What’s Your Codec?

When I first heard Codec I thought the person was saying Kodak and I thought how quaint, they were making some reference to the old cameras.  Well, there is a lot of emphasis placed on different codecs in video and you should know why.  First, the idea of a codec is nothing new to digital photographers, we just don’t usually refer to them as codec but rather formats.  Codec is really short for code/decode or compression/decompression scheme. We have them in still photography as Tiff, Jpg and so on.  In video common ones that photographers run into is H264 coming out of the Canon cameras like the 5D, 7D and T2 which are commonly transcoded into one of the many variations of Apple ProRes.

As photographers, we are all aware that some types of coding will change and adjust the amount of data the represents an image.  If we code a Tiff into a Jpg we are throwing away some data to make the file smaller and quicker to open, in video, it kind of goes both ways.  You still code from a more data filled format like ProRes into a more compressed format like H264 to make a smaller and easier to open video file for web browsers.  But and this is a big but it doesn’t work the same for editing in video.  With the present speed of computers it is hard to edit accurately in the highly compressed H264 at 30:1 because it takes so much processing power to decode (decompress) each of the 24, 30 maybe even 60 frames a second in video that the computer falls behind and skips frames in an attempt to keep up.  If your computer is skipping frames you cannot edit precisely very easily.

While it might be counter intuitive, it is easier to edit if you transcode the video file into at larger data format like ProRes than using a highly compressed H264 30:1 format.  With the ProRes codec the video plays smoother than h264 and allows easier frame by frame edit decisions.  There are endless discussions as to the different codecs to transcode into and which version of each codec to use.  In ProRes, transcoding into anything more than the ProRes LT or regular for  H.264 30:1 from the Canon cameras is generally thought of as a waste.  Those codecs seem to catch all the information that can be used from the more compressed H.264 without creating excessive made up data.

There is more to this including color space of different codec and transcoding applications, which I will get to in later blog entries.

Until then, did you hear the one about the editor who walks up to a woman in a bar and says, “What is your Codec?”  She turns to him  and says …