same timeline no problem.

For firewire transfer some decoders only know how to read the stream as 60i (like nornal DVD players) while the special decoders can remove the flags (like a progressive scan DVD player.)

The progressive scan DVD player should not need to remove the flags because it's not outputting compressed mpeg, just fields or frames.

But more interesting are you comments about chroma sampling. You've said that chroma samples alternate for interlaced video, whether encoded as fields or progressive segmented frames. So the alternating is good for i but bad for p because the chroma is treated as interlaced.

How do you make that observation? Are you viewing with a hex editor or what other method do you use to observe the chroma samples in the mpeg file?

Also, you seem to be saying that 24F is essentially the best 24 progressively encoded format, because for the small penalty in resolution drop from the 2x2 chroma sampling, you avoid the artifacting caused by alternating chroma fields.

Extending that explanation to describe the current cams, I would infer that only 24F is a "true" progressive format, and that 24P from the HV20 and Sony V1 are the segmented frames carried within 60i. In other words, pulldown flags for 24F frames, but field pulldown to weave 1440x540 into full frames for 24P for HV20 and V1.

Your explanations do accurately describe what has been observed, artifact free but lower resolution 24F images, and artifacted but higher resolution 24P from HV20 and V1. If true it just seems contradictory that the marketing emphasis for 24P is the "true progressive" format with true progressive chips, yet the format with the progressive-from-interlaced chip trickery is the one outputting the progressively encoded frames.

Do you see it that way?

http://members.aol.com/ajaynejr/vidbug2.htm

Here is one link that talks about CUE (Chroma Upsampling Error)


http://en.wikipedia.org/wiki/Chroma_subsampling

Here is a link that shows the three forms of 4:2:0 color. Scroll down to the section on 4:2:0. Look at the images of the green text on the red background. You can see why progressive 4:2:0 is much better for keying. Progressive 4:2:0 is actually not all that bad for keying since it is very clean. The problem with 4:1:1 DV was that the blocks of chroma were 4x1 pixels in size. That means on edges you could end up with gaps or holes that were 4 pixels wide. Interlaced 4:2:0 also has a problem due to the alternated lines which can leave odd jagged edges. Progressive 4:2:0 really is a much better method for accurate chroma sampling with progressive images.

The JVC series of cameras also use progressive encoding so they are true 24p as well.

24F has really nothing to do with the detail in the image. The Canon series of cameras still do something with the interlaced chips to make a progressive image in the DSP. From there it goes through a whole new process where it is encoded as progressive frames. So in terms of encoded video yes it is true progressive. Again that really has nothing to do with detail. You could take a 32x32 pixel image and blow it up to 1920x1080 and encode it as a progressive sequence but it still wouldn't look as good as a raw 1920x1080 image encoded.

So yes the video from the HV20 is true 24p video in the DSP but then it gets encoded as 60i which uses the interlaced form of chroma sampling. It really isn't all that bad however. Progressive 4:2:0 is better of course but some decoders and some great tools do a really good job at swapping the chroma lines so they can upsample to 4:2:2 fairly well. With the HV20 there is also the bonus of capturing HDMI live into a 4:2:2 format such as Cineform, jpeg or uncompressed. When the video is 4:2:2 you no longer have to worry about 4:2:0 interlaced chroma patterns because every line has it's own chroma anyway. The HDMI output is still 24p inside of a 60i stream but once you remove the pulldown you will be left with perfect 4:2:2 24p frames. The higher end Canon cameras start with a much easier to use form of HDV for 24p but when dealing with uncompressed you still have to worry about removing the pulldown. The uncompressed output is also still from the magic performed on the interlaced chips so the small resolution loss is still there.

Very intersting! I wonder what will be the case with the PAL HV20 25p?

Salah Baker noted in this thread that HV20 records 24p (not PsF), and sent a clip (which I am downloading now) to David Newman of Cineform. David said that clip had pulldown added inside of 60i, i.e. it *is* PsF.

nope ...PSF is a differing animal(frame blend from ccds)
m streams are fun