Target bitrate in kbit/sec (6-256 per channel) In VBR mode this specifies the average rate for a large and diverse collection of audio. In CVBR and Hard-CBR mode it specifies the specific output bitrate. Default for >=44.1kHz input is 64kbps per mono stream, 96kbps per coupled pair.
Use default bitrate encoding
In default mode, encoder will choose bitrate automatically. For >=44.1kHz input is 64kbps per mono stream, 96kbps per coupled pair.
Use variable bitrate encoding
In VBR mode the bitrate may go up and down freely depending on the content to achieve more consistent quality.
Use constrained variable bitrate encoding
Outputs to a specific bitrate. This mode is analogous to CBR in AAC/MP3 encoders and managed mode in vorbis coders. This delivers less consistent quality than VBR mode but consistent bitrate.
Use hard constant bitrate encoding
With hard-cbr every frame will be exactly the same size, similar to how speech codecs work. This delivers lower overall quality but is useful where bitrate changes might leak data in encrypted channels or on synchronous transports.
Down mix (None)
Don't down mix, keep the channels same as source.
Downmix to mono
Force to Downmix to mono.
Downmix to stereo
Downmix to stereo if input channels > 2.