[Linphone-developers] Linphone iOS Interfering with iOS Music

[Qian Li]

Dear Linphone developers,

I found some issues with Linphone iOS, which related to iOS system music playback.

1. Fresh open Linphone will stop the music playback. This issue exists for a very long time. I suspect starting liblinphone will somehow acquire the audio session and stop the iOS music playback, which is not necessary and can be delayed until there’s a call.

2. When switching Linphone from background to foreground, the current music playback quality will drop, and back to normal when Linphone goes to background. Step to replicate:

- Open Linphone.

- Make a outgoing call.

- Hangup.

- Open iOS Music app and play some music.

- Switch back to Linphone. The music will be paused for half a second, and then resume with a bad quality.

- Press Home and make Linphone to background. The music quality becomes normal again.

This issue only happens after making the call. There are something worth mention based on the output of the log:

When switching Linphone to foreground:

2016-01-04 17:34:19.158 linphone[1208:546918] I configuring resampler output to rate=[8000], nchannels=[1]
2016-01-04 17:34:19.158 linphone[1208:548171] I Priority used: 47
2016-01-04 17:34:19.159 linphone[1208:548171] I Ring MSTicker priority set to SCHED_RR and value (47)
2016-01-04 17:34:19.158 linphone[1208:546918] I ms_filter_link: MSFilePlayer:0x1513967b0,0-->MSDtmfGen:0x1513969b0,0
2016-01-04 17:34:19.159 linphone[1208:546918] I ms_filter_link: MSDtmfGen:0x1513969b0,0-->MSResample:0x151396e10,0
2016-01-04 17:34:19.161 linphone[1208:546918] I ms_filter_link: MSResample:0x151396e10,0-->MSAQWrite:0x151396a50,0
2016-01-04 17:34:19.161 linphone[1208:546918] I Initializing speex resampler in mode [voip] 
2016-01-04 17:34:19.383 linphone[1208:546918] I AQ: Configuring audio session for playback

When switching Linphone to background:

2016-01-04 17:35:48.867 linphone[1208:546918] I ms_filter_unlink: MSFilePlayer:0x14ef98cd0,0-->MSDtmfGen:0x14ef98d90,0
2016-01-04 17:35:48.867 linphone[1208:546918] I ms_filter_unlink: MSDtmfGen:0x14ef98d90,0-->MSResample:0x14ef99f70,0
2016-01-04 17:35:48.867 linphone[1208:546918] I ms_filter_unlink: MSResample:0x14ef99f70,0-->MSAQWrite:0x14ef98e80,0
2016-01-04 17:35:48.871 linphone[1208:549053] I Ring MSTicker thread exiting

Based on the log, Linphone set the output sampling rate to 8000, which I suspect is the cause the the music quality drop. This only happens after a call is made, so I also suspect that when the call is connected, Linphone sets the sampling rate to 8000 for call, and when the call ends, it is not completely cleared or released so the app still think it is in the call.

Any feedback on possible work around is appreciated.

Looking forward to hearing from you.

Best Regards,

Li