lynxarius

first step on a longer journey

After reading some documentation and a lot of code. A somehow working module evolves. It supports simple module argument, it can connect to a remote server and also plays audio.

But the problems starting here, because threads are nice and can hurt you because of context. For the first version it is good to hear voices in my ears coming out of speakers over a network. I implemented an early version with a lot of downsides:

no latency informations
threading issues
no zerocopy
...

What I've done wrong was attaching libpulse on pulse server mainloop. Every context and stream callback was run by the mainloop as well as read operations. Not good thing. Only pa_sink_render is working within the I/O thread. Zero copy for now is broken by libpulse, because using pa_stream_write without a free_callback will copy the samples into an internal buffer.

But for the first version ok. Fixing my threading problem is easy move everything inside our thread. What means create a mainloop for the libpulse. My first thought, that could not be hard, because epoll, a modern efficient select replacement supports chaining. Just chain or combine rt_poll with our libpulse mainloop. Not a easy solution. Combining a mainloop poll and a rt poll is hard, because of two lists of filedescriptors which can not be simple appended. Both lists get generated each time poll runs.

Stepping a step back and asking why should I use rt_poll? Is there another solution which fits much more the concept of using a second mainloop? A thread only working as a mainloop should also work. The only task what the thread must take case is the pa_thread_mq.

lynxarius

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My gsoc project pulseaudio mod-tunnel

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