MediaCoder

A free (open source) audio/video converter, putting together many excellent audio/video softwares into one friendly GUI On video side, MEncoder can be used as back-end, which will provide support for nearly all known video compression and container formats as well as rich and useful video filtering features (e.g. 3D de-noise, post-processing).

On audio side, MPlayer and Winamp input plugins used as decoders, various encoders integrated, MediaCoder can simply batch transcode among any known audio formats, with tags transferred, file names generated, and even performing audio filtering (e.g. resample, normalize) on the fly.

Here are some key features of "MediaCoder":
Typical applications:
Improving compression / reducing file size (audio+video -> audio+video)
e.g. MPG/VOB/AVI/RMVB/MOV/MP4 -> AVI/MKV/MP4 (Xvid/DivX/H.264 + MP3/OGG/AAC)
Extracting audio track (audio+video -> audio)
e.g. MPG/VOB/AVI/RMVB/MOV/MP4 -> MP3/OGG/AAC/MPC
Converting to normal VCD/DVD player ready video files (audio+video -> MPEG)
e.g. RMVB/MOV -> MPEG 1/2
Converting from lossless or high-bitrate audio to low-bitrate audio to play with portable DAP (audio -> audio)
e.g. APE/FLAC/WavPack (+ CUE sheets) -> MP3/AAC/WMA
Ripping CDs and compressing it on the fly
e.g. CD tracks-> APE/FLAC/WavPack/MP3/OGG/AAC/WMA/MPC

Supported source formats:
Audio: MP3, OGG/Vorbis, AAC, MusePack, WMA, RealAudio, FLAC, WavPack, APE/APL, WAV
Video: AVI (Xvid/DivX/H.264), MPEG1/2/4, QuickTime (mov), WMV/ASF, RealMedia (rmvb), MP4, Matroska (mkv)
CUE Sheets, CD, VCD, DVD

Supported target audio formats:
Lossy: MP3, OGG/Vorbis, AAC, AAC+/Parametric Stereo, MusePack, WMA
Lossless: FLAC, WavPack, Monkey's Audio (APE), WMA Lossless, WAV

Supported target video formats:
H.264, Xvid, DivX 4/5, MPEG1/2/4, H.263

Supported target container formats:
AVI, MPEG 1/2, Matroska, MP4