Understanding video compression, file size, and data rate

Recording video and audio to a digital format involves balancing quality with file size and data rate. Most formats use compression to reduce file size and data rate by selectively reducing quality. Without compression, a single frame of standard‑definition video takes up nearly 1 MB (megabyte) of storage. At the NTSC frame rate of approximately 30 frames per second, uncompressed video plays at nearly 30 MB per second, and 45 seconds of footage takes up about 1 GB of storage. By comparison, an NTSC file compressed in DV format fits 5 minutes of footage into 1 GB of storage at a data rate of about 3.6 MB per second. When compressing video for distribution at the highest possible quality, select the smallest compression ratio that delivers video within the file size and data rate constraints of your target delivery media and playback devices.