VENDOR_SPECIFIC

Vendor Specific. A type of processing element not covered by any subsequent type definition.

CONNECTION_POINT

Controls pipelines channel mixing and routing.

GAIN

Gain control, a.k.a. Volume control.

AUTOMATIC_GAIN_CONTROL

Automatic Gain Control. Automatically maintains a suitable signal level regardless of variation of its input.

AUTOMATIC_GAIN_LIMITER

Automatic Gain Limiter. Automatically maintains a signal level below a level specified. Input below the level is unaffected, and peaks above the level are attenuated.

DYNAMICS

Alters the dynamic range of the signal, e.g. dynamic range compression.

MUTE

Mute.

DELAY

Delay.

EQUALIZER

Equalizer.

SAMPLE_RATE_CONVERSION

Sample Rate Conversion.

ENDPOINT

The start/end of a pipeline.

RING_BUFFER

Ring Buffer. This is the first of two types of elements that can start/end processing pipelines.

DAI_INTERCONNECT

Digital Audio Interface Interconnect. This is the second of two types of elements that can start/end processing pipelines.

RING_BUFFER

The endpoint represents a ring buffer. A ring buffer processing element's id allows for multi-ring buffer topologies to be supported by a driver providing the fuchsia.hardware.audio/Composite API.

DAI_INTERCONNECT

The endpoint represents a Digital Audio Interface Interconnect, e.g. connecting an SoC audio subsystem to a DAC + amplifier hardware codec.

PEAK

Increase/decrease in gain_db in the vicinity of a frequency with an optional q.

NOTCH

Narrow band rejection significantly attenuating a frequency with an optional q.

LOW_CUT

Decrease gain below a frequency with an optional q, a.k.a high pass.

HIGH_CUT

Decrease gain above a frequency with an optional q, a.k.a low pass.

LOW_SHELF

Decrease gain below a frequency for a gain_db amount with a plateau effect.

HIGH_SHELF

Decrease gain above a frequency for a gain_db amount with a plateau effect.

DIGITAL

The processing element gain is applied in the digital domain.

ANALOG

The processing element gain is applied in the analog domain.

MIXED

The processing element gain is mixed using digital and analog hardware.

DECIBELS

Gain specified in dB, for example -103.0dB or +3.2dB.

PERCENT

Gain specified as a percentage, for example 10.0% or 80.5%.

PEAK

Level Gain specified as peak.

RMS

Level specified as RMS.

HARDWIRED

Interconnect is hardwired (will always be plugged in).

CAN_ASYNC_NOTIFY

Interconnect can be unplugged/plugged and can asynchronously notify of plug state changes.

ABOVE

Apply dynamics processing above the threshold.

BELOW

Apply dynamics processing below the threshold.

1

Plug Detect Capabilities.

Required.

1

The plug state for this DAI interconnect.

Required.

2

The driver's best estimate of the external delay beyond this DAI endpoint, as the pipeline is currently configured.

external_delay must be taken into account by the client when determining the requirements for minimum lead time (during playback) and minimum capture delay (during capture).

If not included, external_delay is unknown; the client may treat it however it chooses (e.g. consider it zero or some other duration, autodetect it, etc).

Optional.

1

Dynamics elements in this protocol may support multiple bands, each specifying a number of parameters in DynamicsElementState that can be changed with SetElementState. The number of elements of the bands vector determines the number of bands supported by this processing element.

Required. Must contain at least one entry.

2

The controls supported by this processing element.

Optional.

1

Unique ID for this band, only required to be unique within the corresponding Element, and valid until the channel associated with the SignalProcessing protocol is closed.

Required.

1

Unique ID for the band. Must match one of the ids specified in Dynamics bands.

2

Minimum frequency for the band in Hz. This field could be 0, for instance for single band dynamics processing to specify (together with max_frequency) that the band is full range.

3

Maximum frequency for the band in Hz. This field could be the Nyquist frequency, for instance for single band dynamics processing to specify (together with min_frequency) that the band is full range.

Required.

4

The value beyond which the dynamics main processing starts (subject to the knee_width_db), in input dB. Some signal processing like input_gain and output_gain are not affected by this value.

Required.

5

Dynamics processing is applied ABOVE or BELOW the threshold.

Required for a server. A client must not include this field in a SetElementState if DynamicsSupportedControls.THRESHOLD_TYPE is not set in supported_controls.

6

The input-to-output dB ratio above or below (see threshold_type) the knee region.

Required.

7

The width of the knee region, in input dB. If present, cannot be negative. If not included, the width of the knee region is unspecified. A value of zero is a "hard" knee; larger values lead to "softer" knees. This knee is centered on threshold_db.

Optional. A client must not include this field in a SetElementState if DynamicsSupportedControls.KNEE_WIDTH is not set in supported_controls.

8

Attack time. If not included, the attack time is unspecified.

Optional. A client must not include this field in a SetElementState if DynamicsSupportedControls.ATTACK is not set in supported_controls.

9

Release time. If not included, the release time is unspecified.

Optional. A client must not include this field in a SetElementState if DynamicsSupportedControls.RELEASE is not set in supported_controls.

10

Output (a.k.a. make up or post) gain value in dB. If not included, the output gain is unspecified.

Optional. A client must not include this field in a SetElementState if DynamicsSupportedControls.OUTPUT_GAIN is not set in supported_controls.

11

input (a.k.a. pre) gain value in dB. If not included, the input gain is unspecified.

Optional. A client must not include this field in a SetElementState if DynamicsSupportedControls.INPUT_GAIN is not set in supported_controls.

12

Level type (peak or RMS). If not included, the level type is unspecified.

Optional. A client must not include this field in a SetElementState if DynamicsSupportedControls.LEVEL_TYPE is not set in supported_controls.

13

Look-ahead time. If not included, the look-ahead time is unspecified.

Optional. A client must not include this field in a SetElementState if DynamicsSupportedControls.LOOKAHEAD is not set in supported_controls.

14

Linked channels (a.k.a. Stereo linked for 2-channel systems). If not included, the linked channels option is unspecified. If true, the dynamics response is applied to all channels. If false, each channel has its own dynamics response.

Optional. A client must not include this field in a SetElementState if DynamicsSupportedControls.LINKED_CHANNELS is not set in supported_controls.

1

Each id must match an id from Dynamics.bands and ids cannot be repeated. band_states must have at least one element. The bands controlled by band_states are determined by each band.id.

1

Unique ID for this element. The scope of this id is only within the SignalProcessing protocol lifespan, i.e. until the channel associated with the protocol is closed.

Required.

2

Processing element type.

Required.

3

If included, type-specific parameters for the processing element.

Optional.

4

If included and true, the processing element can be disabled via ElementSetState. If not included or false, the processing element is always enabled.

Optional.

Deprecation

Use can_bypass instead.

5

If included, a textual description of the processing element.

Optional.

6

If included and true, the processing element can be stopped via ElementSetState. If not included or false, the processing element is always started.

Optional.

7

If included and true, the processing element can be bypassed via ElementSetState. If not included or false, the processing element cannot be bypassed.

Optional.

1

If included, type-specific state parameters for the processing element.

If this processing element is disabled and its type-specific state is provided, then the type-specific state is only informational (e.g. the state of a stopped element, if it were to be re-started without also providing additional superceding state information).

Optional.

2

Process element enable/disable state. By default processing elements are enabled. If the corresponding Element returned can_disable equals to false, then this field can't be set to false. If enabled is not included, then state must be included if and only if the processing element is currently enabled.

Optional.

Deprecation

Use bypassed instead.

3

If included, how much latency is added to the pipeline if this processing element is enabled. This field must not be present in a SetElementState state since the latency can't be set by a client, it can only provided by the server in a WatchElementState reply.

Optional.

4

If included, an opaque object of octets for exchanging vendor specific information.

Optional.

5

The started/stopped state for this processing element. If true, the hardware associated with the element is started. If false, stopped.

By default processing elements are started.

A stopped processing element does not provide its abstracted functionality. Specifically, no audio data flows through a stopped element.

Required.

6

The bypassed state for this processing element. If true, the hardware associated with the element is bypassed. If false, not bypassed.

By default processing elements are not bypassed. If the corresponding Element returned can_bypass equals to false, then this field can't be set to true.

A bypassed element does not affect the flow of audio through the topology.

Optional.

7

If included, the driver's best estimate of the amount of time it takes the element's hardware to enter a fully operational mode after started has changed from false to true. Hardware may require some duration to get into a fully operational mode after a change in power state, for example.

If this delay is not taken into account, then the initial frames of an audio stream may be lost while an audio element is powering up. If not included, turn_on_delay is unknown.

Optional.

8

If included, the driver's best estimate of the amount of time it takes the element's hardware to enter a fully disabled mode after started has changed from true to false. Hardware may require some duration to get into a fully stopped state after a change in power state, for example.

If this delay is not taken into account, more frames will be emitted/captured than a client may realize, specifically when elements are powering down. If not included, turn_off_delay is unknown.

Optional.

9

If included, the driver's best estimate (as currently configured, including bypassed) of the delay added by this processing element.

This value must be taken into account by clients when determining the requirements for minimum lead time (during playback) and minimum capture delay (during capture).

For an element of type RING_BUFFER, this delay should not include the inherent delay added by the temporary buffering needed to copy data in and out of a ring buffer, which is contained in the RingBufferProperties field driver_transfer_bytes.

Optional.

1

Specifies what the endpoint represents.

Required.

2

Plug Detect Capabilities. Required.

1

If included the plug detect state for this endpoint.

Required for servers.

1

Equalizers in this protocol are built by a number of bands, each specifying a number of parameters here and EqualizerElementState that can be changed with SetElementState. The number of elements of the bands vector determines the number of bands supported by this processing element.

Required.

2

The controls supported by this equalizer.

Optional.

3

If included and true, individual bands can be disabled via SetElementState. If not included or false, the bands are always enabled. For a band to be functional its enclosing equalizer processing element has to be enabled.

Optional.

4

Minimum frequency for the bands in Hz.

Required.

5

Maximum frequency for the bands in Hz.

Required.

6

Maximum quality factor, usually denoted by "Q", for the bands. Indicates how narrow the frequency transition is. Higher Q values imply narrower notches/peaks and steeper cuts/shelves. Must be positive.

Optional.

7

Minimum gain in dB.

Optional, but required if supported_controls is present and includes SUPPORTS_TYPE_PEAK, SUPPORTS_TYPE_LOW_SHELF or SUPPORTS_TYPE_HIGH_SHELF.

8

Maximum gain in dB.

Optional, but required if supported_controls is present and includes SUPPORTS_TYPE_PEAK, SUPPORTS_TYPE_LOW_SHELF or SUPPORTS_TYPE_HIGH_SHELF.

1

Unique ID for this band, only required to be unique within the corresponding Element, and valid until the channel associated with the SignalProcessing protocol is closed.

Required.

1

Unique ID for the band. Must match one of the ids specified in Equalizer bands.

Required.

2

Type of band.

Optional.

3

Center frequency for the band.

Optional.

4

Quality factor, usually denoted as "Q". Indicates how narrow the frequency transition is. Higher Q values imply narrower notches/peaks and steeper cuts/shelves. Must be positive.

Optional.

5

Gain in dB.

Optional, but required for EqualizerBandType PEAK, LOW_SHELF and HIGH_SHELF. May not be included for EqualizerBandType NOTCH, LOW_CUT or HIGH_CUT.

6

Enable/disable the band. By default all bands are enabled. Disabling the enclosing processing element by setting ElementState.enabled to false disables the whole equalizer and it does not change this field. For a band to be functional its enclosing equalizer processing element has to be enabled.

Optional.

1

The number of elements of the bands_state vector must be equal or smaller than the number of elements of the bands returned in returned in the corresponding Equalizer. bands_state must have at least one element. The bands controlled by bands_state are determined by each band.id.

Required.

2

The number of elements of the band_states vector must be equal or smaller than the number of elements of the bands returned in returned in the corresponding Equalizer. band_states must have at least one element. The bands controlled by band_states are determined by each band.id.

Required.

1

Specifies what the numbers for gain represent, e.g. a percentage.

Required.

2

If included, the gain is applied in the specified GainDomain. If not included, the gain domain is unspecified.

Optional.

3

Minimum gain in GainType format.

Required.

4

Maximum gain in GainType format.

Required.

5

Minimum gain step in GainType format, this value must not be negative, but may be zero to convey an effectively continuous range of values. Must not exceed max_gain - min_gain. The actual gain set may be queried by the client with a WatchElementState call.

Required.

1

Current gain in GainType format.

Required.

1

Indicates whether the interconnect is currently plugged in.

Required

2

Indicates when the current plugged state was set, using ZX_CLOCK_MONOTONIC. Cannot be negative.

Required.

1

Type-specific state parameters for the processing element.

If this processing element is disabled and its type-specific state is provided, then the type-specific state is only informational, for instance if a SetElementState enables a disabled processing element providing a SettableTypeSpecificElementState, then any previous informational SettableTypeSpecificElementState is superceded.

If not set, then the element's previous type_specific state will be unchanged.

Optional for Dynamics, Equalizer, Gain and VendorSpecific types. Invalid if included for any other element type.

2

If included, an opaque object of octets for exchanging vendor specific information. This can send vendor-specific data to any element, not just the VendorSpecific type.

Optional.

3

Whether to start this processing element (or to stop it, if false). A stopped processing element does not provide its abstracted functionality. Specifically, no audio data flows through a stopped element.

If the corresponding Element returned can_stop equals to false, then this field must not be set to false. If not set, then the element's previous started state will be unchanged.

Optional.

4

Whether to bypass this processing element (or to enable/"unbypass" it, if false). A bypassed element does not affect the flow of audio through the topology. Specifically, audio flows through the element without any change.

If the corresponding Element contains a can_bypass of false, then this field must not be set to true. If not set, then the element's previous bypassed state will be unchanged.

Optional.

1

Unique ID for this topology. The scope of this id is only within the SignalProcessing protocol lifespan, i.e. until the channel associated with the protocol is closed.

Required.

2

Vector of processing elements edge pairs in this order. The ordering of processing elements with edge pairs form pipelines. To define multiple possible pipelines, return more Topology entries in GetTopologies.

Required.

1

Latency added to the pipeline as a zx.Duration.

2

Latency added to the pipeline as a number of frames.

1

2

1

2

1

3

1

2

3

4

1

2

1

2

1

2

3

4

5

6

1

2

3

4

5

6

KNEE_WIDTH

If included, the knee_width_db parameter can be changed.

ATTACK

If included, the attack parameter can be changed.

RELEASE

If included, the release parameter can be changed.

OUTPUT_GAIN

If included, the output_gain_db parameter can be changed.

INPUT_GAIN

If included, the input_gain_db parameter can be changed.

LOOKAHEAD

If included, the lookahead parameter can be changed.

LEVEL_TYPE

If included, the level_type parameter can be changed.

LINKED_CHANNELS

If included, the linked_channels parameter can be changed.

THRESHOLD_TYPE

If included, the threshold_type parameter can be changed.

CAN_CONTROL_FREQUENCY

If included, the frequency of the equalizer bands can be changed with SetElementState.

CAN_CONTROL_Q

If included, the q of the equalizer bands can be changed with SetElementState.

SUPPORTS_TYPE_PEAK

If included, the type of the equalizer bands can be changed with SetElementState to EqualizerBandType PEAK.

SUPPORTS_TYPE_NOTCH

If included, the type of the equalizer bands can be changed with SetElementState to EqualizerBandType NOTCH.

SUPPORTS_TYPE_LOW_CUT

If included, the type of the equalizer bands can be changed with SetElementState to EqualizerBandType LOW_CUT.

SUPPORTS_TYPE_HIGH_CUT

If included, the type of the equalizer bands can be changed with SetElementState to EqualizerBandType HIGH_CUT.

SUPPORTS_TYPE_LOW_SHELF

If included, the type of the equalizer bands can be changed with SetElementState to EqualizerBandType LOW_SHELF.

SUPPORTS_TYPE_HIGH_SHELF

If included, the type of the equalizer bands can be changed with SetElementState to EqualizerBandType HIGH_SHELF.