Which of the following is NOT a common video CODEC?

The selection of PDF as the option that is not a common video CODEC is correct because PDF (Portable Document Format) is primarily used for presenting and exchanging documents in a format independent of application software, hardware, or operating systems. It is designed to display documents and images in a fixed layout, not for compressing or encoding video data.

In contrast, XVID and Sorenson are indeed video CODECs; they are specifically designed to encode and decode video streams to optimize quality and file size for playback. QuickTime can also refer to a multimedia framework and associated CODECs that Apple developed for handling various media types, including video. Therefore, the presence of XVID, QuickTime, and Sorenson in the context of video CODECs highlights their roles in video compression and playback, while PDF does not serve that purpose.