To check progressive frames...or not?

[wakebrder]

Yes, I have read the guides, but on most of my films(NTSC), the Pic structure tells me progressive while the DCT type & Frame type point to interlaced. What is the bottom line for determining whether to check the progressive box or not? Here is the bitrate viewer info on Soul Survivors:

Num. of picture read: 31
Stream type: MPEG-2 MP@ML VBR
Resolution: 720*480
Aspect ratio: 16:9 Generic
Framerate: 29.97
Nom. bitrate: 9801600 Bit/Sec
VBV buffer size: 112
Constrained param. flag: No
Chroma format: 4:2:0
DCT precision: 10
Pic. structure: Frame
Field topfirst: Yes
DCT type: Field
Quantscale: Nonlinear
Scan type: Alternate
Frame type: Interlaced

I have been going by the Pic structure value with good results. Am I missing something? Thanks in advance.

[slk001]

Hey, Wake,
To interlace, or not to interlace, can sometimes be difficult to determine. Sometimes, Bitrate Viewer will report the wrong thing because the first of the movie may be interlaced (ie, studio logo, FBI warning, etc) but the body of the movie is progressive.

I usually strip out a small chapter (about 1 minute or so) out of the body (preferably with fast movement) and try different encode settings. This only takes about 3 minutes for a 3pass VBR encode (what I normally use) and I can see if the settings will work.

For NTSC films, I believe DCT type is always Field, whether it is interlaced or progressive (since each frame is always made up of two fields). The SCAN TYPE : ALTERNATE is usually used for interlaced projects (but I have successfully used ZIGZAG on interlaced projects, too). I have also had problems with the TOP FIELD FIRST : YES as reported by BRV. My 1 minute encodes sometimes shows that TFF should definitely be NO.

However, I believe that if your 1 minute clip says FRAME TYPE : INTERLACED, you definitely need to use interlace.

In short, alway EXPERIMENT to get the correct settings for a new encode (nothing worse than spending 6+ hours on an encode that has to be discarded).

[wakebrder]

I'm burning on DVD-R, so possibly at higher bitrates, the differences in these settings are harder to see?

However, I believe that if your 1 minute clip says FRAME TYPE : INTERLACED, you definitely need to use interlace.

So I should go by the frame type vs. pic structure? Sometimes DVD2AVI will report a progressive frame type. How accurate is this? It would be nice to have a tool that ACCURATELY reports this info. BTW, experimenting.....what's that:sly:

I encoded Soul Survivors with progressive checked at a whopping 6571 bitrate. Obviously it looks good. (but could it look better?):cool:

Thanks for your reply.