GH1 1 GOP experiment

R

rigs

Well-known member
I have been playing with a 1 GOP - 24p patch that works well for normal detail scenes.
It will crash with static extreme detail and very dark scenes but the cool thing is it will still write the file to the card if it does crash.

I am posting this for experimental purposes only, please test it and report back. Perhaps it can be improved upon.



PTool v3.62d (160811) settings

WRAPPER
Native 24p/25p checked

AVCHD COMPRESSION
Video Bitrate FHD/SH = 70000000
Video Bitrate H = 34000000
Video Bitrate L = 34000000
Overall Bitrate = 44000000

AVCHD GOP LENGTH
720p60 GOP size = 1
1080p24 GOP size = 1

PATCHES FOR TESTERS
AVCHD MOVIE MODE

AVCHD COMPRESSION
Preset bitrate = 4400
Preset bitrate 2 = 7000
Overall bitrate 2 = 7000000

AVCHD Research
Constant for 1080p = 7000600
Constant for 720p = 4405600
Frame related comparison = 24
Video buffer = 50.000.000
 
One of the interesting things I find with Ptools is when you increase the video buffer it will increase the overall bit rate. I would think that it would simply allow for more headroom to purg the data.
 
Last edited:
Keep 'em coming Rigs! Just curious, what is the difference if you keep everything the same and change GOP to 12--is there an obvious difference in quality?
 
Finally got around to play with a GOP1 patch....and interesting. The footage I shot wasn't particularly noteworthy but the stream parser does show some interesting bit rates. Capture one is on the left, two in the middle and three on the right:
Capture.jpgCapture2.jpgCapture3.jpg

Capture 2 is where I played with a Gop setting of 2 and it didn't look good. All the settings were the same as the GOP1, so I figured lets just change it to 2 and....don't even know what happened there.

Capture 3 is....am I seeing that right? Did I hit a peak 300 mbs a few times?!? This is with a Transcend Class 10 16gb card. This was very low light, super under exposed mostly, and a pancake 14mm 2.5, iso 200. I'll take it outside now and try and get some decent footage. Only crashed shooting super dark scenes. Near blackness and low GOP don't mix.
 
I have been having some good luck with this patch it gives you smooth cadence with pans and any fast moving scenes. It averages around 45 -65 Mbps on well lit and exterior high detail scenes.

For most of the scenes I have filmed, it was 97% stable and produced some of the best 24p highest quality I have ever seen coming out to the GH13 to date. I have found that If do get a card write error on high detailed scenes, it will still save the clip file and resume back to live view mode in a few seconds once the clip has been forced to stop recording. Unlike other patches that lock up the camera completely and require you to pull the battery and power it up again with the locked up clip being completely lost.

So far the best camera and lens scenario for this patch has been with non Lumix lenses. I have used several Canon FD lenses ranging from f1.8 - f22 with good ND filters with my tests. It is also advisable to shoot 1/3rd of a stop under exposed and to use a SanDisk Extreme Pro 30Mbps card to help safeguard you with the best possible write error protection.

Here is my lattest GOP1 test patch

PTool v3.62d (160811) settings

WRAPPER
Native 24p/25p checked

AVCHD COMPRESSION
Video Bitrate FHD/SH = 120000000
Video Bitrate H = 34000000
Video Bitrate L = 24000000
Overall Bitrate = 120000000

AVCHD GOP LENGTH
720p60 GOP size = 1
1080p24 GOP size = 1

PATCHES FOR TESTERS
AVCHD MOVIE MODE

AVCHD Research
Encoder setting 1 = 3
Encoder setting 2 = 5
Encoder setting 3 = 7
Video buffer = 33.500.000
 
I just tried this and.....it dies fast in low to no light. Didn't think that would be much of a problem, but literally after 5 seconds or so in darkness, it dies. Lpowell said in his GOP3 fast action patch that in low/no light, the bit rate automatically drops to under 5 mbs and if it stays low for 7 or more seconds, it dies and doesn't save because the AVCHD codec is just buggy like that. This keeps dying on me for that same reason and it dies fast.

I tried GOP4 and it didn't die on me like this so I think GOP4 is the lowest you can go and not worry about it dying on you in low light.
 
You must log in or register to reply here.
Back
Top