audio.driver

Type: Selection (str)

Options: alsa, coreaudio, dart, dsound, file, jack, oboe, opensles, oss, portaudio, pulseaudio, sdl2, sndman, wasapi, waveout

Default: alsa (Linux),
dsound (Windows),
sndman (MacOS9),
coreaudio (Mac OS X),
dart (OS/2)

The audio system to be used. In order to use sdl2 as audio driver, the application is responsible for initializing SDL's audio subsystem.

Note: sdl2 and waveout are available since fluidsynth 2.1.

audio.periods

Type: Integer (int)

Min - Max: 2 - 64

Default: 8 (Windows, MacOS9),
16 (all other)

The number of the audio buffers used by the driver. This number of buffers, multiplied by the buffer size (see setting audio.period-size), determines the maximum latency of the audio driver.

audio.period-size

Type: Integer (int)

Min - Max: 64 - 8192

Default: 512 (Windows),
64 (all other)

This is the number of audio samples most audio drivers will request from the synth at one time. In other words, it's the amount of samples the synth is allowed to render in one go when no state changes (events) are about to happen. Because of that, specifying too big numbers here may cause MIDI events to be poorly quantized (=untimed) when a MIDI driver or the synth's API directly is used, as fluidsynth cannot determine when those events are to arrive. This issue does not matter, when using the MIDI player or the MIDI sequencer, because in this case, fluidsynth does know when events will be received.

audio.realtime-prio

Type: Integer (int)

Min - Max: 0 - 99

Default: 60

Sets the realtime scheduling priority of the audio synthesis thread. This includes the synthesis threads created by the synth (in case synth.cpu-cores was greater 1). A value of 0 disables high priority scheduling. Linux is the only platform which currently makes use of different priority levels as specified by this setting. On other operating systems the thread priority is set to maximum. Drivers which use this option: alsa, oss and pulseaudio

audio.sample-format

Type: Selection (str)

Options: 16bits, float

Default: 16bits

The format of the audio samples. This is currently only an indication; the audio driver may ignore this setting if it can't handle the specified format.

audio.alsa.device

Type: Selection (str)

Options: ALSA device string, such as: "hw:0", "plughw:1", etc.

Default: default

Selects the ALSA audio device to use.

audio.coreaudio.device

Type: String (str)

Default: default

Selects the CoreAudio device to use.

audio.coreaudio.channel-map

Type: String (str)

Default: (empty string)

This setting is a comma-separated integer list that maps fluidsynth mono-channels to CoreAudio device output channels. Each position in the list represents the output channel of the CoreAudio device. The value of each position indicates the zero-based index of the fluidsynth output mono-channel to route there (i.e. the buffer index used for fluid_synth_process()). Additionally, the special value of -1 will turn off an output.

For example, the default map for a single stereo output is "0,1". A value of "0,0" will copy the left channel to the right, a value of "1,0" will flip left and right, and a value of "-1,1" will play only the right channel.

With a six-channel output device, and the synth.audio-channels and synth.audio-groups settings both set to "2", a channel map of "-1,-1,0,1,2,3" will result in notes from odd MIDI channels (audible on the first stereo channel, i.e. mono-indices 0,1) being sent to outputs 3 and 4, and even MIDI channels (audible on the second stereo channel, i.e. mono-indices 2,3) being sent to outputs 5 and 6.

If the list specifies less than the number of available outputs channels, outputs beyond those specified will maintain the default channel mapping given by the CoreAudio driver.

audio.dart.device

Type: String (str)

Default: default

Selects the Dart (OS/2 driver) device to use.

audio.dsound.device

Type: String (str)

Default: default

Selects the DirectSound (Windows) device to use.

audio.file.endian

Type: Selection (str)

Options: auto, big, cpu, little ('cpu' is all that is supported if libsndfile support is not built in)

Default: 'auto' if libsndfile support is built in,
'cpu' otherwise.

Defines the byte order when using the 'file' driver or file renderer to store audio to a file. 'auto' uses the default for the given file type, 'cpu' uses the CPU byte order, 'big' uses big endian byte order and 'little' uses little endian byte order.

audio.file.format

Type: Selection (str)

Options: double, float, s16, s24, s32, s8, u8

Default: s16

Defines the audio format when rendering audio to a file. Limited to 's16' if no libsndfile support.

'double' is 64 bit floating point,
'float' is 32 bit floating point,
's16' is 16 bit signed PCM,
's24' is 24 bit signed PCM,
's32' is 32 bit signed PCM,
's8' is 8 bit signed PCM and
'u8' is 8 bit unsigned PCM.

audio.file.name

Type: String (str)

Default: 'fluidsynth.wav' if libsndfile support is built in,
'fluidsynth.raw' otherwise.

Specifies the file name to store the audio to, when rendering audio to a file.

audio.file.type

Type: Selection (str)

Options: aiff, au, auto, avr, caf, flac, htk, iff, mat, oga, paf, pvf, raw, sd2, sds, sf, voc, w64, wav, xi

Default: 'auto' if libsndfile support is built in,
'raw' otherwise.

Sets the file type of the file which the audio will be stored to. 'auto' attempts to determine the file type from the audio.file.name file extension and falls back to 'wav' if the extension doesn't match any types. Limited to 'raw' if compiled without libsndfile support. Actual options will vary depending on libsndfile library.

audio.jack.autoconnect

Type: Boolean (int)

Values: 0, 1

Default: 0 (FALSE)

If 1 (TRUE), then FluidSynth output is automatically connected to jack system audio output.

audio.jack.id

Type: String (str)

Default: fluidsynth

Unique identifier used when creating Jack client connection.

audio.jack.multi

Type: Boolean (int)

Values: 0, 1

Default: 0 (FALSE)

If 1 (TRUE), then multi-channel Jack output will be enabled if synth.audio-channels is greater than 1.

audio.jack.server

Type: String (str)

Default: (empty string)

Jack server to connect to. Defaults to an empty string, which uses default Jack server.

audio.oboe.id

Type: Integer (int)

Min - Max: 0 - 2147483647

Default: 0

Request an audio device identified device using an ID as pointed out by Oboe's documentation.

audio.oboe.sample-rate-conversion-quality

Type: Selection (str)

Options: None, Fastest, Low, Medium, High, Best

Default: None

Sets the sample-rate conversion quality as pointed out by Oboe's documentation.

audio.oboe.sharing-mode

Type: Selection (str)

Options: Shared, Exclusive

Default: Shared

Sets the sharing mode as pointed out by Oboe's documentation.

audio.oboe.performance-mode

Type: Selection (str)

Options: None, PowerSaving, LowLatency

Default: None

Sets the performance mode as pointed out by Oboe's documentation.

audio.oboe.error-recovery-mode

Type: Selection (str)

Options: Reconnect, Stop

Default: Reconnect

Sets the error recovery mode when audio device error such as earphone disconnection occurred. It reconnects by default (same as OpenSLES behavior), but can be stopped if Stop is specified.

audio.oss.device

Type: String (str)

Default: /dev/dsp

Device to use for OSS audio output.

audio.pipewire.media-category

Type: String (str)

Default: Playback

The media category to use. This value will be passed to PW_KEY_MEDIA_CATEGORY, see Pipewire documentation for valid values.

audio.pipewire.media-role

Type: String (str)

Default: Music

The media role to use. This value will be passed to PW_KEY_MEDIA_ROLE, see Pipewire documentation for valid values.

audio.pipewire.media-type

Type: String (str)

Default: Audio

The media type to use. This value will be passed to PW_KEY_MEDIA_TYPE, see Pipewire documentation for valid values.

audio.portaudio.device

Type: String (str)

Default: PortAudio Default

Device to use for PortAudio driver output. Note that 'PortAudio Default' is a special value which outputs to the default PortAudio device. The format of the device name is: "<device_index>:<host_api_name>:<host_device_name>" e.g. "11:Windows DirectSound:SB PCI"

audio.pulseaudio.adjust-latency

Type: Boolean (int)

Values: 0, 1

Default: 1 (TRUE)

If TRUE initializes the maximum length of the audio buffer to the highest supported value and increases the latency dynamically if PulseAudio suggests so. Else uses a buffer with length of "audio.period-size".

audio.pulseaudio.device

Type: String (str)

Default: default

Device to use for PulseAudio driver output.

audio.pulseaudio.media-role

Type: String (str)

Default: music

PulseAudio media role information.

audio.pulseaudio.server

Type: String (str)

Default: default

Server to use for PulseAudio driver output.

audio.sdl2.device

Type: String (str)

Default: default

Device to use for SDL2 driver output.

audio.wasapi.device

Type: String (str)

Default: default

Device to use for WASAPI driver output.

audio.wasapi.exclusive-mode

Type: Boolean (int)

Values: 0, 1

Default: 0 (FALSE)

By default, WASAPI will operate in shared mode. Set it to 1 (TRUE) to use WASAPI in exclusive mode. In this mode, you'll benefit from direct soundcard access via kernel streaming, which has an extremely low latency. However, you must pay close attention to other settings, such as synth.sample-rate and audio.sample-format as your soundcard may not accept any possible sample configuration.

audio.waveout.device

Type: String (str)

Default: default

Device to use for WaveOut driver output.