Help with Canon HG20 30p ghosting/flickering?

[Vakharn]

So I've been shooting video with a Canon HG20 mostly in 30p mode. I shoot in 30p for upload to youtube, and while I have other problems with youtube upload my biggest problem at the moment is not a youtube issue. The video shot with this camera in 30p has ghosting/flickering on fast motion. The ghosting or flickering is visible with in playback on an HDTV, in playback through VLC and other applications that can play AVCHD video, and when uploaded to youtube. I think it has something to do with the fact that 30p video shot on vixia cameras is actually packaged in a 60i stream with both fields taken at the same time so they can be recombined into a 30p stream. Does anyone know if that's correct, or if not, what is causing this? Here's a clip to show what I mean. It's most clearly visible about 1 minute in when watching the edges of lettering on the side of the train.

[jagabo]

30p flickers like that, especially with high contrast sharp edges. See the video in this post:

https://forum.videohelp.com/threads/307004-Best-framerate-conversion-%28eg-23-97-to-30-...=1#post1888926

I'm sure you've stepped through the video itself and seen that's there's nothing wrong with each individual frame. This is just a natural result of 30 fps video. The same thing happens with film at 24 fps, only worse. Professionals minimize this by avoiding that type of shot, using depth of field to keep the moving background blurred, panning the camera along with the moving object, using a tiny aperture (or ND filter) and long exposure to increase motion blur, etc.

[Vakharn]

I didn't realize 30 fps was that low for such a shot. I'll just have to avoid such shots when shooting in 30p in future. Thanks for the info.

[poisondeathray]

It's hard to say from the description, but he might be referring to the "smearing" of the letters on the side of the train, beside the numbers "303" (or any of the side boxcar numbers). There is an orange patch, as if the chroma got smeared, and when viewed normally, looks like it's "ghosting" but really isn't. And it's present adjacent to all the numbers in virtually every frame

If this is what you're referring to, this would not have anything to do with 30p in 60i; it's more likely a motion interpretation error, combined with low bitrate from the encoder

My question is do you see it in the native stream from the camera (before YT butchers it) ?

1:1 crop of a frame of the YT 720p version

[Vakharn]

No, that wasn't what I was referring to, that's just a youtube issue. Jagabo answered my question.

[edDV]

Ditto Jagabo.

The issue isn't "flicker" but low motion sample rate combined with sharp edges. The additional artifacts you see are player related (e.g. edge shimmer), as the player attempts interpolation to the 60Hz computer monitor. Shooting 59.94p reduces the problem by half. Like Jagabo said, the pros mask the problem with narrow depth of field lenses.

Similar to this problem is moire beats when panning detailed backgrounds. Again this is solved byslightly blurring the background.