GH2 DO NOT POST SEPARATE THREADS: GH2 Hack | Questions and Answers Thread

GH2 Hack bitrates - no difference?

GH2 Hack bitrates - no difference?

So I've had my GH2 for a while now and decided to enter this hacking business. I'm currently using the latest version of PTools (3.6) with EOSHD's Vanilla 44mb patch. I'm using Transcend Class 10 16gb SD cards. Using various ISO and testing last night and this morning, I'm still getting an average bitrate of ~13 mbps according to CinemaTools. I checked my pre-hack GH2 files with CinemaTools and it sill has the same rate.

Am I doing something wrong? Am I suppose to see bitrates closer to 30-40? My Canon 5D Mark II clips have an average bitrate of ~23mbps.
 
Also... I've used both Apple ProRes 422 and Apple ProRes 422 (HQ) codecs.. no differences in bitrates between original and hacked GH2.

ProRes 422 - ~13mbs
ProRess 422 (HQ) - ~20mbs
 
alright, i've read a couple of threads, and for the life of me don't understand GOP sufficiently to be able to explain it to someone else.

What does GOP do? Why do we need either a high or low GOP, what is the best case scenario, why does that scenario not work sometimes?
 
AVCHD records images in "Group of Pictures" which means that those groups of pictures are not independent of one another. They always start out with an "I" frame and the resulting frames can vary. Some examples are from Wiki:

I-picture or I-frame (intra coded picture) - reference picture, which represents a fixed image and which is independent of other picture types. Each GOP begins with this type of picture.
P-picture or P-frame (predictive coded picture) - contains motion-compensated difference information from the preceding I- or P-frame.
B-picture or B-frame (bidirectionally predictive coded picture) - contains difference information from the preceding and following I- or P-frame within a GOP.
D-picture or D-frame (DC direct coded picture) - serves the fast advance.

The "P", "B" and "D" examples above are ways to make the codec more efficient. What I mean is you get high quality images but taking up less space on the card etc. Usually that means the GOP is higher. For example. the GH-2's "stock" 24p uses a GOP of 12 (I believe). Or...simply...Groups of 12 (which could mean two "I" frames out of 24 and the rest are "B" frames etc.). I'm not sure of the exact setup (someone can fill us in with better info) but it could mean one "I" frame and several "B" or "D" frames grouped all into one (creating one second's worth of images). All of these "B" and "D" frames etc. are a form of "compression." And....you know what compression means??....Artifacts galore!!!. Those artifacts can lead to the smoothing out of noise in the shadow areas....killing detail. It can mean...macroblocking hell. It can mean...fill in the blank. I'm sure you get the picture by now (no pun intended)? :)


So, why do we need high bit rates for GOP1?? Simple...GOP 1 represents just one big whopping frame by itself. It's the highest quality image out of the camera. So...in order to make that "One Second" of images like the above example you would need (for 24p) 24 "I" frames. That's a lot of needed data...thus why we need...a very high bit rate. That is like taking 24 high quality still picture (JPEGS) in a row to make just a ONE SECOND image. This is what you call "Intra Frame." In the past....one could only shoot "Intra-Frame" with very expensive professional cameras. BUT....not anymore...thanks to the hack. If you think about real" film and how it behaves...then the Intra-Frame shooting mimicks that perfectly...which is why a lot of folks say the motion of GOP1 looks very filmic. This is also why the GH-2 is worth so much more than the $700 it's currently priced at.

All this is a little vague....but was meant to give you a better ideo on the "whys"....in terms of using a high bit rate. Hope this sort of helped.
 
Last edited:
that helps tremendously, thank you for taking the time to explain Ian!

Now i guess the question is always about geting to the lowest GOP setting to mimic the right motion of 24 that we all love and strive to get. But then if we have too low of a GOP, the data rate is too high and makes capturing unstable.

GOP of 3 seems to have been working the best i assume because i read mostly GOP 3 when i see the hacked versions.
 
It does seem like GOP3 is supposed to be right for 24P, but I'm actually kind of satisfied with the cadence of GOP1 hacks and a shutter of 1/40.
 
NP Papa.

Actually the Nick Driftwood GOP 1 176 MB hack has been very stable. He has newer variations of it called Aquamotion and others...but it's by far the most popular hack out there. I've been using his orginal version for the last few months and never had a crash on my SanDisk Extreme Pro 30MBs card.
 
It would be interesting to see at what point bitrate because pointless. I mean, how much do you gain versus file size. Both in terms of noticeable difference from the eye as well as color correction difference. That just seems like it would take up an enormous amount of space and i wonder if there is a popular happy medium between bit rate and file size.
 
PaPa said:
It would be interesting to see at what point bitrate because pointless. I mean, how much do you gain versus file size. Both in terms of noticeable difference from the eye as well as color correction difference. That just seems like it would take up an enormous amount of space and i wonder if there is a popular happy medium between bit rate and file size.
Click to expand...

It does take up a decent amount of space. On a 16Gb Card I'm getting 14~15 minutes of footage. However, I guess it's not that big of a deal to me because I've been shooting raw for so long, I'm used to it.

I do NOT know, however, if over this would be much of a difference. Right now, it's more about getting the encoder to become stable, spanning, and refining what the hack brings. Quantum V2 was an absolute image jump over the seaQuake hack. I saw it immediately.

Experimenting with GOP1 and 3, and how shutter speeds affect that, seems like a solid way to waste a day or two.
 
I may be doing something fundamentally wrong, but no matter which patch I install (88mpbs / 44mbps).. all of my clips are coming out the same size and the same average bitrate than with the original un-hacked GH2.

I'm using ProRes 422(HQ) and Cinema Tools to analyze my clips. On the hacked GH2, my 1080p 24H clips average 20.5 MB/s and in my original GH2 my 1080p 24H clips average 20.8 MB/s. What am I doing wrong? The only difference I see in the hack vs non hack is that I now have ISO 12,800 available, but visually and file size - nothing.
 
GH2 firmware v1.1 vs Hack

GH2 firmware v1.1 vs Hack

I have a stock GH2 and am wondering if I should install the new firmware v1.1 or try a hack?
 
I personally went with installing the firmware update, but would imagine I was in the vast minority.

Someone will figure out how to hack it in no time.
 
What is more important to you? Extremely accurate continuous auto focus during recording, 1080p @ 25/30 FPS, improved noise reduction(mostly for stills though), and full screen touch auto focus. Or high bit rate and high ISO video without the 30 minute time limit and switchable regions?

If you want the new features then by all means install the new firmware. If you want the high bit rates then wait. Or you could just install the firmware and determine which one suites your needs the best. You can always revert back to the hacked firmware later.

 
man, I'm getting a headache trying to nagivate personal views for all the patches.

Can we put together a list of what's available and try to organize some of the details?
 
Since I was less than charmed by the GH2 noise, even at 400 ISO, I installed the new firmware, and so far, I have seen what appears to be a small improvement.
 
http://www.personal-view.com/talks/...ch-vault-most-popular-patches-in-one-place/p1

this has most of everthing, but it's quite a mess. Given the information gathered, Low GOP = better motion and more like the 24fps we all know and love.

But deciding between GOP of 3 and GOP of 1...

What are the choices here. The page is far too random to keep track.

Need to make a list of what's available in order of bit rate from low to high with appropriate GOP.

oh, and the cam just arrived in the mail about 2 hours ago and I've been reading as much as i can since, but not getting the exact info i'm looking for.
 
You must log in or register to reply here.
Back
Top