[PATCH v6 1/2] pipe-source: generate silence when no writers connected

[georg@xxxxxxxx (Georg Chini)]

On 14.02.2018 23:16, Raman Shyshniou wrote:
> Currently the pipe-source does not produce any data if no
> writer is connected. This patch enable silence generator
> when last writer closed pipe. It will stop automatically
> when any data appears.
> ---
After my fixes to module-null-source, I think your logic is not yet
completely correct. I would propose to do it like that:

In source_process_msg():

 Â Â Â Â Â Â Â Â Â  case PA_SOURCE_MESSAGE_GET_LATENCY:
 Â Â Â Â Â Â Â Â Â Â Â Â Â Â  current_latency = now - time stamp
 Â Â Â Â Â Â Â Â Â Â Â Â Â Â  if (u->corkfd < 0)
 Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â  current_latency += data in pipe

 Â Â Â Â Â Â Â Â Â  case PA_SOURCE_MESSAGE_SET_STATE:
 Â Â Â Â Â Â Â Â Â Â Â Â Â Â  if (SUSPENDED or INIT -> IDLE || SUSPENDED or INIT -> 
RUNNING) {
 Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â  get time stamp
 Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â  u->starting = true
 Â Â Â Â Â Â Â Â Â Â Â Â Â Â  }

In thread_func():

close u->corkfd
u->corkfd = -1
u->starting = true

timer_elapsed = false
revents = 0
get time stamp

for (;;) {
 Â Â Â  if (source is open) {

 Â Â Â Â Â Â Â  /* We have to wait at least one configured source latency 
before starting
 Â Â Â Â Â Â Â Â  * to read data */
 Â Â Â Â Â Â Â  if (revents & POLLIN && !u->starting) {
 Â Â Â Â Â Â Â Â Â Â Â  read data from pipe
 Â  Â  Â  Â  Â  Â  if (u->corkfd >=0) {
 Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â  close corkfd
 Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â  u->corkfd = -1
 Â Â Â Â Â Â Â Â Â Â  }

 Â  Â  Â  Â  } else if (timer_elapsed && u->corkfd > 0)
 Â Â Â Â Â  Â  Â  Â  generate silence

 Â Â Â Â Â Â  if (data was read/generated) {
 Â  Â  Â  Â Â  Â Â  post data
 Â Â Â Â Â Â Â Â Â Â Â  time stamp += data written
 Â Â Â Â Â Â  }

 Â Â Â Â Â Â  set timer absolute time stamp + configured (or fixed) source latency
 Â Â  } else
 Â  Â  Â Â  set timer disabled

 Â Â  run rtpoll
 Â Â  get timer_elapsed

 Â Â Â  if (u->starting && timer_elapsed)
 Â Â Â Â Â Â Â  u->starting = false

 Â Â  if (revents & POLLHUP) {
 Â Â Â Â Â Â  open pipe for writing
 Â Â Â Â Â Â  u->corkfd = write file descriptor
 Â Â Â Â Â Â  revents = revents & ~POLLHUP
 Â Â  }

 Â Â  error check
}

You can also add a source_update_requested_latency_cb() like
in module-null-source and pass  PA_SOURCE_DYNAMIC_LATENCY
to pa_source_new() to make the latency configurable.

I hope I did not forget anything ...