[pulseaudio-discuss] [PATCH] module-virtual-sink: Speed up draining

[Alexander E. Patrakov]

02.10.2014 19:58, David Henningsson wrote:
> @@ -216,6 +216,10 @@ static int sink_input_pop_cb(pa_sink_input *i, size_t nbytes, pa_memchunk *chunk
>           pa_memchunk nchunk;
>
>           pa_sink_render(u->sink, nbytes, &nchunk);
> +        if (nchunk.memblock == u->sink->silence.memblock) {
> +            pa_memblock_unref(nchunk.memblock);
> +            return -1;
> +        }
>           pa_memblockq_push(u->memblockq, &nchunk);
>           pa_memblock_unref(nchunk.memblock);
>       }

This chunk looks correct if we ignore the tail of the filter response. 
It should be split out as a separate patch and applied.

> @@ -265,6 +269,23 @@ static int sink_input_pop_cb(pa_sink_input *i, size_t nbytes, pa_memchunk *chunk
>       return 0;
>   }
>
> +/* Called from thread context */
> +
> +static bool sink_input_process_underrun_cb(pa_sink_input *i) {
> +    struct userdata *u;
> +
> +    pa_sink_input_assert_ref(i);
> +    pa_assert_se(u = i->userdata);
> +
> +    if (!PA_SINK_IS_LINKED(u->sink->thread_info.state) ||
> +        !PA_SINK_INPUT_IS_LINKED(u->sink_input->thread_info.state))
> +        return false;
> +
> +    pa_log_debug("sink_input_process_underrun_cb for virtual sink");
> +    return pa_sink_process_input_underruns(u->sink, 0);
> +}
> +
> +
>   /* Called from I/O thread context */
>   static void sink_input_process_rewind_cb(pa_sink_input *i, size_t nbytes) {
>       struct userdata *u;
> @@ -586,6 +607,7 @@ int pa__init(pa_module*m) {
>           goto fail;
>
>       u->sink_input->pop = sink_input_pop_cb;
> +    u->sink_input->process_underrun = sink_input_process_underrun_cb;
>       u->sink_input->process_rewind = sink_input_process_rewind_cb;
>       u->sink_input->update_max_rewind = sink_input_update_max_rewind_cb;
>       u->sink_input->update_max_request = sink_input_update_max_request_cb;
>

And for this I have doubts whether this is a right approach at all. By 
analogy with the ALSA sink, I'd expect that 
pa_sink_process_input_underruns() will be called from 
sink_input_pop_cb() - but I am also not sure if this is a viable 
approach. But at least it won't have the "correct for only one sink 
input" limitation.

-- 
Alexander E. Patrakov