General options

-h, --help

Show command help.

-V, --version

Show version information.

--help-picture

Show help on attaching album art.

--quiet

Enable quiet mode. No messages are displayed.

Encoding options

--bitrate N

Set target bitrate in kbit/s (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.

The default for input with a sample rate of 44.1 kHz or higher is 64 kbit/s per mono stream and 96 kbit/s per coupled pair.

--vbr

Use variable bitrate encoding (default). In VBR mode the bitrate may go up and down freely depending on the content to achieve more consistent quality.

--cvbr

Use constrained variable bitrate encoding. Outputs a specific bitrate. This mode is analogous to CBR in AAC and MP3 encoders and managed mode in Vorbis coders. This delivers less consistent quality than VBR mode but consistent bitrate.

--hard-cbr

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.

--music

Override automatic detection and tune low bitrate encoding for music. By default, music is detected automatically and the classification may vary over time.

Tuning impacts lower bitrates that involve tradeoffs between speech clarity and musical accuracy, and has no impact at bitrates typically used for high quality music encoding.

--speech

Override automatic detection and tune low bitrate encoding for speech. By default, speech is detected automatically and the classification may vary over time.

Tuning impacts lower bitrates that involve tradeoffs between speech clarity and musical accuracy, and has no impact at bitrates typically used for high quality music encoding.

--comp N

Set encoding computational complexity (0–10, default: 10). Zero gives the fastest encodes but lower quality, while 10 gives the highest quality but slower encoding.

--framesize N

Set maximum frame size in milliseconds (2.5, 5, 10, 20, 40, 60, default: 20). Smaller framesizes achieve lower latency but less quality at a given bitrate. Sizes greater than 20 ms are only interesting at fairly low bitrates.

--expect-loss N

Set expected packet loss in percent (default: 0).

--downmix-mono

Downmix stereo, surround, ambisonics, or discrete audio channels to mono. Audio that is already mono is unchanged. Ambisonic downmixes include a downmix of any non-diegetic channels. Independent discrete channels are downmixed by weighting each channel equally.

--downmix-stereo

Downmix surround or ambisonics to stereo. Mono and stereo audio is unchanged. Ambisonic downmixes include any non-diegetic channels. Independent discrete channels are downmixed to mono.

--no-phase-inv

Disable use of phase inversion for intensity stereo. This trades some stereo quality for a higher quality mono downmix, and is useful when encoding stereo audio that is likely to be downmixed to mono after decoding.

--max-delay N

Set maximum container delay in milliseconds (0–1000, default: 1000).

Metadata options

--title TITLE

Set the track title comment field to TITLE.

--artist ARTIST

Set the artist comment field to ARTIST. This may be used multiple times to list contributing artists individually. Note that some playback software does not display multiple artists gracefully.

--album ALBUM

Set the album or collection title field to ALBUM.

--genre GENRE

Set the genre comment field to GENRE. This option may be used multiple times to tag a track with multiple overlapping genres.

--date YYYY-MM-DD

Set the date comment field to YYYY-MM-DD. This may be shortened to YYYY-MM or YYYY.

--tracknumber N

Set the track number comment field to N.

--comment TAG=VALUE

Add an extra comment. This may be used multiple times. The argument should be in the form TAG=VALUE. See the vorbis-comment specification <https://www.xiph.org/vorbis/doc/v-comment.html> for well known tag names.

--picture FILENAME | SPECIFICATION

Attach album art for the track. JPEG and PNG image formats are accepted. Either a FILENAME for the artwork or a more complete SPECIFICATION form can be used. The picture is added to a METADATA_BLOCK_PICTURE comment field similar to what is used in FLAC.

The SPECIFICATION is a string whose parts are separated by | (pipe) characters. Except for the filename all parts are optional. A plain FILENAME is equivalent to a ||||FILENAME specification.

The format of SPECIFICATION is: [TYPE]|[MEDIATYPE]|[DESCRIPTION]|[DIMENSIONS]|FILENAME

TYPE is a number denoting the nature of the picture (default 3):

There may only be one picture each of type 1 and 2 in a file.

The default DESCRIPTION is an empty string. FILENAME is the path to the picture file to be imported. MEDIATYPE and DIMENSIONS are obtained from the file and any specified values are ignored.

More than one --picture option can be specified to attach multiple pictures.

--padding N

Reserve N extra bytes for metadata tags. This can make later tag editing more efficient. Defaults to 512.

--discard-comments

Don't propagate metadata tags from the input file.

--discard-pictures

Don't propagate pictures or art from the input file.

Input options

--raw

Interpret input as raw PCM data without headers.

--raw-float

Interpret input as raw floating point data without headers.

--raw-bits N

Set bits/sample for raw input (default: 16; 32 for floating point). May be 8, 16, or 24 for integer PCM or 32 for floating point.

--raw-rate N

Set sampling rate for raw input (default: 48000).

--raw-chan N

Set number of channels for raw input (default: 2).

--raw-endianness 0|1

Set the endianness for raw input: 1 for big endian, 0 for little (default: 0).

--ignorelength

Ignore the data length in Wave headers. The length will always be ignored when it is implausible (very small or very large), but some stdin usage may still need this option to avoid truncation.

--channels ambix|discrete

Override the format of the input channels.

"ambix" indicates that the input is ambisonics using ACN channel ordering with SN3D normalization. All channels in a full ambisonics order must be included. A pair of non-diegetic stereo channels can be optionally placed after the ambisonics channels.

"discrete" indicates that the input channels are independent discrete channels with no assigned meaning or speaker position.

Diagnostic options

--serial N

Force use of a specific stream serial number, rather than one that is randomly generated. This is used to make the encoder deterministic for testing and is not generally recommended.

--save-range FILENAME

Save check values for every frame to a file.

--set-ctl-int [S:]X=Y

Pass the encoder control X with value Y (advanced). Preface with S: to direct the ctl to multistream stream number S. This may be used multiple times.