QCIF

QCIF, which stands for Quarter Common Intermediate Format, is a video resolution standard commonly used in early digital video and telecommunication systems. It defines a 176 by 144 pixel grid, giving a 4:3 aspect ratio comparable to the full Common Intermediate Format (CIF) but at a quarter of its pixel count. The QCIF resolution is thus 1/4 the area of CIF (352×288) and 1/2 the width and height of CIF.

QCIF was introduced in the late 1990s as part of the ITU‑T recommendations for video conferencing and web cameras, providing a good trade‑off between image quality and bandwidth requirements. Its compact size makes it suitable for low‑bitrate applications such as early IP telephony, video chat, and embedded video surveillance on bandwidth‑constrained networks. The format also serves as an intermediate scaling target for compression algorithms and video codecs that need to process frames rapidly while using limited resources.

In practice, QCIF videos are often encoded with standard codecs such as H.264, MPEG‑4 Part 2, or VP8, and are frequently down‑scaled to 176×144 from higher resolutions for real‑time transmission. The format has largely been superseded by more efficient codecs and higher resolutions like 240p and 360p, but it remains relevant in legacy systems and low‑power devices. QCIF is also closely related to QCV (Quarter Common Video) and QCIF, which have a 176×144 resolution but are used in video coding research and simulation environments.