Advanced CCE Settings - ZigZag etc

[MarkGrigsby]

Can someone please explain how / why it is important to use the correct 'Zigzag / Alternate' settings, as well as the Progressive flag, in the advanced options in CCE?

I have already done a lot of converting from 720p video-based HDTV material to NTSC DVD, and had both these settings 'wrong'. But the output still looked good! Is there something I'm missing?!

[Axed]

It just encodes the media correctly. I believe there are issues with colour bleeding, and artifacts if you encode an interlaced movie as progressive or vica versa.

My impression on the progressive option is a flag for your DVD set top box. So if your using a progressive scan DVD player, it will know what it has to deinterlace, and what it doesnt. But, these are just guesses on the reason of the flag.

[fccHandler]

Zigzag is suitable for progressive video, and was the order used in the (strictly progressive) MPEG-1 standard. "Alternate scan" changes the order of the DCT coefficients for better RLE compression (in theory) when the source is interlaced. Therefore, use Zigzag if your video is progressive, and Alternate if you are encoding interlaced video.

The "progressive" checkbox sets a flag for your DVD player, but I believe it also affects CCE's motion prediction algorithm. In MPEG-2 there is the concept of "frame-based prediction" versus "field-based prediction." You don't want CCE to perform frame-based prediction on an interlaced frame, because it will smear the fields. For best results, set the "progressive" flag appropriately for your source.

Setting Zigzag/Alternate wrong won't hurt the video at all, but you'll probably get more efficient RLE compression by setting it right.

Setting the Progressive Flag wrong will hurt an interlaced video, but it probably won't hurt a progressive video. It's just more efficient to encode a progressive video with the flag checked.

[MarkGrigsby]

Thank you!