Merge branch 'master' into mailnews-work

1 files changed, 429 insertions, 131 deletions

diff --git a/media/libcubeb/src/cubeb_alsa.c b/media/libcubeb/src/cubeb_alsa.c
index 72a6acfb1..a564fbfc6 100644
--- a/media/libcubeb/src/cubeb_alsa.c
+++ b/media/libcubeb/src/cubeb_alsa.c
@@ -14,10 +14,58 @@
 #include <limits.h>
 #include <poll.h>
 #include <unistd.h>
+#include <dlfcn.h>
 #include <alsa/asoundlib.h>
 #include "cubeb/cubeb.h"
 #include "cubeb-internal.h"
 
+#ifdef DISABLE_LIBASOUND_DLOPEN
+#define WRAP(x) x
+#else
+#define WRAP(x) cubeb_##x
+#define LIBASOUND_API_VISIT(X)                   \
+  X(snd_config)                                  \
+  X(snd_config_add)                              \
+  X(snd_config_copy)                             \
+  X(snd_config_delete)                           \
+  X(snd_config_get_id)                           \
+  X(snd_config_get_string)                       \
+  X(snd_config_imake_integer)                    \
+  X(snd_config_search)                           \
+  X(snd_config_search_definition)                \
+  X(snd_lib_error_set_handler)                   \
+  X(snd_pcm_avail_update)                        \
+  X(snd_pcm_close)                               \
+  X(snd_pcm_delay)                               \
+  X(snd_pcm_drain)                               \
+  X(snd_pcm_frames_to_bytes)                     \
+  X(snd_pcm_get_params)                          \
+  X(snd_pcm_hw_params_any)                       \
+  X(snd_pcm_hw_params_get_channels_max)          \
+  X(snd_pcm_hw_params_get_rate)                  \
+  X(snd_pcm_hw_params_set_rate_near)             \
+  X(snd_pcm_hw_params_sizeof)                    \
+  X(snd_pcm_nonblock)                            \
+  X(snd_pcm_open)                                \
+  X(snd_pcm_open_lconf)                          \
+  X(snd_pcm_pause)                               \
+  X(snd_pcm_poll_descriptors)                    \
+  X(snd_pcm_poll_descriptors_count)              \
+  X(snd_pcm_poll_descriptors_revents)            \
+  X(snd_pcm_readi)                               \
+  X(snd_pcm_recover)                             \
+  X(snd_pcm_set_params)                          \
+  X(snd_pcm_start)                               \
+  X(snd_pcm_state)                               \
+  X(snd_pcm_writei)                              \
+
+#define MAKE_TYPEDEF(x) static typeof(x) * cubeb_##x;
+LIBASOUND_API_VISIT(MAKE_TYPEDEF);
+#undef MAKE_TYPEDEF
+/* snd_pcm_hw_params_alloca is actually a macro */
+#define snd_pcm_hw_params_sizeof cubeb_snd_pcm_hw_params_sizeof
+#endif
+
 #define CUBEB_STREAM_MAX 16
 #define CUBEB_WATCHDOG_MS 10000
 
@@ -36,6 +84,7 @@ static struct cubeb_ops const alsa_ops;
 
 struct cubeb {
   struct cubeb_ops const * ops;
+  void * libasound;
 
   pthread_t thread;
 
@@ -76,13 +125,15 @@ enum stream_state {
 };
 
 struct cubeb_stream {
+  /* Note: Must match cubeb_stream layout in cubeb.c. */
   cubeb * context;
+  void * user_ptr;
+  /**/
   pthread_mutex_t mutex;
   snd_pcm_t * pcm;
   cubeb_data_callback data_callback;
   cubeb_state_callback state_callback;
-  void * user_ptr;
-  snd_pcm_uframes_t write_position;
+  snd_pcm_uframes_t stream_position;
   snd_pcm_uframes_t last_position;
   snd_pcm_uframes_t buffer_size;
   cubeb_stream_params params;
@@ -107,6 +158,12 @@ struct cubeb_stream {
      being logically active and playing. */
   struct timeval last_activity;
   float volume;
+
+  char * buffer;
+  snd_pcm_uframes_t bufframes;
+  snd_pcm_stream_t stream_type;
+
+  struct cubeb_stream * other_stream;
 };
 
 static int
@@ -235,6 +292,14 @@ set_timeout(struct timeval * timeout, unsigned int ms)
 }
 
 static void
+stream_buffer_decrement(cubeb_stream * stm, long count)
+{
+  char * bufremains = stm->buffer + WRAP(snd_pcm_frames_to_bytes)(stm->pcm, count);
+  memmove(stm->buffer, bufremains, WRAP(snd_pcm_frames_to_bytes)(stm->pcm, stm->bufframes - count));
+  stm->bufframes -= count;
+}
+
+static void
 alsa_set_stream_state(cubeb_stream * stm, enum stream_state state)
 {
   cubeb * ctx;
@@ -249,97 +314,173 @@ alsa_set_stream_state(cubeb_stream * stm, enum stream_state state)
 }
 
 static enum stream_state
-alsa_refill_stream(cubeb_stream * stm)
+alsa_process_stream(cubeb_stream * stm)
 {
+  unsigned short revents;
   snd_pcm_sframes_t avail;
-  long got;
-  void * p;
   int draining;
 
   draining = 0;
 
   pthread_mutex_lock(&stm->mutex);
 
-  avail = snd_pcm_avail_update(stm->pcm);
-  if (avail < 0) {
-    snd_pcm_recover(stm->pcm, avail, 1);
-    avail = snd_pcm_avail_update(stm->pcm);
-  }
+  /* Call _poll_descriptors_revents() even if we don't use it
+     to let underlying plugins clear null events.  Otherwise poll()
+     may wake up again and again, producing unnecessary CPU usage. */
+  WRAP(snd_pcm_poll_descriptors_revents)(stm->pcm, stm->fds, stm->nfds, &revents);
 
-  /* Failed to recover from an xrun, this stream must be broken. */
-  if (avail < 0) {
+  avail = WRAP(snd_pcm_avail_update)(stm->pcm);
+
+  /* Got null event? Bail and wait for another wakeup. */
+  if (avail == 0) {
     pthread_mutex_unlock(&stm->mutex);
-    stm->state_callback(stm, stm->user_ptr, CUBEB_STATE_ERROR);
-    return ERROR;
+    return RUNNING;
   }
 
-  /* This should never happen. */
+  /* This could happen if we were suspended with SIGSTOP/Ctrl+Z for a long time. */
   if ((unsigned int) avail > stm->buffer_size) {
     avail = stm->buffer_size;
   }
 
-  /* poll(2) claims this stream is active, so there should be some space
-     available to write.  If avail is still zero here, the stream must be in
-     a funky state, bail and wait for another wakeup. */
-  if (avail == 0) {
+  /* Capture: Read available frames */
+  if (stm->stream_type == SND_PCM_STREAM_CAPTURE && avail > 0) {
+    snd_pcm_sframes_t got;
+
+    if (avail + stm->bufframes > stm->buffer_size) {
+      /* Buffer overflow. Skip and overwrite with new data. */
+      stm->bufframes = 0;
+      // TODO: should it be marked as DRAINING?
+    }
+
+    got = WRAP(snd_pcm_readi)(stm->pcm, stm->buffer+stm->bufframes, avail);
+
+    if (got < 0) {
+      avail = got; // the error handler below will recover us
+    } else {
+      stm->bufframes += got;
+      stm->stream_position += got;
+
+      gettimeofday(&stm->last_activity, NULL);
+    }
+  }
+
+  /* Capture: Pass read frames to callback function */
+  if (stm->stream_type == SND_PCM_STREAM_CAPTURE && stm->bufframes > 0 &&
+      (!stm->other_stream || stm->other_stream->bufframes < stm->other_stream->buffer_size)) {
+    snd_pcm_sframes_t wrote = stm->bufframes;
+    struct cubeb_stream * mainstm = stm->other_stream ? stm->other_stream : stm;
+    void * other_buffer = stm->other_stream ? stm->other_stream->buffer + stm->other_stream->bufframes : NULL;
+
+    /* Correct write size to the other stream available space */
+    if (stm->other_stream && wrote > (snd_pcm_sframes_t) (stm->other_stream->buffer_size - stm->other_stream->bufframes)) {
+      wrote = stm->other_stream->buffer_size - stm->other_stream->bufframes;
+    }
+
     pthread_mutex_unlock(&stm->mutex);
-    return RUNNING;
+    wrote = stm->data_callback(mainstm, stm->user_ptr, stm->buffer, other_buffer, wrote);
+    pthread_mutex_lock(&stm->mutex);
+
+    if (wrote < 0) {
+      avail = wrote; // the error handler below will recover us
+    } else {
+      stream_buffer_decrement(stm, wrote);
+
+      if (stm->other_stream) {
+        stm->other_stream->bufframes += wrote;
+      }
+    }
   }
 
-  p = calloc(1, snd_pcm_frames_to_bytes(stm->pcm, avail));
-  assert(p);
+  /* Playback: Don't have enough data? Let's ask for more. */
+  if (stm->stream_type == SND_PCM_STREAM_PLAYBACK && avail > (snd_pcm_sframes_t) stm->bufframes &&
+      (!stm->other_stream || stm->other_stream->bufframes > 0)) {
+    long got = avail - stm->bufframes;
+    void * other_buffer = stm->other_stream ? stm->other_stream->buffer : NULL;
+    char * buftail = stm->buffer + WRAP(snd_pcm_frames_to_bytes)(stm->pcm, stm->bufframes);
+
+    /* Correct read size to the other stream available frames */
+    if (stm->other_stream && got > (snd_pcm_sframes_t) stm->other_stream->bufframes) {
+      got = stm->other_stream->bufframes;
+    }
 
-  pthread_mutex_unlock(&stm->mutex);
-  got = stm->data_callback(stm, stm->user_ptr, NULL, p, avail);
-  pthread_mutex_lock(&stm->mutex);
-  if (got < 0) {
     pthread_mutex_unlock(&stm->mutex);
-    stm->state_callback(stm, stm->user_ptr, CUBEB_STATE_ERROR);
-    free(p);
-    return ERROR;
+    got = stm->data_callback(stm, stm->user_ptr, other_buffer, buftail, got);
+    pthread_mutex_lock(&stm->mutex);
+
+    if (got < 0) {
+      avail = got; // the error handler below will recover us
+    } else {
+      stm->bufframes += got;
+
+      if (stm->other_stream) {
+        stream_buffer_decrement(stm->other_stream, got);
+      }
+    }
   }
-  if (got > 0) {
+
+  /* Playback: Still don't have enough data? Add some silence. */
+  if (stm->stream_type == SND_PCM_STREAM_PLAYBACK && avail > (snd_pcm_sframes_t) stm->bufframes) {
+    long drain_frames = avail - stm->bufframes;
+    double drain_time = (double) drain_frames / stm->params.rate;
+
+    char * buftail = stm->buffer + WRAP(snd_pcm_frames_to_bytes)(stm->pcm, stm->bufframes);
+    memset(buftail, 0, WRAP(snd_pcm_frames_to_bytes)(stm->pcm, drain_frames));
+    stm->bufframes = avail;
+
+    /* Mark as draining, unless we're waiting for capture */
+    if (!stm->other_stream || stm->other_stream->bufframes > 0) {
+      set_timeout(&stm->drain_timeout, drain_time * 1000);
+
+      draining = 1;
+    }
+  }
+
+  /* Playback: Have enough data and no errors. Let's write it out. */
+  if (stm->stream_type == SND_PCM_STREAM_PLAYBACK && avail > 0) {
     snd_pcm_sframes_t wrote;
 
     if (stm->params.format == CUBEB_SAMPLE_FLOAT32NE) {
-      float * b = (float *) p;
-      for (uint32_t i = 0; i < got * stm->params.channels; i++) {
+      float * b = (float *) stm->buffer;
+      for (uint32_t i = 0; i < avail * stm->params.channels; i++) {
         b[i] *= stm->volume;
       }
     } else {
-      short * b = (short *) p;
-      for (uint32_t i = 0; i < got * stm->params.channels; i++) {
+      short * b = (short *) stm->buffer;
+      for (uint32_t i = 0; i < avail * stm->params.channels; i++) {
         b[i] *= stm->volume;
       }
     }
-    wrote = snd_pcm_writei(stm->pcm, p, got);
+
+    wrote = WRAP(snd_pcm_writei)(stm->pcm, stm->buffer, avail);
     if (wrote < 0) {
-      snd_pcm_recover(stm->pcm, wrote, 1);
-      wrote = snd_pcm_writei(stm->pcm, p, got);
-    }
-    if (wrote < 0 || wrote != got) {
-      /* Recovery failed, somehow. */
-      pthread_mutex_unlock(&stm->mutex);
-      stm->state_callback(stm, stm->user_ptr, CUBEB_STATE_ERROR);
-      return ERROR;
+      avail = wrote; // the error handler below will recover us
+    } else {
+      stream_buffer_decrement(stm, wrote);
+
+      stm->stream_position += wrote;
+      gettimeofday(&stm->last_activity, NULL);
     }
-    stm->write_position += wrote;
-    gettimeofday(&stm->last_activity, NULL);
   }
-  if (got != avail) {
-    long buffer_fill = stm->buffer_size - (avail - got);
-    double buffer_time = (double) buffer_fill / stm->params.rate;
 
-    /* Fill the remaining buffer with silence to guarantee one full period
-       has been written. */
-    snd_pcm_writei(stm->pcm, (char *) p + got, avail - got);
+  /* Got some error? Let's try to recover the stream. */
+  if (avail < 0) {
+    avail = WRAP(snd_pcm_recover)(stm->pcm, avail, 0);
 
-    set_timeout(&stm->drain_timeout, buffer_time * 1000);
+    /* Capture pcm must be started after initial setup/recover */
+    if (avail >= 0 &&
+        stm->stream_type == SND_PCM_STREAM_CAPTURE &&
+        WRAP(snd_pcm_state)(stm->pcm) == SND_PCM_STATE_PREPARED) {
+      avail = WRAP(snd_pcm_start)(stm->pcm);
+    }
+  }
 
-    draining = 1;
+  /* Failed to recover, this stream must be broken. */
+  if (avail < 0) {
+    pthread_mutex_unlock(&stm->mutex);
+    stm->state_callback(stm, stm->user_ptr, CUBEB_STATE_ERROR);
+    return ERROR;
   }
 
-  free(p);
   pthread_mutex_unlock(&stm->mutex);
   return draining ? DRAINING : RUNNING;
 }
@@ -395,7 +536,7 @@ alsa_run(cubeb * ctx)
       if (stm && stm->state == RUNNING && stm->fds && any_revents(stm->fds, stm->nfds)) {
         alsa_set_stream_state(stm, PROCESSING);
         pthread_mutex_unlock(&ctx->mutex);
-        state = alsa_refill_stream(stm);
+        state = alsa_process_stream(stm);
         pthread_mutex_lock(&ctx->mutex);
         alsa_set_stream_state(stm, state);
       }
@@ -445,26 +586,26 @@ get_slave_pcm_node(snd_config_t * lconf, snd_config_t * root_pcm)
 
   slave_def = NULL;
 
-  r = snd_config_search(root_pcm, "slave", &slave_pcm);
+  r = WRAP(snd_config_search)(root_pcm, "slave", &slave_pcm);
   if (r < 0) {
     return NULL;
   }
 
-  r = snd_config_get_string(slave_pcm, &string);
+  r = WRAP(snd_config_get_string)(slave_pcm, &string);
   if (r >= 0) {
-    r = snd_config_search_definition(lconf, "pcm_slave", string, &slave_def);
+    r = WRAP(snd_config_search_definition)(lconf, "pcm_slave", string, &slave_def);
     if (r < 0) {
       return NULL;
     }
   }
 
   do {
-    r = snd_config_search(slave_def ? slave_def : slave_pcm, "pcm", &pcm);
+    r = WRAP(snd_config_search)(slave_def ? slave_def : slave_pcm, "pcm", &pcm);
     if (r < 0) {
       break;
     }
 
-    r = snd_config_get_string(slave_def ? slave_def : slave_pcm, &string);
+    r = WRAP(snd_config_get_string)(slave_def ? slave_def : slave_pcm, &string);
     if (r < 0) {
       break;
     }
@@ -473,7 +614,7 @@ get_slave_pcm_node(snd_config_t * lconf, snd_config_t * root_pcm)
     if (r < 0 || r > (int) sizeof(node_name)) {
       break;
     }
-    r = snd_config_search(lconf, node_name, &pcm);
+    r = WRAP(snd_config_search)(lconf, node_name, &pcm);
     if (r < 0) {
       break;
     }
@@ -482,7 +623,7 @@ get_slave_pcm_node(snd_config_t * lconf, snd_config_t * root_pcm)
   } while (0);
 
   if (slave_def) {
-    snd_config_delete(slave_def);
+    WRAP(snd_config_delete)(slave_def);
   }
 
   return NULL;
@@ -505,22 +646,22 @@ init_local_config_with_workaround(char const * pcm_name)
 
   lconf = NULL;
 
-  if (snd_config == NULL) {
+  if (*WRAP(snd_config) == NULL) {
     return NULL;
   }
 
-  r = snd_config_copy(&lconf, snd_config);
+  r = WRAP(snd_config_copy)(&lconf, *WRAP(snd_config));
   if (r < 0) {
     return NULL;
   }
 
   do {
-    r = snd_config_search_definition(lconf, "pcm", pcm_name, &pcm_node);
+    r = WRAP(snd_config_search_definition)(lconf, "pcm", pcm_name, &pcm_node);
     if (r < 0) {
       break;
     }
 
-    r = snd_config_get_id(pcm_node, &string);
+    r = WRAP(snd_config_get_id)(pcm_node, &string);
     if (r < 0) {
       break;
     }
@@ -529,7 +670,7 @@ init_local_config_with_workaround(char const * pcm_name)
     if (r < 0 || r > (int) sizeof(node_name)) {
       break;
     }
-    r = snd_config_search(lconf, node_name, &pcm_node);
+    r = WRAP(snd_config_search)(lconf, node_name, &pcm_node);
     if (r < 0) {
       break;
     }
@@ -540,12 +681,12 @@ init_local_config_with_workaround(char const * pcm_name)
     }
 
     /* Fetch the PCM node's type, and bail out if it's not the PulseAudio plugin. */
-    r = snd_config_search(pcm_node, "type", &node);
+    r = WRAP(snd_config_search)(pcm_node, "type", &node);
     if (r < 0) {
       break;
     }
 
-    r = snd_config_get_string(node, &string);
+    r = WRAP(snd_config_get_string)(node, &string);
     if (r < 0) {
       break;
     }
@@ -556,18 +697,18 @@ init_local_config_with_workaround(char const * pcm_name)
 
     /* Don't clobber an explicit existing handle_underrun value, set it only
        if it doesn't already exist. */
-    r = snd_config_search(pcm_node, "handle_underrun", &node);
+    r = WRAP(snd_config_search)(pcm_node, "handle_underrun", &node);
     if (r != -ENOENT) {
       break;
     }
 
     /* Disable pcm_pulse's asynchronous underrun handling. */
-    r = snd_config_imake_integer(&node, "handle_underrun", 0);
+    r = WRAP(snd_config_imake_integer)(&node, "handle_underrun", 0);
     if (r < 0) {
       break;
     }
 
-    r = snd_config_add(pcm_node, node);
+    r = WRAP(snd_config_add)(pcm_node, node);
     if (r < 0) {
       break;
     }
@@ -575,21 +716,21 @@ init_local_config_with_workaround(char const * pcm_name)
     return lconf;
   } while (0);
 
-  snd_config_delete(lconf);
+  WRAP(snd_config_delete)(lconf);
 
   return NULL;
 }
 
 static int
-alsa_locked_pcm_open(snd_pcm_t ** pcm, snd_pcm_stream_t stream, snd_config_t * local_config)
+alsa_locked_pcm_open(snd_pcm_t ** pcm, char const * pcm_name, snd_pcm_stream_t stream, snd_config_t * local_config)
 {
   int r;
 
   pthread_mutex_lock(&cubeb_alsa_mutex);
   if (local_config) {
-    r = snd_pcm_open_lconf(pcm, CUBEB_ALSA_PCM_NAME, stream, SND_PCM_NONBLOCK, local_config);
+    r = WRAP(snd_pcm_open_lconf)(pcm, pcm_name, stream, SND_PCM_NONBLOCK, local_config);
   } else {
-    r = snd_pcm_open(pcm, CUBEB_ALSA_PCM_NAME, stream, SND_PCM_NONBLOCK);
+    r = WRAP(snd_pcm_open)(pcm, pcm_name, stream, SND_PCM_NONBLOCK);
   }
   pthread_mutex_unlock(&cubeb_alsa_mutex);
 
@@ -602,7 +743,7 @@ alsa_locked_pcm_close(snd_pcm_t * pcm)
   int r;
 
   pthread_mutex_lock(&cubeb_alsa_mutex);
-  r = snd_pcm_close(pcm);
+  r = WRAP(snd_pcm_close)(pcm);
   pthread_mutex_unlock(&cubeb_alsa_mutex);
 
   return r;
@@ -658,6 +799,7 @@ silent_error_handler(char const * file, int line, char const * function,
 alsa_init(cubeb ** context, char const * context_name)
 {
   (void)context_name;
+  void * libasound = NULL;
   cubeb * ctx;
   int r;
   int i;
@@ -668,9 +810,30 @@ alsa_init(cubeb ** context, char const * context_name)
   assert(context);
   *context = NULL;
 
+#ifndef DISABLE_LIBASOUND_DLOPEN
+  libasound = dlopen("libasound.so.2", RTLD_LAZY);
+  if (!libasound) {
+    libasound = dlopen("libasound.so", RTLD_LAZY);
+    if (!libasound) {
+      return CUBEB_ERROR;
+    }
+  }
+
+#define LOAD(x) {                               \
+    cubeb_##x = dlsym(libasound, #x);            \
+    if (!cubeb_##x) {                           \
+      dlclose(libasound);                        \
+      return CUBEB_ERROR;                       \
+    }                                           \
+  }
+
+  LIBASOUND_API_VISIT(LOAD);
+#undef LOAD
+#endif
+
   pthread_mutex_lock(&cubeb_alsa_mutex);
   if (!cubeb_alsa_error_handler_set) {
-    snd_lib_error_set_handler(silent_error_handler);
+    WRAP(snd_lib_error_set_handler)(silent_error_handler);
     cubeb_alsa_error_handler_set = 1;
   }
   pthread_mutex_unlock(&cubeb_alsa_mutex);
@@ -679,6 +842,7 @@ alsa_init(cubeb ** context, char const * context_name)
   assert(ctx);
 
   ctx->ops = &alsa_ops;
+  ctx->libasound = libasound;
 
   r = pthread_mutex_init(&ctx->mutex, NULL);
   assert(r == 0);
@@ -712,7 +876,7 @@ alsa_init(cubeb ** context, char const * context_name)
 
   /* Open a dummy PCM to force the configuration space to be evaluated so that
      init_local_config_with_workaround can find and modify the default node. */
-  r = alsa_locked_pcm_open(&dummy, SND_PCM_STREAM_PLAYBACK, NULL);
+  r = alsa_locked_pcm_open(&dummy, CUBEB_ALSA_PCM_NAME, SND_PCM_STREAM_PLAYBACK, NULL);
   if (r >= 0) {
     alsa_locked_pcm_close(dummy);
   }
@@ -722,12 +886,12 @@ alsa_init(cubeb ** context, char const * context_name)
   pthread_mutex_unlock(&cubeb_alsa_mutex);
   if (ctx->local_config) {
     ctx->is_pa = 1;
-    r = alsa_locked_pcm_open(&dummy, SND_PCM_STREAM_PLAYBACK, ctx->local_config);
+    r = alsa_locked_pcm_open(&dummy, CUBEB_ALSA_PCM_NAME, SND_PCM_STREAM_PLAYBACK, ctx->local_config);
     /* If we got a local_config, we found a PA PCM.  If opening a PCM with that
        config fails with EINVAL, the PA PCM is too old for this workaround. */
     if (r == -EINVAL) {
       pthread_mutex_lock(&cubeb_alsa_mutex);
-      snd_config_delete(ctx->local_config);
+      WRAP(snd_config_delete)(ctx->local_config);
       pthread_mutex_unlock(&cubeb_alsa_mutex);
       ctx->local_config = NULL;
     } else if (r >= 0) {
@@ -769,24 +933,28 @@ alsa_destroy(cubeb * ctx)
 
   if (ctx->local_config) {
     pthread_mutex_lock(&cubeb_alsa_mutex);
-    snd_config_delete(ctx->local_config);
+    WRAP(snd_config_delete)(ctx->local_config);
     pthread_mutex_unlock(&cubeb_alsa_mutex);
   }
 
+  if (ctx->libasound) {
+    dlclose(ctx->libasound);
+  }
+
   free(ctx);
 }
 
 static void alsa_stream_destroy(cubeb_stream * stm);
 
 static int
-alsa_stream_init(cubeb * ctx, 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)
+alsa_stream_init_single(cubeb * ctx, cubeb_stream ** stream, char const * stream_name,
+                        snd_pcm_stream_t stream_type,
+                        cubeb_devid deviceid,
+                        cubeb_stream_params * stream_params,
+                        unsigned int latency_frames,
+                        cubeb_data_callback data_callback,
+                        cubeb_state_callback state_callback,
+                        void * user_ptr)
 {
   (void)stream_name;
   cubeb_stream * stm;
@@ -794,23 +962,17 @@ alsa_stream_init(cubeb * ctx, cubeb_stream ** stream, char const * stream_name,
   snd_pcm_format_t format;
   snd_pcm_uframes_t period_size;
   int latency_us = 0;
-
+  char const * pcm_name = deviceid ? (char const *) deviceid : CUBEB_ALSA_PCM_NAME;
 
   assert(ctx && stream);
 
-  if (input_stream_params) {
-    /* Capture support not yet implemented. */
-    return CUBEB_ERROR_NOT_SUPPORTED;
-  }
+  *stream = NULL;
 
-  if (input_device || output_device) {
-    /* Device selection not yet implemented. */
-    return CUBEB_ERROR_DEVICE_UNAVAILABLE;
+  if (stream_params->prefs & CUBEB_STREAM_PREF_LOOPBACK) {
+    return CUBEB_ERROR_NOT_SUPPORTED;
   }
 
-  *stream = NULL;
-
-  switch (output_stream_params->format) {
+  switch (stream_params->format) {
   case CUBEB_SAMPLE_S16LE:
     format = SND_PCM_FORMAT_S16_LE;
     break;
@@ -842,20 +1004,27 @@ alsa_stream_init(cubeb * ctx, cubeb_stream ** stream, char const * stream_name,
   stm->data_callback = data_callback;
   stm->state_callback = state_callback;
   stm->user_ptr = user_ptr;
-  stm->params = *output_stream_params;
+  stm->params = *stream_params;
   stm->state = INACTIVE;
   stm->volume = 1.0;
+  stm->buffer = NULL;
+  stm->bufframes = 0;
+  stm->stream_type = stream_type;
+  stm->other_stream = NULL;
 
   r = pthread_mutex_init(&stm->mutex, NULL);
   assert(r == 0);
 
-  r = alsa_locked_pcm_open(&stm->pcm, SND_PCM_STREAM_PLAYBACK, ctx->local_config);
+  r = pthread_cond_init(&stm->cond, NULL);
+  assert(r == 0);
+
+  r = alsa_locked_pcm_open(&stm->pcm, pcm_name, stm->stream_type, ctx->local_config);
   if (r < 0) {
     alsa_stream_destroy(stm);
     return CUBEB_ERROR;
   }
 
-  r = snd_pcm_nonblock(stm->pcm, 1);
+  r = WRAP(snd_pcm_nonblock)(stm->pcm, 1);
   assert(r == 0);
 
   latency_us = latency_frames * 1e6 / stm->params.rate;
@@ -868,7 +1037,7 @@ alsa_stream_init(cubeb * ctx, cubeb_stream ** stream, char const * stream_name,
     latency_us = latency_us < min_latency ? min_latency: latency_us;
   }
 
-  r = snd_pcm_set_params(stm->pcm, format, SND_PCM_ACCESS_RW_INTERLEAVED,
+  r = WRAP(snd_pcm_set_params)(stm->pcm, format, SND_PCM_ACCESS_RW_INTERLEAVED,
                          stm->params.channels, stm->params.rate, 1,
                          latency_us);
   if (r < 0) {
@@ -876,20 +1045,22 @@ alsa_stream_init(cubeb * ctx, cubeb_stream ** stream, char const * stream_name,
     return CUBEB_ERROR_INVALID_FORMAT;
   }
 
-  r = snd_pcm_get_params(stm->pcm, &stm->buffer_size, &period_size);
+  r = WRAP(snd_pcm_get_params)(stm->pcm, &stm->buffer_size, &period_size);
   assert(r == 0);
 
-  stm->nfds = snd_pcm_poll_descriptors_count(stm->pcm);
+  /* Double internal buffer size to have enough space when waiting for the other side of duplex connection */
+  stm->buffer_size *= 2;
+  stm->buffer = calloc(1, WRAP(snd_pcm_frames_to_bytes)(stm->pcm, stm->buffer_size));
+  assert(stm->buffer);
+
+  stm->nfds = WRAP(snd_pcm_poll_descriptors_count)(stm->pcm);
   assert(stm->nfds > 0);
 
   stm->saved_fds = calloc(stm->nfds, sizeof(struct pollfd));
   assert(stm->saved_fds);
-  r = snd_pcm_poll_descriptors(stm->pcm, stm->saved_fds, stm->nfds);
+  r = WRAP(snd_pcm_poll_descriptors)(stm->pcm, stm->saved_fds, stm->nfds);
   assert((nfds_t) r == stm->nfds);
 
-  r = pthread_cond_init(&stm->cond, NULL);
-  assert(r == 0);
-
   if (alsa_register_stream(ctx, stm) != 0) {
     alsa_stream_destroy(stm);
     return CUBEB_ERROR;
@@ -900,6 +1071,45 @@ alsa_stream_init(cubeb * ctx, cubeb_stream ** stream, char const * stream_name,
   return CUBEB_OK;
 }
 
+static int
+alsa_stream_init(cubeb * ctx, 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 result = CUBEB_OK;
+  cubeb_stream * instm = NULL, * outstm = NULL;
+
+  if (result == CUBEB_OK && input_stream_params) {
+    result = alsa_stream_init_single(ctx, &instm, stream_name, SND_PCM_STREAM_CAPTURE,
+                                     input_device, input_stream_params, latency_frames,
+                                     data_callback, state_callback, user_ptr);
+  }
+
+  if (result == CUBEB_OK && output_stream_params) {
+    result = alsa_stream_init_single(ctx, &outstm, stream_name, SND_PCM_STREAM_PLAYBACK,
+                                     output_device, output_stream_params, latency_frames,
+                                     data_callback, state_callback, user_ptr);
+  }
+
+  if (result == CUBEB_OK && input_stream_params && output_stream_params) {
+    instm->other_stream = outstm;
+    outstm->other_stream = instm;
+  }
+
+  if (result != CUBEB_OK && instm) {
+    alsa_stream_destroy(instm);
+  }
+
+  *stream = outstm ? outstm : instm;
+
+  return result;
+}
+
 static void
 alsa_stream_destroy(cubeb_stream * stm)
 {
@@ -912,10 +1122,15 @@ alsa_stream_destroy(cubeb_stream * stm)
 
   ctx = stm->context;
 
+  if (stm->other_stream) {
+    stm->other_stream->other_stream = NULL; // to stop infinite recursion
+    alsa_stream_destroy(stm->other_stream);
+  }
+
   pthread_mutex_lock(&stm->mutex);
   if (stm->pcm) {
     if (stm->state == DRAINING) {
-      snd_pcm_drain(stm->pcm);
+      WRAP(snd_pcm_drain)(stm->pcm);
     }
     alsa_locked_pcm_close(stm->pcm);
     stm->pcm = NULL;
@@ -934,6 +1149,8 @@ alsa_stream_destroy(cubeb_stream * stm)
   ctx->active_streams -= 1;
   pthread_mutex_unlock(&ctx->mutex);
 
+  free(stm->buffer);
+
   free(stm);
 }
 
@@ -957,12 +1174,14 @@ alsa_get_max_channel_count(cubeb * ctx, uint32_t * max_channels)
     return CUBEB_ERROR;
   }
 
-  r = snd_pcm_hw_params_any(stm->pcm, hw_params);
+  assert(stm);
+
+  r = WRAP(snd_pcm_hw_params_any)(stm->pcm, hw_params);
   if (r < 0) {
     return CUBEB_ERROR;
   }
 
-  r = snd_pcm_hw_params_get_channels_max(hw_params, max_channels);
+  r = WRAP(snd_pcm_hw_params_get_channels_max)(hw_params, max_channels);
   if (r < 0) {
     return CUBEB_ERROR;
   }
@@ -983,34 +1202,34 @@ alsa_get_preferred_sample_rate(cubeb * ctx, uint32_t * rate) {
 
   /* get a pcm, disabling resampling, so we get a rate the
    * hardware/dmix/pulse/etc. supports. */
-  r = snd_pcm_open(&pcm, CUBEB_ALSA_PCM_NAME, SND_PCM_STREAM_PLAYBACK, SND_PCM_NO_AUTO_RESAMPLE);
+  r = WRAP(snd_pcm_open)(&pcm, CUBEB_ALSA_PCM_NAME, SND_PCM_STREAM_PLAYBACK, SND_PCM_NO_AUTO_RESAMPLE);
   if (r < 0) {
     return CUBEB_ERROR;
   }
 
-  r = snd_pcm_hw_params_any(pcm, hw_params);
+  r = WRAP(snd_pcm_hw_params_any)(pcm, hw_params);
   if (r < 0) {
-    snd_pcm_close(pcm);
+    WRAP(snd_pcm_close)(pcm);
     return CUBEB_ERROR;
   }
 
-  r = snd_pcm_hw_params_get_rate(hw_params, rate, &dir);
+  r = WRAP(snd_pcm_hw_params_get_rate)(hw_params, rate, &dir);
   if (r >= 0) {
     /* There is a default rate: use it. */
-    snd_pcm_close(pcm);
+    WRAP(snd_pcm_close)(pcm);
     return CUBEB_OK;
   }
 
   /* Use a common rate, alsa may adjust it based on hw/etc. capabilities. */
   *rate = 44100;
 
-  r = snd_pcm_hw_params_set_rate_near(pcm, hw_params, rate, NULL);
+  r = WRAP(snd_pcm_hw_params_set_rate_near)(pcm, hw_params, rate, NULL);
   if (r < 0) {
-    snd_pcm_close(pcm);
+    WRAP(snd_pcm_close)(pcm);
     return CUBEB_ERROR;
   }
 
-  snd_pcm_close(pcm);
+  WRAP(snd_pcm_close)(pcm);
 
   return CUBEB_OK;
 }
@@ -1034,8 +1253,19 @@ alsa_stream_start(cubeb_stream * stm)
   assert(stm);
   ctx = stm->context;
 
+  if (stm->stream_type == SND_PCM_STREAM_PLAYBACK && stm->other_stream) {
+    int r = alsa_stream_start(stm->other_stream);
+    if (r != CUBEB_OK)
+      return r;
+  }
+
   pthread_mutex_lock(&stm->mutex);
-  snd_pcm_pause(stm->pcm, 0);
+  /* Capture pcm must be started after initial setup/recover */
+  if (stm->stream_type == SND_PCM_STREAM_CAPTURE &&
+      WRAP(snd_pcm_state)(stm->pcm) == SND_PCM_STATE_PREPARED) {
+    WRAP(snd_pcm_start)(stm->pcm);
+  }
+  WRAP(snd_pcm_pause)(stm->pcm, 0);
   gettimeofday(&stm->last_activity, NULL);
   pthread_mutex_unlock(&stm->mutex);
 
@@ -1059,6 +1289,12 @@ alsa_stream_stop(cubeb_stream * stm)
   assert(stm);
   ctx = stm->context;
 
+  if (stm->stream_type == SND_PCM_STREAM_PLAYBACK && stm->other_stream) {
+    int r = alsa_stream_stop(stm->other_stream);
+    if (r != CUBEB_OK)
+      return r;
+  }
+
   pthread_mutex_lock(&ctx->mutex);
   while (stm->state == PROCESSING) {
     r = pthread_cond_wait(&stm->cond, &ctx->mutex);
@@ -1069,7 +1305,7 @@ alsa_stream_stop(cubeb_stream * stm)
   pthread_mutex_unlock(&ctx->mutex);
 
   pthread_mutex_lock(&stm->mutex);
-  snd_pcm_pause(stm->pcm, 1);
+  WRAP(snd_pcm_pause)(stm->pcm, 1);
   pthread_mutex_unlock(&stm->mutex);
 
   return CUBEB_OK;
@@ -1085,8 +1321,8 @@ alsa_stream_get_position(cubeb_stream * stm, uint64_t * position)
   pthread_mutex_lock(&stm->mutex);
 
   delay = -1;
-  if (snd_pcm_state(stm->pcm) != SND_PCM_STATE_RUNNING ||
-      snd_pcm_delay(stm->pcm, &delay) != 0) {
+  if (WRAP(snd_pcm_state)(stm->pcm) != SND_PCM_STATE_RUNNING ||
+      WRAP(snd_pcm_delay)(stm->pcm, &delay) != 0) {
     *position = stm->last_position;
     pthread_mutex_unlock(&stm->mutex);
     return CUBEB_OK;
@@ -1095,8 +1331,8 @@ alsa_stream_get_position(cubeb_stream * stm, uint64_t * position)
   assert(delay >= 0);
 
   *position = 0;
-  if (stm->write_position >= (snd_pcm_uframes_t) delay) {
-    *position = stm->write_position - delay;
+  if (stm->stream_position >= (snd_pcm_uframes_t) delay) {
+    *position = stm->stream_position - delay;
   }
 
   stm->last_position = *position;
@@ -1111,7 +1347,7 @@ alsa_stream_get_latency(cubeb_stream * stm, uint32_t * latency)
   snd_pcm_sframes_t delay;
   /* This function returns the delay in frames until a frame written using
      snd_pcm_writei is sent to the DAC. The DAC delay should be < 1ms anyways. */
-  if (snd_pcm_delay(stm->pcm, &delay)) {
+  if (WRAP(snd_pcm_delay)(stm->pcm, &delay)) {
     return CUBEB_ERROR;
   }
 
@@ -1131,22 +1367,84 @@ alsa_stream_set_volume(cubeb_stream * stm, float volume)
   return CUBEB_OK;
 }
 
+static int
+alsa_enumerate_devices(cubeb * context, cubeb_device_type type,
+                       cubeb_device_collection * collection)
+{
+  cubeb_device_info* device = NULL;
+
+  if (!context)
+    return CUBEB_ERROR;
+
+  uint32_t rate, max_channels;
+  int r;
+
+  r = alsa_get_preferred_sample_rate(context, &rate);
+  if (r != CUBEB_OK) {
+    return CUBEB_ERROR;
+  }
+
+  r = alsa_get_max_channel_count(context, &max_channels);
+  if (r != CUBEB_OK) {
+    return CUBEB_ERROR;
+  }
+
+  char const * a_name = "default";
+  device = (cubeb_device_info *) calloc(1, sizeof(cubeb_device_info));
+  assert(device);
+  if (!device)
+    return CUBEB_ERROR;
+
+  device->device_id = a_name;
+  device->devid = (cubeb_devid) device->device_id;
+  device->friendly_name = a_name;
+  device->group_id = a_name;
+  device->vendor_name = a_name;
+  device->type = type;
+  device->state = CUBEB_DEVICE_STATE_ENABLED;
+  device->preferred = CUBEB_DEVICE_PREF_ALL;
+  device->format = CUBEB_DEVICE_FMT_S16NE;
+  device->default_format = CUBEB_DEVICE_FMT_S16NE;
+  device->max_channels = max_channels;
+  device->min_rate = rate;
+  device->max_rate = rate;
+  device->default_rate = rate;
+  device->latency_lo = 0;
+  device->latency_hi = 0;
+
+  collection->device = device;
+  collection->count = 1;
+
+  return CUBEB_OK;
+}
+
+static int
+alsa_device_collection_destroy(cubeb * context,
+                               cubeb_device_collection * collection)
+{
+  assert(collection->count == 1);
+  (void) context;
+  free(collection->device);
+  return CUBEB_OK;
+}
+
 static struct cubeb_ops const alsa_ops = {
   .init = alsa_init,
   .get_backend_id = alsa_get_backend_id,
   .get_max_channel_count = alsa_get_max_channel_count,
   .get_min_latency = alsa_get_min_latency,
   .get_preferred_sample_rate = alsa_get_preferred_sample_rate,
-  .enumerate_devices = NULL,
+  .enumerate_devices = alsa_enumerate_devices,
+  .device_collection_destroy = alsa_device_collection_destroy,
   .destroy = alsa_destroy,
   .stream_init = alsa_stream_init,
   .stream_destroy = alsa_stream_destroy,
   .stream_start = alsa_stream_start,
   .stream_stop = alsa_stream_stop,
+  .stream_reset_default_device = NULL,
   .stream_get_position = alsa_stream_get_position,
   .stream_get_latency = alsa_stream_get_latency,
   .stream_set_volume = alsa_stream_set_volume,
-  .stream_set_panning = NULL,
   .stream_get_current_device = NULL,
   .stream_device_destroy = NULL,
   .stream_register_device_changed_callback = NULL,