VIDEO COMPRESSION SLIMS DOWN FOR SPRING

摘要

Several of edn's recent multimedia articles have pointed out the bloated sizes of high-fidelity audio files and the consequent appeal of compressing them in lossless or lossy ways for storage and transmission. In comparison to video, though, uncompressed audio seems downright diminutive. Consider the following uncompressed-video bit-rate examples. (Multiply by 60 and divide by 8 to get the required per-minute storage capacity in bytes.): 1. Cellular phones: 15 frames/sec, 8-bit color, QCIF (176x 144-pixel) res-olution=3.1 Mbps; 2. PDAs: 30 frames/sec, 16-bit color, CIF (352x288-pixel) resolution= 48.7 Mbps; 3. PCs: 30 frames/sec, 24-bit color, VGA (640x480-pixel) resolution 221.2 Mbps; 4. HDTV: 60 frames/sec, 24-bit color, 720P (1280x720-pixel, progressive-scan) resolution=1.4 Gbps (1000 times higher than the audio-CD bit rate); 5. Digital cinema: 24 frames/sec, 30-bit color, 1080P (1920 x1080-pixel, progressive-scan) resolution=1.5 Gbps.