Some of you may recall some time ago I bought a Sony AS100VR for use in my work, primarily because I wanted the image stabilisation feature. Unfortunately I was not happy with the camera due to the severe fisheye distortion and the odd clumpy video artefacts that made the pictures poor in apparent resolution.

On the fortunate side, I was able to put the AS100 up on EvilBay and got a top bid that was only 6 bucks under what I paid for the camera (don’t you just love it when people get carried away with bidding), so I then ordered one of the new GoPro Hero4 Black cameras. There was not a lot of material around to judge the Hero4 by, as the camera was quite new, and this made me a bit nervous. But the small amount I saw led me to believe it would be reasonably good for the price, even though it was a couple of hundred more that the AS100.

I now have the camera and have been performing tests with it to try and develop an optimum workflow for processing it. My target is to produce 1080p HD material that is crisp and sharp, so the Hero 4 material will be mixed with footage from my Blackmagic Pocket Cinema Camera, and I would like to get them to look as close as possible when cut together.

With that in mind, I shot a test clip in 2.7K 24fps using the GoPro Protune settings to obtain a clip that was as unprocessed as possible. To obtain the footage, I attached the camera to the front of my car using a suction mount on the hood and drove from my house down to the nearby town of Garfield and back. This is a close approximation to the sort of shooting I want the camera for, where it will be mounted on moving railway vehicles, often quite low down.

The Hero 4 offers 4 setting for the FOV, SuperView, Ultra Wide, Medium and Narrow. The 2.7K resolution setting offers 3 of these, omitting the narrow FOV. I chose the medium setting as I wanted to begin with the least distorted image possible. I then tried processing the footage through the GoPro Studio application, a free download authored by Cineform. GoPro Studio has a function to remove the fisheye distortion, and even though it was not particularly objectionable, I thought it might be worth a try. The result was not very good, it cropped the image quite a bit, reduced the resolution of the image and more importantly, totally cancelled all the Protune settings. I rather suspect the GoPro Studio application is not for the discerning professional but most likely aimed at the GoPro fans who have little idea about good image processing.

So I turned to DaVinci Resolve 11 Lite, which is a free download. I was able to import the footage easily into Resolve, and then graded the footage lightly (the color was close to ideal as it came out of the camera). I restored blacks, adjusted the gamma, increased overall saturation a touch and just added a small degree of sharpening to the image. I then rendered the footage as a uncompressed 10 bit YUV file, and noted the growth in file size. The original camera footage was about 1.7GB, it grew to 42GB when rendered. Under normal circumstances I would then use this file to edit in Vegas and perform all titling and audio work. However as this is a test only, I then processed the file through trusty Handbrake to arrive at a file size around 578Mb. The resultant file is a compromise between keeping the file down in size and the appearance of ‘clumping’ in the tree foliage. For my final work, the size will not be a problem.

My conclusions are these. I will probably not attempt to correct the fisheye distortion, as I do not find it that objectionable if I shoot in ‘Medium’ FOV. I may increase my rate to shoot at 30fps to try and minimise movement artefacts. And I will use Resolve to do the grading and output scaling (its free and works a treat). I think the Hero4 is a very good investment, even though the cost is getting a little high, but the pictures prove it is worth the extra money. My only beef is the fact that it blows out the highlights a little too much for my liking, but all the other automatic features make it a winner for this sort of operation where you are not able to control all the parameters during shooting. The WiFi capability of the Hero4 was a pain to use, consumed lots of battery and frankly I will not bother with it again. I tried the Wifi using the GoPro App on my iPad and came close to throwing the iPad over the fence. I really only wanted to be able to see the framing when setting it up, but in the end I cut a hole in the side of the GoPro waterproof housing and plugged in my 7” viewfinder via the micro HDMI connection, much better result.

I was investigating purchasing the Backbone Ribcage conversion that allows you to remove the GoPro lens and fit a mount for C and CS lenses, but the combined cost of this conversion plus a suitable lens amounts to around the same price as another Hero4, and having sampled the footage using the ‘Medium’ FOV setting, I am now inclined to drop that idea.

Would I recommend the Hero4? Certainly, it is a very worthwhile tool to have in your armoury. Best way to process the Hero4 files? Resolve Lite, absolutely.

If you would like to see the clip after processing, you can download it from here, it is Clip 5 at the bottom of the list: http://www.hollywoodfoundry.com/film%20files.htm

But be warned, it is 578Mb in size. I do welcome critical discussion on the clip and my findings.

Geoff

PS, my next experiment will be to explore the stabilisation feature in Resolve 11, although this clip hardly needs it.