Many ITU-T Recommendations contain test signals intended to test end-to-end quality of telecommunications systems and to assess implementations conformity to specific Recommendation provisions. These test data cover the different types of media: audio, still images and moving images. ITU-T test signals are a highly valuable collection of more than 20 GB size that constitute a worldwide reference for assessing the different components of telecommunications systems. In order to facilitate their use, ITU-T test signals were grouped into a single database.
The list of ITU-T Recommendations that contain freely available test signals for download. Each link opens a webpage with a short description of the relevant content and a link to download the relevant test signals: http://www.itu.int/net/itu-t/sigdb/menu.aspx