Wednesday, October 17, 2007

Video Lessons I've Learned

Hi, I'm fairly new to online video, but here are a few tips that I've painfully learned dealing with three projects. The first project was video composting 3D footage, the next was a composite of a lecture and slides, and the third was recording a seminar. I will combine lessons from all three.

Before You Shoot
  • If you are shooting live video, think about placing your camera where you can get as much of a straight on shot as you can. Sounds like common sense, but sometimes due to various factors you won't be able to do a straight on shot of say a screen. If you can't, try to get the media that will be displayed on the screen and composite that back in over the trapezoided screen you will film.
  • Talk to the lighting guys. When people are talking and there is no slides or video being presented, have the light guys up the lights as much as possible. True, you don't want to have the lights going up and down all the time, so this might take a little bit of pre planning and coordination.
  • Think about your workflow. Video rendering is very time consuming, so run a few small test end to end of extracting to video from the camera to final screen presentation. It is good to work out kinks before timelines are established. Get a good realistic feal for how long things will take, then use 2.5x that amount of time for an estimate of completion.

If you are rending digital video, here are a few tips.

  • If you are using programs like 3D Max, Max likes to crash sometimes. Render your output as images rather then video, so if Max crashes at frame 700, you can pick up rendering again at frame 700. If your rendering is taking 2 minutes a frame, you will be saving yourself quiet a bit of time. Editors like Adobe Premier allow you to drag and drop folders of images in the timeline.
  • Only render the parts of scenes that are changing. In Max, there is a setting (it has been about two years so I'm a little foggy as to where) where you can have Max just render a small section of the screen. If you render one frame as a background, Max will render the full frames, but only update the part of the frame that you are worried about. Again, a huge time saver if render speeds are low.

General Tips

  • Generally you are talking about three steps. Getting source video, composting and editing source video, rendering an output video. Often times you will need a fourth step for web video, rendering to Flash (although youTube is an option worth checking out, they do it for you). Generally with the exception of the composting and editing phase, you want to be doing something else productive while these steps are taking place as each of these phases takes anywhere from 1/4 to 3/4 the time of the desired length of your end video. So depending on your hardware setup, you definitely want one machine available for you to work on other projects while the other machine(s) are trudging along.
  • Expect problems. Don't get frustrated. Just start again.
  • On low end cameras like mine, you end up pulling the video off of a tape in a lossy format. You can bring some of the color back when editing. The more you manipulate your video, the more color and detail will be lossed. You can use different codec's like DivX, but generally you want to keep your video as lossless as possible until you generate for the final presentation layer. Use a lossless codec like Lagarith. Unfortunately that means you will need a lot of disk space.
  • Make sure interleave each frame is checked. It will take a bit longer to render things, but the height in quality is worth it.
  • If you are outputting for the web, remember that most video will come off your camera slightly rectangular at a .9 height to width ratio at (720 x 480). Usually for my final render if I'm going to the web after the edits are done I go to square pixels and then cut the size down to 320x240 or 640x480. I might drop the frame rate down by half to if I'm low on disk space or time. The Flash video encoder seems to do a better job at making things a little less choppy if you set a custom video frame rate when encoding then the video software I've used (Vegas and Adobe Premier Pro 2). But if the extended render time is a big hit and the slight improvement in quality isn't that big a deal, render your final output at half NTSC.

Encoding for Flash

  • I've had pretty good luck in filming at NTSC speeds (29.97 fps, or something like that) and then halving that ( fps) when I'm encoding to Flash. For 320x240, 300 kb a sec seems to always do the trick. You might be able to go down lower if you don't have a lot of red colors nor a lot of movement. Maybe run a few quick test (in Flash itself you don't have to encode the whole video when importing, just import a chunk, render, test, adjust).
  • For Audio, I've used Stereo 16kbs. You might want to buff that up to 32kbs, which might in turn cause you to buff up your streaming a little over 300kbs.

Well, most of these tips are commons sense, but it is good to be reminded of them.

No comments: