Audio Options

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You can adjust the levels of input and output sound using the Mic and Spk sliders on the Main panel. The Mic and Spk controls on the Main panel are connected with the standard system audio controls. Any changes in their settings automatically change the corresponding system settings.

 

Additional sound settings can be set with the Audio tab.

 

SJphone uses the OSS audio interface. For ALSA drivers, the OSS emulation should be enabled (the snd-pcm-oss and snd-mixer-oss modules should be loaded). The driver should support the full-duplex 8kHz-16 bit mode. Audio devices in the OSS audio interface are usually listed in the following order: /dev/dsp1, /dev/dsp2, etc. The /dev/dsp device usually is a system default audio device. The same listing order is used for mixer devices: /dev/mixer1, /dev/mixer2, etc. The /dev/mixer device usually is a system default mixer device

 

Sound Devices

If your computer has several sound devices, you may select which one will be used.

The default audio device for SJphone is /dev/dsp. This is typical for most systems. If you have another configuration, specify it in the Sound devices.

If there is only one sound card in your system, the sound device is almost certainly /dev/dsp.

 

Mixer Devices

The mixer device should correspond to the sound card for which the sound device is selected. The listing number of the mixer device does not necessarily coincide with the listing number of the sound device, but usually they do. Check the configuration of your audio system.

If there is only one sound card in your system, the mixer device is almost certainly /dev/mixer.

 

Channels allow you to specify which channels in the Mixer devices will be connected to the Mic and Spk sliders. Available channels can be seen in a used mixer software (aumix, for example).

 

The Set input source option specifies the physical source for the input sound. Please note that most likely the level of sound coming from a microphone should be adjusted using the igain control in the Input: option.

 

Compression and Advanced Audio Settings (available in the Advanced Mode interface)

Attention! You must completely understand what you are doing while changing these settings, or you can severely degrade SJphone performance.

 

Compression Settings

Click the Compression Settings... button on the Audio tab to reach the Compression Settings panel.

When two VoIP systems are establishing a call, they negotiate an audio compression codec they are going to use. Which codec to choose depends on many factors: what codecs are installed on both systems, bandwidth limitations, desired sound quality, etc. You may adjust SJphone codec preferences on the Compression Settings panel. During the negotiation, SJphone offers to the remote system the first codec from the list. If the remote system rejects the codec, SJphone offers the next one from top to bottom until they both accept the codec. You may arrange the codecs in the desired order using the Move Up and Move Down buttons. The Use Default button selects the default codec preference. You may also select/unselect codecs to enable/disable them.

 

Advanced Audio Settings

Click the Advanced Settings... button on the Audio tab to reach the Advanced Audio Settings panel.

This panel allows you to change sizes of various internal SJphone sound buffers and queues if you experience problems with sound

Do not change them unless you completely understand what you are doing, or you may severely degrade the SJphone performance.

 

Recommended advanced audio settings

Minimum

Recommended

Input queue

2

4

Output queue

2

3

RTP jitter queue length

2

3

Driver buffer size

 

20

 

If SJphone plays back DTMF signals too loudly, you may disable local DTMF playback by selecting the Disable local DTMF playback option.

 

Do not Send Silence: If this option is selected, SJphone does not send IP packets when you are silent, or you mute SJphone. That reduces network load.