Successfully getting a video file delivered to your audience usually means it will be compressed (heck it’s often compressed just so we can work with it in the first place). Making the video file available to your target audience is your goal, but the challenges of hardware, connection speed, and even operating system can affect the decisions you make. Let’s take a common sense approach to getting your video out there.
The ‘Illities’
There are four major facets that will shape your compression approach. I call them the illities to make them easier to remember.
- Portability – How easy is the file to get from one device to another? Is the compressed file small enough to transfer via the Internet (and at what connection speed)?
- Compatibility – Can the file be viewed by multiple applications and/or web browsers?
- Affordability – Are the codec or hardware requirements within your budget? Are there any licensing fees involved?
- Quality – Does the image or sound quality match your audience’s needs?
The Language
There are several bits of lingo that will pop-up when working with compression. Here are the most common with their plain English translations.
Architecture: This is like the global family or classification of a file. It includes those such as MPEG, QuickTime, Windows Media, AIFF, etc. It is the ‘global’ picture.
Batch Processing: A benefit of many compression utilities as it allows you to set up several files to run. This is a key benefit as it allows you to walk away and leave your computer working hard.
Bit Rate: How much data per second there is in your file. The higher the number, the larger the file.
Channels: Most common will be the choice between stereo and mono. Stereo files use two channels of audio data and occupy twice the space as mono files.
Compress: The process of shrinking the file using mathematical algorithms. Modern compression techniques are significantly more effective than their historical counterparts.
Codec: Stands for Compressor/Decompressor. The algorithm ot code allows for further shrinking of the files. In some cases, compressors cost additional money to the content creator. Decompressors are usually free to improve the distribution plan and market share.
Encode: To turn an analog source (such as audio waves) into a digital file. This is also called capturing by some.
Pixel Aspect Ratio: Computer pixels are square in shape, digital video pixels can be rectangular or non-square. The video editing software or playback device (such as a television) usually compensates for this. If you plan to show the video on a computer, you will need to manually resize the document to the right shape.
Resolution: Also called sample size, which is the number of bits used by the computer to describe the analog data. Audio CDs are usually 16-bit, however newer DVD audio discs are frequently 24-bit. Bigger is higher quality.
Sampling Rate: The number of samples captured per second. Audio CDs are usually 44.1kJz while digital video is usually 48 kHz. Bigger is higher quality.
Variable Bit Rate (VBR) Compression: One of the most effective ways to create smaller files. The computer analyzes the video file before compressing the data. Encoding this way is far slower, but if you can choose this method for superior results.