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MPEG-2 Encoding problems (white background has stripes)

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PJ Palomaki
MPEG-2 Encoding problems (white background has stripes)
on Mar 18, 2009 at 10:35:37 am

Hi guys,

I'm having problems compressing an 1920x1080i25 ProRes 422 (HQ) Apple's Motion-created DVD Studio Pro menu background loop to MPEG-2 without the white background having faint grey lines.

Workflow:

PS CS3 RGB 1920x1080 background PSD (white 255,255,255) ->
Apple Motion, elements animated -> Export ProRes 422 (HQ) 1920x1080 interlaced -> no lines yet
ProRes file -> Compressor -> MPEG-2 Encode (One Pass CBR 7.5, Field order top as original, frame controls on; all set to 'better') -> Stripes appear

I understand that it would be better to export with animation codec or PNG from motion, could it just be ProRes issue? I've noticed that ProRes doesn't deal well with animation (esp. with reds in the animation).

Interestingly, the grey lines do not appear on a 40-inch flat screen when the DVD is played, but does appear on a computer LCD (Cinema display or Laptop LCD).

Here's a frame export from the MPEG-2 video



Any ideas?



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Daniel Low
Re: MPEG-2 Encoding problems (white background has stripes)
on Mar 18, 2009 at 2:46:08 pm

You can't use pure white (255) with most delivery/broadcast-type codecs, the transcode process will knock this back to a broadcast legal value of 235. Nor should you use pure black but rather the lowest legal value of 16.

Remember that you are converting from an RGB value and colour space to the colour space of YUV.

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PJ Palomaki
Re: MPEG-2 Encoding problems (white background has stripes)
on Mar 24, 2009 at 5:41:00 pm

Thanks, I'll keep that in mind next time, though I've never had problems with encoding pure white out of motion to MPEG-2 before, it just seemed odd that the grey stripes would appear on this particular project...



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