diff --git a/CMakeLists.txt b/CMakeLists.txt
index 349ba8e..5aeb622 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -199,6 +199,18 @@ if(USE_OPENSL)
   target_link_libraries(cubeb PRIVATE OpenSLES)
 endif()
 
+check_include_files(sys/soundcard.h HAVE_SYS_SOUNDCARD_H)
+if(HAVE_SYS_SOUNDCARD_H)
+  try_compile(USE_OSS "${PROJECT_BINARY_DIR}/compile_tests"
+    ${PROJECT_SOURCE_DIR}/cmake/compile_tests/oss_is_v4.c)
+  if(USE_OSS)
+    target_sources(cubeb PRIVATE
+      src/cubeb_oss.c)
+    target_compile_definitions(cubeb PRIVATE USE_OSS)
+    target_link_libraries(cubeb PRIVATE pthread)
+  endif()
+endif()
+
 check_include_files(android/log.h USE_AUDIOTRACK)
 if(USE_AUDIOTRACK)
   target_sources(cubeb PRIVATE
diff --git a/cmake/compile_tests/oss_is_v4.c b/cmake/compile_tests/oss_is_v4.c
new file mode 100644
index 0000000..a46bb15
--- /dev/null
+++ b/cmake/compile_tests/oss_is_v4.c
@@ -0,0 +1,10 @@
+#include <sys/soundcard.h>
+
+#if SOUND_VERSION < 0x040000
+# error "OSSv4 is not available in sys/soundcard.h"
+#endif
+
+int main()
+{
+	return 0;
+}
diff --git a/src/cubeb.c b/src/cubeb.c
index 8d077bd..74c17db 100644
--- a/src/cubeb.c
+++ b/src/cubeb.c
@@ -60,6 +60,9 @@ int sun_init(cubeb ** context, char const * context_name);
 #if defined(USE_OPENSL)
 int opensl_init(cubeb ** context, char const * context_name);
 #endif
+#if defined(USE_OSS)
+int oss_init(cubeb ** context, char const * context_name);
+#endif
 #if defined(USE_AUDIOTRACK)
 int audiotrack_init(cubeb ** context, char const * context_name);
 #endif
@@ -165,6 +168,10 @@ cubeb_init(cubeb ** context, char const * context_name, char const * backend_nam
     } else if (!strcmp(backend_name, "opensl")) {
 #if defined(USE_OPENSL)
       init_oneshot = opensl_init;
+#endif
+    } else if (!strcmp(backend_name, "oss")) {
+#if defined(USE_OSS)
+      init_oneshot = oss_init;
 #endif
     } else if (!strcmp(backend_name, "audiotrack")) {
 #if defined(USE_AUDIOTRACK)
@@ -200,6 +207,9 @@ cubeb_init(cubeb ** context, char const * context_name, char const * backend_nam
 #if defined(USE_ALSA)
     alsa_init,
 #endif
+#if defined (USE_OSS)
+    oss_init,
+#endif
 #if defined(USE_AUDIOUNIT_RUST)
     audiounit_rust_init,
 #endif
diff --git a/src/cubeb_oss.c b/src/cubeb_oss.c
new file mode 100644
index 0000000..a95a4dd
--- /dev/null
+++ b/src/cubeb_oss.c
@@ -0,0 +1,1259 @@
+/*
+ * Copyright © 2019-2020 Nia Alarie <nia@NetBSD.org>
+ * Copyright © 2020 Ka Ho Ng <khng300@gmail.com>
+ * Copyright © 2020 The FreeBSD Foundation
+ *
+ * Portions of this software were developed by Ka Ho Ng
+ * under sponsorship from the FreeBSD Foundation.
+ *
+ * This program is made available under an ISC-style license.  See the
+ * accompanying file LICENSE for details.
+ */
+
+#include <assert.h>
+#include <ctype.h>
+#include <limits.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/soundcard.h>
+#include <sys/ioctl.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <pthread.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <poll.h>
+#include "cubeb/cubeb.h"
+#include "cubeb_mixer.h"
+#include "cubeb_strings.h"
+#include "cubeb-internal.h"
+
+/* Supported well by most hardware. */
+#ifndef OSS_PREFER_RATE
+#define OSS_PREFER_RATE (48000)
+#endif
+
+/* Standard acceptable minimum. */
+#ifndef OSS_LATENCY_MS
+#define OSS_LATENCY_MS (8)
+#endif
+
+#ifndef OSS_NFRAGS
+#define OSS_NFRAGS (4)
+#endif
+
+#ifndef OSS_DEFAULT_DEVICE
+#define OSS_DEFAULT_DEVICE "/dev/dsp"
+#endif
+
+#ifndef OSS_DEFAULT_MIXER
+#define OSS_DEFAULT_MIXER "/dev/mixer"
+#endif
+
+#define ENV_AUDIO_DEVICE "AUDIO_DEVICE"
+
+#ifndef OSS_MAX_CHANNELS
+# if defined(__FreeBSD__) || defined(__DragonFly__)
+/*
+ * The current maximum number of channels supported
+ * on FreeBSD is 8.
+ *
+ * Reference: FreeBSD 12.1-RELEASE
+ */
+#  define OSS_MAX_CHANNELS (8)
+# elif defined(__sun__)
+/*
+ * The current maximum number of channels supported
+ * on Illumos is 16.
+ *
+ * Reference: PSARC 2008/318
+ */
+#  define OSS_MAX_CHANNELS (16)
+# else
+#  define OSS_MAX_CHANNELS (2)
+# endif
+#endif
+
+#if defined(__FreeBSD__) || defined(__DragonFly__)
+#define SNDSTAT_BEGIN_STR "Installed devices:"
+#define SNDSTAT_USER_BEGIN_STR "Installed devices from userspace:"
+#define SNDSTAT_FV_BEGIN_STR "File Versions:"
+#endif
+
+static struct cubeb_ops const oss_ops;
+
+struct cubeb {
+  struct cubeb_ops const * ops;
+
+  /* Our intern string store */
+  pthread_mutex_t mutex; /* protects devid_strs */
+  cubeb_strings *devid_strs;
+};
+
+struct oss_stream {
+  oss_devnode_t name;
+  int fd;
+  void * buf;
+
+  struct stream_info {
+    int channels;
+    int sample_rate;
+    int fmt;
+    int precision;
+  } info;
+
+  unsigned int frame_size; /* precision in bytes * channels */
+  bool floating;
+};
+
+struct cubeb_stream {
+  struct cubeb * context;
+  void * user_ptr;
+  pthread_t thread;
+  bool doorbell; /* (m) */
+  pthread_cond_t doorbell_cv; /* (m) */
+  pthread_cond_t stopped_cv; /* (m) */
+  pthread_mutex_t mtx; /* Members protected by this should be marked (m) */
+  bool thread_created; /* (m) */
+  bool running; /* (m) */
+  bool destroying; /* (m) */
+  cubeb_state state;
+  float volume /* (m) */;
+  struct oss_stream play;
+  struct oss_stream record;
+  cubeb_data_callback data_cb;
+  cubeb_state_callback state_cb;
+  uint64_t frames_written /* (m) */;
+  unsigned int nfr; /* Number of frames allocated */
+  unsigned int nfrags;
+  unsigned int bufframes;
+};
+
+static char const *
+oss_cubeb_devid_intern(cubeb *context, char const * devid)
+{
+  char const *is;
+  pthread_mutex_lock(&context->mutex);
+  is = cubeb_strings_intern(context->devid_strs, devid);
+  pthread_mutex_unlock(&context->mutex);
+  return is;
+}
+
+int
+oss_init(cubeb **context, char const *context_name) {
+  cubeb * c;
+
+  (void)context_name;
+  if ((c = calloc(1, sizeof(cubeb))) == NULL) {
+    return CUBEB_ERROR;
+  }
+
+  if (cubeb_strings_init(&c->devid_strs) == CUBEB_ERROR) {
+    goto fail;
+  }
+
+  if (pthread_mutex_init(&c->mutex, NULL) != 0) {
+    goto fail;
+  }
+
+  c->ops = &oss_ops;
+  *context = c;
+  return CUBEB_OK;
+
+fail:
+  cubeb_strings_destroy(c->devid_strs);
+  free(c);
+  return CUBEB_ERROR;
+}
+
+static void
+oss_destroy(cubeb * context)
+{
+  pthread_mutex_destroy(&context->mutex);
+  cubeb_strings_destroy(context->devid_strs);
+  free(context);
+}
+
+static char const *
+oss_get_backend_id(cubeb * context)
+{
+  return "oss";
+}
+
+static int
+oss_get_preferred_sample_rate(cubeb * context, uint32_t * rate)
+{
+  (void)context;
+
+  *rate = OSS_PREFER_RATE;
+  return CUBEB_OK;
+}
+
+static int
+oss_get_max_channel_count(cubeb * context, uint32_t * max_channels)
+{
+  (void)context;
+
+  *max_channels = OSS_MAX_CHANNELS;
+  return CUBEB_OK;
+}
+
+static int
+oss_get_min_latency(cubeb * context, cubeb_stream_params params,
+                    uint32_t * latency_frames)
+{
+  (void)context;
+
+  *latency_frames = (OSS_LATENCY_MS * params.rate) / 1000;
+  return CUBEB_OK;
+}
+
+static void
+oss_free_cubeb_device_info_strings(cubeb_device_info *cdi)
+{
+  free((char *)cdi->device_id);
+  free((char *)cdi->friendly_name);
+  free((char *)cdi->group_id);
+  cdi->device_id = NULL;
+  cdi->friendly_name = NULL;
+  cdi->group_id = NULL;
+}
+
+#if defined(__FreeBSD__) || defined(__DragonFly__)
+/*
+ * Check if the specified DSP is okay for the purpose specified
+ * in type. Here type can only specify one operation each time
+ * this helper is called.
+ *
+ * Return 0 if OK, otherwise 1.
+ */
+static int
+oss_probe_open(const char *dsppath, cubeb_device_type type,
+               int *fdp, oss_audioinfo *resai)
+{
+  oss_audioinfo ai;
+  int error;
+  int oflags = (type == CUBEB_DEVICE_TYPE_INPUT) ? O_RDONLY : O_WRONLY;
+  int dspfd = open(dsppath, oflags);
+  if (dspfd == -1)
+    return 1;
+
+  ai.dev = -1;
+  error = ioctl(dspfd, SNDCTL_AUDIOINFO, &ai);
+  if (error < 0) {
+    close(dspfd);
+    return 1;
+  }
+
+  if (resai)
+    *resai = ai;
+  if (fdp)
+    *fdp = dspfd;
+  else
+    close(dspfd);
+  return 0;
+}
+
+struct sndstat_info {
+  oss_devnode_t devname;
+  const char *desc;
+  cubeb_device_type type;
+  int preferred;
+};
+
+static int
+oss_sndstat_line_parse(char *line, int is_ud, struct sndstat_info *sinfo)
+{
+    char *matchptr = line, *n = NULL;
+    struct sndstat_info res;
+
+    memset(&res, 0, sizeof(res));
+
+    n = strchr(matchptr, ':');
+    if (n == NULL)
+      goto fail;
+    if (is_ud == 0) {
+      unsigned int devunit;
+
+      if (sscanf(matchptr, "pcm%u: ", &devunit) < 1)
+        goto fail;
+
+      if (snprintf(res.devname, sizeof(res.devname), "/dev/dsp%u", devunit) < 1)
+        goto fail;
+    } else {
+      if (n - matchptr >= (ssize_t)(sizeof(res.devname) - strlen("/dev/")))
+        goto fail;
+
+      strlcpy(res.devname, "/dev/", sizeof(res.devname));
+      strncat(res.devname, matchptr, n - matchptr);
+    }
+    matchptr = n + 1;
+
+    n = strchr(matchptr, '<');
+    if (n == NULL)
+      goto fail;
+    matchptr = n + 1;
+    n = strrchr(matchptr, '>');
+    if (n == NULL)
+      goto fail;
+    *n = 0;
+    res.desc = matchptr;
+    matchptr = n + 1;
+
+    n = strchr(matchptr, '(');
+    if (n == NULL)
+      goto fail;
+    matchptr = n + 1;
+    n = strrchr(matchptr, ')');
+    if (n == NULL)
+      goto fail;
+    *n = 0;
+    if (!isdigit(matchptr[0])) {
+      if (strstr(matchptr, "play") != NULL)
+        res.type |= CUBEB_DEVICE_TYPE_OUTPUT;
+      if (strstr(matchptr, "rec") != NULL)
+        res.type |= CUBEB_DEVICE_TYPE_INPUT;
+    } else {
+      int p, r;
+      if (sscanf(matchptr, "%dp:%*dv/%dr:%*dv", &p, &r) != 2)
+        goto fail;
+      if (p > 0)
+        res.type |= CUBEB_DEVICE_TYPE_OUTPUT;
+      if (r > 0)
+        res.type |= CUBEB_DEVICE_TYPE_INPUT;
+    }
+    matchptr = n + 1;
+    if (strstr(matchptr, "default") != NULL)
+      res.preferred = 1;
+
+    *sinfo = res;
+    return 0;
+
+fail:
+    return 1;
+}
+
+/*
+ * XXX: On FreeBSD we have to rely on SNDCTL_CARDINFO to get all
+ * the usable audio devices currently, as SNDCTL_AUDIOINFO will
+ * never return directly usable audio device nodes.
+ */
+static int
+oss_enumerate_devices(cubeb * context, cubeb_device_type type,
+                      cubeb_device_collection * collection)
+{
+  cubeb_device_info *devinfop = NULL;
+  char *line = NULL;
+  size_t linecap = 0;
+  FILE *sndstatfp = NULL;
+  int collection_cnt = 0;
+  int is_ud = 0;
+  int skipall = 0;
+
+  devinfop = calloc(1, sizeof(cubeb_device_info));
+  if (devinfop == NULL)
+    goto fail;
+
+  sndstatfp = fopen("/dev/sndstat", "r");
+  if (sndstatfp == NULL)
+    goto fail;
+  while (getline(&line, &linecap, sndstatfp) > 0) {
+    const char *devid = NULL;
+    struct sndstat_info sinfo;
+    oss_audioinfo ai;
+
+    if (!strncmp(line, SNDSTAT_FV_BEGIN_STR, strlen(SNDSTAT_FV_BEGIN_STR))) {
+      skipall = 1;
+      continue;
+    }
+    if (!strncmp(line, SNDSTAT_BEGIN_STR, strlen(SNDSTAT_BEGIN_STR))) {
+      is_ud = 0;
+      skipall = 0;
+      continue;
+    }
+    if (!strncmp(line, SNDSTAT_USER_BEGIN_STR, strlen(SNDSTAT_USER_BEGIN_STR))) {
+      is_ud = 1;
+      skipall = 0;
+      continue;
+    }
+    if (skipall || isblank(line[0]))
+      continue;
+
+    if (oss_sndstat_line_parse(line, is_ud, &sinfo))
+      continue;
+
+    devinfop[collection_cnt].type = 0;
+    switch (sinfo.type) {
+    case CUBEB_DEVICE_TYPE_INPUT:
+      if (type & CUBEB_DEVICE_TYPE_OUTPUT)
+        continue;
+      break;
+    case CUBEB_DEVICE_TYPE_OUTPUT:
+      if (type & CUBEB_DEVICE_TYPE_INPUT)
+        continue;
+      break;
+    case 0:
+      continue;
+    }
+
+    if (oss_probe_open(sinfo.devname, type, NULL, &ai))
+      continue;
+
+    devid = oss_cubeb_devid_intern(context, sinfo.devname);
+    if (devid == NULL)
+      continue;
+
+    devinfop[collection_cnt].device_id = strdup(sinfo.devname);
+    asprintf((char **)&devinfop[collection_cnt].friendly_name, "%s: %s",
+             sinfo.devname, sinfo.desc);
+    devinfop[collection_cnt].group_id = strdup(sinfo.devname);
+    devinfop[collection_cnt].vendor_name = NULL;
+    if (devinfop[collection_cnt].device_id == NULL ||
+        devinfop[collection_cnt].friendly_name == NULL ||
+        devinfop[collection_cnt].group_id == NULL) {
+      oss_free_cubeb_device_info_strings(&devinfop[collection_cnt]);
+      continue;
+    }
+
+    devinfop[collection_cnt].type = type;
+    devinfop[collection_cnt].devid = devid;
+    devinfop[collection_cnt].state = CUBEB_DEVICE_STATE_ENABLED;
+    devinfop[collection_cnt].preferred =
+        (sinfo.preferred) ? CUBEB_DEVICE_PREF_ALL : CUBEB_DEVICE_PREF_NONE;
+    devinfop[collection_cnt].format = CUBEB_DEVICE_FMT_S16NE;
+    devinfop[collection_cnt].default_format = CUBEB_DEVICE_FMT_S16NE;
+    devinfop[collection_cnt].max_channels = ai.max_channels;
+    devinfop[collection_cnt].default_rate = OSS_PREFER_RATE;
+    devinfop[collection_cnt].max_rate = ai.max_rate;
+    devinfop[collection_cnt].min_rate = ai.min_rate;
+    devinfop[collection_cnt].latency_lo = 0;
+    devinfop[collection_cnt].latency_hi = 0;
+
+    collection_cnt++;
+
+    void *newp = reallocarray(devinfop, collection_cnt + 1,
+                              sizeof(cubeb_device_info));
+    if (newp == NULL)
+      goto fail;
+    devinfop = newp;
+  }
+
+  free(line);
+  fclose(sndstatfp);
+
+  collection->count = collection_cnt;
+  collection->device = devinfop;
+
+  return CUBEB_OK;
+
+fail:
+  free(line);
+  if (sndstatfp)
+    fclose(sndstatfp);
+  free(devinfop);
+  return CUBEB_ERROR;
+}
+
+#else
+
+static int
+oss_enumerate_devices(cubeb * context, cubeb_device_type type,
+                      cubeb_device_collection * collection)
+{
+  oss_sysinfo si;
+  int error, i;
+  cubeb_device_info *devinfop = NULL;
+  int collection_cnt = 0;
+  int mixer_fd = -1;
+
+  mixer_fd = open(OSS_DEFAULT_MIXER, O_RDWR);
+  if (mixer_fd == -1) {
+    LOG("Failed to open mixer %s. errno: %d", OSS_DEFAULT_MIXER, errno);
+    return CUBEB_ERROR;
+  }
+
+  error = ioctl(mixer_fd, SNDCTL_SYSINFO, &si);
+  if (error) {
+    LOG("Failed to run SNDCTL_SYSINFO on mixer %s. errno: %d", OSS_DEFAULT_MIXER, errno);
+    goto fail;
+  }
+
+  devinfop = calloc(si.numaudios, sizeof(cubeb_device_info));
+  if (devinfop == NULL)
+    goto fail;
+
+  collection->count = 0;
+  for (i = 0; i < si.numaudios; i++) {
+    oss_audioinfo ai;
+    cubeb_device_info cdi = { 0 };
+    const char *devid = NULL;
+
+    ai.dev = i;
+    error = ioctl(mixer_fd, SNDCTL_AUDIOINFO, &ai);
+    if (error)
+      goto fail;
+
+    assert(ai.dev < si.numaudios);
+    if (!ai.enabled)
+      continue;
+
+    cdi.type = 0;
+    switch (ai.caps & DSP_CAP_DUPLEX) {
+    case DSP_CAP_INPUT:
+      if (type & CUBEB_DEVICE_TYPE_OUTPUT)
+        continue;
+      break;
+    case DSP_CAP_OUTPUT:
+      if (type & CUBEB_DEVICE_TYPE_INPUT)
+        continue;
+      break;
+    case 0:
+      continue;
+    }
+    cdi.type = type;
+
+    devid = oss_cubeb_devid_intern(context, ai.devnode);
+    cdi.device_id = strdup(ai.name);
+    cdi.friendly_name = strdup(ai.name);
+    cdi.group_id = strdup(ai.name);
+    if (devid == NULL || cdi.device_id == NULL || cdi.friendly_name == NULL ||
+        cdi.group_id == NULL) {
+      oss_free_cubeb_device_info_strings(&cdi);
+      continue;
+    }
+
+    cdi.devid = devid;
+    cdi.vendor_name = NULL;
+    cdi.state = CUBEB_DEVICE_STATE_ENABLED;
+    cdi.preferred = CUBEB_DEVICE_PREF_NONE;
+    cdi.format = CUBEB_DEVICE_FMT_S16NE;
+    cdi.default_format = CUBEB_DEVICE_FMT_S16NE;
+    cdi.max_channels = ai.max_channels;
+    cdi.default_rate = OSS_PREFER_RATE;
+    cdi.max_rate = ai.max_rate;
+    cdi.min_rate = ai.min_rate;
+    cdi.latency_lo = 0;
+    cdi.latency_hi = 0;
+
+    devinfop[collection_cnt++] = cdi;
+  }
+
+  collection->count = collection_cnt;
+  collection->device = devinfop;
+
+  if (mixer_fd != -1)
+    close(mixer_fd);
+  return CUBEB_OK;
+
+fail:
+  if (mixer_fd != -1)
+    close(mixer_fd);
+  free(devinfop);
+  return CUBEB_ERROR;
+}
+
+#endif
+
+static int
+oss_device_collection_destroy(cubeb * context,
+                              cubeb_device_collection * collection)
+{
+  size_t i;
+  for (i = 0; i < collection->count; i++) {
+    oss_free_cubeb_device_info_strings(&collection->device[i]);
+  }
+  free(collection->device);
+  collection->device = NULL;
+  collection->count = 0;
+  return 0;
+}
+
+static unsigned int
+oss_chn_from_cubeb(cubeb_channel chn)
+{
+  switch (chn) {
+    case CHANNEL_FRONT_LEFT:
+      return CHID_L;
+    case CHANNEL_FRONT_RIGHT:
+      return CHID_R;
+    case CHANNEL_FRONT_CENTER:
+      return CHID_C;
+    case CHANNEL_LOW_FREQUENCY:
+      return CHID_LFE;
+    case CHANNEL_BACK_LEFT:
+      return CHID_LR;
+    case CHANNEL_BACK_RIGHT:
+      return CHID_RR;
+    case CHANNEL_SIDE_LEFT:
+      return CHID_LS;
+    case CHANNEL_SIDE_RIGHT:
+      return CHID_RS;
+    default:
+      return CHID_UNDEF;
+  }
+}
+
+static unsigned long long
+oss_cubeb_layout_to_chnorder(cubeb_channel_layout layout)
+{
+  unsigned int i, nchns = 0;
+  unsigned long long chnorder = 0;
+
+  for (i = 0; layout; i++, layout >>= 1) {
+    unsigned long long chid = oss_chn_from_cubeb((layout & 1) << i);
+    if (chid == CHID_UNDEF)
+      continue;
+
+    chnorder |= (chid & 0xf) << nchns * 4;
+    nchns++;
+  }
+
+  return chnorder;
+}
+
+static int
+oss_copy_params(int fd, cubeb_stream * stream, cubeb_stream_params * params,
+                struct stream_info * sinfo)
+{
+  unsigned long long chnorder;
+
+  sinfo->channels = params->channels;
+  sinfo->sample_rate = params->rate;
+  switch (params->format) {
+  case CUBEB_SAMPLE_S16LE:
+    sinfo->fmt = AFMT_S16_LE;
+    sinfo->precision = 16;
+    break;
+  case CUBEB_SAMPLE_S16BE:
+    sinfo->fmt = AFMT_S16_BE;
+    sinfo->precision = 16;
+    break;
+  case CUBEB_SAMPLE_FLOAT32NE:
+    sinfo->fmt = AFMT_S32_NE;
+    sinfo->precision = 32;
+    break;
+  default:
+    LOG("Unsupported format");
+    return CUBEB_ERROR_INVALID_FORMAT;
+  }
+  if (ioctl(fd, SNDCTL_DSP_CHANNELS, &sinfo->channels) == -1) {
+    return CUBEB_ERROR;
+  }
+  if (ioctl(fd, SNDCTL_DSP_SETFMT, &sinfo->fmt) == -1) {
+    return CUBEB_ERROR;
+  }
+  if (ioctl(fd, SNDCTL_DSP_SPEED, &sinfo->sample_rate) == -1) {
+    return CUBEB_ERROR;
+  }
+  /* Mono layout is an exception */
+  if (params->layout != CUBEB_LAYOUT_UNDEFINED && params->layout != CUBEB_LAYOUT_MONO) {
+    chnorder = oss_cubeb_layout_to_chnorder(params->layout);
+    if (ioctl(fd, SNDCTL_DSP_SET_CHNORDER, &chnorder) == -1)
+      LOG("Non-fatal error %d occured when setting channel order.", errno);
+  }
+  return CUBEB_OK;
+}
+
+static int
+oss_stream_stop(cubeb_stream * s)
+{
+  pthread_mutex_lock(&s->mtx);
+  if (s->thread_created && s->running) {
+    s->running = false;
+    s->doorbell = false;
+    pthread_cond_wait(&s->stopped_cv, &s->mtx);
+  }
+  if (s->state != CUBEB_STATE_STOPPED) {
+    s->state = CUBEB_STATE_STOPPED;
+    pthread_mutex_unlock(&s->mtx);
+    s->state_cb(s, s->user_ptr, CUBEB_STATE_STOPPED);
+  } else {
+    pthread_mutex_unlock(&s->mtx);
+  }
+  return CUBEB_OK;
+}
+
+static void
+oss_stream_destroy(cubeb_stream * s)
+{
+  pthread_mutex_lock(&s->mtx);
+  if (s->thread_created) {
+    s->destroying = true;
+    s->doorbell = true;
+    pthread_cond_signal(&s->doorbell_cv);
+  }
+  pthread_mutex_unlock(&s->mtx);
+  pthread_join(s->thread, NULL);
+
+  pthread_cond_destroy(&s->doorbell_cv);
+  pthread_cond_destroy(&s->stopped_cv);
+  pthread_mutex_destroy(&s->mtx);
+  if (s->play.fd != -1) {
+    close(s->play.fd);
+  }
+  if (s->record.fd != -1) {
+    close(s->record.fd);
+  }
+  free(s->play.buf);
+  free(s->record.buf);
+  free(s);
+}
+
+static void
+oss_float_to_linear32(void * buf, unsigned sample_count, float vol)
+{
+  float * in = buf;
+  int32_t * out = buf;
+  int32_t * tail = out + sample_count;
+
+  while (out < tail) {
+    int64_t f = *(in++) * vol * 0x80000000LL;
+    if (f < -INT32_MAX)
+      f = -INT32_MAX;
+    else if (f > INT32_MAX)
+      f = INT32_MAX;
+    *(out++) = f;
+  }
+}
+
+static void
+oss_linear32_to_float(void * buf, unsigned sample_count)
+{
+  int32_t * in = buf;
+  float * out = buf;
+  float * tail = out + sample_count;
+
+  while (out < tail) {
+    *(out++) = (1.0 / 0x80000000LL) * *(in++);
+  }
+}
+
+static void
+oss_linear16_set_vol(int16_t * buf, unsigned sample_count, float vol)
+{
+  unsigned i;
+  int32_t multiplier = vol * 0x8000;
+
+  for (i = 0; i < sample_count; ++i) {
+    buf[i] = (buf[i] * multiplier) >> 15;
+  }
+}
+
+/* 1 - Stopped by cubeb_stream_stop, otherwise 0 */
+static int
+oss_audio_loop(cubeb_stream * s, cubeb_state *new_state)
+{
+  cubeb_state state = CUBEB_STATE_STOPPED;
+  int trig = 0;
+  int drain = 0;
+  struct pollfd pfds[2];
+  unsigned int ppending, rpending;
+
+  pfds[0].fd = s->play.fd;
+  pfds[0].events = POLLOUT;
+  pfds[1].fd = s->record.fd;
+  pfds[1].events = POLLIN;
+
+  ppending = 0;
+  rpending = s->bufframes;
+
+  if (s->record.fd != -1) {
+    if (ioctl(s->record.fd, SNDCTL_DSP_SETTRIGGER, &trig)) {
+      LOG("Error %d occured when setting trigger on record fd", errno);
+      state = CUBEB_STATE_ERROR;
+      goto breakdown;
+    }
+    trig |= PCM_ENABLE_INPUT;
+    if (ioctl(s->record.fd, SNDCTL_DSP_SETTRIGGER, &trig)) {
+      LOG("Error %d occured when setting trigger on record fd", errno);
+      state = CUBEB_STATE_ERROR;
+      goto breakdown;
+    }
+    memset(s->record.buf, 0, s->bufframes * s->record.frame_size);
+  }
+
+  while (1) {
+    long nfr = 0;
+
+    pthread_mutex_lock(&s->mtx);
+    if (!s->running || s->destroying) {
+      pthread_mutex_unlock(&s->mtx);
+      break;
+    }
+    pthread_mutex_unlock(&s->mtx);
+    if (s->play.fd == -1 && s->record.fd == -1) {
+      /*
+       * Stop here if the stream is not play & record stream,
+       * play-only stream or record-only stream
+       */
+
+      goto breakdown;
+    }
+
+    while ((s->bufframes - ppending) >= s->nfr && rpending >= s->nfr) {
+      long n = ((s->bufframes - ppending) < rpending) ? s->bufframes - ppending : rpending;
+      char *rptr = NULL, *pptr = NULL;
+      if (s->record.fd != -1)
+        rptr = (char *)s->record.buf;
+      if (s->play.fd != -1)
+        pptr = (char *)s->play.buf + ppending * s->play.frame_size;
+      if (s->record.fd != -1 && s->record.floating) {
+        oss_linear32_to_float(s->record.buf, s->record.info.channels * n);
+      }
+      nfr = s->data_cb(s, s->user_ptr, rptr, pptr, n);
+      if (nfr == CUBEB_ERROR) {
+        state = CUBEB_STATE_ERROR;
+        goto breakdown;
+      }
+      if (pptr) {
+        float vol;
+
+        pthread_mutex_lock(&s->mtx);
+        vol = s->volume;
+        pthread_mutex_unlock(&s->mtx);
+
+        if (s->play.floating) {
+          oss_float_to_linear32(pptr, s->play.info.channels * nfr, vol);
+        } else {
+          oss_linear16_set_vol((int16_t *)pptr, s->play.info.channels * nfr, vol);
+        }
+      }
+      if (pptr) {
+        ppending += nfr;
+        assert(ppending <= s->bufframes);
+      }
+      if (rptr) {
+        assert(rpending >= nfr);
+        rpending -= nfr;
+        memmove(rptr, rptr + nfr * s->record.frame_size,
+                (s->bufframes - nfr) * s->record.frame_size);
+      }
+      if (nfr < n) {
+        if (s->play.fd != -1) {
+          drain = 1;
+          break;
+        } else {
+          /*
+           * This is a record-only stream and number of frames
+           * returned from data_cb() is smaller than number
+           * of frames required to read. Stop here.
+           */
+
+          state = CUBEB_STATE_STOPPED;
+          goto breakdown;
+        }
+      }
+    }
+
+    ssize_t n, frames;
+    int nfds;
+
+    pfds[0].revents = 0;
+    pfds[1].revents = 0;
+
+    nfds = poll(pfds, 2, 1000);
+    if (nfds == -1) {
+      if (errno == EINTR)
+        continue;
+      LOG("Error %d occured when polling playback and record fd", errno);
+      state = CUBEB_STATE_ERROR;
+      goto breakdown;
+    } else if (nfds == 0)
+      continue;
+
+    if ((pfds[0].revents & (POLLERR | POLLHUP)) ||
+        (pfds[1].revents & (POLLERR | POLLHUP))) {
+      LOG("Error occured on playback, record fds");
+      state = CUBEB_STATE_ERROR;
+      goto breakdown;
+    }
+
+    if (pfds[0].revents) {
+      while (ppending > 0) {
+        size_t bytes = ppending * s->play.frame_size;
+        if ((n = write(s->play.fd, (uint8_t *)s->play.buf, bytes)) < 0) {
+          if (errno == EINTR)
+            continue;
+          if (errno == EAGAIN) {
+            if (drain)
+              continue;
+            break;
+          }
+          state = CUBEB_STATE_ERROR;
+          goto breakdown;
+        }
+        frames = n / s->play.frame_size;
+        pthread_mutex_lock(&s->mtx);
+        s->frames_written += frames;
+        pthread_mutex_unlock(&s->mtx);
+        ppending -= frames;
+        memmove(s->play.buf, (uint8_t *)s->play.buf + n,
+                (s->bufframes - frames) * s->play.frame_size);
+      }
+    }
+    if (pfds[1].revents) {
+      while (s->bufframes - rpending > 0) {
+        size_t bytes = (s->bufframes - rpending) * s->record.frame_size;
+        size_t read_ofs = rpending * s->record.frame_size;
+        if ((n = read(s->record.fd, (uint8_t *)s->record.buf + read_ofs, bytes)) < 0) {
+          if (errno == EINTR)
+            continue;
+          if (errno == EAGAIN)
+            break;
+          state = CUBEB_STATE_ERROR;
+          goto breakdown;
+        }
+        frames = n / s->record.frame_size;
+        rpending += frames;
+      }
+    }
+    if (drain) {
+      state = CUBEB_STATE_DRAINED;
+      goto breakdown;
+    }
+  }
+
+  return 1;
+
+breakdown:
+  pthread_mutex_lock(&s->mtx);
+  *new_state = s->state = state;
+  s->running = false;
+  pthread_mutex_unlock(&s->mtx);
+  return 0;
+}
+
+static void *
+oss_io_routine(void *arg)
+{
+  cubeb_stream *s = arg;
+  cubeb_state new_state;
+  int stopped;
+
+  do {
+    pthread_mutex_lock(&s->mtx);
+    if (s->destroying) {
+      pthread_mutex_unlock(&s->mtx);
+      break;
+    }
+    pthread_mutex_unlock(&s->mtx);
+
+    stopped = oss_audio_loop(s, &new_state);
+    if (s->record.fd != -1)
+      ioctl(s->record.fd, SNDCTL_DSP_HALT_INPUT, NULL);
+    if (!stopped)
+      s->state_cb(s, s->user_ptr, new_state);
+
+    pthread_mutex_lock(&s->mtx);
+    pthread_cond_signal(&s->stopped_cv);
+    if (s->destroying) {
+      pthread_mutex_unlock(&s->mtx);
+      break;
+    }
+    while (!s->doorbell) {
+      pthread_cond_wait(&s->doorbell_cv, &s->mtx);
+    }
+    s->doorbell = false;
+    pthread_mutex_unlock(&s->mtx);
+  } while (1);
+
+  pthread_mutex_lock(&s->mtx);
+  s->thread_created = false;
+  pthread_mutex_unlock(&s->mtx);
+  return NULL;
+}
+
+static inline int
+oss_calc_frag_shift(unsigned int frames, unsigned int frame_size)
+{
+  int n = 4;
+  int blksize = (frames * frame_size + OSS_NFRAGS - 1) / OSS_NFRAGS;
+  while ((1 << n) < blksize)
+    n++;
+  return n;
+}
+
+static inline int
+oss_get_frag_params(unsigned int shift)
+{
+  return (OSS_NFRAGS << 16) | shift;
+}
+
+static int
+oss_stream_init(cubeb * context,
+                cubeb_stream ** stream,
+                char const * stream_name,
+                cubeb_devid input_device,
+                cubeb_stream_params * input_stream_params,
+                cubeb_devid output_device,
+                cubeb_stream_params * output_stream_params,
+                unsigned int latency_frames,
+                cubeb_data_callback data_callback,
+                cubeb_state_callback state_callback,
+                void * user_ptr)
+{
+  int ret = CUBEB_OK;
+  unsigned int playnfr = 0, recnfr = 0;
+  cubeb_stream *s = NULL;
+  const char *defdsp;
+
+  if (!(defdsp = getenv(ENV_AUDIO_DEVICE)) || *defdsp == '\0')
+    defdsp = OSS_DEFAULT_DEVICE;
+
+  (void)stream_name;
+  if ((s = calloc(1, sizeof(cubeb_stream))) == NULL) {
+    ret = CUBEB_ERROR;
+    goto error;
+  }
+  s->record.fd = s->play.fd = -1;
+  s->nfr = latency_frames;
+  if (input_device != NULL) {
+    strlcpy(s->record.name, input_device, sizeof(s->record.name));
+  } else {
+    strlcpy(s->record.name, defdsp, sizeof(s->record.name));
+  }
+  if (output_device != NULL) {
+    strlcpy(s->play.name, output_device, sizeof(s->play.name));
+  } else {
+    strlcpy(s->play.name, defdsp, sizeof(s->play.name));
+  }
+  if (input_stream_params != NULL) {
+    unsigned int nb_channels;
+    if (input_stream_params->prefs & CUBEB_STREAM_PREF_LOOPBACK) {
+      LOG("Loopback not supported");
+      ret = CUBEB_ERROR_NOT_SUPPORTED;
+      goto error;
+    }
+    nb_channels = cubeb_channel_layout_nb_channels(input_stream_params->layout);
+    if (input_stream_params->layout != CUBEB_LAYOUT_UNDEFINED &&
+        nb_channels != input_stream_params->channels) {
+      LOG("input_stream_params->layout does not match input_stream_params->channels");
+      ret = CUBEB_ERROR_INVALID_PARAMETER;
+      goto error;
+    }
+    if (s->record.fd == -1) {
+      if ((s->record.fd = open(s->record.name, O_RDONLY | O_NONBLOCK)) == -1) {
+        LOG("Audio device \"%s\" could not be opened as read-only",
+            s->record.name);
+        ret = CUBEB_ERROR_DEVICE_UNAVAILABLE;
+        goto error;
+      }
+    }
+    if ((ret = oss_copy_params(s->record.fd, s, input_stream_params,
+                               &s->record.info)) != CUBEB_OK) {
+      LOG("Setting record params failed");
+      goto error;
+    }
+    s->record.floating = (input_stream_params->format == CUBEB_SAMPLE_FLOAT32NE);
+    s->record.frame_size = s->record.info.channels * (s->record.info.precision / 8);
+    recnfr = (1 << oss_calc_frag_shift(s->nfr, s->record.frame_size)) / s->record.frame_size;
+  }
+  if (output_stream_params != NULL) {
+    unsigned int nb_channels;
+    if (output_stream_params->prefs & CUBEB_STREAM_PREF_LOOPBACK) {
+      LOG("Loopback not supported");
+      ret = CUBEB_ERROR_NOT_SUPPORTED;
+      goto error;
+    }
+    nb_channels = cubeb_channel_layout_nb_channels(output_stream_params->layout);
+    if (output_stream_params->layout != CUBEB_LAYOUT_UNDEFINED &&
+        nb_channels != output_stream_params->channels) {
+      LOG("output_stream_params->layout does not match output_stream_params->channels");
+      ret = CUBEB_ERROR_INVALID_PARAMETER;
+      goto error;
+    }
+    if (s->play.fd == -1) {
+      if ((s->play.fd = open(s->play.name, O_WRONLY | O_NONBLOCK)) == -1) {
+        LOG("Audio device \"%s\" could not be opened as write-only",
+            s->play.name);
+        ret = CUBEB_ERROR_DEVICE_UNAVAILABLE;
+        goto error;
+      }
+    }
+    if ((ret = oss_copy_params(s->play.fd, s, output_stream_params,
+                               &s->play.info)) != CUBEB_OK) {
+      LOG("Setting play params failed");
+      goto error;
+    }
+    s->play.floating = (output_stream_params->format == CUBEB_SAMPLE_FLOAT32NE);
+    s->play.frame_size = s->play.info.channels * (s->play.info.precision / 8);
+    playnfr = (1 << oss_calc_frag_shift(s->nfr, s->play.frame_size)) / s->play.frame_size;
+  }
+  /* Use the largest nframes among playing and recording streams */
+  s->nfr = (playnfr > recnfr) ? playnfr : recnfr;
+  s->nfrags = OSS_NFRAGS;
+  s->bufframes = s->nfr * s->nfrags;
+  if (s->play.fd != -1) {
+    int frag = oss_get_frag_params(oss_calc_frag_shift(s->nfr, s->play.frame_size));
+    if (ioctl(s->record.fd, SNDCTL_DSP_SETFRAGMENT, &frag))
+      LOG("Failed to set record fd with SNDCTL_DSP_SETFRAGMENT. frag: 0x%x",
+          frag);
+  }
+  if (s->record.fd != -1) {
+    int frag = oss_get_frag_params(oss_calc_frag_shift(s->nfr, s->record.frame_size));
+    if (ioctl(s->record.fd, SNDCTL_DSP_SETFRAGMENT, &frag))
+      LOG("Failed to set record fd with SNDCTL_DSP_SETFRAGMENT. frag: 0x%x",
+          frag);
+  }
+  s->context = context;
+  s->volume = 1.0;
+  s->state_cb = state_callback;
+  s->data_cb = data_callback;
+  s->user_ptr = user_ptr;
+
+  if (pthread_mutex_init(&s->mtx, NULL) != 0) {
+    LOG("Failed to create mutex");
+    goto error;
+  }
+  if (pthread_cond_init(&s->doorbell_cv, NULL) != 0) {
+    LOG("Failed to create cv");
+    goto error;
+  }
+  if (pthread_cond_init(&s->stopped_cv, NULL) != 0) {
+    LOG("Failed to create cv");
+    goto error;
+  }
+  s->doorbell = false;
+
+  if (s->play.fd != -1) {
+    if ((s->play.buf = calloc(s->bufframes, s->play.frame_size)) == NULL) {
+      ret = CUBEB_ERROR;
+      goto error;
+    }
+  }
+  if (s->record.fd != -1) {
+    if ((s->record.buf = calloc(s->bufframes, s->record.frame_size)) == NULL) {
+      ret = CUBEB_ERROR;
+      goto error;
+    }
+  }
+
+  *stream = s;
+  return CUBEB_OK;
+error:
+  if (s != NULL) {
+    oss_stream_destroy(s);
+  }
+  return ret;
+}
+
+static int
+oss_stream_thr_create(cubeb_stream * s)
+{
+  if (s->thread_created) {
+    s->doorbell = true;
+    pthread_cond_signal(&s->doorbell_cv);
+    return CUBEB_OK;
+  }
+
+  if (pthread_create(&s->thread, NULL, oss_io_routine, s) != 0) {
+    LOG("Couldn't create thread");
+    return CUBEB_ERROR;
+  }
+
+  return CUBEB_OK;
+}
+
+static int
+oss_stream_start(cubeb_stream * s)
+{
+  s->state_cb(s, s->user_ptr, CUBEB_STATE_STARTED);
+  pthread_mutex_lock(&s->mtx);
+  /* Disallow starting an already started stream */
+  assert(!s->running && s->state != CUBEB_STATE_STARTED);
+  if (oss_stream_thr_create(s) != CUBEB_OK) {
+    pthread_mutex_unlock(&s->mtx);
+    s->state_cb(s, s->user_ptr, CUBEB_STATE_ERROR);
+    return CUBEB_ERROR;
+  }
+  s->state = CUBEB_STATE_STARTED;
+  s->thread_created = true;
+  s->running = true;
+  pthread_mutex_unlock(&s->mtx);
+  return CUBEB_OK;
+}
+
+static int
+oss_stream_get_position(cubeb_stream * s, uint64_t * position)
+{
+  pthread_mutex_lock(&s->mtx);
+  *position = s->frames_written;
+  pthread_mutex_unlock(&s->mtx);
+  return CUBEB_OK;
+}
+
+static int
+oss_stream_get_latency(cubeb_stream * s, uint32_t * latency)
+{
+  int delay;
+
+  if (ioctl(s->play.fd, SNDCTL_DSP_GETODELAY, &delay) == -1) {
+    return CUBEB_ERROR;
+  }
+
+  /* Return number of frames there */
+  *latency = delay / s->play.frame_size;
+  return CUBEB_OK;
+}
+
+static int
+oss_stream_set_volume(cubeb_stream * stream, float volume)
+{
+  if (volume < 0.0)
+    volume = 0.0;
+  else if (volume > 1.0)
+    volume = 1.0;
+  pthread_mutex_lock(&stream->mtx);
+  stream->volume = volume;
+  pthread_mutex_unlock(&stream->mtx);
+  return CUBEB_OK;
+}
+
+static int
+oss_get_current_device(cubeb_stream * stream, cubeb_device ** const device)
+{
+  *device = calloc(1, sizeof(cubeb_device));
+  if (*device == NULL) {
+    return CUBEB_ERROR;
+  }
+  (*device)->input_name = stream->record.fd != -1 ?
+    strdup(stream->record.name) : NULL;
+  (*device)->output_name = stream->play.fd != -1 ?
+    strdup(stream->play.name) : NULL;
+  return CUBEB_OK;
+}
+
+static int
+oss_stream_device_destroy(cubeb_stream * stream, cubeb_device * device)
+{
+  (void)stream;
+  free(device->input_name);
+  free(device->output_name);
+  free(device);
+  return CUBEB_OK;
+}
+
+static struct cubeb_ops const oss_ops = {
+    .init = oss_init,
+    .get_backend_id = oss_get_backend_id,
+    .get_max_channel_count = oss_get_max_channel_count,
+    .get_min_latency = oss_get_min_latency,
+    .get_preferred_sample_rate = oss_get_preferred_sample_rate,
+    .enumerate_devices = oss_enumerate_devices,
+    .device_collection_destroy = oss_device_collection_destroy,
+    .destroy = oss_destroy,
+    .stream_init = oss_stream_init,
+    .stream_destroy = oss_stream_destroy,
+    .stream_start = oss_stream_start,
+    .stream_stop = oss_stream_stop,
+    .stream_reset_default_device = NULL,
+    .stream_get_position = oss_stream_get_position,
+    .stream_get_latency = oss_stream_get_latency,
+    .stream_get_input_latency = NULL,
+    .stream_set_volume = oss_stream_set_volume,
+    .stream_get_current_device = oss_get_current_device,
+    .stream_device_destroy = oss_stream_device_destroy,
+    .stream_register_device_changed_callback = NULL,
+    .register_device_collection_changed = NULL};