Codec is the abbreviation for compressor/decompressor. Codecs are applied to audio, video and image files to compress their size. The benefit is that the files don't use as much disk space when stored or as much network bandwidth when streamed. To open a compressed file, the same codec must be used to decompress the file.
Compression is the coding of data to reduce file size or the bit rate of a stream.
Lossy is a compression technique that decreases image, audio, or video quality in order to reduce the file size.
So, the video codec is responsible for compressing the video frames during recording and for reconstructing the video frames during playback. Often, the makers of a codec will sacrifice image quality in order to achieve higher compression and smaller file sizes. These codecs are termed "lossy" and are incapable of reconstructing the video at its original fidelity. Most commonly available codecs for recording screen videos are lossy, resulting in screen capture videos with reduced image quality and a "fuzzy" appearance.
Camtasia includes TechSmith's own Screen Capture Codec (TSCC), providing lossless image quality coupled with excellent compression ratios. Since the TSCC is lossless, it preserves 100% of the image quality, even through multiple decompression/recompression cycles that are typical during the production process. The TSCC is optimized for screen capture so that the resulting files are small and highly compressed.
The compression codec also affects the capture frame rate or speed of compression. The high frame rates required for smooth video increase the need for high compression speed. High color screens also impact compression speed. The TechSmith codec offers exceptional compression speed at all color depths - unlike, for example, some codecs that only support 8-bit color. (The Microsoft RLE codec is lossless but is restricted to 8-bit color.)
