pulse audio 에서 device list 보기.

출처 :https://gist.github.com/andrewrk/6470f3786d05999fcb48

//gcc ./pa-device.c -lpulse
#include <stdio.h>
#include <string.h>
#include <pulse/pulseaudio.h>

// Field list is here: http://0pointer.de/lennart/projects/pulseaudio/doxygen/structpa__sink__info.html
typedef struct pa_devicelist {
    uint8_t        initialized;
    char        name[512];
    uint32_t    index;
    char        description[256];
} pa_devicelist_t;

void pa_state_cb(pa_context *c, void *userdata);
void pa_sinklist_cb(pa_context *c, const pa_sink_info *l, int eol, void *userdata);
void pa_sourcelist_cb(pa_context *c, const pa_source_info *l, int eol, void *userdata);
int pa_get_devicelist(pa_devicelist_t *input, pa_devicelist_t *output);

// This callback gets called when our context changes state.  We really only
// care about when it's ready or if it has failed
void pa_state_cb(pa_context *c, void *userdata)
{
    pa_context_state_t state;
    int *pa_ready = userdata;

    state = pa_context_get_state(c);
    switch (state) {
    // There are just here for reference
    case PA_CONTEXT_UNCONNECTED:
    case PA_CONTEXT_CONNECTING:
    case PA_CONTEXT_AUTHORIZING:
    case PA_CONTEXT_SETTING_NAME:
    default:
        break;
    case PA_CONTEXT_FAILED:
    case PA_CONTEXT_TERMINATED:
        *pa_ready = 2;
        break;
    case PA_CONTEXT_READY:
        *pa_ready = 1;
        break;
    }
}

// pa_mainloop will call this function when it's ready to tell us about a sink.
// Since we're not threading, there's no need for mutexes on the devicelist
// structure
void pa_sinklist_cb(pa_context *c, const pa_sink_info *l, int eol, void *userdata)
{
    pa_devicelist_t *pa_devicelist = userdata;
    int ctr = 0;

    // If eol is set to a positive number, you're at the end of the list
    if (eol > 0)
        return;

    // We know we've allocated 16 slots to hold devices.  Loop through our
    // structure and find the first one that's "uninitialized."  Copy the
    // contents into it and we're done.  If we receive more than 16 devices,
    // they're going to get dropped.  You could make this dynamically allocate
    // space for the device list, but this is a simple example.
    for (ctr = 0; ctr < 16; ctr++) {
        if (!pa_devicelist[ctr].initialized) {
            strncpy(pa_devicelist[ctr].name, l->name, 511);
            strncpy(pa_devicelist[ctr].description, l->description, 255);
            pa_devicelist[ctr].index = l->index;
            pa_devicelist[ctr].initialized = 1;
            break;
        }
    }
}

// See above.  This callback is pretty much identical to the previous
void pa_sourcelist_cb(pa_context *c, const pa_source_info *l, int eol, void *userdata)
{
    pa_devicelist_t *pa_devicelist = userdata;
    int ctr = 0;

    if (eol > 0)
        return;

    for (ctr = 0; ctr < 16; ctr++) {
        if (!pa_devicelist[ctr].initialized) {
            strncpy(pa_devicelist[ctr].name, l->name, 511);
            strncpy(pa_devicelist[ctr].description, l->description, 255);
            pa_devicelist[ctr].index = l->index;
            pa_devicelist[ctr].initialized = 1;
            break;
        }
    }
}

int pa_get_devicelist(pa_devicelist_t *input, pa_devicelist_t *output)
{
    // Define our pulse audio loop and connection variables
    pa_mainloop *pa_ml;
    pa_mainloop_api *pa_mlapi;
    pa_operation *pa_op;
    pa_context *pa_ctx;


    // We'll need these state variables to keep track of our requests
    int state = 0;
    int pa_ready = 0;

    // Initialize our device lists
    memset(input, 0, sizeof(pa_devicelist_t) * 16);
    memset(output, 0, sizeof(pa_devicelist_t) * 16);

    // Create a mainloop API and connection to the default server
    pa_ml = pa_mainloop_new();
    pa_mlapi = pa_mainloop_get_api(pa_ml);
    pa_ctx = pa_context_new(pa_mlapi, "test");

    // This function connects to the pulse server
    pa_context_connect(pa_ctx, NULL, 0, NULL);


    // This function defines a callback so the server will tell us it's state.
    // Our callback will wait for the state to be ready.  The callback will
    // modify the variable to 1 so we know when we have a connection and it's
    // ready.
    // If there's an error, the callback will set pa_ready to 2
    pa_context_set_state_callback(pa_ctx, pa_state_cb, &pa_ready);

    // Now we'll enter into an infinite loop until we get the data we receive
    // or if there's an error
    for (;;) {
        // We can't do anything until PA is ready, so just iterate the mainloop
        // and continue
        if (pa_ready == 0) {
            pa_mainloop_iterate(pa_ml, 1, NULL);
            continue;
        }
        // We couldn't get a connection to the server, so exit out
        if (pa_ready == 2) {
            pa_context_disconnect(pa_ctx);
            pa_context_unref(pa_ctx);
            pa_mainloop_free(pa_ml);
            return -1;
        }
        // At this point, we're connected to the server and ready to make
        // requests
        switch (state) {
        // State 0: we haven't done anything yet
        case 0:
            // This sends an operation to the server.  pa_sinklist_info is
            // our callback function and a pointer to our devicelist will
            // be passed to the callback The operation ID is stored in the
            // pa_op variable
            pa_op = pa_context_get_sink_info_list(pa_ctx,
                                  pa_sinklist_cb,
                                  output
                                  );

            // Update state for next iteration through the loop
            state++;
            break;
        case 1:
            // Now we wait for our operation to complete.  When it's
            // complete our pa_output_devicelist is filled out, and we move
            // along to the next state
            if (pa_operation_get_state(pa_op) == PA_OPERATION_DONE) {
                pa_operation_unref(pa_op);

                // Now we perform another operation to get the source
                // (input device) list just like before.  This time we pass
                // a pointer to our input structure
                pa_op = pa_context_get_source_info_list(pa_ctx,
                                    pa_sourcelist_cb,
                                    input
                                    );
                // Update the state so we know what to do next
                state++;
            }
            break;
        case 2:
            if (pa_operation_get_state(pa_op) == PA_OPERATION_DONE) {
                // Now we're done, clean up and disconnect and return
                pa_operation_unref(pa_op);
                pa_context_disconnect(pa_ctx);
                pa_context_unref(pa_ctx);
                pa_mainloop_free(pa_ml);
                return 0;
            }
            break;
        default:
            // We should never see this state
            fprintf(stderr, "in state %d\n", state);
            return -1;
        }
        // Iterate the main loop and go again.  The second argument is whether
        // or not the iteration should block until something is ready to be
        // done.  Set it to zero for non-blocking.
        pa_mainloop_iterate(pa_ml, 1, NULL);
    }
}

int main(int argc, char *argv[])
{
    int ctr;

    // This is where we'll store the input device list
    pa_devicelist_t pa_input_devicelist[16];

    // This is where we'll store the output device list
    pa_devicelist_t pa_output_devicelist[16];

    if (pa_get_devicelist(pa_input_devicelist, pa_output_devicelist) < 0) {
        fprintf(stderr, "failed to get device list\n");
        return 1;
    }

    for (ctr = 0; ctr < 16; ctr++) {
        if (!pa_output_devicelist[ctr].initialized)
            break;
        printf("=======[ Output Device #%d ]=======\n", ctr + 1);
        printf("Description: %s\n", pa_output_devicelist[ctr].description);
        printf("Name: %s\n", pa_output_devicelist[ctr].name);
        printf("Index: %d\n", pa_output_devicelist[ctr].index);
        printf("\n");
    }

    for (ctr = 0; ctr < 16; ctr++) {
        if (!pa_input_devicelist[ctr].initialized)
            break;
        printf("=======[ Input Device #%d ]=======\n", ctr + 1);
        printf("Description: %s\n", pa_input_devicelist[ctr].description);
        printf("Name: %s\n", pa_input_devicelist[ctr].name);
        printf("Index: %d\n", pa_input_devicelist[ctr].index);
        printf("\n");
    }
    return 0;
}

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