http://TrinityDigitalMedia.com/church-tech On today’s Tech, No Babel: Making your video file size smaller
When your create, record, and edit videos, they often turn out to be huge. How can you minimize file size for distribution and archiving? Here are some things to look at.
For archiving, save the most editable file you can. When you don’t, you’re giving up options for the future. Often, there’s a cost in long-term storage, but that cost is much less than it used to be.
For distribution, the key is balancing the quality with the file size so that you can get the best looking, but smallest file size (in combination). Some of these things will be small improvements, but others will be large. Make sure you aren’t sacrificing quality to save a MB in one area where another choice with save you a GB without the loss of quality (at least as far as the viewer can tell).
Start with resolution. Do you need a 1080p video or will 360p (wide screen) be enough? Often people assume that wide screen videos are HD when they’re not, so you can save quite a lot there if resolution isn’t necessary (as with small text).
Consider lower frame rates. Sixty frames a second is a great way to shoot sports, but you don’t need that much for someone sitting in one place against a static background, talking. Thirty or even 24 or 15 might be enough.
Make sure you’re using a delivery codec instead of an editing codec. A “codec” is a set of instructions for the computer to use for compression and decompression. It’s easier to edit a ProRes 422 file than an H.264 file, but an H.264 file tends to be smaller. Use H.264 for distribution and you’ll often see a huge savings in file size.
For bit rate, you have some options. Bit rate is how large a sample the computer uses to reproduce the video. Larger bit rates are more accurate, but also yield larger file sizes.
To get the most out of bit rate, you can use a variable bit rate (as opposed to constant bit rate). With a VBR (variable bit rate), the computer determines if it needs to use a larger or smaller bit rate based on what’s going on in the frame. I can do this by looking at the file once (single-pass) or multiple times (multi-pass). A multi-pass will take longer, but will yield higher quality at lower bit rates.
Finally, look at sample rate. Measured in Hertz (or samples per second), the larger the number the better the quality and larger the file size. As you lower the sample rate, you should notice smaller file sizes and a decrease in quality. Try to balance these concerns.
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