Quality (-q quality)
Set default variable bitrate (VBR) quantizer quality in percent (default: 100, averages at approx. 120 kbps VBR for a normal stereo input file with 16 bit and 44.1 kHz sample rate; max. value 500, min. 10). Bitrate (-b bitrate)
Set average bitrate (ABR) to approximately bitrate kbps. Bandwidth (-c freq)
Set the bandwidth in Hz (default: automatic, i.e. adapts maximum value to input sample rate). Raw AAC output mode (-r)
Don't add ADTS headers. Needed when directly using the AAC bitstream in a MP4 container like e.g. mp4live does (-w, wrap AAC data, uses this mode automatically). Wrap AAC data in MP4 container (-w)
Default for "mp4" and "m4a" extensions.