By disabling the "write speed detection" failsafe of the Panasonic GH1, hacker Chris has doubled the GH1's AVCHD bitrate from 44Mbit to 86Mbit -- a drastic increase over the camera's stock speed of 17Mbit/sec. The culprit in limiting the previous incarnation of the hack to 44Mbit was apparently Panasonic's desire to make the camera compatible with cheaper SD cards, thus placing an artificial limit on the SD write speed, independent of the actual speed of the card used -- since removed by Chris. From EOSHD:
Chris has been reading the GH1's actual firmware code in order to make the discovery. It is believed the failsafes were put in place by Panasonic to make the camera compatible with El Cheapo SD memory cards across the board and for 100% reliability whilst recording video with a deep depth of field - for example highly detailed wide shots, foliage and grass with a sharp lens at F8.
When the Panasonic GH1 was first hacked, I posited that the 5D Mark II was still a better camera for filmmakers. Some have angrily rebutted that claim -- but my position was based on the instability of the original hack (when the hack was first released, the camera would consistently crash). Because, you know, filmmakers require a camera that actually works. Since then the hacked GH1 has been able to record at 44Mbits reliably, giving a much-improved (and aliasing-free) image that rivals and in many cases exceeds that of the 5D. Wanting to test the cameras side-by-side, I obtained a GH1 courtesy B&H Photo -- but have been to busy too put it to the test. Now it looks like I'll be able to test it with double the datarate of the previous hack. Or will I?
GH1 shooters looking to substantially increase the bitrate of their AVCHD footage should check their camera's serial number to see if it is hackable. Panasonic has apparently locked down the firmware on models manufactured after June 2010, and it looks like my test cam was made... in July 2010. So much for that -- it's up to you guys to test this 86Mbit hack once it's released (it is still undergoing testing).
If you're curious to see a side-by-side test of the two cameras, you can see in this test by Eye Patch Entertainment that the GH1 is night-and-day sharper than the Canon 7D. Click through and watch it in 1080p if your computer can handle Flash video at that resolution:
Of course, for anyone looking to buy a GH1, the currently shipping models don't allow this hack. Come to think of it, eBay!