24p via 60i, what a pain in the ass!

loocas | opinions,software,technical | Thursday, August 20th, 2009

Why is it such a big deal to make a consumer level camera (hell, even some pro-sumer level ones) that does a true, native 24p video?

I have a VIXIA HG20 that records everything via its 60i mode. I have no idea why, or what was the technical reason for this, but it’s a pain!

Ultimately, when I record at the 30p mode, I get a 29.97 progressive video (no fields), however, when recording at 24p, I get interlaced 29.97 embedded in the 60i mode! WHAT THE HELL? Well, no big deal, I thought, I’ll record everything at 24p (via 60i) and have it converted to the regular 24p. Well, it would be a good idea if the software I run here worked as advertised! For instance, ProCoder 3 has a known issue decoding native 1920×1080 AVCHD video (it has no problems with 1440×1080 with the 1.33 PAR though), so I can’t use that, not directly at least. Which sucks real bad as ProCoder can apply pulldown filters and generally does a pretty good job of removing fields.

So, I had to use Adobe Media Encoder, that reads the 1920×1080 AVCHD perfectly fine, but, on the other had, has problems removing fields! So I exported the embedded 29.97 interlaced footage in a file sequence (I have no idea if this is the right way of doing things, not sure if the AVCHD container treats fields in a different way than simply writing down each single file with odd/even lines “messed up”, so, if you know better, please do let me know in the comments below), then I took this sequence and fed ProCoder with it. Setting up the input parameters properly is the key. Then I applied the Pulldown filter and specified another output, this time I set it to 24 progressive and exported.

The resulting footage looks crisp and doesn’t suffer from repeating frames (like when exporting via Media Encoder). However, this way, I’m not 100% sure I’m keeping the proper timing of the original footage, since the sequence only looks to be fine to me, but technically? I have no idea! :( I’ll have to investigate further, but generally, this is a real pain in the ass for non-video dudes (like myself) that only want to shoot footage for later post-fx manipulation/treatment.

There are also some more severe problems like the rolling-shutter distortion that all CMOS cameras suffer from (even RED!), which is another story… But basically, there’s no way I could affort to buy a film camera and scan it every time for the proper workflow


  1. hdmi and sdi require it to be transported over the cable as 60i, thats why cameras do this.

    Comment by Deke Kincaid — August 21, 2009 @ 22:19

  2. Thanks for the clarification, Deke, I appretiate it.

    Comment by loocas — August 21, 2009 @ 22:33

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