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In H.261 and H.263 video, CIF stands for Common Intermediate Format. It describes picture dimensions—not a video codec or a way to transmit video. In H.263, CIF uses 352 × 288 luminance pixels and 176 × 144 chrominance pixels.
What does CIF mean?
CIF is a picture format used in standards-based digital video and videoconferencing. The name describes a common image size that a video coding system can use; it does not specify how the image is compressed or sent over a network.
The term is easy to mix up with other uses of the acronym. For example, technical glossaries also use CIF for “Common Interface Format.” In the H.261 and H.263 video-resolution context, the intended expansion is Common Intermediate Format.
What is CIF resolution?
For H.263, CIF’s luminance plane is 352 × 288 pixels. Its chrominance planes are each 176 × 144 pixels—half the luminance width and height. These are image-plane dimensions, rather than a single conventional color-pixel count. The dimensions are specified in RFC 2190 and listed in ITU-T Recommendation J.161 (2007).
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How does CIF compare with QCIF and larger formats?
The related labels describe different picture sizes. QCIF is smaller than CIF; 4CIF and 16CIF are larger. The table gives the luminance and chrominance dimensions listed for these formats in RFC 2190.
| Format | Luminance dimensions | Chrominance dimensions |
|---|---|---|
| Sub-QCIF | 128 × 96 | 64 × 48 |
| QCIF | 176 × 144 | 88 × 72 |
| CIF | 352 × 288 | 176 × 144 |
| 4CIF | 704 × 576 | 352 × 288 |
| 16CIF | 1408 × 1152 | 704 × 576 |
ITU-T J.161 identifies CIF and QCIF as H.261 formats, and lists sub-QCIF, QCIF, CIF, 4CIF, and 16CIF for H.263. Its examples describe CIF for casual videoconferencing, QCIF for compatibility with endpoints that cannot encode or decode CIF and for multiple-stream calls, and the larger formats for applications seeking higher resolution per frame. Those are use cases in that recommendation’s cable-video context, not universal deployment rules.
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Why was a common intermediate format used?
The format was intended to provide a common picture basis across regions using different television line standards. ITU-T J.161 reproduces H.263’s rationale: “To permit a single recommendation to cover use in and between regions using 625-(PAL) and 525-(NTSC) line television standards, the source coder operates on pictures based on a common intermediate format (CIF).” The quoted text says that input and output signal standards and the methods for conversion to and from the coding format are not subject to the recommendation.
Does CIF determine video quality, bitrate, or frame rate?
No. CIF gives picture dimensions, but the label alone does not establish a fixed bitrate or frame rate. Codec support, the negotiated frame interval, bitrate, and transport packetization are separate implementation details.
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For example, ITU-T J.161 describes CIF as efficient for conferencing with a reasonable amount of motion at 128–768 kbit/s in its specific IPCablecom MTA-2 context. That range is a scoped engineering example, not a universal CIF bitrate requirement. RFC 4629 explains that H.263 picture sizes and minimum picture intervals can be advertised through capability signaling; a CIF label alone does not say which settings a particular connection will use.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How do CIF, H.263, and RTP fit together?
- CIF: the picture-size format.
- H.261 or H.263: video coding recommendations that use or describe picture formats.
- RTP: a transport protocol that can carry encoded video. RFC 2190 describes an RTP payload format for H.263; RFC 4629 later covers H.263 RTP payload signaling and picture-size negotiation, noting that the RFC 2190 format is for legacy-system interaction.
Keeping these roles separate avoids a common misunderstanding: CIF is neither the compression method nor the network protocol.
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