Solution for pulsing I-frames?

A

AKED

Well-known member
Has there been a solution for the pulsing Iframes in the AVCHS 25p hack?

I searched for it but I did not find anything.
Was somebody more successful and found a solutoin?
 
lower GOP = better quality

lower GOP = better quality

A lower GOP setting should smooth out the pulsing.

If you use the C settings and change your GOP to something like 8 (6 and lower seem to freeze the camera) your quality should improve dramatically. I have not noticed any pulsing over the last week using these settings.
 
I did manage to get some pulsing with the GOP set to 8, though not as much. I looked at the frames where pulsing occurred and they looked fine. I have no idea what the pulsing is affecting because I can't see anything visually wrong with those frames. Strange...

Chris
 
OK, I changed the GOP to 8 and then the pumping is gone.
But then what Svart writes, if I put it on a tripod, after a few seconds in FHD, the class 10 card 16 GB from Sandisc stops recoreding due too high write speed and it does not have the clip that has been recorded to up that time on the SD cars.
I have to draw the battery and the3e clip is lost.
To avoid this it was said, to change GOP to 12. I try this now.


OK, I tried GOP 12 and it did not work. Also freezes the camera.
 
Transcend 32GB class 6, no problems

Transcend 32GB class 6, no problems

AKED said:
OK, I changed the GOP to 8 and then the pumping is gone.
But then what Svart writes, if I put it on a tripod, after a few seconds in FHD, the class 10 card 16 GB from Sandisc stops recoreding due too high write speed and it does not have the clip that has been recorded to up that time on the SD cars.
I have to draw the battery and the3e clip is lost.
To avoid this it was said, to change GOP to 12. I try this now.


OK, I tried GOP 12 and it did not work. Also freezes the camera.
Click to expand...

I have been using the C settings, GOP of 8 and a Transcend 32GB class 6 card for about a week and shot at least 3 hours with it in all sorts of conditions with no problems.
 
AKED said:
OK, I changed the GOP to 8 and then the pumping is gone.
But then what Svart writes, if I put it on a tripod, after a few seconds in FHD, the class 10 card 16 GB from Sandisc stops recoreding due too high write speed and it does not have the clip that has been recorded to up that time on the SD cars.
I have to draw the battery and the3e clip is lost.
To avoid this it was said, to change GOP to 12. I try this now.


OK, I tried GOP 12 and it did not work. Also freezes the camera.
Click to expand...

I'm guessing this is somewhat related to the problem I've seen.

Vitaliy suggested moving the GOP up, not down. This means, in the native 24p problem, that you would move from 12 up to 15. Again, that was fairly specific to my issue and I do not know if it would fix the pumping issue, but try going upwards.
 
OK, I have solved my problem.

I have NOT ticked native 24p, because it does not work for me.
I have NOT tiicked and GOP change.

I only used for AVCHD the suggested b setting of the ptool.

Noe no pulsing any more and no stop of the recording while on a tripod.

But no 25p at 1080.

But that's ok for me.

Thanks for the help and the thoughts
 
Has anybody determined whether the pulsing is really a problem? I don't see anything funny visually. I've checked it frame by frame - and nothing looks funny.

chris
 
I think he's suggested it, however, I would try changing the GOP up slightly to see if things change. As always, we need more testing before we determine anything as a fix.
 
Well, I got rid of the pulsing by changing the GOP to 8 or to 12.
but then the camera was on a tripod and there was no movement, it stopped recording due to speed limitations of the card.
That is all I can say.
i am not technician enough to have other solutions, that may be there when once can use the ptool better than I can.
 
I took 30 minutes of continuos recording on a tripod with settings "C" in 720p mode, just avchd bitrate changed. I GOT pulses. I was able to see them while pixel-peeping the recording on a 50" screen from 10 cm... From a standard viewing distance of 2mt I could not see any pulsing. The same on a computer monitor, no pulsing visible
 
cbrandin said:
Can you describe what the pulsing looked like on your screen? I don't know what to look for.
Click to expand...

I try

It was a recording of a theater show. Light is low, gh-1 set on 800 iso, manual 50mm f/1.8 lens set at 1.8, SH (720 50p)**, camera on a tripod

At the back of the actor there were some curtains, and curtains have "waves" (don't know the word,... look at your house curtains, they have "waves") and these waves generate shadows.

So in the backgrounds there were some small shadows... going very near to a 50" fullhd screen I could see these shadows changing from mud/not shown to very detailed in 26/27 frame and then back to mud/not shown in 1 frame..... bigger shadows doesn't show such behaviour... also actors doesn't show this behaviour.

So, to me, it seems a problem with static little defined objects...

If you tell me which software to use, I may try to cut a couple of seconds from the avchd stream but the software should not recompress the stream...

**: I just upped avchd bitrate

I try to attach 2 crops that are about 1 second from each other... I had to use jpg,...

the more detailed is on the right, you can see more shadows... or waves... :-)
 

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I've just seen pulsing for the first time- almost like very fast focus hunting, on FHD. Probably much easier to see on running video of a static detail shot than on frozen frames.

PAL camera,

native 24/25p
Video bitrate adjustment 38000000
Overall bitrate adjustment 40000000
Limiting bitrate adjustment 42000000

I'll try turning off native 24/25p.
 
Thanks guys. The only time I got pulses was during quick pans - where everything is blurry anyway. Now I understand why I couldn't see it.

Chris
 
Here is my 2 cents:

The GH1 has some AVCHD codec issues, pretty nasty at times, a painful thing because often the picture is very good. The GH13 has the same exact codec issues, regardless of gop or bitrate setting, but they are much more mitigated due to brute force bitrate increase. So this is the same stuff as seen on stock firmware. The codec in the GH1 seems to hate large areas that are in focus but are simple, such as solid wall colors, and like to put 'pulsing' or noticeable artifactyness there. I wish we could replace the codec with the code from x264, which is better than many commercial coders, how impossibly hard this might be I don't even fathom, even with hardware encoding many routines could still be tweakable, but finding them and changing them in the way we are changing values now in the firmware... I can only hope.. anyway I digress, I just don't think some of the pulsing, and artifacting on blank surfaces is fixable with the existing bitrate and gop tunables.
 
I've now seen the same pulsing I saw before in PTool firmware, but this time in original Panasonic firmware. But the pulsing I'm seeing may be different from what others are seeing.
 
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