While we test the Panasonic Lumix GH4 slow motion mode we have come across the fact that the 96fps mode is actually better than expected at above 720p resolution. Many claims suggested that it was just 720 up-resed to 1080p and leave it at that.
See our first test video:
By blowing up the included 720p mode on the GH4 which only maxes out at 11 Mbps we were able to compare it directly with the 96fps mode claimed to be 1080p and see that the hi speed mode does indeed look superior, has more detail and scales up much better than regular in camera 720p.
Is it real 1080p? Not really, it is more like an in between resolution that is skipping lines at 96p to make up for bandwidth limitations. The 96fps mode is recorded in camera at 24Mbps maximum data rate at 24p which means that the camera is delivering the 96 frames from a 100Mbit a second recording stream. Same as the 4k and 1080p modes.
So 100 Mbps is the limit of quality here and there have to be some trade offs to the regular modes which output 100Mbps and up to 200Mbps up to 60p in 1080. The 60fps mode in 1080p is beautifully clean and is a perfect match to the 50mbit/sec 24p mode if recorded at 100Mbps and a match for the 1080p mode at 100Mbps if the 60p are recorded at 200Mbps. We recommend shooting 60p at 200Mbps which is jaw droppingly free of artifacts, noise and full of minute detail. No 1080p mode is free from Aliasing in the GH4 and only the 4k mode will deliver an Aliasing and Moire free image. So if you must have an artifact free image we recommend shooting in 4k and down-sampling to 1080p if you don’t need slow motion.
Looking at the 100 Mbps data ceiling in the hi speed mode, there is a probability that if hacked, it could yield better bit rates at 96fps if tapped into the 200 Mbps encoder or better yet higher frame rates. The camera processor may be the limit here so it will be an exciting hacking development to extract this improved performance out of the camera.
The Slow and Fast motion VFR modes which go from 2fps to 96fps in multiples of two record in continuous mode. You can record at 96fps until the card is full in the US and Japanese GH4 models which don’t have the European limit of 29min 59sec.
We can’t help but wonder if the camera was hacked to only record for a few seconds but at higher frame frequencies how would it fare? Will the buffer let the camera store 240fps or even more for lets say 5 seconds and then write it slowly to the cards or will the sensor readout rate be the determining factor in the equation… Most high speed cameras can do high frame rates because the sensor allows for the rapid read and clear out of voltages; which can determine how fast you may actually be able to capture frames. The other is the buffer size which lets the data be stored before processing and writing to media. If the GH4 is able to read off the sensor at higher frequencies like 120p and above which is likely, the buffer will be the limiting factor.
We can only dream of the camera being hacked to find out the limitations. We don’t expect it will be easy or happen at all. It would be however an interesting experiment for the hardware hacker community!
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