I hear only one side when I playback a call

Wave form

This problem can be caused by one of the following:

  1. Your headphones play incorrectly in stereo audio
  2. Firewall is running on your computer, which blocks one way of network traffic
  3. QoS (802.1p) is not supported by Network Interface Card
  4. Out-of-date drivers for Network Interface Card
  5. One of network cables, which are connected to HUB, is broken
  6. Rtp packets are non-symmetric or Rtp SyncId is changed unexpectedly in a middle of a call
  7. Changes in voip protocol or "bug" inside MiaRec

 


1. Your headphones play incorrectly in stereo audio

First of all, check if your headphones play correctly in audio stereo format.

By default, MiaRec saves audio in stereo format. One call party is recorded in the left audio channel and the other party is recorded in the right audio channel.

Try to play the file on another computer and using different headphones.

If you cannot do that, then send a sample audio file to us for review. We will tell you for sure if your audio file contains two sides or only one side.

 


2. Firewall is running on your computer, which blocks one way of network traffic

Some firewalls may block one side of the conversation. Try to disable firewall on your computer and make a test call again.

Note, many antiviruses today include own built-in firewall. Check settings of your antivirus and make sure that firewall is disabled or configured correctly.

Below you will find step-by-step configuration guides for some known firewalls:

 


3. QoS (802.1p) is not not supported by Network Interface Card

This problem sometimes occurs with 3Com network interface cards.

Read 802.1p support on Network Card

 


4. Out-of-date drivers for Network Interface Card

This problem occurs with some old drivers on Windows XP.

On newer operating systems (Vista, 7, 2008) such problem should not occur.

Read Update drivers of Network Card

 


5. One of network cables, which are connected to HUB, is broken

Such problem occurs only if HUB is used. Switch with Port Mirroring is not affected by this problem.

Try to replace network cables, which are connected to HUB.

Or at least rotate them (for example, exchange cables "Modem -> Router" and "HUB -> Computer").

Make sure that all cables are firmly plugged into connectors on all devices.

 


6. Rtp packets are non-symmetric or Rtp SyncId is changed unexpectedly in a middle of a call

Some voip phones use non-symmertic ports for sending and receiving of RTP packets.

Others may change Rtp SyncId in a middle of call.

Both these reasons will cause a situation when MiaRec creates two files for a single call.

You will see inside MiaRec two call recordings instead of one.

The first file will have audio from one side of the conversation and the second file will have audio from the other side. The second file may have no audio at all if your license doesn't allow recording of more than one concurrent call.

Below you will find a workaround for this non-standard behavior of your phone.

But we suggest you to contact us and collect log as described in point 7 because this issue may be caused also by a bug inside MiaRec.

 

Workaround for MiaRec Solo:

Go to Settings -> Advanced and enable following options:

  • Ignore UDP port change
  • Ignore RTP SyncSourceId change

 

Workaround for MiaRec Business:

Open configuration file MiaRec.ini and change following options:

  • IgnoreRtpPortChange=no
  • IgnoreRtpSyncInfoChange=no

To:

  • IgnoreRtpPortChange=yes
  • IgnoreRtpSyncInfoChange=yes
It is not recommended to change both options at the same time. Usually a change of only one option will solve the issue. Situation, when both options should be changed to "yes" is very rare.

 


7. Changes in voip protocol or "bug" inside MiaRec

If none of the above helped, please collect network log and send it to our support team for investigation.