webrtcdsp: GStreamer Bad Plugins 1.0 Plugins Reference Manual

## webrtcdsp webrtcdsp — Audio Filter using WebRTC Audio Processing library |

## Properties

gboolean | echo-cancel | Read / Write / Construct
gboolean | experimental-agc | Read / Write / Construct
gboolean | extended-filter | Read / Write / Construct
gboolean | gain-control | Read / Write / Construct
gboolean | high-pass-filter | Read / Write / Construct
gboolean | noise-suppression | Read / Write / Construct
gchar * | probe | Read / Write / Construct
GstWebrtcEchoSuppressionLevel | echo-suppression-level | Read / Write / Construct
GstWebrtcNoiseSuppressionLevel | noise-suppression-level | Read / Write / Construct

## Types and Values

| GstWebrtcDsp

## Description

A voice enhancement filter based on WebRTC Audio Processing library. This library provides a whide variety of enhancement algorithms. This element tries to enable as much as possible. The currently enabled enhancements are High Pass Filter, Echo Canceller, Noise Suppression, Automatic Gain Control, and some extended filters.

While webrtcdsp element can be used alone, there is an exception for the echo canceller. The audio canceller need to be aware of the far end streams that are played to loud speakers. For this, you must place a webrtcechoprobe element at that far end. Note that the sample rate must match between webrtcdsp and the webrtechoprobe. Though, the number of channels can differ. The probe is found by the DSP element using it's object name. By default, webrtcdsp looks for webrtcechoprobe0, which means it just work if you have a single probe and DSP.

The probe can only be used within the same top level GstPipeline. Additonally, to simplify the code, the probe element must be created before the DSP sink pad is activated. It does not need to be in any particular state and does not even need to be added to the pipeline yet.

### Example launch line

As a conveniance, the echo canceller can be tested using an echo loop. In this configuration, one would expect a single echo to be heard.

    1
    gst-launch-1.0 pulsesrc ! webrtcdsp ! webrtcechoprobe ! pulsesink

In real environment, you'll place the probe before the playback, but only process the far end streams. The DSP should be placed as close as possible to the audio capture. The following pipeline is astracted and does not represent a real pipeline.

    1
    2
    gst-launch-1.0 far-end-src ! audio/x-raw,rate=48000 ! webrtcechoprobe ! pulsesink \
                   pulsesrc ! audio/x-raw,rate=48000 ! webrtcdsp ! far-end-sink

## Synopsis

### Element Information

plugin | webrtcdsp
author | Nicolas Dufresne <nicolas.dufresne@collabora.com>
class | Generic/Audio

### Element Pads

name | sink
direction | sink
presence | always
details | audio/x-raw, format=(string)S16LE, layout=(string)interleaved, rate=(int){ 48000, 32000, 16000, 8000 }, channels=(int)[ 1, 2147483647 ]

name | src
direction | source
presence | always
details | audio/x-raw, format=(string)S16LE, layout=(string)interleaved, rate=(int){ 48000, 32000, 16000, 8000 }, channels=(int)[ 1, 2147483647 ]

## Functions

## Types and Values

### GstWebrtcDsp

    typedef struct _GstWebrtcDsp GstWebrtcDsp;

## Property Details

### The `“echo-cancel”` property

      “echo-cancel”              gboolean

Enable or disable echo canceller, note that it will be disabled if no webrtcechoprobe has been found.

Flags: Read / Write / Construct

Default value: TRUE

### The `“experimental-agc”` property

      “experimental-agc”         gboolean

Enable or disable experimental automatic gain control.

Flags: Read / Write / Construct

Default value: FALSE

### The `“extended-filter”` property

      “extended-filter”          gboolean

Enable or disable the extended filter.

Flags: Read / Write / Construct

Default value: TRUE

### The `“gain-control”` property

      “gain-control”             gboolean

Enable or disable automatic digital gain control.

Flags: Read / Write / Construct

Default value: TRUE

### The `“high-pass-filter”` property

      “high-pass-filter”         gboolean

Enable or disable high pass filtering.

Flags: Read / Write / Construct

Default value: TRUE

### The `“noise-suppression”` property

      “noise-suppression”        gboolean

Enable or disable noise suppression.

Flags: Read / Write / Construct

Default value: TRUE

### The `“probe”` property

      “probe”                    gchar *

The name of the webrtcechoprobe element that record the audio being played through loud speakers. Must be set before PAUSED state.

Flags: Read / Write / Construct

Default value: "webrtcechoprobe0"

### The `“echo-suppression-level”` property

      “echo-suppression-level”   GstWebrtcEchoSuppressionLevel

Controls the aggressiveness of the suppressor. A higher level trades off double-talk performance for increased echo suppression.

Flags: Read / Write / Construct

Default value: Moderate Suppression

### The `“noise-suppression-level”` property

      “noise-suppression-level”  GstWebrtcNoiseSuppressionLevel

Controls the aggressiveness of the suppression. Increasing the level will reduce the noise level at the expense of a higher speech distortion.

Flags: Read / Write / Construct

Default value: Moderate Suppression