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-   -   HG10 24P stuttering "myth" (http://www.dvinfo.net/forum/canon-vixia-series-avchd-hdv-camcorders/105293-hg10-24p-stuttering-myth.html)

Dmitriy Uchakin October 9th, 2007 11:37 AM

HG10 24P stuttering "myth"
 
Some source online made a conclusion that the 24p mode on the new HG10 is "unusable". I do have certain doubts that the reviewer made that conclusion by viewing the 24P footage still embedded in the 60i stream on the computer monitor. I doubt that because I want to believe that they know better than that. Is it possible that they just hooked up the camera to the HDTV and played back the 24p footage directly from camera?

I have viewed the clips that were posted here by Austin Meyers and the clip named "hg10 24p-10k.mov" got me a little worried as I saw the stuttering in the panning from the fountain to the table. I blamed my machine of choking at the 1920x1080 prores codec (I am running a MacBook Pro 2.33 C2D) and decided to convert that scene to a 640x480 MJPEG file to see what happens. The stuttering dissapeared confirming my guess that it was the computer that had the bottleneck. Provided I am little dissapointed that my fairly new and what I thought to be a pretty powerful machine chokes at playing back the footage, I am fairly certain that the stuttering artifacts happen not on the encoding stage in camera but at the decoding of the footage afterwards. Also, am I right to assume that this clip was shot at 1/48? Austin?

Anybody has been able to get their hands on any other 24p footage with panning of the camera so we can lay that myth to rest once and for all?

Chris Barcellos October 9th, 2007 11:44 AM

I think it was from same footage from Austin Meyers ( a city scene with a building in it.) In any event, I downloaded the raw footage to try to play it. I couldn't open it in WMP or VLC. I did open it in Vegas 8, it stuttered as I played it on preview. I then converted it to an intermediate Cineform file, and was able to play it fine on Window Media player, VLC, and could edit fine in Vegas, without stutter issues. I couldn't do a direct convert in HDLink with the raw file to do pulldown.

Dmitriy Uchakin October 9th, 2007 11:48 AM

I am not sure I saw the city scene footage. Could you please tell me the name of that file?

David Sayed October 9th, 2007 12:28 PM

Quote:

Originally Posted by Dmitriy Uchakin (Post 756414)
Anybody has been able to get their hands on any other 24p footage with panning of the camera so we can lay that myth to rest once and for all?

I've ordered one, so I'll post something once it arrives (end of week hopefully).

David Saraceno October 9th, 2007 12:43 PM

I wish this wasn't true because it cost me $175.00 in restocking fees when I returned the camera.

I shot in the 24p mode in a moderate and slow pan across some outside scenary and brought it into FCS2. I then removed the pulldown to get a true 24p, and was very disappointed with what I consider strobing.

I then shot the same movement with a HVX200 in both 24pNative and 24 over 60.

The footage was dramatically better. There was strobing, but it was hardly noticable and then could be attentuated with a different shutter speed and a slower pan.

In my view, the loss of that $175.00 coupled with the disapointment of the footage wasn't a "myth."

I also encoded the 24p footage to a HD DVD and saw it there as well on a plasma Pioneer Elite via HDMI from a Toshiba A1 HD DVD set top.

David Sayed October 9th, 2007 01:16 PM

Sounds like a thorough test. I thought long and hard about whether to get the HG10 or an HV20. I have an XH-A1, so that's my "quality" camera. I want something small, easy to use and to live with for high quality home videos. Both the HG and HV fit the small and easy to use category. For me, tapeless makes the HG easier to live with. Given the material I'll be shooting (toddlers running amok basically), I'm going to be in 60i land.
Still, I'll try 24p when I get my hands on it just for grins.

Dmitriy Uchakin October 9th, 2007 02:57 PM

David Saraceno,

What shutter speed did you shoot the HG10 footage at? Also, I did hear that the HVX has a lot more smoother motion signature compared to cameras like xh a1 and hv20. So what I am trying to figure out is whether the HG10 24p footage is identical to HV20 footage. It would be a stretch to try to compare it to HVX. Also, if indeed this strobing is embedded in the HG10 footage, then where might it be coming from. CMOS, or in-camera encoder. I doubt its the CMOS since the HG10 shares the same chip with the HV20.

So far, what we have are two people on this board(Austin Meyers, and David Saraceno) that did a fairly thorough examination of the 24p mode on the HG10. However, the results of this testing seemed to be contradicting. In David's testing, he was comparing HG10 to HVX200, when Austin was putting it head to head with the HV20, which I think is a more realistic comparison.

David, did you have chance to look at HV20 footage shot in 24p mode? I wonder if you are just used to the HVX200 24p motion. And also, thank you for your testing and informative input, as well as for your warnings as they will most definitely save a lot of early adopters money.

Chris Barcellos October 9th, 2007 04:06 PM

Quote:

Originally Posted by Dmitriy Uchakin (Post 756422)
I am not sure I saw the city scene footage. Could you please tell me the name of that file?

See post 14 in this thread:

http://www.dvinfo.net/conf/showthread.php?t=101059

Michael Eskin October 11th, 2007 10:16 AM

It wasn't clear to me from the HG10 sample video postings which files were 24p in 1080i and which were just 1080i. Anyone know which is which? I want to try some Cineform pulldown tests, but the panning clip I tested sure looks like an interlaced source.

Thanks,

Michael

Philip Williams October 11th, 2007 11:29 AM

Quote:

Originally Posted by Dmitriy Uchakin (Post 756549)
<snip>
Also, I did hear that the HVX has a lot more smoother motion signature compared to cameras like xh a1
<snip>

You heard absolutely wrong I'm afraid. In Barry Green's comparative article between the XHA1 and the HVX on dvxuser he literally put both cameras next to each other and filmed traffic driving by them. Exactly 100% totally and completely the same motion rendition and blur at 24P with 1/48th shutter.

David Saraceno October 11th, 2007 12:03 PM

I shot everything with the stock settings when I did the testing.

I'm not comparing the image quality with the HVX200. What I am comparing is the incidence of strobing when both shot at 24p 1080i.

And there was pronounced strobing with the HG-10 after to removed the pulldown. Unfortunately, this wasn't a "close" issue; it was pronounced.

As an aside, the images were not favorable for what I shot, although as a b cam, the HG 10 would have been used sparingly.

I'm not dissing the HG-10. It just won't work with our HVX200

Les Dit October 12th, 2007 04:37 AM

I'm seeing evry 4th frame has field mismatch/tear
 
I just received a HG10, and tried some tests in cineform's HDLink tool to convert 24p into a QT file. After importing the result QT into After Effects, I see interlace artifacts every 4th frame. I shot 1/48 and 1/24th second shutter. The clip is seen as 23.97 by After Effects. The HDLink prefs had the progressive and the 'remove 3:2 ... HV20 ' settings on.
So far, I'm not seeing a clean progressive frame sequence. I hate interlaced footage!

Also: I'm able to choose 1/6 second exposure on 24P, the manual says that's not supposed to be available on 24p mode. LCD says PF24 . 1/12 is the manuals limit. ( these are probably duplicate frames modes )
-Les


Quote:

Originally Posted by Michael Eskin (Post 757410)
It wasn't clear to me from the HG10 sample video postings which files were 24p in 1080i and which were just 1080i. Anyone know which is which? I want to try some Cineform pulldown tests, but the panning clip I tested sure looks like an interlaced source.

Thanks,

Michael


Chris Hurd October 12th, 2007 06:39 AM

Quote:

Originally Posted by Les Dit (Post 757851)
I see interlace artifacts every 4th frame.

But that's exactly how it's supposed to be... it's 24p within a 60i stream. Just like the Canon XL2 and Panasonic DVX100. See Adam Wilt's article and the accompanying graphic at:

http://www.adamwilt.com/24p/index.html#24pRecording

"The A, B, and D frames can be recovered by using two fields from the same 60i frame. The C frame cannot be; it is split across field 2 of the third 60i frame and field 1 of the fourth 60i frame."

See also http://www.tvtechnology.com/pages/s.0079/t.1976.html

"This sequence of four film frames being converted into 10 video fields is then repeated. This generates some "blur frames;" video frames containing two fields that have been derived from separate film frames."

The HG10 isn't performing differently from any other camcorder using basic 24p.

Dmitriy Uchakin October 12th, 2007 11:31 AM

I received the camera yesterday. Not too impressed overall. For some reason, reverse telecine technique in Compressor, and outputting to Prores does yield a somewhat of a strobe effect and a noticeable loss in resolution. Maybe my machine is too slow? But with a same technique encoded to MJPEG seems to solve the issue of strobing . There are also compression related "motion trails/ghosting" in low light and plenty of color noise. I myself was holding out for what it seems like forever to get a hard disk based camera. Now I wish I would have gotten an HV20 a long time ago.

Also, hard disk work flow was much more difficult than "transfer and edit away". If you are doing 24p, you gotta first "Log and transfer" to AIC(you can do prores at this stage but Compressor wont convert it back to prores when removing pulldown, maybe that will be fixed in the future). That process takes roughly as long as the length of the clip. So you got your HUGE AIC file, you now gotta feed it to Compressor that will reverse telecine it to get a 24p ProRes file, which is also huge. And NOW, you can start editing. Provided that tape workflow has to go through the same steps, the time saving characteristic of hard disk workflow become moot. Of course, you have your clips separated and that is one good selling point of a hard disk based camera.

I am sending it back today and "maybe" getting an HV20.

Michael Jouravlev October 12th, 2007 11:34 AM

Quote:

Originally Posted by Chris Hurd (Post 757871)
But that's exactly how it's supposed to be... it's 24p within a 60i stream. Just like the Canon XL2 and Panasonic DVX100. See Adam Wilt's article and the accompanying graphic at:

http://www.adamwilt.com/24p/index.html#24pRecording

"The A, B, and D frames can be recovered by using two fields from the same 60i frame. The C frame cannot be; it is split across field 2 of the third 60i frame and field 1 of the fourth 60i frame."

As Adam's article points out, frame C can be restored from two 60i frames, where one field of frame C is taken from the third frame, and another from the fourth frame. As he points out, the frames have to be recompressed, degrading video. Also, if it is HDV, the chroma loss will occur (this topic was discussed on DVX forum).

But with all above said, there should be NO interlace artifacts, at least in luma. I suppose that After Effects is just not advanced enough to restore split frame.


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