In Lync Server 2013 the dedicated A/V Conferencing Server role that was introduced with Lync Server 2010 has been removed. This might come as a shock, especially considering the introduction of 1080p video to Lync video conferences. However, it shows how powerful the H.264 SVC codec is, and how much it really has allowed Microsoft to expand on video conferencing technology with little processing requirement on the servers.
With that said, the A/V Conferencing Server role will always live in a Lync Front End server. This can be part of an Enterprise Edition Pool, or a Standard Edition Server. Table 19.5 outlines the requirements for each.