DIY Chroma Key, Lessons Learnt

Posted: November 25, 2011 in Chroma Key, Cover Videos, Music & Slice, Video Editing
Tags: , , , , , , , , , , , , ,

Our first attempt to make a cover video with Chroma Key was published here last week.

Slice covering Gun’s N’ Roses – Don’t Cry


I must confirm that I am fairly happy with the result, though far from professional, it is acceptable in the video side of things. With the Audio on the contrary I am very satisfied even when it needed a second mastering for Slice’s performance to blend in to the original track in a way that could be noticed. The first mix was far to blended and it didn’t sound credible. As he put it himself unless you spot my mistakes you wouldn’t believe that I was doing a cover just a playback.

So once we where pleased with the audio, we went on to editing the video. Al the video footage was captured from a single camera head on focused at eye sight height and taking a mid body shot so we got Slice and the guitar. Video and audio where recorded in the same take so they are live performances. As soon as I started editing the footage I came across the shortcoming’s of the material we had. Most of witch where fault of the set and the lightning. Also my inexperience with video paid a hard toll on the amount of effort that was needed to get the current results and be some what happy with  them. In general I find video 10 or more times harder that audio depending on the task. The recording to start with, most of the takes where ok on the audio side (Slice knows his stuff fairly well), but when it comes to performing in front of a camera he finds it more of a challenge, having to take up to 6 or 7 takes of the same track over the 2 to 3 necessary for audio, putting the recording in an average of 10 takes per track. This all adds up over 5 hours of recording to get footage to build a 5 minute video. Editing is the second big issue, I can forgive what has happened to the first video since I take it as a learning curve and a very steep one I must admit. I have spent a minimum of 18 hours editing or trying to to get the 5 minute result. I don’t know how far I am up the learning curve but looking back I am far from the start. The last issue is the setup, of course I had experience in audio setup and that has played back but the Chroma set took it’s time and thinking, and now I know where to improve and will for the future.

image     Chroma Set during recording session

I didn’t get into this blindfolded, I have read and followed tons of tutorials on the web about the correct procedure to getting a good quality Chroma Key. The theory is very simple, straight forward and clear to follow and so I did. But reality is a very different beast. When I got my first take up on the editor I found shades and shines that weren’t present during the recording, or that I couldn’t spot at the least. As you can see in the following picture most of the back drop seems to be evenly lit up.

DSC01699Backdrop with lights.

Well it is not and I have learnt this the hard way.  Another tuff lesson was the subject. Slice in this case, has to be wearing cloth’s that can’t merge in to the back drop chromatic spectrum. In this case the prints on his tee-shirt did juts that. Making the keying far more difficult, trying to avoid that his torso was keyed out in to the background. The lights, well I have learnt a thing or two on the subject, it is not that much a case of flooding things in as much light as possible, as it is more about getting the light evenly spread on the backdrop, avoiding shadows cast by the subject main light on the backdrop and separating the subject physically and with a back light from the backdrop it self that make the difference.  Getting all this right is a matter of try and error until you get the appropriate setup, don’t count on getting it in the first attempt.

The theory says that any colour can bee keyed out and while this may be true, it is the selection of a colour that will not be present on the subject that make it easier. An other factor is that it is not too dark, since it can get merged with some shadows on the subject. obviously my choice of back drop has been far from perfect. Green is along with Blue Royal the least present or easier colours to avoid and I went for green, but my cloth has a large mix of tonalities it is green in the major but it has blues and reds and other tonalities to it specially under uneven light conditions.

There will be an entire post about light (not that I am an expert) just to share experience, but I want to put something down here just a few quick note. You need to get light on the backdrop, the subject and the subject back light but direct light is not the solution it needs to be defused and softened, you will need at the least 2 lights on the back drop, 1 on the subject as main light and it is recommended to have another one on the backlight to the subject. I have been using bounce cards to get indirect light exposure. As shown on the picture these are two 1.5m x 0.25m Polyethylene boards stuck together in angle to provide a disperse light to the back drop, the lamps 350W halogen have a filter trans lucid paper to diffuse the light. the main subject spotlight is another 350W halogen bouncing off the celling and a bounce card placed behind and oriented to the subject. the subject back light is a 200W lamp positioned to the right of the subject behind and bellow the frame area also filtered.

 DSC01705Celling lights on back drop with bounce cards

The camera is the week part in this gig, we are using a handycam from Sony DCR-SR47 60GB HHD, it has a HQ function but on the recordings of this video it was set to SP 6Mb/s that is mid quality, I have tuned it up to max quality and we should get a more crispy result next time. I also try to avoid as much zoom as possible to prevent getting degraded image, thou it supposedly has a 60x Optical zoom that should not present an issue. It is obvious that the better the quality of your picture the easier and more room for editing.

imageMain Camera

For editing SW I am using Adobe Premier Pro 5.5, this is my main tool but I also use Director Pro 9 for some things. using any video editing SW is a challenge in any way you want to put it ,there are virtually thousands of online video tutorials and I haven’t seen 2 do the same thing in the same way. I have learnt a lot of ways of getting things done, not just Chroma but this is a real head on battle. I have found out that you need to know about exposure, matte, hue, spill, and a hole bunch of bits and pieces that make up your frames, a slight touch on one will bring a value to undesired range in any other, there are so many parameters so similar, and at the same time so different you can get lost and it is best to go back to the beginning if this happens. I recommend anyone that wants to give video editing a sot, to keep a good copy of all your raw material and originals in a safe place and work with a copies. 

image Adobe Premier Pro Cs 5.5 UI

As I said earlier on I have room for improvement and I already have an idea of how I am going to go about it, forgive me for not detailing this plan here but I want to see it work first instead of embaying my self with new failures, that I am not going to be able to prevent form happening but are better handles in the private zone.

Thanks again to all for your interest and support
I really hope that you enjoyed this

Ian A Burt.

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