suggested I use CBR, which I am doing, but is taking a long timt to convert because I incremented the quality of other settings availabl... My 20 minute short film is taking about 30 hours to convert!"

Your short is 20 minutes - my advice is to compress with CBR, with an IP GOP structure. I usually use about 6.5Mbps for video and make sure that the audio is compressed with AC3. Total bit rate won't exceed 7.5Mbps even with multiple audio tracks and all DVD players can handle playing it back. Motion estimation should be set to Better - only use Best if you want to wait a while. Turn on Frame Controls and set Resize to Better, same as source fields, fast for everything else. Output frame size should be 720x480 with 16:9 pixel aspect ratio. A good thing to check as well is how Compressor is interpreting your source footage. Before you add your compression setting, check the inspector and make sure it's set to progressive. Occasionally it reads things incorrectly and winds up doing a lot of unnecessary processing as a result.



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