7. What do I need for AAC playback?
Download and install the CoreAAC DirectShow filter or the 3ivx audio decoder (bundled with 3ivx codec), both are excellent for AAC (Both LC and HE) playback in any directshow compatible media player. For the latest CoreAAC filter and winamp/foobar plugins, refer to john33's thread at HydrogenAudio.org.
Note that for MP4 streams, 3ivx or another MPEG-4 splitter is required for playback in DirectShow compatible media players. For raw AAC streams, the AACparser filter from rarewares is required. When muxing in OGM or Matroska, an appropriate splitter is needed as well. See the FAQs in the New Container Formats forum for more information.