13 May 2011

Shooting video for online delivery

Use a tripod

The best advice I can give is to use a tripod whenever possible if you are shooting video footage intended for online delivery. The compressed movie will have a much smaller file size and therefore a lower datarate (faster download) than a similar movie which uses footage shot with a hand-held camera.

Why is this? Codecs (compression/decompression formats) compare adjacent frames in your movie and the less difference there is between frames the more effective will be the compression. Footage shot using a tripod will have objects which remain in the same place and retain their colour information (barring extreme changes in light conditions) and the background will remain pretty much the same across the frames. The codec will use occasional key frames to take care of these similarities and for the frames in between will only have to compress the differences – the objects that move or change. With footage shot from a hand-held camera practically every pixel of every single frame will be different due to camera movement and this will result in a higher datarate.

If you are using a tripod you might also consider moving the camera/tripod well away from the scene you are shooting and using optical zoom. Once you've established your point of view, zoom right in on the main object of the shot and manually focus on it. Then zoom out slightly to your desired frame composition and you should notice that objects behind and in front of your focus of attention are slightly blurred. If you like this effect then you have the added bonus of shooting footage which will compress even better.


Most movies are of course a combination of hand-held and tripod-mounted shots, and there are times when a hand-held video camera is the only option. You can reduce unwanted camera movement by zooming right out. Zooming in will only exaggerate camera movement so you should instead move towards the action you are shooting and leave the zoom out altogether. In a well lit scene practically everything should be in focus. My wife Genie followed this advice when shooting her first movie which you will find below.

11 May 2011

Adventures with a digital frame

So you think you're a videographer…

I thought I knew all I needed to know about compressing movies. CD-ROM, DVD-video, online streaming? No problem. Then about a month ago I bought a digital frame (15" Living Images) from Digital Frames Direct (DFD) in order to show some short films at an upcoming exhibition, and I ran into problems.

I'm a Mac user and use Final Cut Pro (FCP) for editing. FCP can export any type of movie I like, using whichever codec (compression-decompression format) that seems appropriate. My new digital frame is supposed to display videos in "either the mpeg 1,2,4 format or AVI/divx format" according to DFD's short (seven-sentence) document "Converting videos". A doddle, I thought.

After hours of exporting batches of test movies from FCP and trying them out on the digital frame I started to wonder whether it could indeed display movies in any shape or form.

Back to DFD's "Converting videos" document:

"You can use many programmes but one of the easiest and the one we used is Xilisoft which you can download here."

Normally I only use my Dell laptop for checking that my projects work the same on a PC as they do on my Mac, but I downloaded the free version of Xilisoft's video converter to my PC laptop out of curiosity. The only limit to the free version is that movies can't exceed 3 minutes, but as the movies I was hoping to exhibit were "one-minute wonders" I could give it a go.

The first test movies I exported using Xilisoft's video converter wouldn't play on the digital frame. Then I had a wee epiphany. I'd been exporting movies at a size of 1024x768 pixels, the supposed resolution of the digital frame, and at 768x576 pixels, thinking that datarate might have been the problem. But what if the frame was using oblong pixels like a TV screen rather than the square pixels you get on a computer monitor? Was it expecting DV-footage resolution?

I tried Xilisoft's standard MP4 codec at 720x576 pixels but with its aspect ratio set to 4:3. Lo and behold, a format that the digital frame can display. Not only that, but by tweaking the datarate to "3500 kbits/s" in the program I ended up with a quite acceptable result playing back at around 2525 kbits/s.

And here's a preview of my "one-minute wonders" series:

10 May 2011

Video for multimedia engineers

The Canon XL1 – my favourite video camera

I bought this Canon XL1 about six years ago on eBay, having sold my Fender Jazz bass and Stratocaster, both of which had been collecting dust in the studio. It was already a bit of an antique when I bought it, but this video camera has a fantastic zoom lens and records broadcast-quality footage.

Canon XL1 video camera
After years of intensive use my footage had started to display digital noise (intermittent blocks of colour in the recordings) and the usual head-cleaning solution failed to solve the problem. It was time for a service!

The only Canon-approved photographic engineers in Scotland are A. J. Johnstone & Co Ltd in Glasgow, and although it took a month from delivering the camera to getting the call to say it was ready to collect, I've just put it through its paces and my Canon XL1 is now squeaky clean. The service cost £153.60 (including VAT at 20%) which I find quite reasonable considering the work involved: dismantling to overhaul and service, resetting and aligning the deck assembly, cleaning contaminated tape paths and guides, followed by a systems check and test.

If you are using a mini-DV-format camera for your footage and think it may be ready for a service, please check the following before laying out your cash.

Check list

Does the footage look okay when played back in-camera? If so, check the leads you are using for video capture. Firewire (IEEE 1394) leads are easily damaged, so try another lead. If you are capturing to an external hard-drive also check that it isn't at the end of a daisy chain. There's a limit to the number (length) of Firewire leads you can use for video capture and digital noise will be introduced if you exceed the limit. I don't know what the limit is but have certainly experienced noise during capture which was solved by connecting the hard-drive in question directly to the computer.

If your footage does look blocky in-camera then try using a tape-head cleaner. It may save you paying for an unnecessary service.

One thing I'd advise strongly against is dismantling your video camera in order to clean it yourself. If you don't know what you're doing and/or can't do it in a dust-free environment you will probably be doing more harm than good.