Enumerate input/output devices discoverable though libavdevice

enum-libavdevice.c

#include <stdio.h>

#include <libavformat/avformat.h>
#include <libavdevice/avdevice.h>
#include <libavutil/avutil.h>

static char errbuf[AV_ERROR_MAX_STRING_SIZE];

static void print_streams (int i, int ddev, AVDeviceInfo *d)
{
  printf ("\t%c[%d] %s (%s)\n",
          /* star = device is default */
          ddev == i ? '*' : ' ', i,
          d->device_name, d->device_description);
}

static void print_input_device (const AVInputFormat *d)
{
  AVDeviceInfoList *list;
  int i, ret;
  
  ret = avdevice_list_input_sources (d, NULL, NULL, &list);

  if (ret < 0)
  {
    av_strerror(ret, errbuf, AV_ERROR_MAX_STRING_SIZE);
    fprintf (stderr, "\terror: libavdevice: %s\n", errbuf);
    return;
  }

  for (i = 0; i < list->nb_devices; ++i)
    print_streams(i, list->default_device, list->devices[i]);

  avdevice_free_list_devices(&list);
}

static void print_output_device (const AVOutputFormat *d)
{
  AVDeviceInfoList *list;
  int i, ret;
  
  ret = avdevice_list_output_sinks (d, NULL, NULL, &list);

  if (ret < 0)
  {
    av_strerror(ret, errbuf, AV_ERROR_MAX_STRING_SIZE);
    fprintf (stderr, "\terror: libavdevice: %s\n", errbuf);
    return;
  }

    
  for (i = 0; i < list->nb_devices; ++i)
    print_streams(i, list->default_device, list->devices[i]);

  avdevice_free_list_devices(&list);
}

int main()
{
  avdevice_register_all();

  const AVInputFormat *in_device = NULL;
  const AVOutputFormat *out_device = NULL;

  printf ("-- Audio --\n-- Inputs --\n");
  
  while ((in_device = av_input_audio_device_next (in_device)) != NULL)
  {
    printf ("%s (%s)\n", in_device->name, in_device->long_name);

    print_input_device(in_device);
    putc('\n', stdout);
  }

  printf ("-- Outputs --\n");

  while ((out_device = av_output_audio_device_next (out_device)) != NULL)
  {
    printf ("%s (%s)\n", out_device->name, out_device->long_name);

    print_output_device(out_device);
    putc('\n', stdout);
  }
  
  printf ("-- Video --\n-- Inputs --\n");
  
  in_device = NULL;
  while ((in_device = av_input_video_device_next (in_device)) != NULL)
  {
    printf ("%s (%s)\n", in_device->name, in_device->long_name);

    print_input_device(in_device);
    putc('\n', stdout);
  }

  printf ("-- Outputs --\n");
  
  out_device = NULL;
  while ((out_device = av_output_video_device_next (out_device)) != NULL)
  {
    printf ("%s (%s)\n", out_device->name, out_device->long_name);

    print_output_device(out_device);
    putc('\n', stdout);
  }
}