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In this article I will explain the differences between CIF and SIF. In keeping with our sanity and to continue the theme of keeping it simple, I’ll try to use as little technical jargon as possible. CIF and SIF are primarily used to describe video resolution and are largely used to specify the resolution of CCTV camera equipment.

So you say, what’s the difference? And why double spellings as double spelled words? Which is better? I am going to answer these questions but first a little history of the word. Surprisingly, CIF and SIF are not double-spelled words like “plane and plane”, a British or American spelling difference. CIF and SIF are actually three letter acronyms that do the same thing. Depending on the spelling, you may be buying an inferior product or a robust, highly adaptable product.

OK, enough talking in codes. Let’s first take the word CIF and break it down into a much simpler term. CIF is not a three letter acronym that stands for “California Interscholastic Federation”, CIF is a resolution format that stands for Common Intermediate Format. Note that we are talking about resolution format. If you are using hardware that specifies the resolution as CIF and is written with a “C”, you are using technology that has a resolution of 352×288 pixels. If you need to know, the H-point number that CIF is commonly associated with is H.261/H.263.

So, what is SIF?, you may ask. SIF is a three-letter acronym that stands for Source Input Format. SIF is most commonly associated with the MPEG video format, and to further confuse it, I’ve seen it written as CIF. Depending on which side of the world you are on, you will use PAL for the European standard or NTSC for the North and South American standard. PAL SIF resolution is 352×288. The NTSC SIF resolution is 352×240. Doesn’t seem like much of an advantage over the old regular CIF resolution.

This is what I haven’t told you. If your hardware says it uses CIF resolution (spelled with a C or 2CIF or 4CIF), you are using an older H.261/263 codec. If your hardware specifies that you are using SIF resolution (spelled with an S), then you can take advantage of the MPEG-4 and H.264 compression format. I will have another “Keep It Simple” article to discuss the MPEG and H.264 compression standards.

So which one is right? They are both right. CIF is still used for video conferencing solutions or applications. SIF, on the other hand, has evolved and is being used efficiently as the codec of choice for encoders and IP cameras. What you need to know is how to speak the jargon and what to write in your RFP is the correct resolution you are looking for.

One last thing, SIF and CIF are used interchangeably, which is where most of the confusion is. In writing this article, I read various resource materials. Each used SIF and CIF to describe 325×240, which is SIF. So how did I determine which SIF/CIF they were referring to? Here’s a little tip. If CIF is followed by 352×240 (NTSC), then they refer to SIF. If you see CIF followed by 352×288, they really mean CIF. Another telltale sign is that if the encoder, transmitter, encoder is H.264 compliant or MPEG-4 compliant, then it is most likely SIF.