Shooting progressive with HC1?
 

I don't know all that much about shutter speeds, but I noticed mine was set at 1/60 for the default, which makes sense because it's once per field. So I tried setting down to 1/30, thinking that would be once per frame and would give me progressive video, but it didn't. It looks "choppier" on a television screen but on the computer there are still the interlaced lines.

Is it at all possible to shoot progressively with the HC1? I'd really like to.

No, it shoots interlaced. And the CF24/25 functions aren't very good.

HC1 probably has the fields flipped. For no reason too, when shooting in 1/30 there should be no interlace lines.

Why are there interlaced lines if there should be none? Is it, like, the 1/30 image being recorded to B field frame 1 and A field frame 2 instead of A and B same frame?

Why wouldn't there be interlace lines if you're shooting 1080i, which is interlaced?

When you shoot at 1/30 there is no way to make it into two interlaced fields in one frame. Unless the fields are flipped like Michael said.

1/30th should be basically like progressive because 60i has 30 frames per second. Interlacing isn't a "special kind of signal", it's just two frames encoded into one. There's only one frame when shooting at 1/30. Or 1/15, 1/3 etc.

Why would the fields be flipped? To purposefully 'disallow' progressive in this lower-model camera? Or for some other technical reason?

Anyway, thank you for answering my question. :)

Michael, I'm thinking you're not understanding that frame rate and shutter speed are not the same thing? No matter what shutterspeed you shoot, the camera is interlaced in this particular model. Not to keep you from shooting something the way you want to shoot it, it's an interlaced camera source. The A1 does offer CF30, which I personally like very much, and is used quite a bit. Additionally, if you'll be going to 24p, the PAL model of the cam shoots CF25, which is very nice on its own, or you can convert that easily to 24p.
No, you cannot shoot progressive at any time with the HC1. You can deinterlace in post and lose some resolution, or you can keep it interlaced. Either way, this cam is interlaced only.

Actually there is the the Cinema Effect mode which kind of looks like garbage but if you can find a way to remove the pulldown with software then you will have progressive images. The motion is kind of jerky due to the faked way of creating those 24p frames plus the camera uses a shutter speed of 125 with the Cinema Effect mode which makes it even jerkier. Maybe it will look good enough for you.

Actually, when the extra frames are removed using CineForm, the movement isn't jerky at all. It looks as it should. If your camera management isn't as a 24p camera should be managed, of course there are problems stemming from operator error, but not from anything frame-rate related.

What is the difference? It was my understanding (just through observation) that shudder speed controlled how long the shudder was open before printing what it took in to the frame? When I really lower the shudder speed, it gets very choppy, so I assumed that's what was going on (still always at 60 fields per second, but a bunch of fields showing the same image from the most recent shudder "refresh").

Is there a website you could recommend to explain this stuff better?

The frame rate is "how many individual frames are displayed/recorded per second." In America, it's always either 24 or 30 frames per second. If it's interlaced media, there is no 24 frames per second (fps) format. It's always 60 interlaced frames, which is the same as 30 half-frames.
In most of the rest of the world, it's 25 frames as a progressive, or 50 half-frames interlaced, per second.
Shutter speed is how fast the shutter is opening/closing per second. You could have a shutter speed of 1/8000, but that doesn't equate to 8000 frames per second, as that would generate incredible slow motion. You can shoot 1/60, which is common for film-destined, or film-like destined media, and that shutter speed is recorded in a 30 fps sequence, or a 24p sequence. However, 24p is usually shot in increments of 24's, ie; 1/24, 1/48, etc.

Think of it this way..
you can have 1000 people painting pictures at one time. However, the boxes that are used for shipping the paintings to the store only hold 60 paintings each. Therefore, you can have 1000 people painting, 10 people painting, or 10,000 people painting pictures, but still, only 60 paintings can go into a box at once.
People painting=shutter speed
Boxes containing paintings=frame rate

Does that help you make sense of the differences?

That explanation doesn't really matter in this case because the frame rate of 1/30th shutter speed is 30. 1/3th shutter speed has a frame rate of 3 per second. You can't interlace those frames. You can't make 60 interlaced frames out of 30. UNLESS the camera displays the fields in the wrong order. That wrong order won't make any difference in an interlaced monitor because there are only 30 frames, but it will cause progressive monitors to show interlace lines.

The fields are flipped because sony engineers didn't spot the problem. It won't show up on any interlace monitor and progressive monitors always show interlace lines on 1/60th material. They won't care that it's possible to make 1/30th look progressive. It's like at the bottom of the "to do list".

I haven't actually looked very closely at the 1/3th shutter speed files, but 1/30th does have fields flipped.

What do you mean "the Sony engineers didn't spot the problem?" It's HDV. HDV is *always* uff. And of course there are interlace lines, at any shutter speed. It's *always* an interlaced output from the HC1.

Spot even the Cineform website shows examples of how Cineframe24 can be a little bit jerkier then true 24p or even 25 CF. I know it works well but it is not a perfect 24p.

Thomas,
I didn't say the images were "perfect 24p." I said they're not jerky. The cadence doesn't "feel" like the perfect 24p, but it is not "jerky."
In real-world use of the cam with CineForm vs measurebating by reading text on a web page, I'd submit I'm at least marginally qualified to hold the opinion that I hold. Additionally, CF24 samples both with and without CineForm processing have been available and comparable on my website for nearly 2 years now. In other words, I've viewed them side by side on many an occasion, and am quite familiar with the differences.

I also happen to own a HC1 and to me it looks jerky. A non perfect 24p does mean it is slightly jerky. If it was that good then why do more people not use it on a mainstream level. I love my HC1 to death and think for the money it does a great job but I can tell you it stobes a little bit more than true 24p footage does. Maybe that doesn't fit your definition of jerky but to me it does. I recently used my HC1 to work on a documentary in South Africa with my wife that is from there. We spent 5 weeks in many different areas and I shot well over 8 hours of HDV with my HC1 that I am very happy with but I'm not sure if I would use the CF mode. I have done some visual effects tests and it looked nice but it did strobe more so then other 24p footage I have worked with.

I am not measurbating here but going off my own personal experience as a visual effects artist using the camera. Besides in the case of measurbating, 95% of Dvinfo users do it and the other 5% lie about it.

I'm not sure why you have to get so negative with me. I'm also perfectly qualified to know what the camera does and I do not appreciate you indicating that I only know things from reading text on a website.

Unless something changed in later HC1's, the Cinema Effect mode isn't the same as the CineFrame 24 mode of the Z1/A1.
"Strobes a little bit more" doesn't equate to jerky for me. Personally, I'm very impressed as to how CineForm removes the "pulldown" that CineFrame 24 embues. No, it's not perfect, but given the opportunity it provides for artistic creativity, it's useful in the hands of someone who has made informed decisions. I've seen several very impressive pieces of work using the CF24mode and the CineForm HDI.
Reading information from the CineForm website vs experience with the actual Cineframe modes doesn't equate to personal experience, but rather forming an opinion based on written word.
I don't own an HC1, given that I have several A1's, but based on my short experience with the HC1 prior to its introduction, and information from Sony; it's not the same. If your HC1 has exactly the same CF24 mode as the A1/Z1, I'll stand corrected.

Output is interlaced? Sameway like the output of some toshiba hd-dvd players is interlaced even though the material is progressive? That doesn't matter if the material is progressive. You can't just add lines everywhere, because the lines are created from the frames that are encoded together.

You miss how interlace works. It works by combining two frames into one to create one frame with fields. Those fields are played back lower field first (dv) to separate the fields from the frame.

Now if you combine twoo frames that are exactly the same frame (like for example shutter speeds 1/30 etc) then there will be no interlace lines. Because the frames are the same (combine a and b that are exactly the same, you will not get lines), there cannot be any lines. Those lines are different frames encoded into one, there's nothing magical about it.

So how come hc1 has interlace lines in 1/30th mode? Because the fields are flipped. Not flipped as in upper or lower but flipped in time. Frame A is displayed in the wrong place than frame B. They encode the wrong frames together. I'll make some captures and study them more this week.

you're apparently right, Mikko. I guess I don't know how interlaced or progressive works. I look forward to reading your whitepaper on how interlacing and the HC1 operate.

Mikko, either you are having trouble saying what you want to say, or you have real misunderstandings regarding interlaced versus progressive. Shutter speed has nothing to do with whether two interlaced fields are identical. The only time two interlaced fields are identical is when there has been no motion of anything being recorded during the time between the recording of the fields. Thus, interlaced video of a perfectly motionless scene could be deinterlaced electronically to frames that would be identical to video recorded by a progressive frame camera. Similarly, true progressive frames can be interlaced into fields and recorded, as is done in some modes on the Panasonic HVX-200 camera.

I may not always agree with Spot but trust me when I say I am pretty sure he knows the difference between interlaced and progressive.

A shutter speed of 30 is interlaced on the SONY HC1. I have one and have tried pretty much everything with this camera to fool it into doing progressive. Trust me it does not work.

I'm not sure what the HC1 is doing with the shutter but it is not the same as other cameras with a 30 shutter. I have captured uncompressed component video by using a shutter of 30 and even putting the camera in photo mode and all of the frames are interlaced. They may look different but they are interlaced. The only way and I mean the only way to get progressive frames from the HC1 is to use the Cinema mode which does work fairly well if you give it a chance. It isn't perfect but neither is using a $1,500 camera.

My understanding has always been that for 60i-based cameras, when using shutter speeds of less than 1/60th, the image is recorded to a buffer and then written to the appropriate number of 1/60th second fields. So at, say, a 1/15th shutter, the buffer writes the identical images to 4 successive fields, and then refreshes and repeats.

I think Mikko believes the same thing, and hence he (and I) would expect successive pairs of fields in 1/30th footage to be identical.

that's a bit uncalled for. i think that mikkos explanation makes alot of sense to me.

the way i see it, when people say interlaced 'lines' what they mean is that you can see discontinuities between fields a and b when you combine both fields into a frame. if fields a and b were recorded at the same time then one would not expect to see those lines - interlacing or not!

it's also hard to see how when the shutter stays open for 1/30th of second and the camera derives two fields from that one exposure how the resulting two fields can be different enough to show up 'interlacing lines' - because there are only 30 exposures during one second yet the camera needs to derive 60 frames from that. similarly if you shoot footage of a static object (camera on a tripod) you would also not expect to see interlacing lines.

whether you see interlacing or not, it's there. It's an interlaced stream regardless of what your eyes might tell you.
No way around it, it's interlaced. However, according to Mikko, I don't understand interlacing vs progressive. It's not a subject I'm going to reduce myself to debating. The camera is interlaced. Mikko claims it's not. So, I look forward to seeing how he demonstrates that it is not interlaced at 1/30 when shooting anything other than a static object with the camera on a tripod.

Oh good grief, if I pan or zoom then everything sucks.

Give him a break for language and terminology. He says this: "... if you combine twoo frames that are exactly the same frame (like for example shutter speeds 1/30 etc) then there will be no interlace lines"

Now he means two fields not two frames when he says that. He's saying when you combine two identical fields you should not SEE any interlace lines, even though the image is indeed interlaced.

I agree with him on that point.

Regardless of language, terminology, or any other point to be nit-picked, it's an interlaced stream. Period. Now, whether your NLE correctly interprets those two fields and does or does not display interlacing is up to your NLE. But it is still, and always will be, an interlaced image regardless of what your eyes see, or what you *think* it should be.
From my perspective, shooting a non-moving subject with a non-moving camera for purposes of being able to deinterlace an interlaced stream that doesn't have horizontal artifacting somewhat goes against the grain of producing motion pictures, wouldn't you agree?
More importantly, it's simply dishonest to tell others that the HC1 is progressive at any state of it's shooting function.
Further, from what we have shot with the A1, Sony does not invert the fields, HDV is upper field first. Our NLE's (Vegas and Avid XPress) interpret the fields in correct order.
I'm not at all trying to create chaos, but rather settle it out. Mikko claims the camcorder has progressive qualities, it does not. He claims Sony deliberately inverts the fields; they do not. Mikko claims I don't understand interlacing vs progressive scan formats, I do.
either way, it's not something worth debate; the camcorder and its functions are quite well documented.
If you want a deinterlaced image of a non-moving object with a non-moving camera, the HC1 has a great still photo mode, which would be the better (and higher resolution) image.

Yes, fine to all of that.

But the question that kicked off this thread still stands.....I fail to understand how interlace lines could be VISIBLE in footage shot at 1/30.

I think the important distinction to make here is the 'appearance' of interlaced or progressive vs. the 'aquisition mode' of interlaced or progressive.

What DSE is saying is that no matter what it 'appears' to be, the camera 'aquires' the image using an interlaced scan in all modes of the camera's operation.

That doesn't mean that under certain conditions that an interlaced image comprised of two fields can't 'appear' to be progressive. In fact, that's the magic of 'frame' mode on the XLH1 and its two newer siblings.

-gb-

The NLE may not be interpreting the frame/two fields correctly. There are a few other reasons, but that would be my first suspect.

[edit] as Greg succinctly worded, the difference is entirely in the acquisition timing. The HC1 is always offset, which is why you can't move the camera at all, or have motion if you don't want to see interlacing offsets. Canon have a proprietary (and brilliant) implementation similar to Psf that works wonderfully well to give the look of progressive in an interlaced image.

Just to take a wild guess without having a clue about how Sony reads the CMOS chip in the HC1 -- Could it be that, even at 1/30sec shutter, Sony is reading the odd and even lines from the CMOS chip at different time points (differing by 1/60th of a second), so the two fields really are temporally distinct? That is:

frame 1, odd: exposed for time points 1 & 2 (each time point representing 1/60sec)
frame 1, even: exposed for time points 2 & 3
frame 2, odd: time points 3 & 4
frame 2, even: time points 4 & 5

I think you could see this with a strobe light (or even just a camera flash), which half the time would only illuminate one field and not the other.

Or did I just reveal my stupidity? (don't answer that)

-Terence

I think I may have the answer.

HC1 footage shot at 1/30 is indeed composed of pairs of identical fields ... except for the first one!

So the fields are: abbccddeeffgghhiijjkk and so on.

Displayed in pairs on an NLE, this shows up as ...ab bc cd de ef... which of course looks interlaced.

But if you clip off that first field (which I did just now in avisynth) this converts to ... bb cc dd ee ff gg hh ii jj kk ... which LOOKS perfectly progressive, with NO lines, even though the underlying structure is of course still interlaced.

You are stuck with a 1/30th shutter, but the result really looks rather nice! Someone wiser than I should write a little app to implement this!

Very interesting Graham! I have tried to figure out a way to us this type of video but I have never tried to set the order of the fields in a different way. I also use Avisynth a lot and I will have to play around with the fields now that you figured out the pattern. Very interesting indeed. I guess now I will not get any sleep tonight. I need to try this out.

Thomas,

Just FYI, here's the script I used to access the raw fields:

avisource("original.avi")
assumetff
separatefields

I then manually set the in-point 1 frame in, rendered to a new file named trimmed.avi, and then converted that back to 1080i with this script:

avisource("trimmed.avi")
assumefieldbased
weave

There is undoubtably an elegent way of doing all 3 steps with a single script - but I was rushing a bit this evening ....

So it's higher quality way of deinterlace, but for only 1/30 footage?

That's exactly what I interpreted Mikko's comment that "the fields are flipped" to mean. Shame we couldn't have arrived at the answer without the unnecessary sarcasm...

I have no issues shooting with CF30 or 25, or even not shooting with it and de-interlacing. The video looks great!

heath

so in conclusion what i derive from this thread is:

with a shutter speed of 1/30 sec and appropriate post processing of the captured HDV signal the HC1 can produce video that is indistinguishable from one captured using a progressive (i.e. 30p) camera? is that right?

surely it cant be that easy! how cool would that be?

I'm not sure if this approach produces something that's identical to CF30 (which the HC1 doesn't have although the A1 does).

I can say, however, that it's an improvement on the "Cinema Efect" digital effect on the HC1, because Cinema Efect disables manual exposure control.

(By the way - I'm typing 'Efect' intentionally as that's what the HC1 menu says - ha!)