Archive for August, 2011
The GH2 offers a burst JPEG mode @ 40fps for 1 second. With the new release of Ptool 3.62, I wanted to test how it held up to 132mb with the hacked GH2. While 132mb might not be the best quality setting that will be discovered for the GH2, for the time being, I think it makes a good benchmark for comparison versus other cameras, or even other camera modes, such as this burst mode.
It’s actually fairly shocking how close the two modes are. They could be easily intercut with each other, although I would certainly use the burst mode if it was avaliable for full time shooting.
I’ve been testing multiple GH2 settings for weeks, and I’ve wanted to reach the highest stable bitrate. I think 132mb GOP 3 is going to be fairly close to that for the time being. I’m no AVC expert, certainly someone who is will come up with the penultimate hacked GH2 settings in the next few months, like lpowell did with the GH13.
To get started with these settings, you’re first going to need one of these cards
Be certain to get one of the Extreme Pro cards, anything less will crash. The only other option is a Kingston Extreme XX card. In terms of sequential writes, both cards are very similar in writing performance, however the Kingston cards are more expensive and have faster reading speeds.
I need to find an SD card that can actually write 25MB per second across the card. I don’t think any of the current Class 10 cards will, maybe one of the UHS-1 cards, but I’ve read conflicting reports in any case. Why do I need to write at this speed? Well I’ve seen bursts over 180mb per second. The reason I’m using GOP 3 is because it actually saves the file when the camera crashes. With GOP 6 and GOP 12, I have to eject the battery and restart the camera. In any case, I’ll post a couple of PNG stills below from the peaked 186mb bitrate footage.
Again, this high of bitrate may never be stable on the GH2. It may not even be necessary for 4:2:0 1080p footage. Below are 3 PNG images taken directly from footage at 88mb, 132mb and 176mb. The 176mb footage is one stop brighter due to bumping the lens while flashing the camera. Everything else is the same.
176mb needs a fast card. Out of the few Class 10 cards I have, none are fast enough to record more than a few seconds at a time. This is the highest bitrate I’ve been able to record with the GH2, and it only works at GOP 3. I have no doubt someone in the future will push 200 with the right settings and right card. This setting is not stable. It’s stable enough for a few seconds, or stable while recording with the lens cap on – not really useful in real world situations. Low GOP settings are broken at this point as well with 3.62d, so this is in no way something you’d want to load on your GH2. Oh! In camera Black and White is fairly stable at this setting, probably due to the fact there is no chroma information being recorded and that drops the bitrate way down to the mid 90′s.
Be awesome, play this in the background while watching.
I’ve hit a new benchmark
While testing for max bitrate, I’ve been able to hit a very very unstable 176mb which, while not useful right now, may be stable in the future. I don’t know if this bitrate is actually useful for 4:2:0 1080p, but it sure looks nice.
Try it out with ptools- link below