I am trying to create 2 simple programs that are basically the parec-simple and pacat-simple examples from the pulseaudio documentation. The only difference is that I would like to create a null sink, equivalent of
pactl load-module module-null-sink sink_name=steam
(see example here) which I would then use instead of the default device on both ends - playback and record.
My question is: how can I create this null sink using pulseaudio's C API? From what I saw, pulse/simple.h does not contain any function definition to do this, so I guess I would have to use libpulse.
I couldn't find the pulseaudio API for it so I just use the pactl interface directly.
For anyone interested, here is a sample code that worked for me. I just used popen to execute the pactl command to create a (null) sink:
static bool createNullPaSink(const std::string& sinkName, int* paHandleId) {
// this is the command to create the null sink with some specific setup (format, channels, rate, etc.0
std::string pacmd = "pactl load-module module-null-sink latency_msec=100 format=s16le rate=48000 channels=2 channel_map=front-left,front-right sink_properties=device.description=QM sink_name=" + sinkName;
// execute the pactl command
FILE* f = popen(pacmd.c_str(), "r");
if (!f) {
// creating the sink failed
return false;
}
// now get the handle of the sink by reading the output of the popen command above
std::array<char, 128> buffer;
std::string spaHandleId;
while (fgets(buffer.data(), 128, f) != NULL) {
spaHandleId += buffer.data();
}
auto returnCode = pclose(f);
if (returnCode) {
return false;
}
*paHandleId = std::stoi(spaHandleId);
return true;
}