Audio settings

Volume, EQ, DSP, ReplayGain, crossfade and the rest of the rbcodec pipeline.

The Rockbox DSP pipeline runs between the codec output and the active PCM sink. Settings live in global_settings (in the C firmware) and are mirrored in settings.toml. Most can also be changed at runtime via GraphQL or gRPC and they persist on the next save cycle.

Equalizer

10-band parametric EQ — gain, centre frequency, Q per band.

DSP

Crossfeed, surround, PBE, AFR, compressor, dithering.

ReplayGain

Track / album normalisation with optional clipping protection.

Crossfade

Overlap track ends with the next track’s start.

Where settings live

Layer	Lives in	Lifetime
Compiled-in defaults	apps/settings_list.c	Build-time
settings.toml	~/.config/rockbox.org/settings.toml	Read once at startup
Runtime (API)	In-memory global_settings	Persisted on save

Hardware settings flow through firmware/sound.c → sound_set_*(). DSP settings flow through lib/rbcodec/dsp/* and are applied in the PCM pipeline before samples reach the sink.

Volume

global_status.volume — decibels relative to the device’s clipping point. 0 dB is the maximum undistorted level. Negative values reduce output; positive values may distort. On the CPAL target, volume is implemented as a software mixer.

volume_limit = 0   # ceiling in dB (default = device max)

Channels & stereo

Setting	Storage	Range / values
Balance	balance	−100..+100
Channel config	channel_config	Stereo / Mono / Custom / Mono L / R / Karaoke / Swap
Stereo width (when Custom)	stereo_width	0..255 %

Pitch & time-stretch

Persisted in global_status so they survive across restarts. Time-stretch uses a TDHS algorithm — best for speech, may sound rough on dense music.

Setting	Storage	Range
Pitch	global_status.resume_pitch	~50..200 %
Speed	global_status.resume_speed	~35..250 %
Time-stretch enable	global_settings.timestretch_enabled	bool

Output sample rate

play_frequency = 0   # 0=auto, 44100, 48000, 88200, 96000

UI feedback

beep              = 0   # off / weak / moderate / strong
keyclick          = 0
keyclick_repeats  = false