CIF – SIF What’s the Difference
In this article I’m going to explain the differences between CIF and SIF. In keeping with our sanity and to continuing with the theme of keeping it simple I’m going to attempt to use as few techno jargons as possible. CIF and SIF are most notably used to describe video resolution and are used heavily to specify CCTV camera equipment resolution.
So you say, what’s the difference? And why the double spellings like double spelled words? Which one is better? I’m going to answer these questions but first little history of the word. CIF and SIF are surprisingly not double spelled word like “aeroplane and airplane” a British or American spelling difference. CIF and SIF actually are three letter acronyms that do the same thing. Depending on the spelling you may be buying inferior product or a highly adaptable robust product.
OK, enough talking in codes. Let’s first take the word CIF and break this down to a much simpler term. C.I.F is not a three letter acronym meaning “California Interscholastic Federation”, CIF is a resolution format meaning Common Intermediate Format. Keep in mind we are talking about resolution format. If you are using hardware that specifies the resolution as CIF and spelled with a “C” you are using technology that has a resolution of 352×288 pixels. If you need to know the H-dot number CIF is commonly associated with is H.261/H.263.
So what’s SIF, you ask. SIF is a three letter acronym meaning Source Input Format. SIF is most commonly associated with MPEG video format and to confuse you more I’ve seen it spelled as CIF. Depending what side of the world you’re on you are either using PAL for the European standard or NTSC the North and South American standard. PAL SIF resolution is 352×288. NTSC SIF resolution is 352×240. Doesn’t seem like much of an advantage over old regular CIF resolution.
Here 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 old H.261/263 codec. If your Hardware specifies it is using SIF resolution (spelled with an S) then it can take advantage of MPEG-4 and H.264 compression format. I will have another “Keep It Simple” article to discuss MPEG and H.264 compression standards.
So which one’s right? They are both right. CIF is still being used for video conferencing solutions or applications. SIF on other hand has evolved and is predominantly being used as the codec of choice for IP cameras and encoders. What you need to know is how to talk the lingo and that what to write on 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. To write this article I read several resource materials. Each one used both SIF and CIF to describe 325×240 which is SIF. So how did I determine which SIF/CIF they were referring to? Here is little tip. If the CIF is followed by 352×240 (NTSC) then they are referring to SIF. If you see CIF followed by 352×288 then they really mean CIF. Another tell, tell sign is if the encoder, transmitter, coded is H.264 compatible or MPEG-4 compatible then there is a good chance they are talking about SIF.