How to avoid opening of audio source?

[j...@tutpro.com]

In Android, if user has not granted microphone permission then during a call audio can only be received, not sent, and the app does not have access to microphone as audio source device.

When such a user makes a call, my baresip makes API call:

ua_connect_dir(ua, &call, uri, VIDMODE_OFF,  SDP_RECVONLY, SDP_INACTIVE);

Thus audio dir is SDP_RECVONLY and INVITE's sdp has attribute

a=recvonly

The callee answers and 200 OK has attribute

a=sendonly

When caller receives the 200 OK, I get to log:

call: update media

stream: update 'audio'

stream: audio: starting RTCP with remote 192.168.109.95:26205

audio: update

audio: start

opensles: opening player 16000Hz, 1channels

audio: player started with sample format S16LE

audio: Set audio encoder: AMR-WB 16000Hz 1ch

audio: start

webrtc_aecm: creating shared state: [16000 Hz, 1 channels, subframe 160 samples, num_bands 1]

opensles: opening recorder 16000Hz, 1channels

audio: start_source failed (opensles.nil): No such device

Why is baresip trying to start audio source even when it is only supposed to receive audio?

Is there a way to prevent access to the audio source device?

[j...@tutpro.com]

I looked at the source and found that call.c calls audio_start() that starts both player and source:

err  = start_player(&a->rx, a, baresip_auplayl());

err |= start_source(&a->tx, a, baresip_ausrcl());

How to fix this?  Should enum sdp_dir dir param be added to audio_start:

int audio_start(struct audio *a, enum sdp_dir dir)

so that it would know what to do?  

Or should call.c make separate audio_start_source() and audio_start_player() calls depending on audio dir?

Currently of those two only audio_start_source() exists.

[Juha Heinanen]

'j...@tutpro.com' via baresip writes:

> I looked at the source and found that call.c calls audio_start() that
> starts both player and source:
>
> err = start_player(&a->rx, a, baresip_auplayl());
> err |= start_source(&a->tx, a, baresip_ausrcl());

I made a test where I commented out the latter line and later references
to &a->tx. With those mods call without microphone permission worked
fine. Audio source was not started and caller was able receive audio.

So what is the proper fix?