diff -r 000000000000 -r 6474c204b198 media/libcubeb/src/cubeb_winmm.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/media/libcubeb/src/cubeb_winmm.c	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,641 @@
+/*
+ * Copyright © 2011 Mozilla Foundation
+ *
+ * This program is made available under an ISC-style license.  See the
+ * accompanying file LICENSE for details.
+ */
+#undef NDEBUG
+#define __MSVCRT_VERSION__ 0x0700
+#define WINVER 0x0501
+#define WIN32_LEAN_AND_MEAN
+#include <malloc.h>
+#include <assert.h>
+#include <windows.h>
+#include <mmreg.h>
+#include <mmsystem.h>
+#include <process.h>
+#include <stdlib.h>
+#include "cubeb/cubeb.h"
+#include "cubeb-internal.h"
+
+/* This is missing from the MinGW headers. Use a safe fallback. */
+#if !defined(MEMORY_ALLOCATION_ALIGNMENT)
+#define MEMORY_ALLOCATION_ALIGNMENT 16
+#endif
+
+#define CUBEB_STREAM_MAX 32
+#define NBUFS 4
+
+const GUID KSDATAFORMAT_SUBTYPE_PCM =
+{ 0x00000001, 0x0000, 0x0010, { 0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71 } };
+const GUID KSDATAFORMAT_SUBTYPE_IEEE_FLOAT =
+{ 0x00000003, 0x0000, 0x0010, { 0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71 } };
+
+struct cubeb_stream_item {
+  SLIST_ENTRY head;
+  cubeb_stream * stream;
+};
+
+static struct cubeb_ops const winmm_ops;
+
+struct cubeb {
+  struct cubeb_ops const * ops;
+  HANDLE event;
+  HANDLE thread;
+  int shutdown;
+  PSLIST_HEADER work;
+  CRITICAL_SECTION lock;
+  unsigned int active_streams;
+  unsigned int minimum_latency;
+};
+
+struct cubeb_stream {
+  cubeb * context;
+  cubeb_stream_params params;
+  cubeb_data_callback data_callback;
+  cubeb_state_callback state_callback;
+  void * user_ptr;
+  WAVEHDR buffers[NBUFS];
+  size_t buffer_size;
+  int next_buffer;
+  int free_buffers;
+  int shutdown;
+  int draining;
+  HANDLE event;
+  HWAVEOUT waveout;
+  CRITICAL_SECTION lock;
+  uint64_t written;
+};
+
+static size_t
+bytes_per_frame(cubeb_stream_params params)
+{
+  size_t bytes;
+
+  switch (params.format) {
+  case CUBEB_SAMPLE_S16LE:
+    bytes = sizeof(signed short);
+    break;
+  case CUBEB_SAMPLE_FLOAT32LE:
+    bytes = sizeof(float);
+    break;
+  default:
+    assert(0);
+  }
+
+  return bytes * params.channels;
+}
+
+static WAVEHDR *
+winmm_get_next_buffer(cubeb_stream * stm)
+{
+  WAVEHDR * hdr = NULL;
+
+  assert(stm->free_buffers > 0 && stm->free_buffers <= NBUFS);
+  hdr = &stm->buffers[stm->next_buffer];
+  assert(hdr->dwFlags & WHDR_PREPARED ||
+         (hdr->dwFlags & WHDR_DONE && !(hdr->dwFlags & WHDR_INQUEUE)));
+  stm->next_buffer = (stm->next_buffer + 1) % NBUFS;
+  stm->free_buffers -= 1;
+
+  return hdr;
+}
+
+static void
+winmm_refill_stream(cubeb_stream * stm)
+{
+  WAVEHDR * hdr;
+  long got;
+  long wanted;
+  MMRESULT r;
+
+  EnterCriticalSection(&stm->lock);
+  stm->free_buffers += 1;
+  assert(stm->free_buffers > 0 && stm->free_buffers <= NBUFS);
+
+  if (stm->draining) {
+    LeaveCriticalSection(&stm->lock);
+    if (stm->free_buffers == NBUFS) {
+      stm->state_callback(stm, stm->user_ptr, CUBEB_STATE_DRAINED);
+    }
+    SetEvent(stm->event);
+    return;
+  }
+
+  if (stm->shutdown) {
+    LeaveCriticalSection(&stm->lock);
+    SetEvent(stm->event);
+    return;
+  }
+
+  hdr = winmm_get_next_buffer(stm);
+
+  wanted = (DWORD) stm->buffer_size / bytes_per_frame(stm->params);
+
+  /* It is assumed that the caller is holding this lock.  It must be dropped
+     during the callback to avoid deadlocks. */
+  LeaveCriticalSection(&stm->lock);
+  got = stm->data_callback(stm, stm->user_ptr, hdr->lpData, wanted);
+  EnterCriticalSection(&stm->lock);
+  if (got < 0) {
+    LeaveCriticalSection(&stm->lock);
+    /* XXX handle this case */
+    assert(0);
+    return;
+  } else if (got < wanted) {
+    stm->draining = 1;
+  }
+  stm->written += got;
+
+  assert(hdr->dwFlags & WHDR_PREPARED);
+
+  hdr->dwBufferLength = got * bytes_per_frame(stm->params);
+  assert(hdr->dwBufferLength <= stm->buffer_size);
+
+  r = waveOutWrite(stm->waveout, hdr, sizeof(*hdr));
+  if (r != MMSYSERR_NOERROR) {
+    LeaveCriticalSection(&stm->lock);
+    stm->state_callback(stm, stm->user_ptr, CUBEB_STATE_ERROR);
+    return;
+  }
+
+  LeaveCriticalSection(&stm->lock);
+}
+
+static unsigned __stdcall
+winmm_buffer_thread(void * user_ptr)
+{
+  cubeb * ctx = (cubeb *) user_ptr;
+  assert(ctx);
+
+  for (;;) {
+    DWORD rv;
+    PSLIST_ENTRY item;
+
+    rv = WaitForSingleObject(ctx->event, INFINITE);
+    assert(rv == WAIT_OBJECT_0);
+
+    /* Process work items in batches so that a single stream can't
+       starve the others by continuously adding new work to the top of
+       the work item stack. */
+    item = InterlockedFlushSList(ctx->work);
+    while (item != NULL) {
+      PSLIST_ENTRY tmp = item;
+      winmm_refill_stream(((struct cubeb_stream_item *) tmp)->stream);
+      item = item->Next;
+      _aligned_free(tmp);
+    }
+
+    if (ctx->shutdown) {
+      break;
+    }
+  }
+
+  return 0;
+}
+
+static void CALLBACK
+winmm_buffer_callback(HWAVEOUT waveout, UINT msg, DWORD_PTR user_ptr, DWORD_PTR p1, DWORD_PTR p2)
+{
+  cubeb_stream * stm = (cubeb_stream *) user_ptr;
+  struct cubeb_stream_item * item;
+
+  if (msg != WOM_DONE) {
+    return;
+  }
+
+  item = _aligned_malloc(sizeof(struct cubeb_stream_item), MEMORY_ALLOCATION_ALIGNMENT);
+  assert(item);
+  item->stream = stm;
+  InterlockedPushEntrySList(stm->context->work, &item->head);
+
+  SetEvent(stm->context->event);
+}
+
+static unsigned int
+calculate_minimum_latency(void)
+{
+  OSVERSIONINFOEX osvi;
+  DWORDLONG mask;
+
+  /* Running under Terminal Services results in underruns with low latency. */
+  if (GetSystemMetrics(SM_REMOTESESSION) == TRUE) {
+    return 500;
+  }
+
+  /* Vista's WinMM implementation underruns when less than 200ms of audio is buffered. */
+  memset(&osvi, 0, sizeof(OSVERSIONINFOEX));
+  osvi.dwOSVersionInfoSize = sizeof(OSVERSIONINFOEX);
+  osvi.dwMajorVersion = 6;
+  osvi.dwMinorVersion = 0;
+
+  mask = 0;
+  VER_SET_CONDITION(mask, VER_MAJORVERSION, VER_EQUAL);
+  VER_SET_CONDITION(mask, VER_MINORVERSION, VER_EQUAL);
+
+  if (VerifyVersionInfo(&osvi, VER_MAJORVERSION | VER_MINORVERSION, mask) != 0) {
+    return 200;
+  }
+
+  return 100;
+}
+
+static void winmm_destroy(cubeb * ctx);
+
+/*static*/ int
+winmm_init(cubeb ** context, char const * context_name)
+{
+  cubeb * ctx;
+
+  assert(context);
+  *context = NULL;
+
+  ctx = calloc(1, sizeof(*ctx));
+  assert(ctx);
+
+  ctx->ops = &winmm_ops;
+
+  ctx->work = _aligned_malloc(sizeof(*ctx->work), MEMORY_ALLOCATION_ALIGNMENT);
+  assert(ctx->work);
+  InitializeSListHead(ctx->work);
+
+  ctx->event = CreateEvent(NULL, FALSE, FALSE, NULL);
+  if (!ctx->event) {
+    winmm_destroy(ctx);
+    return CUBEB_ERROR;
+  }
+
+  ctx->thread = (HANDLE) _beginthreadex(NULL, 64 * 1024, winmm_buffer_thread, ctx, STACK_SIZE_PARAM_IS_A_RESERVATION, NULL);
+  if (!ctx->thread) {
+    winmm_destroy(ctx);
+    return CUBEB_ERROR;
+  }
+
+  SetThreadPriority(ctx->thread, THREAD_PRIORITY_TIME_CRITICAL);
+
+  InitializeCriticalSection(&ctx->lock);
+  ctx->active_streams = 0;
+
+  ctx->minimum_latency = calculate_minimum_latency();
+
+  *context = ctx;
+
+  return CUBEB_OK;
+}
+
+static char const *
+winmm_get_backend_id(cubeb * ctx)
+{
+  return "winmm";
+}
+
+static void
+winmm_destroy(cubeb * ctx)
+{
+  DWORD rv;
+
+  assert(ctx->active_streams == 0);
+  assert(!InterlockedPopEntrySList(ctx->work));
+
+  DeleteCriticalSection(&ctx->lock);
+
+  if (ctx->thread) {
+    ctx->shutdown = 1;
+    SetEvent(ctx->event);
+    rv = WaitForSingleObject(ctx->thread, INFINITE);
+    assert(rv == WAIT_OBJECT_0);
+    CloseHandle(ctx->thread);
+  }
+
+  if (ctx->event) {
+    CloseHandle(ctx->event);
+  }
+
+  _aligned_free(ctx->work);
+
+  free(ctx);
+}
+
+static void winmm_stream_destroy(cubeb_stream * stm);
+
+static int
+winmm_stream_init(cubeb * context, cubeb_stream ** stream, char const * stream_name,
+                  cubeb_stream_params stream_params, unsigned int latency,
+                  cubeb_data_callback data_callback,
+                  cubeb_state_callback state_callback,
+                  void * user_ptr)
+{
+  MMRESULT r;
+  WAVEFORMATEXTENSIBLE wfx;
+  cubeb_stream * stm;
+  int i;
+  size_t bufsz;
+
+  assert(context);
+  assert(stream);
+
+  *stream = NULL;
+
+  memset(&wfx, 0, sizeof(wfx));
+  if (stream_params.channels > 2) {
+    wfx.Format.wFormatTag = WAVE_FORMAT_EXTENSIBLE;
+    wfx.Format.cbSize = sizeof(wfx) - sizeof(wfx.Format);
+  } else {
+    wfx.Format.wFormatTag = WAVE_FORMAT_PCM;
+    if (stream_params.format == CUBEB_SAMPLE_FLOAT32LE) {
+      wfx.Format.wFormatTag = WAVE_FORMAT_IEEE_FLOAT;
+    }
+    wfx.Format.cbSize = 0;
+  }
+  wfx.Format.nChannels = stream_params.channels;
+  wfx.Format.nSamplesPerSec = stream_params.rate;
+
+  /* XXX fix channel mappings */
+  wfx.dwChannelMask = SPEAKER_FRONT_LEFT | SPEAKER_FRONT_RIGHT;
+
+  switch (stream_params.format) {
+  case CUBEB_SAMPLE_S16LE:
+    wfx.Format.wBitsPerSample = 16;
+    wfx.SubFormat = KSDATAFORMAT_SUBTYPE_PCM;
+    break;
+  case CUBEB_SAMPLE_FLOAT32LE:
+    wfx.Format.wBitsPerSample = 32;
+    wfx.SubFormat = KSDATAFORMAT_SUBTYPE_IEEE_FLOAT;
+    break;
+  default:
+    return CUBEB_ERROR_INVALID_FORMAT;
+  }
+
+  wfx.Format.nBlockAlign = (wfx.Format.wBitsPerSample * wfx.Format.nChannels) / 8;
+  wfx.Format.nAvgBytesPerSec = wfx.Format.nSamplesPerSec * wfx.Format.nBlockAlign;
+  wfx.Samples.wValidBitsPerSample = wfx.Format.wBitsPerSample;
+
+  EnterCriticalSection(&context->lock);
+  /* CUBEB_STREAM_MAX is a horrible hack to avoid a situation where, when
+     many streams are active at once, a subset of them will not consume (via
+     playback) or release (via waveOutReset) their buffers. */
+  if (context->active_streams >= CUBEB_STREAM_MAX) {
+    LeaveCriticalSection(&context->lock);
+    return CUBEB_ERROR;
+  }
+  context->active_streams += 1;
+  LeaveCriticalSection(&context->lock);
+
+  stm = calloc(1, sizeof(*stm));
+  assert(stm);
+
+  stm->context = context;
+
+  stm->params = stream_params;
+
+  stm->data_callback = data_callback;
+  stm->state_callback = state_callback;
+  stm->user_ptr = user_ptr;
+  stm->written = 0;
+
+  if (latency < context->minimum_latency) {
+    latency = context->minimum_latency;
+  }
+
+  bufsz = (size_t) (stm->params.rate / 1000.0 * latency * bytes_per_frame(stm->params) / NBUFS);
+  if (bufsz % bytes_per_frame(stm->params) != 0) {
+    bufsz += bytes_per_frame(stm->params) - (bufsz % bytes_per_frame(stm->params));
+  }
+  assert(bufsz % bytes_per_frame(stm->params) == 0);
+
+  stm->buffer_size = bufsz;
+
+  InitializeCriticalSection(&stm->lock);
+
+  stm->event = CreateEvent(NULL, FALSE, FALSE, NULL);
+  if (!stm->event) {
+    winmm_stream_destroy(stm);
+    return CUBEB_ERROR;
+  }
+
+  /* winmm_buffer_callback will be called during waveOutOpen, so all
+     other initialization must be complete before calling it. */
+  r = waveOutOpen(&stm->waveout, WAVE_MAPPER, &wfx.Format,
+                  (DWORD_PTR) winmm_buffer_callback, (DWORD_PTR) stm,
+                  CALLBACK_FUNCTION);
+  if (r != MMSYSERR_NOERROR) {
+    winmm_stream_destroy(stm);
+    return CUBEB_ERROR;
+  }
+
+  r = waveOutPause(stm->waveout);
+  if (r != MMSYSERR_NOERROR) {
+    winmm_stream_destroy(stm);
+    return CUBEB_ERROR;
+  }
+
+  for (i = 0; i < NBUFS; ++i) {
+    WAVEHDR * hdr = &stm->buffers[i];
+
+    hdr->lpData = calloc(1, bufsz);
+    assert(hdr->lpData);
+    hdr->dwBufferLength = bufsz;
+    hdr->dwFlags = 0;
+
+    r = waveOutPrepareHeader(stm->waveout, hdr, sizeof(*hdr));
+    if (r != MMSYSERR_NOERROR) {
+      winmm_stream_destroy(stm);
+      return CUBEB_ERROR;
+    }
+
+    winmm_refill_stream(stm);
+  }
+
+  *stream = stm;
+
+  return CUBEB_OK;
+}
+
+static void
+winmm_stream_destroy(cubeb_stream * stm)
+{
+  DWORD rv;
+  int i;
+  int enqueued;
+
+  if (stm->waveout) {
+    EnterCriticalSection(&stm->lock);
+    stm->shutdown = 1;
+
+    waveOutReset(stm->waveout);
+
+    enqueued = NBUFS - stm->free_buffers;
+    LeaveCriticalSection(&stm->lock);
+
+    /* Wait for all blocks to complete. */
+    while (enqueued > 0) {
+      rv = WaitForSingleObject(stm->event, INFINITE);
+      assert(rv == WAIT_OBJECT_0);
+
+      EnterCriticalSection(&stm->lock);
+      enqueued = NBUFS - stm->free_buffers;
+      LeaveCriticalSection(&stm->lock);
+    }
+
+    EnterCriticalSection(&stm->lock);
+
+    for (i = 0; i < NBUFS; ++i) {
+      if (stm->buffers[i].dwFlags & WHDR_PREPARED) {
+        waveOutUnprepareHeader(stm->waveout, &stm->buffers[i], sizeof(stm->buffers[i]));
+      }
+    }
+
+    waveOutClose(stm->waveout);
+
+    LeaveCriticalSection(&stm->lock);
+  }
+
+  if (stm->event) {
+    CloseHandle(stm->event);
+  }
+
+  DeleteCriticalSection(&stm->lock);
+
+  for (i = 0; i < NBUFS; ++i) {
+    free(stm->buffers[i].lpData);
+  }
+
+  EnterCriticalSection(&stm->context->lock);
+  assert(stm->context->active_streams >= 1);
+  stm->context->active_streams -= 1;
+  LeaveCriticalSection(&stm->context->lock);
+
+  free(stm);
+}
+
+static int
+winmm_get_max_channel_count(cubeb * ctx, uint32_t * max_channels)
+{
+  assert(ctx && max_channels);
+
+  /* We don't support more than two channels in this backend. */
+  *max_channels = 2;
+
+  return CUBEB_OK;
+}
+
+static int
+winmm_get_min_latency(cubeb * ctx, cubeb_stream_params params, uint32_t * latency)
+{
+  // 100ms minimum, if we are not in a bizarre configuration.
+  *latency = ctx->minimum_latency;
+
+  return CUBEB_OK;
+}
+
+static int
+winmm_get_preferred_sample_rate(cubeb * ctx, uint32_t * rate)
+{
+  WAVEOUTCAPS woc;
+  MMRESULT r;
+
+  r = waveOutGetDevCaps(WAVE_MAPPER, &woc, sizeof(WAVEOUTCAPS));
+  if (r != MMSYSERR_NOERROR) {
+    return CUBEB_ERROR;
+  }
+
+  /* Check if we support 48kHz, but not 44.1kHz. */
+  if (!(woc.dwFormats & WAVE_FORMAT_4S16) &&
+      woc.dwFormats & WAVE_FORMAT_48S16) {
+    *rate = 48000;
+    return CUBEB_OK;
+  }
+  /* Prefer 44.1kHz between 44.1kHz and 48kHz. */
+  *rate = 44100;
+
+  return CUBEB_OK;
+}
+
+static int
+winmm_stream_start(cubeb_stream * stm)
+{
+  MMRESULT r;
+
+  EnterCriticalSection(&stm->lock);
+  r = waveOutRestart(stm->waveout);
+  LeaveCriticalSection(&stm->lock);
+
+  if (r != MMSYSERR_NOERROR) {
+    return CUBEB_ERROR;
+  }
+
+  stm->state_callback(stm, stm->user_ptr, CUBEB_STATE_STARTED);
+
+  return CUBEB_OK;
+}
+
+static int
+winmm_stream_stop(cubeb_stream * stm)
+{
+  MMRESULT r;
+
+  EnterCriticalSection(&stm->lock);
+  r = waveOutPause(stm->waveout);
+  LeaveCriticalSection(&stm->lock);
+
+  if (r != MMSYSERR_NOERROR) {
+    return CUBEB_ERROR;
+  }
+
+  stm->state_callback(stm, stm->user_ptr, CUBEB_STATE_STOPPED);
+
+  return CUBEB_OK;
+}
+
+static int
+winmm_stream_get_position(cubeb_stream * stm, uint64_t * position)
+{
+  MMRESULT r;
+  MMTIME time;
+
+  EnterCriticalSection(&stm->lock);
+  time.wType = TIME_SAMPLES;
+  r = waveOutGetPosition(stm->waveout, &time, sizeof(time));
+  LeaveCriticalSection(&stm->lock);
+
+  if (r != MMSYSERR_NOERROR || time.wType != TIME_SAMPLES) {
+    return CUBEB_ERROR;
+  }
+
+  *position = time.u.sample;
+
+  return CUBEB_OK;
+}
+
+static int
+winmm_stream_get_latency(cubeb_stream * stm, uint32_t * latency)
+{
+  MMRESULT r;
+  MMTIME time;
+  uint64_t written;
+
+  EnterCriticalSection(&stm->lock);
+  time.wType = TIME_SAMPLES;
+  r = waveOutGetPosition(stm->waveout, &time, sizeof(time));
+  written = stm->written;
+  LeaveCriticalSection(&stm->lock);
+
+  *latency = written - time.u.sample;
+
+  return CUBEB_OK;
+}
+
+static struct cubeb_ops const winmm_ops = {
+  /*.init =*/ winmm_init,
+  /*.get_backend_id =*/ winmm_get_backend_id,
+  /*.get_max_channel_count=*/ winmm_get_max_channel_count,
+  /*.get_min_latency=*/ winmm_get_min_latency,
+  /*.get_preferred_sample_rate =*/ winmm_get_preferred_sample_rate,
+  /*.destroy =*/ winmm_destroy,
+  /*.stream_init =*/ winmm_stream_init,
+  /*.stream_destroy =*/ winmm_stream_destroy,
+  /*.stream_start =*/ winmm_stream_start,
+  /*.stream_stop =*/ winmm_stream_stop,
+  /*.stream_get_position =*/ winmm_stream_get_position,
+  /*.stream_get_latency = */ winmm_stream_get_latency
+};