What SIP library should we pay attention to in order to solve the problem of audio delay / delay for Android phones with operating systems 4.0 and higher?
Our experiments show that latency is a problem with the SIP library. If not for the library problem, what else could it be?
We have created a simple VOIP application for Android and iPhone. You simply dial the caller ID of another user, press the call button and start talking to him. The iPhone version works fine, and we used a commercial API for SIP functionality. But the Android version doesn’t work very well due to sound delay issues, which seem to depend on what Android phone you have. We used the following Android SIP library .
Our experiments and conclusions
When we make calls between one Android phone and another Android phone, there is too much audio delay. One person will say something, and it may take 1-2 seconds before another hears it. At the moment, this problem is typical for Samsung devices, unlike other hardware (although our tests were limited). For example, Galaxy Note 1, which calls GS3, experiences a longer delay than Galaxy Note 1, which calls the Nexus 7 (Asus) tablet, and Galaxy Note 1, which calls the Xiaomi MI-2 phone.
We are sure to exclude our Asterisk server as the probable cause of the delay because calls from iphone to iphone are great and calls from iphone to android are reasonable.
Here is a list of device speed tests listed in increasing order of delay
- from iphone to iphone (fastest, no noticeable delay)
- Android (Samsung) on iphone (slight delay, but still acceptable)
- Android (Samsung) to Android (Xiaomi MI-2) (slight delay, but still acceptable)
- Android (Samsung) to Android (ASUS) (too much delay, unacceptable)
- Android (Samsung) to Android (Samsung) (very slow, unacceptable)
Now my team is inclined to think that the Android SIP library we use is not good enough. We are interested in using another SIP library for the call.
We noticed that other Android SIP phones, such as CSipSimple, also run into this problem.
Anyone have any ideas on how we can solve our problems with audio delay / delay?
Additional notes
We noticed that when using Skype on the Galaxy Note 1 and Skype on the Galaxy S3 there was no audio delay. Therefore, we thought that perhaps we will find a solution to this problem by choosing a SIP library, a codec, or something like that ...
We know that we use G.711 Codec , if that matters.