Vitaliy hacks ‘photographic’ looking 42Mbit 1080/24p AVCHD out of GH2

Hacked GH2

Above: EOSHD’s hacked GH2 with Zacuto EVF Flip and Iscorama!!

Codecs are currently the biggest weakness of DSLR video but that is about to change, and no – not with an external record but inside the camera.

The hacker Vitaliy Kiselev says he has had ‘a break-through’ – raising the AVCHD bitrate of the hacked GH2 to an average of 42Mbit – almost double the original Panasonic specification and higher than the top AVCHD PS setting of 28Mbit. And unlike the GH1′s encoder, the GH2 has B-frames making it more efficient, so for the same bitrate it delivers more image quality than other DSLRs in the 40Mbit ballpark like the Canon 5D Mark II.

Vitaliy says on his forum that the video looks ‘like a photo’ in terms of quality. The next PTools release containing the patch is due out soon.

It’s important to note that testing is ongoing and nothing is final or 100% reliable – there will be more progress as Vitaliy and testers seek to understand the GH2′s inner workings. He currently thinks that 42Mbit isn’t the top rate and he thinks the camera will go further.

There is also the question of 1080/60p and improvements to the HDMI output of the GH2 which will make it into a real monster, but testing on those so far hasn’t unlocked the full potential. I’ve been testing the HDMI behaviour of the camera and 1080/60p. As an example, there are several settings in PTools that nobody, not even Vitaliy knows the function of yet and must be tested.

The purpose of testing is to methodically change one at a time, in an effort to understand how it effects the camera. Seeking out better image quality and fine tuning settings is the last thing that happens – first testers must be very systematic and understand the camera’s programming. There is one setting Vitaliy has labeled as Encoder Setting 4, for example. When this is changed, it seems to affect the type of feed which is given to the LCD and HDMI output during recording, but in a very limited way. So the mission goes on to find more settings, combine settings and understand what they do.

ExTele crop mode now works over HDMI but only after the record button is hit. Quality is exceptional.

In terms of 1080/60p, things are nowhere near there yet. PTools seems to change the encoder to progressive 60p but information in each frame is corrupt, with some kind of interlaced image in the top half and garbage in the other half. But I am optimistic we will get 1080/60p in the end. According to Panasonic’s own specifications the GH2′s sensor output is ’60p’ in 1080i mode, so it should be a case of changing just the high level firmware parameters and image processor, not the fundamental operation of the sensor.

The AVCHD implementation in the GH2 is highly advanced, and understanding it takes time. In the GH1 it was very basic in comparison!

Without the heavy compression or poor scaling common on DSLRs, the hacked GH2 really will look like a Micro Four Thirds version of a RED camera at this rate. No line skipping and no heavy compression artefacts as well as an efficient encoder and super high bitrates.

It certainly beats the hassle of having an uncompressed HD-SDI and external recorder. The GH2 can rival the quality of that all inside it’s own toy consumer shell! Incredibly powerful hardware for the money.

Viva the revolution.

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