[pulseaudio-discuss] Expand the simple API?

[David Henningsson]

I spent yesterday afternoon writing a small PulseAudio client using the 
asynchronous API and found that it was a few things to setup; the 
mainloop, the context, the stream, callbacks etc.

Just to recap, there are three strategies for feeding data to PulseAudio:

  * Blocking:

    pa_simple_write(data, length);

    or:

    while (length > 0) {
        while (pa_stream_writable_size() == 0)
           pa_mainloop_wait();
        pa_stream_write(data, pa_stream_writable_size());
        data += pa_stream_writable_size();
        length -= pa_stream_writable_size();
    }

  * Polling:

    every now and then do:
        pa_stream_write(data, pa_stream_writable_size());


  * Callback:

    pa_stream_set_write_callback(my_write_callback);
    pa_mainloop_run();

    my_write_callback(size_t length) {
        pa_stream_write(data, length);
    }


Looking at the client code, it seems very simple to add 
pa_simple_writable_size() to the client API, and thus enable the polling 
scenario for the simple API too.

Even the callback scenario - which is the most efficient one, I would 
assume - seems not too difficult to implement in the simple API, as long 
as the user is aware that the callback will be called from a separate 
thread (as the simple API is based on a threaded mainloop).

Sure, more options makes a simple API less simple, but at least the 
pa_simple_writable_size API wouldn't hurt to implement IMO. The 
user-friendliness of providing this outweighs the possible lack of 
simplicity. Or what do you think?

For recording streams; the same reasoning applies.

-- 
David Henningsson, Canonical Ltd.
https://launchpad.net/~diwic