Codecs Explained

In last month’s article, “Video File Formats”, I discussed the basics of video file formats, including the difference between a container and codec and compressed and non-compressed video files. I also provided an overview of Audio Video Interleave (AVI) and Apple QuickTime (QT), two common container file formats. In this article, I will be discussing the various video codecs you may come across while downloading, ripping and/or burning Video CDs or DVDs. This will also come in very handy when looking through our Mac CD burning software review site.

What is a codec?

A codec is a term that is short for “encoder – decoder”. It encodes and decodes video data so that it can be stored and played back on your computer. A codec is necessary because a computer is not able to store and process true analog video. Everything must be converted into binary code—1’s and 0’s—for your computer to process it. A codec does this for you.

Types of Codecs

H.264/MPEG-4 Part 10 / Advanced Video Coding (AVC)

The ISO/IEC Moving Pictures Experts Group (MPEG) and ITU-T Video Coding Experts Group (VCEG) collaborated to make H.264/MPEG-4 AVC, a lossy compression-based video codec used for a variety of applications, including low quality streaming videos to high quality HDTV and digital camera recordings. H.264/MPEG-4 AVC has industry-wide support and is one of the three codecs for Blu-ray video. Compared to MPEG-2, H.264/MPEG-4 AVC encoded videos appear to have similar quality with half of the bit-rate. If you are wanting to back up high quality video but want to be frugal with disk space, H.264/MPEG-4 AVC is an excellent option to consider.

MPEG-2

MPEG-2 is a widely used codec for transmitting over-the-air broadcasts, satellite television programs and DVD movies. The Moving Pictures Expert Group (MPEG) developed MPEG-2 in collaboration with ITU-T Video Coding Experts Group (VCEG). A major drawback of MPEG-2 is that it takes up a relatively large amount of disk space, especially compared to H.264, with a rather insignificant gain, if any gain at all, in quality. However, if storage space is not a significant concern, MPEG-2 is an excellent option for storing your DVD movies.

RV30 & RV40

RealNetworks created their proprietary codecs RV30 and RV40 to replace previous RealVideo codecs which were based on the now defunct H.263 codec. RealVideo 10, the latest version of RealVideo as of the time of print, uses RV40. The intended use for RealVideo is for storing relatively low quality videos that will be streamed over the web. If you are storing video that will be used only for the web, the RV40 codec may be a viable option for you. However, if you are looking for a codec for high quality DVD movies, Blu-ray discs, or HDTV recordings, you will want to pass on RV40 and consider H.264 or MPEG-2.

Now that you have a little better understand of what a codec is, you will be much better prepare for any type of CD or DVD burning you may be doing in the future.

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