Sound Issues |
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If you experience bad sound quality, clicks, long sound delay, or dropped sound fragments, you may try to adjust Advanced Audio Settings.
Do not change them unless you completely understand what you are doing, or you may severely degrade the SJphone performance. You may always return to the default values by clicking the Use Default.
Sometimes, when SJphone is connected with a regular telephone through a Gateway, direct and inverse sound lags may be different, because audio packet buffers may have different size in SJphone and the Gateway.
Audio channel latency time
Output audio channel latency is proportional to the Driver buffer size.
Input audio channel latency is proportional to the Driver buffer size*(Driver output queue length + RTP jitter queue length). The Driver input queue length does not affect this latency.
To minimize the latency,
1. On the Advanced Audio Settings set the RTP jitter queue length to 2 and Driver buffer size to 20 msec.
2. Select any direct profile
3. Make a call to localhost.
4. Say something into the microphone. If there are sound distortions, increase the Driver buffer size.
5. End the call to localhost.
6. Decrease the Driver input queue length and Driver output queue length.
Repeat steps 3...6 until sound distortions and/or drops appear.
7. Increase the Driver input queue length by 1:2. Check that sound distortions and/or drops disappear.
8. Select a profile that you plan to use. Make a test call. If sound distortions and/or drops appear, increase the RTP jitter queue length until they disappear.
Distorted sound and clicks
If you hear clicks or sound is distorted:
• | on the remote side, increase Driver input queue length. |
• | on your side: increase Driver output queue length. If this does not help: increase Driver buffer size. |
Sound drops
If you experience sound drops,
• | Try to increase RTP jitter queue length. |
Sound system
Most notebooks have embedded microphone and speakers. To get better audio quality and to avoid echo you may use any USBphone or a simple wired headset.
For the best voice quality use G.711 codec on broadbands, for dial-ups try GSM, iLBC, or other codes.
Sound problems may be connected both with the audio system of your computer and with some external problems (the network, remote party, etc.). To test the audio system, select a direct PC-to-PC profile (H.323 or SIP), make a call to the localhost, and accept this call.
Say something and if you hear your "echoed" voice with a small delay, the audio systems works correctly.
The status of audio devices is shown in the session line. An active session looks like:
If one or both arrows are not shown, SJphone failed to open or initialize the corresponding audio device. The log in its MME (OSS) records should show a reason for that.
Typical problems:
If the audio device is not initialized properly (no arrow)
SJphone uses the OSS audio interface. For ALSA drivers, the OSS emulation should be enabled (the snd-pcm-oss module should be loaded). The driver should support the full-duplex 8kHz-16 bit mode.
An incorrect device is selected. Specify a correct device on the Audio tab.
Other applications hold the audio device. Depending on audio hardware and drivers, several applications may not possibly hold the same audio device. Stop such applications. Some sound daemons (artsd, esd, jack, etc.) may cause this problem.
If the audio devices are initialized properly, but still there is no sound:
• | Check the record source and recording/playback levels in the system. SJphone does not change these settings. You may use any mixer, for example, alsamixer or aumix. |
• | Check recording and playback with your current settings. You may do it using the utilities rec(1) and play(1) from the sox(1) package. Close all active calls, open the terminal, and enter the following commands: |
rec -c1 -fs -r8000 -sw test.wav # record to the file test.wav
play -c1 -fs -r8000 -sw test.wav # playback from the file test.wav
• | If you use a non-standard device for recording or playback, use the -d<sound device> option. |
• | Check that your sound system is full-duplex. Enter these commands SIMULTANEOUSLY with different files, for example, from two terminals, or run one command in a background mode. The sound system should record and playback simultaneously. If this test fails, SJphone will NOT work with this device. |
If all the tests passed, but still there is no sound, try to increase the Driver output/input queue lengths and buffer
• | Check Mixer settings: |
1. Start the alsmixer program.
2. Increase levels for Master, PCM, and check that these channels are not muted (no M above the level indicator). If necessary, clear M using the M key.
3. Some soundcards require to remove M from Mic, Mic Boost, and to increase the Mic level.
4. Press F4 to display Recording settings
5. Using the Space key, set the CAPTUR flag on the Mic and Capture channels. For some sound cards, this flag is available for the Mic only, for other sound cards this flag should also be set for the ADC channel, if it is present.
6. Increase the level for the Capture channel
For a simple case, these settings can be made from the KDE mixer or likes. Increase the level for the Master (Volume), PCM, and Input gain channels, and set the Record flag for the microphone channel. For some sound cards, the KDE mixer is not enough, and the full procedure will be required.
If the problem persists, contact SJ Labs technical support.