Using a custom audio driver

You can define a custom audio device, to supply audio to all publishers in the client and to handle the mixed audio stream from all streams the client subscribes to.

A custom audio device is represented by an otc_audio_device struct.

And an otc_audio_device_callbacks struct includes function pointers to functions that act as the audio-related callbacks that the Vonage Video Linux SDK invokes.

Setting the audio volume for a subscriber

You can individually set the audio volume for each subscriber by calling the otc_subscriber_set_audio_volume() function.

To fine tune audio quality for a publisher stream the following methods can be used:

Audio bitrate

otc_publisher_set_max_audio_bitrate(otc_publisher* publisher, uint32_t bitrate);

The desired bitrate for the published audio, in bits per second. The supported range of values is 6,000 - 510,000. (Invalid values are ignored.) Set this value to enable high-quality audio (or to reduce bandwidth usage with lower-quality audio). If you do not set this option, Vonage automatically assigns an audio bitrate for the stream.

The following are recommended settings:

• 8,000 - 12,000 for narrowband (NB) speech
• 16,000 - 20,000 for wideband (WB) speech
• 28,000 - 40,000 for full-band (FB) speech
• 48,000 - 64,000 for full-band (FB) music

Disable Audio Processing

otc_publisher_settings_set_disable_audio_processing (otc_publisher_settings* settings, otc_bool disabled);

Whether to disable echo cancellation, automatic gain control, and noise suppression for the published audio. You may want to set this to true when publishing high-quality audio. The default value is false.

Automatic Gain Control

otc_publisher_settings_set_auto_gain_control(otc_publisher_settings* settings, otc_bool enabled);

Whether to enable automatic gain control for the published audio. You may want to set this to false when publishing high-quality audio. The default value is true. This setting is ignored if you disable audio processing.

Echo Cancellation

otc_publisher_settings_set_echo_cancellation(otc_publisher_settings* settings, otc_bool enabled);

Whether to enable echo cancellation for the published audio. You may want to set this to false when publishing high-quality audio. The default value is true. This setting is ignored if you disable audio processing

Noise Suppression

otc_publisher_settings_set_noise_suppression(otc_publisher_settings* settings, otc_bool enabled);

Whether to enable noise suppression for the published audio. You may want to set this to false when publishing high-quality audio. The default value is true. This setting is ignored if you if you disable audio processing.

Stereo

otc_publisher_settings_set_stereo(otc_publisher_settings* settings, otc_bool enabled);

Whether to publish stereo audio. The default value is false.