Has anyone solved the pulsing issue with 24p native?

P

Pickles

Carbonite Member
Has anyone come up with a solution to get rid of the pulsing issue that occurs when using 24p native? I get the pulse, almost like pulsing mud, every second, usually where anything is out of focus, like the background behind the subject I'm shooting.

My settings are:

Version Increment- checked
3rd Party Battery- checked
Native 24p- checked
Video Bitrate FHD/SH- 40.000.000
Video Bitrate H- 40.000.000
Video Bitrate L- 40.000.000
Overall Bitrate- 50.000.000
Limiting Bitrate- 60.000.000
1080p 24 GOP Size- 15
 
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I wish there was a reply here besides my own. I think I'm going to re-hack my GH1 to UN-tick the 24pn! I didn't notice this pulsing until just yesterday... never even read about it.

I'm trying to shoot some critical footage for a lens comparison and it basically ruins the shot.

I have the same experience as you... that it seems to create fade in/out mud dots in an otherwise good image.

I'm using standard C settings with default GOP size. The 3-rd party batt is no issue (mine is unchecked). I suspect this pulsing issue won't be able to be fixed... because just as you said (and I'm seeing) it's exactly once per second... i.e. it's definitely tied to the 24pn. For other GH1 settings I read that to get 24p frame-rate the cam was basically dumping frames... I think it STILL is in AVCHD... I don't know what's happening, but it definitely makes some little details "fuzzy" for a partial second... every second.

I think the best/worst way to see this is to put your cam on sticks shooting stationary subjects... otherwise the effect will be hidden... and you need a little DOF to the shot.

If you try to see this with a chart you may be able to bring it out by angling the chart so that only part of the chart is in focus.
 
I un clicked the 24pN yesterday.... Sad that it won't work but it's got this pulsing glitch that you guys have noted and it causes crashes....
 
I thought it was just my computer not being fast enough to process the footage when I first saw it.

But if other people are seeding it then it's not just my computer then.

I don't see it all the time though. I did a shot looking up through some tree branches. The leaves looked great but the tree limbs that were out of focus would pulse. But other shots that have out of focus areas don't pulse.

I've not seen it when I've used my Nikon lenses in out of focus stuff but I've seen it with the kit lens.
 
Sad is right... in my opinion this simply makes 24pn an unrealistic option. The thing is, if you have multiple cams and know that say, the B cam, will always be moving even if that only means hand-held and/or rig shots... then I don't think you'd ever see it.

But a great example of how this could be really bad would be an interview situation... where you have a book-shelf or something in the BG... and assorted details of that static portion of the image were pulsing... another great example would be putting this on sticks at the back of a church and setting the shot wide for a master-shot at a wedding... your eye would be constantly pulled to the pulsing in the final edit.

So yeah... I'm going to un-tick 24pn today also.

I've got a bunch of FD lenses + the kit lens and the pancake. It's not lens-specific... it's a 24pn thing when the shot has portions that are just out of focus and static. I'm sure it's happening all the time, but if the cam or objects in the shot move I don't think you'll ever notice it.
 
Nope never have and I've tried just about every setting under the sun, it occurs on highly detailed scenes where little movement is present. The "pulse" is actually a muddy I frame where the previous P frame was blank/duplicated. After the muddy I frame it takes a couple more frames before the detail snaps back, only to do it all over again when the next I frame comes up. The mud that appears suddenly then fades away is what gives the footage that pulsing look. If allowed to go on too long it freezes up the camera and you lose the footage. Changing the GOP can change how often the pulse occurs but it's still there. On borderline scenes I have seen a milder pulse that isn't so bad; it does not have a blank P frame right before the I frame but there is still some mud in the I frame, just not as bad.
 
Yep the very reason i went back to 50i. SH is still my preferred mode though ....720p is underrated.

Rambo
 
Can someone post an example of what this pulsing looks like. I'm not seeing anything out of the ordinary in my footage. Not saying something isn't there but I've been following this guys link (tests) on several different settings where he states there are hicks (I guess he means pulse) in the image. He documents all of his settings from the most to the least (smoothest) hicks in the image. I have my camera on what seems to be his optimal settings and the image looks great to me (24p). I guess I'll have to look harder. Here's his link:

http://aster.nu/gh1.php

EDIT: The settings I'm using is the very last one under "Regular Resolution Filming City Life at very tight Apertures"
 
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If you want to see the pulsing clearly you HAVE to put your GH1 on a tripod... and point it at something with a reasonable level of detail in it. I've been working on a FD lens comparison to show what different FD lenses look like on a GH1... yesterday I took my dad to one of his old hangouts... with old bar stools, and a checkered tile floor... the tiles have speckled detail in them as well.

I focused on the closest stool and hit record... the speckle details in the tile... just behind the focal plane... all "pulse"... it's very clear and almost impossible to ignore.

Set your cam up in some way like that (do you have tile or linoleum kitchen floor? anything with detail and a pattern?)... I'll bet you see it instantly (on play-back through a TV).

Hand-held and/or other movement is pretty good at masking it. There are some pulsing examples on Vimeo, but the shots are hand-held... the slight-movements of which are good at hiding the pulse within what looks like blur from frame blending... in another words... with hand-held... especially on the internet, you aren't going to see it clearly.
 
I couldn't see it on Vimeo either.

You need some distance with the DOF. The pulsing doesn't show up in things that are in sharp focus OR fully blurred (for me)... it shows best in the area where things are starting to go out of focus... so macro-type stuff probably won't make it obvious.

I was shooting at f/4.0 with the in-focus objects about 4 feet away... If you want to test it on your cam don't zoom... don't have any movement in the shot, then have something of simple detail in that "going out of focus" zone, just behind the focal plane... like a white sheet of paper with a few shapes drawn on it. Then when you check for the pulsing... you don't have to look around the frame to find it.

While this makes it sound like something you'd never see in real life use... I'm just trying to tell you an easy way to see it. In my "bar stools on checkered floor" lens test shot the pulsing instantly jumps out at me, even on a 32" 1080p TV.
 
Well yes and no, if the hack didn't exist you would never see the pulse because you wouldn't have the ability to select native 24 or 25p. But it does seem likely that the reasons behind the pulse may be due to something in the hardware, so in that sense yes it is an issue with the GH1
 
Yes, what he said.

Set your cam in 60i and you're not going to see it... and when you convert your footage into 24p that program isn't going to add it in either.

I hate to make a metaphysical argument, but as far as I'm concerned... if I don't see it, then it doesn't exist :)
 
MattinSTL said:
Yes, what he said.

Set your cam in 60i and you're not going to see it... and when you convert your footage into 24p that program isn't going to add it in either.

I hate to make a metaphysical argument, but as far as I'm concerned... if I don't see it, then it doesn't exist :)
Click to expand...

gotcha:thumbsup: but I've seen it on factory settings in my own footage--I'll post a clip when I get a sec.--
The funny thing is...I think the hack either has exacerbated the issue or is just cleaning the image to reveal it even more-- because, when it was pointed out to me, I then looked at footage immediately and compared 'hacked' vs. factory imagery-- BOTH SHOWED IT, and it really agitated me, b/c now I could see it in a lot of footage- but it's so minor, that you almost have to train your eye to see it... funny like that, but it is undoubtedly THERE.
REALLY, the only times you'll see it, is in locked down static shots; still life.

I think there is even a vid someone posted here last year when GH1 first came out--complaining of this, I'll have to dig around....

Anyhow- if you have any locked down shots pre-hack/and hacked take a look....it's there in BOTH.:Drogar-Dolar(DBG):
 
alignment1 said:
REALLY, the only times you'll see it, is in locked down static shots; still life.
Click to expand...

Yep... my experience for sure. I shot some video over at the ADRL races at Gateway this weekend, from the top of the suites, looking down at the cars on the strip... it's just like my other checkered floor video... the various dots and marks on the pavement pulse, but you don't notice if your eyes are on the cars (which are mainly in focus). It's not horrible... it's a cheap enough cam... there are a lot of shots where you'd never see it, but if the footage is critical... I'd definitely do whatever I could to avoid even a chance of seeing it...

I've got some more experimenting to go. I can see a helpful "practical use of the GH13" thread/blog in our future. I don't think this pulsing thing was well-covered before... and I'd also like to come up with something like the Pappas Chart to test for this. I'll see if I can figure something out or make something that can be laid out flat in front of my cam to reveal it. Then anybody who wants to see if their cam does it can do their own quick test.

HDMI to mini-HDMI cables are CHEAP on Amazon... I highly suggest everybody buy one... we're talking less then $6 or so. Then you can play your footage directly back on a 1080p TV. I've been judging my footage on either a vizio 32 or an aquos 60... which brutally reveals any issues (even on the 32").

Still... to keep a realistic perspective on this... I'm mostly blown away by how good the footage is. I wouldn't freak out about this pulsing. It's just that for SOME shots I find it highly annoying. It definitely takes the proper conditions to show up clearly, but in 2 different days out I've seen it in 2 completely different types of content.
 
MattinSTL said:
Still... to keep a realistic perspective on this... I'm mostly blown away by how good the footage is. I wouldn't freak out about this pulsing. It's just that for SOME shots I find it highly annoying. It definitely takes the proper conditions to show up clearly, but in 2 different days out I've seen it in 2 completely different types of content.
Click to expand...
I think when the pulsing issue is present it is quite a serious one as far as issues go. Take a look at the following post, where I analyzed a richtrav's clip with GH13StreamParser.
http://www.dvxuser.com/V6/showpost.php?p=2058748&postcount=34
The last P-frame in a GOP is a tiny 192-bit packet. It almost seems like AVCHD encoder runs out of all allocated bandwidth before writing out that last frame in a GOP cycle. In practical terms, it means that 1 in every 12 frames is missing image data completely. How this is manifested visually seems to be up to decoder, perhaps the previous P frame is duplicated, or decoder goes back to I frame for reference. The problem is there, however, and definitely needs further inquiry, but it seems to be very difficult to reproduce. I, for one, have not been able to do that yet.
 
I have small idea to start opening up project from AVCHD encoder related parts.
Frash eyes can be good.
I'll post more news af soon as scripts and some tools will be ready.
 
svecher said:
Take a look at the following post, where I analyzed a richtrav's clip with GH13StreamParser.
http://www.dvxuser.com/V6/showpost.php?p=2058748&postcount=34
The last P-frame in a GOP is a tiny 192-bit packet. It almost seems like AVCHD encoder runs out of all allocated bandwidth before writing out that last frame in a GOP cycle.
Click to expand...
Yes, while working on my last patch I saw these truncated P-frames in numerous examples of Native 24p streams. If I pushed the bitrate hard enough, I'd often get actual write failures, leading me to conclude that truncated P-frames are an indication that the encoder is close to breaking down. On rare occasions I've seen a consecutive sequence of truncated P-frames within a single GOP, which makes the video appear to pause for a fraction of a second.
 
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