[pulseaudio-discuss] Fwd: [LOW LATENCY] PA_simple

[Tanu Kaskinen]

On Wed, 2016-01-13 at 10:19 +0530, Swapnali Patil wrote:
> Hello all,
> we are using Pulse Audio API to playback audio received from network. So
> far we are using pa_simple_api, with this we get latency of 2+ seconds.
> From internet documents we got to about PA_STREAM_ADJUST_LATENCY flags. But
> it seem this flag can be set for PA_STREAM_API.

The PA_STREAM_ADJUST_LATENCY flag is automatically set for all streams
created with the simple API.

> We tried to set /use
> PA_STREAM_API as mentioned below
> . but it fails in
> 
> pa_stream_new
> () it self. 
> 
>     pa_ml = pa_mainloop_new();
>     pa_mlapi = pa_mainloop_get_api(pa_ml);
>     pa_ctx = pa_context_new(pa_mlapi, "ivcloudapp");
>     pa_context_connect(pa_ctx, NULL,PA_CONTEXT_NOFLAGS, NULL);
> 
>      if(!s)
>      {
> s =
> 
> pa_stream_new(pa_ctx, "Playback", &ss, NULL);
>        if (!s) {
>   printf("pa_stream_new failed\n");

This will fail, because pa_context_connect() doesn't immediately
establish the connection. You need to monitor the connection state by
setting up a callback with pa_context_set_state_callback().

> Please give direction how we can set low latency with pa_simple_api.

The latency is controlled by the tlength parameter in pa_buffer_attr,
which you pass to pa_simple_new().

-- 
Tanu