Fast action GOP 2 54 mBS settings for GH1

Magnus387 said:
On normal, well lit room scenes I was not having any freeze-ups, but the second I began shooting outside and capturing all of the tiny little branches and dead grass my GH13 gave up.

I have spent the last hour or two doing some experiments with the Patch, and I finally found a slight modification that works without fail for me, and gave me a 54mBS readout.

Change the first "overall bitrate" to 90000000
Change the second "overall bitrate" to 99000000
Click to expand...
Thanks, Magnus387, I tried your modifications as well as the original patch on sunlit foliage. Unfortunately, video recording fails with SD card write-speed errors, and Stream Parser displays corrupted GOP's and empty P-frames similar to previous Native 24p attempts. After trying a few of my own stabilization tricks, I was unable to stabilize the 2-frame GOP with the Native 24p patch.

Past experience has shown that the encoder frequently records empty 192-byte P-frames when it is very close to breaking down from the stress of capturing video at high bitrates. Under normal operation, there is always some valid data written to each frame, even when the camera is perfectly static. Whenever empty frames occur, it is a symptom of AVCHD encoder malfunction.
 
Thanks Lee for you efforts to see how reliable this high data rate patch is. For my work I am hardly ever shooting dense brightly lit footage. I shoot shaloe DOF with lots of mediums and close ups plus a lot of green screens. I carry a more reliable patch on an SD card when I encounter one of those codec breaking scenes. But for 99 percent of what I do, 1080 HD TV spots, this patch gives me the highest resolution and the lowest noise. Since this is a hack and a trial and error one for now, I think it is not probable to find a panacea of patches. This patch does offer me a much higher quality product as long as I work around it's limitations. Perhaps the best we are going to get out of all this will be a series of patches all offering something unique.
 
lpowell said:
Thanks, Magnus387, I tried your modifications as well as the original patch on sunlit foliage. Unfortunately, video recording fails with SD card write-speed errors, and Stream Parser displays corrupted GOP's and empty P-frames similar to previous Native 24p attempts. After trying a few of my own stabilization tricks, I was unable to stabilize the 2-frame GOP with the Native 24p patch.

Past experience has shown that the encoder frequently records empty 192-byte P-frames when it is very close to breaking down from the stress of capturing video at high bitrates. Under normal operation, there is always some valid data written to each frame, even when the camera is perfectly static. Whenever empty frames occur, it is a symptom of AVCHD encoder malfunction.
Click to expand...


lpowell,

Maybe you can answer this question for me. What is the advantage of having a 2-frame GOP over a 3-frame GOP?
 
Magnus387 said:
What is the advantage of having a 2-frame GOP over a 3-frame GOP?
Click to expand...
My Fast Action 3-Frame GOP Patch uses 3 frames in SH 720p30 mode and over time it's proven itself to be highly reliable. Since no 2-frame GOP I've seen has worked in a stable manner, I'd have to say that was a serious disadvantage.
 
I didn't get empty P frames on the clips that did record, but there was a faulty P and I frame at the start of each clip, they were not empty. As you say it's still encoder malfunction and so not acceptable if you want reliability. I thought this patch may have helped with the 60/50p high bitrate that i seek that's why i tried it.

The high birate clips i shot were very detailed, this might be useful for recording indoor type footage under lights (i had 50Mbps+ under lights) where you have the option to do multiple takes but too risky for one off situations.

R
 
Last edited:
I should be more specific...

With the Fast Action Gop 2 54 Mbps hack. If I change the 1080p Gop Size to 3, my error count goes way down, so I was wondering what the real advantage of a Gop size of 2 was.
 
A GOP-length of 2 may have a slight advantage over 3 in capturing very rapid motion. However, the compression ratio will drop, making file sizes significantly larger.
 
And that's what I'm after when I shoot a green screen. I want a big high rez file, 1080 not 720, with the lowest compression possible. GOP 1 would of course be best. But 2 looks outstanding.
 
I think Blackout does something similar that works (high data rate) but you never know what tricks he hides under that big hat :)
 
some of my AVC 1080p tests
bitrate will be about 60mbs (i think it's maximum bitrate, wich avc can do)
There is still problems with high and low light scenes
I find when "GOP 1" there is no matter what settings set on overall bitrate, overall bitrate 2

Wrapper Native 24p Check

AVC compression
FHD 59000000 (with bigger setting camera will freez, please check it out for yourself)

AVC GOP
1080 24P 1

All others bitrate settings keep unchecked
 
humpman said:
some of my AVC 1080p tests
bitrate will be about 60mbs (i think it's maximum bitrate, wich avc can do)
There is still problems with high and low light scenes
I find when "GOP 1" there is no matter what settings set on overall bitrate, overall bitrate 2

Wrapper Native 24p Check

AVC compression
FHD 59000000 (with bigger setting camera will freez, please check it out for yourself)

AVC GOP
1080 24P 1

All others bitrate settings keep unchecked
Click to expand...

humpman,

Could you be more specific about your settings, I'd love to try them out. Where did you set the 59000000?
 
Magnus387 said:
humpman,

Could you be more specific about your settings, I'd love to try them out. Where did you set the 59000000?
Click to expand...
AVCHD Compression
Video Bitrate FHD/SH 59000000

Still testing...
When Native 24p/25p is checked Overall Bitrate settings don't give any difference.
I was shoot pappasarts test chart, i just defocus it and slowly back into focus.
Most stable data rate i can get with GOP 5, bigger gop is not interesting for me.
 
I tried your settings, berndporr, at 640 ISO and FHD 50i.

You're right: The results are appreciably grainier than with the normal GOP settings. But vertical fixed pattern noise seems to be reduced as well (maybe due to the overall graininess).

So for me it's a tossup: grain or FPN?

Does anyone else have an opinion? I'd be particularly interested in LPowell's...



EDIT: Camera just froze up on me (Sandisk 30 MB/s). This has never happened before except in 25p native mode. So these settings are not for me.
 
Last edited:
Hi,

I've made more tests and the GOP=2 is only stable with tripod and interior. Outside in the woods the camera freezes. After a couple of trips to the local park I've now settled for the settings shown in this clip which uses GOP=5.
http://www.vimeo.com/23182548
You get loads of blocking artifacts when the camera is quickly panning but they are only visible of you look at single frames. The noise in even surfaces is still bearable. The bitrate is at 20Mbit/sec more or less all the time.
[Information]
Comment=40Mbit/sec GOP 5
SD_Card=SDHC 10
Camera=GH1 v1.32
[Settings]
Version increment=1
Prevent version compare=Checked
Third-party battery=Checked
All Interface Languages=Checked
30min limit removal=Checked
PALNTSC Menu=Checked
720p30->720p24=Checked
720p30->1080p30=Checked
720p30 420->422 color sampling=Checked
E1 Quality=400
E1 Table=103
E2 Quality=350
E2 Table=116
E3 Quality=250
E3 Table=120
E4 Quality=200
E4 Table=125
Video Bitrate FHD/SH=40000000
Video Bitrate H=17000000
Video Bitrate L=10000000
Overall Bitrate=41000000
720p50 GOP Size=5
720p60 GOP Size=5
1080p25 GOP Size=5
1080p24 GOP Size=5

emory said:
I tried your settings, berndporr, at 640 ISO and FHD 50i.

You're right: The results are appreciably grainier than with the normal GOP settings. But vertical fixed pattern noise seems to be reduced as well (maybe due to the overall graininess).

So for me it's a tossup: grain or FPN?

Does anyone else have an opinion? I'd be particularly interested in LPowell's...



EDIT: Camera just froze up on me (Sandisk 30 MB/s). This has never happened before except in 25p native mode. So these settings are not for me.
Click to expand...
 
You must log in or register to reply here.
Back
Top