gstreamer/ext/alsa/gstalsa.c

/*
 * Copyright (C) 2001 CodeFactory AB
 * Copyright (C) 2001 Thomas Nyberg <thomas@codefactory.se>
 * Copyright (C) 2001-2002 Andy Wingo <apwingo@eos.ncsu.edu>
 * Copyright (C) 2003 Benjamin Otte <in7y118@public.uni-hamburg.de>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the Free
 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <sys/time.h>

#include "gstalsa.h"
#include "gstalsaclock.h"
#include "gstalsamixer.h"

/* GObject functions */
static void			gst_alsa_class_init		(gpointer               g_class,
                                                                 gpointer               class_data);
static void			gst_alsa_init			(GstAlsa *		this);
static void			gst_alsa_dispose		(GObject *		object);
static void			gst_alsa_set_property		(GObject *		object,
								 guint			prop_id,
								 const GValue *		value,
								 GParamSpec *		pspec);
static void			gst_alsa_get_property		(GObject *		object,
								 guint			prop_id,
								 GValue *		value,
								 GParamSpec *		pspec);

/* GStreamer functions for pads and state changing */
static GstPad *			gst_alsa_request_new_pad	(GstElement *		element,
								 GstPadTemplate *	templ,
								 const gchar *		name);
static GstElementStateReturn	gst_alsa_change_state		(GstElement *		element);
static GstClock *		gst_alsa_get_clock		(GstElement *		element);
static void			gst_alsa_set_clock		(GstElement *		element,
								 GstClock *		clock);
/* ALSA setup / start / stop functions */
static gboolean			gst_alsa_probe_hw_params	(GstAlsa *		this,
								 GstAlsaFormat *	format);
static gboolean			gst_alsa_set_hw_params		(GstAlsa *		this);
static gboolean			gst_alsa_set_sw_params		(GstAlsa *		this);

static gboolean			gst_alsa_open_audio		(GstAlsa *		this);
static gboolean			gst_alsa_start_audio		(GstAlsa *		this);
static gboolean			gst_alsa_drain_audio		(GstAlsa *		this);
static gboolean 		gst_alsa_stop_audio		(GstAlsa *		this);
static gboolean 		gst_alsa_close_audio		(GstAlsa *		this);

/* GStreamer querying, conversion, and format functions */
static const GstFormat * 	gst_alsa_get_formats	 	(GstPad *		pad);
static gboolean 		gst_alsa_convert 		(GstAlsa *		this,
								 GstFormat		src_format,
								 gint64			src_value,
	            						 GstFormat *		dest_format,
								 gint64 *		dest_value);
static gboolean 		gst_alsa_pad_convert 		(GstPad *		pad,
								 GstFormat		src_format,
								 gint64			src_value,
	            						 GstFormat *		dest_format,
								 gint64 *		dest_value);
static const GstQueryType * 	gst_alsa_get_query_types 	(GstPad *		pad);
static gboolean 		gst_alsa_query_func 		(GstElement *		element,
								 GstQueryType		type,
								 GstFormat *		format,
								 gint64 *		value);
static gboolean 		gst_alsa_query	 		(GstElement *		element,
								 GstQueryType		type,
								 GstFormat *		format,
								 gint64 *		value);
static gboolean 		gst_alsa_pad_query 		(GstPad *		pad,
								 GstQueryType		type,
								 GstFormat *		format,
								 gint64 *		value);

/*** TYPE FUNCTIONS ***********************************************************/

GType
gst_alsa_get_type (void)
{
  static GType alsa_type = 0;

  if (!alsa_type) {
    static const GTypeInfo alsa_info = {
      sizeof (GstAlsaClass),
      NULL,
      NULL,
      gst_alsa_class_init,
      NULL,
      NULL,
      sizeof (GstAlsa),
      0,
      (GInstanceInitFunc) gst_alsa_init,
    };

    alsa_type = g_type_register_static (GST_TYPE_ELEMENT, "GstAlsa", &alsa_info, 0);
  }

  return alsa_type;
}

/*** GOBJECT FUNCTIONS ********************************************************/

enum
{
  ARG_0,
  ARG_DEVICE,
  ARG_PERIODCOUNT,
  ARG_PERIODSIZE,
  ARG_BUFFERSIZE,
  ARG_AUTORECOVER,
  ARG_MMAP,
  ARG_MAXDISCONT
};

static GstElement *parent_class = NULL;

static void
gst_alsa_class_init (gpointer g_class, gpointer class_data)
{
  GObjectClass *object_class;
  GstElementClass *element_class;
  GstAlsaClass *klass;

  klass = (GstAlsaClass *)g_class;
  object_class = (GObjectClass *) g_class;
  element_class = (GstElementClass *) g_class;

  if (parent_class == NULL)
    parent_class = g_type_class_ref (GST_TYPE_ELEMENT);

  object_class->dispose = gst_alsa_dispose;
  object_class->get_property = gst_alsa_get_property;
  object_class->set_property = gst_alsa_set_property;

  g_object_class_install_property (object_class, ARG_DEVICE,
    g_param_spec_string ("device", "Device",
                         "ALSA device, as defined in an asoundrc",
                         "default", G_PARAM_READWRITE));
  g_object_class_install_property (object_class, ARG_PERIODCOUNT,
    g_param_spec_int ("period-count", "Period count",
                      "Number of hardware buffers to use",
                      2, 64, 2, G_PARAM_READWRITE | G_PARAM_CONSTRUCT));
  g_object_class_install_property (object_class, ARG_PERIODSIZE,
    g_param_spec_int ("period-size", "Period size",
                      "Number of frames (samples on each channel) in one hardware period",
                      2, 8192, 8192, G_PARAM_READWRITE | G_PARAM_CONSTRUCT));
  g_object_class_install_property (object_class, ARG_BUFFERSIZE,
    g_param_spec_int ("buffer-size", "Buffer size",
                      "Number of frames the hardware buffer can hold",
                      4, 65536, 16384, G_PARAM_READWRITE));
  g_object_class_install_property (object_class, ARG_AUTORECOVER,
    g_param_spec_boolean ("autorecover", "Automatic xrun recovery",
                          "When TRUE tries to reduce processor load on xruns",
                          TRUE, G_PARAM_READWRITE | G_PARAM_CONSTRUCT));
  g_object_class_install_property (object_class, ARG_MMAP,
    g_param_spec_boolean ("mmap", "Use mmap'ed access",
                          "Wether to use mmap (faster) or standard read/write (more compatible)",
                          TRUE, G_PARAM_READWRITE | G_PARAM_CONSTRUCT));
  g_object_class_install_property (object_class, ARG_MAXDISCONT,
    g_param_spec_uint64 ("max-discont", "Maximum Discontinuity",
                         "GStreamer timeunits before the timestamp syncing starts dropping/inserting samples",
   /* rounding errors */ 1000, GST_SECOND, GST_ALSA_DEFAULT_DISCONT, G_PARAM_READWRITE | G_PARAM_CONSTRUCT));

  element_class->change_state    = GST_DEBUG_FUNCPTR (gst_alsa_change_state);
  element_class->query	 	 = GST_DEBUG_FUNCPTR (gst_alsa_query);
  element_class->request_new_pad = GST_DEBUG_FUNCPTR (gst_alsa_request_new_pad);
  element_class->set_clock 	 = GST_DEBUG_FUNCPTR (gst_alsa_set_clock);
  element_class->get_clock 	 = GST_DEBUG_FUNCPTR (gst_alsa_get_clock);
}

static void
gst_alsa_init (GstAlsa *this)
{
  this->device = g_strdup("default");

  GST_FLAG_SET (this, GST_ELEMENT_EVENT_AWARE);
  GST_FLAG_SET (this, GST_ELEMENT_THREAD_SUGGESTED);
}

static void
gst_alsa_dispose (GObject *object)
{
  GstAlsa *this = GST_ALSA (object);

  g_free (this->device);

  if (this->clock)
    gst_object_unparent (GST_OBJECT (this->clock));

  G_OBJECT_CLASS (parent_class)->dispose (object);
}

static void
gst_alsa_set_property (GObject *object, guint prop_id, const GValue *value, GParamSpec *pspec)
{
  GstAlsa *this;
  gint buffer_size;

  this = (GstAlsa *) object;
  switch (prop_id) {
  case ARG_DEVICE:
    if (this->device)
      g_free (this->device);
    this->device = g_strdup (g_value_get_string (value));
    break;
  case ARG_PERIODCOUNT:
    g_return_if_fail (!GST_FLAG_IS_SET (this, GST_ALSA_RUNNING));
    this->period_count = g_value_get_int (value);
    break;
  case ARG_PERIODSIZE:
    g_return_if_fail (!GST_FLAG_IS_SET (this, GST_ALSA_RUNNING));
    this->period_size = g_value_get_int (value);
    break;
  case ARG_BUFFERSIZE:
    g_return_if_fail (!GST_FLAG_IS_SET (this, GST_ALSA_RUNNING));
    buffer_size = g_value_get_int (value);
    this->period_count = buffer_size / this->period_size;
    break;
  case ARG_AUTORECOVER:
    this->autorecover = g_value_get_boolean (value);
    return;
  case ARG_MMAP:
    this->mmap = g_value_get_boolean (value);
    return;
  case ARG_MAXDISCONT:
    this->max_discont = (GstClockTime) g_value_get_uint64 (value);
    return;
  default:
    G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
    return;
  }

  if (GST_STATE (this) == GST_STATE_NULL)
    return;

  if (GST_FLAG_IS_SET (this, GST_ALSA_RUNNING)) {
    gst_alsa_stop_audio (this);
    gst_alsa_start_audio (this);
  }
}

static void
gst_alsa_get_property (GObject *object, guint prop_id, GValue *value, GParamSpec *pspec)
{
  GstAlsa *this;

  this = (GstAlsa *) object;

  switch (prop_id) {
  case ARG_DEVICE:
    g_value_set_string (value, this->device);
    break;
  case ARG_PERIODCOUNT:
    g_value_set_int (value, this->period_count);
    break;
  case ARG_PERIODSIZE:
    g_value_set_int (value, this->period_size);
    break;
  case ARG_BUFFERSIZE:
    g_value_set_int (value, this->period_size * this->period_count);
    break;
  case ARG_AUTORECOVER:
    g_value_set_boolean (value, this->autorecover);
    break;
  case ARG_MMAP:
    g_value_set_boolean (value, this->mmap);
    break;
  case ARG_MAXDISCONT:
    g_value_set_uint64 (value, (guint64) this->max_discont);
    return;
  default:
    G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
    break;
  }
}

/*** GSTREAMER PAD / QUERY / CONVERSION / STATE FUNCTIONS *********************/

static GstPad *
gst_alsa_request_new_pad (GstElement *element, GstPadTemplate *templ, const gchar *name)
{
  GstAlsa *this;
  gint track = 0;

  g_return_val_if_fail ((this = GST_ALSA (element)), NULL);
  g_return_val_if_fail (!GST_FLAG_IS_SET (element, GST_ALSA_RUNNING), NULL);

  if (name) {
    /* locate the track number in the requested pad name. */
    track = (gint) strtol (name + (strchr(templ->name_template, '%') -
                                   templ->name_template), NULL, 0);
    if (track < 1 || track >= GST_ALSA_MAX_TRACKS) {
      GST_INFO_OBJECT (this, "invalid track requested. (%d)", track);
      return NULL;
    }
  }

  /* make sure the requested track is free. */
  if (track > 0 || this->pad[track] != NULL) {
    GST_INFO_OBJECT (this, "requested track %d already in use.", track);
    return NULL;
  }

  /* if the user doesn't care, use the lowest available track number */
  if (track == 0) {
    for (track = 1; track < GST_ALSA_MAX_TRACKS; track++) {
      if (this->pad[track] != NULL) goto found_track;
    }
    return NULL;
  }

found_track:
  this->pad[track] = gst_pad_new_from_template (templ, name);

  gst_pad_set_link_function (this->pad[track], gst_alsa_link);
  gst_pad_set_getcaps_function (this->pad[track], gst_alsa_get_caps);

  gst_element_add_pad (GST_ELEMENT (this), this->pad[track]);

  gst_pad_set_convert_function (this->pad[track], gst_alsa_pad_convert);
  gst_pad_set_query_function (this->pad[track], gst_alsa_pad_query);
  gst_pad_set_query_type_function (this->pad[track], gst_alsa_get_query_types);
  gst_pad_set_formats_function (this->pad[track], gst_alsa_get_formats);

  return this->pad[track];
}

/* gets the matching alsa format or NULL if none matches */
static GstAlsaFormat *
gst_alsa_get_format (const GstStructure *structure)
{
  const gchar *mimetype;
  GstAlsaFormat *ret;

  if (! (ret = g_new (GstAlsaFormat, 1)))
    return NULL;

  /* we have to differentiate between int and float formats */
  mimetype = gst_structure_get_name (structure);

  if (! strncmp (mimetype, "audio/x-raw-int", 15)) {
    gboolean sign;
    gint width, depth, endianness;

    /* extract the needed information from the cap */
    if (!(gst_structure_get_int (structure, "width", &width) &&
	  gst_structure_get_int (structure, "depth", &depth) &&
	  gst_structure_get_boolean (structure, "signed", &sign)))
        goto error;

    /* extract endianness if needed */
    if (width > 8) {
      if (!gst_structure_get_int (structure, "endianness", &endianness))
        goto error;
    } else {
      endianness = G_BYTE_ORDER;
    }

    ret->format = snd_pcm_build_linear_format (depth, width, sign ? 0 : 1, endianness == G_LITTLE_ENDIAN ? 0 : 1);

  } else if (! strncmp (mimetype, "audio/x-raw-float", 17)) {
    gint width;

    /* get layout */
    if (!gst_structure_get_int (structure, "width", &width))
      goto error;

    /* match layout to format wrt to endianness */
    if (width == 32) {
      if (G_BYTE_ORDER == G_LITTLE_ENDIAN) {
        ret->format = SND_PCM_FORMAT_FLOAT_LE;
      } else if (G_BYTE_ORDER == G_BIG_ENDIAN) {
        ret->format = SND_PCM_FORMAT_FLOAT_BE;
      } else {
        ret->format = SND_PCM_FORMAT_FLOAT;
      }
    } else if (width == 64) {
      if (G_BYTE_ORDER == G_LITTLE_ENDIAN) {
        ret->format = SND_PCM_FORMAT_FLOAT64_LE;
      } else if (G_BYTE_ORDER == G_BIG_ENDIAN) {
        ret->format = SND_PCM_FORMAT_FLOAT64_BE;
      } else {
        ret->format = SND_PCM_FORMAT_FLOAT64;
      }
    } else {
      goto error;
    }
  } else if (! strncmp (mimetype, "audio/x-alaw", 12)) {
    ret->format = SND_PCM_FORMAT_A_LAW;
  } else if (! strncmp (mimetype, "audio/x-mulaw", 13)) {
    ret->format = SND_PCM_FORMAT_MU_LAW;
  }

  /* get rate and channels */
  if (!(gst_structure_get_int (structure, "rate", &ret->rate) &&
	gst_structure_get_int (structure, "channels", &ret->channels)))
    goto error;

  return ret;

error:
  g_free (ret);
  return NULL;
}

static inline gboolean
gst_alsa_formats_match (GstAlsaFormat *one, GstAlsaFormat *two)
{
  if (one == two) return TRUE;
  if (one == NULL || two == NULL) return FALSE;
  return (one->format == two->format) &&
         (one->rate == two->rate) &&
         (one->channels == two->channels);
}

/* get props for a spec */
static GstCaps *
gst_alsa_get_caps_internal (snd_pcm_format_t format)
{
  if (format == SND_PCM_FORMAT_A_LAW) {
    return gst_caps_new_simple ("audio/x-alaw", NULL);
  } else if (format == SND_PCM_FORMAT_MU_LAW) {
    return gst_caps_new_simple ("audio/x-mulaw", NULL);
  } else if (snd_pcm_format_linear (format)) {
    /* int */
    GstStructure *structure = gst_structure_new ("audio/x-raw-int",
	    "width",  G_TYPE_INT, (gint) snd_pcm_format_physical_width (format),
            "depth",  G_TYPE_INT, (gint) snd_pcm_format_width (format),
            "signed", G_TYPE_BOOLEAN, snd_pcm_format_signed (format) == 1 ? TRUE : FALSE,
            NULL);
    /* endianness */
    if (snd_pcm_format_physical_width (format) > 8) {
      switch (snd_pcm_format_little_endian (format)) {
      case 0:
        gst_structure_set (structure, "endianness", G_TYPE_INT, G_BIG_ENDIAN, NULL);
        break;
      case 1:
        gst_structure_set (structure, "endianness", G_TYPE_INT, G_LITTLE_ENDIAN, NULL);
        break;
      default:
        GST_WARNING ("Unknown byte order in sound driver. Continuing by assuming system byte order.");
        gst_structure_set (structure, "endianness", G_TYPE_INT, G_BYTE_ORDER, NULL);
        break;
      }
    }
    return gst_caps_new_full (structure, NULL);
  } else if (snd_pcm_format_float (format)) {
    /* no float with non-platform endianness */
    if (!snd_pcm_format_cpu_endian (format))
      return NULL;

    return gst_caps_new_simple ("audio/x-raw-float",
	    "width",      G_TYPE_INT, (gint) snd_pcm_format_width (format),
	    "endianness", G_TYPE_INT, G_BYTE_ORDER,
            NULL);
  }
  return NULL;
}

static inline void
add_channels (GstStructure *structure, gint min_rate, gint max_rate,
    gint min_channels, gint max_channels)
{
  if (min_rate < 0) {
    min_rate = GST_ALSA_MIN_RATE;
    max_rate = GST_ALSA_MAX_RATE;
  }
  if (max_rate < 0) {
    gst_structure_set (structure, "rate", G_TYPE_INT, min_rate, NULL);
  } else {
    gst_structure_set (structure, "rate", GST_TYPE_INT_RANGE, min_rate,
        max_rate, NULL);
  }
  if (min_channels < 0) {
    min_channels = 1;
    max_channels = GST_ALSA_MAX_CHANNELS;
  }
  if (max_channels < 0) {
    gst_structure_set (structure, "channels", G_TYPE_INT, min_channels, NULL);
  } else {
    gst_structure_set (structure, "channels", GST_TYPE_INT_RANGE,
        min_channels, max_channels, NULL);
  }
}

/**
 * Get all available caps.
 * @format: SND_PCM_FORMAT_UNKNOWN for all formats, desired format else
 * @rate: allowed rates if < 0, else desired rate
 * @channels: all allowed values for channels if < 0, else desired channels
 */
GstCaps *
gst_alsa_caps (snd_pcm_format_t format, gint rate, gint channels)
{
  GstCaps *ret_caps;

  if (format != SND_PCM_FORMAT_UNKNOWN) {
    /* there are some caps set already */
    ret_caps = gst_alsa_get_caps_internal (format);

    /* we can never use a format we can't set caps for */
    g_assert (ret_caps != NULL);
    g_assert (gst_caps_get_size (ret_caps) == 1);

    add_channels (gst_caps_get_structure (ret_caps, 0), rate, -1, channels, -1);
  } else {
    int i;
    GstCaps *temp;

    ret_caps = gst_caps_new_empty ();
    for (i = 0; i <= SND_PCM_FORMAT_LAST; i++) {
      temp = gst_alsa_get_caps_internal (i);

      /* can be NULL, because not all alsa formats can be specified as caps */
      if (temp != NULL) {
	g_assert (gst_caps_get_size (temp) == 1);
        add_channels (gst_caps_get_structure (temp, 0), rate, -1, channels, -1);
        gst_caps_append (ret_caps, temp);
      }
    }
  }

  return ret_caps;
}

/* Return better caps when device is open */
GstCaps *
gst_alsa_get_caps (GstPad *pad)
{
  GstAlsa *this;
  snd_pcm_hw_params_t *hw_params;
  snd_pcm_format_mask_t *mask;
  int i;
  unsigned int min_rate, max_rate;
  gint min_channels, max_channels;
  GstCaps *ret = NULL;

  g_return_val_if_fail (pad != NULL, NULL);

  this = GST_ALSA (gst_pad_get_parent (pad));

  if (!GST_FLAG_IS_SET (this, GST_ALSA_OPEN))
    return gst_caps_copy (GST_PAD_TEMPLATE_CAPS (GST_PAD_PAD_TEMPLATE (pad)));
  
  snd_pcm_hw_params_alloca (&hw_params);
  ERROR_CHECK (snd_pcm_hw_params_any (this->handle, hw_params),
               "Broken configuration for this PCM: %s");

  if (((GstElement *) this)->numpads > 1) {
    min_channels = 1;
    max_channels = -1;
  } else {
    ERROR_CHECK (snd_pcm_hw_params_get_channels_min (hw_params, &min_rate),
                 "Couldn't get minimum channel count for device %s: %s", this->device);
    ERROR_CHECK (snd_pcm_hw_params_get_channels_max (hw_params, &max_rate),
                 "Couldn't get maximum channel count for device %s: %s", this->device);
    min_channels = min_rate;
    max_channels = max_rate > GST_ALSA_MAX_CHANNELS ? GST_ALSA_MAX_CHANNELS : max_rate;
  }

  ERROR_CHECK (snd_pcm_hw_params_get_rate_min (hw_params, &min_rate, &i),
               "Couldn't get minimum rate for device %s: %s", this->device);
  min_rate = min_rate < GST_ALSA_MIN_RATE ? GST_ALSA_MIN_RATE : min_rate + i;
  ERROR_CHECK (snd_pcm_hw_params_get_rate_max (hw_params, &max_rate, &i),
               "Couldn't get maximum rate for device %s: %s", this->device);
  max_rate = max_rate > GST_ALSA_MAX_RATE ? GST_ALSA_MAX_RATE : max_rate + i;

  snd_pcm_format_mask_alloca (&mask);
  snd_pcm_hw_params_get_format_mask (hw_params, mask);
  for (i = 0; i <= SND_PCM_FORMAT_LAST; i++) {
    if (snd_pcm_format_mask_test (mask, i)) {
      GstCaps *caps = gst_alsa_get_caps_internal (i);
      /* we can never use a format we can't set caps for */
      if (caps != NULL) {
	g_assert (gst_caps_get_size (caps) == 1);
        add_channels (gst_caps_get_structure (caps, 0), min_rate, max_rate, min_channels, max_channels);
	if (ret) {
	  gst_caps_append (ret, caps);
	} else {
	  ret = caps;
	}
      }
    }
  }

  if (ret == NULL) {
    GST_WARNING_OBJECT (this, "no supported caps found, returning empty caps");
    return gst_caps_new_empty ();
  } else {
    G_GNUC_UNUSED gchar *str = gst_caps_to_string (ret);
    GST_LOG_OBJECT (this, "get_caps returns %s", str);
    g_free (str);
    return ret;
  }
}

/* Negotiates the caps */
GstPadLinkReturn
gst_alsa_link (GstPad *pad, const GstCaps *caps)
{
  GstAlsa *this;
  GstAlsaFormat *format;
  GstPadLinkReturn ret;

  g_return_val_if_fail (caps != NULL, GST_PAD_LINK_REFUSED);
  g_return_val_if_fail (pad != NULL, GST_PAD_LINK_REFUSED);

  this = GST_ALSA (gst_pad_get_parent (pad));

  if (this->handle == NULL)
    if (!gst_alsa_open_audio (this))
      return GST_PAD_LINK_REFUSED;

  format = gst_alsa_get_format (gst_caps_get_structure (caps, 0));
  if (format == NULL)
    return GST_PAD_LINK_REFUSED;
    
  GST_DEBUG ("found format %s", snd_pcm_format_name (format->format));
    
  if (!GST_FLAG_IS_SET (this, GST_ALSA_CAPS_NEGO)) {
    gint i;

    GST_FLAG_SET (this, GST_ALSA_CAPS_NEGO);

    if (gst_alsa_formats_match (this->format, format)) {
      ret = GST_PAD_LINK_OK;
      goto out;
    }

    if (!gst_alsa_probe_hw_params (this, format)) {
      ret = GST_PAD_LINK_REFUSED;
      goto out;
    }

    for (i = 0; i < ((GstElement *) this)->numpads; i++) {
      g_assert (this->pad[i] != NULL);
      if (this->pad[i] == pad)
	continue;
      if (gst_pad_try_set_caps (this->pad[i], caps) == GST_PAD_LINK_REFUSED) {
	if (this->format) {
	  GstCaps *old = gst_alsa_caps (this->format->format, this->format->rate, this->format->channels);
	  for (--i; i >= 0; i--) {
	    if (gst_pad_try_set_caps (this->pad[i], old) == GST_PAD_LINK_REFUSED) {
	      gst_element_error (GST_ELEMENT (this), "error resetting caps to sane value");
	      gst_caps_free (old);
	      break;
	    } else {
	      /* FIXME: unset caps on pads somehow */
	    }
	  }
          gst_caps_free (old);
          ret = GST_PAD_LINK_REFUSED;
	  goto out;
        }
      }
    }

    GST_FLAG_UNSET (this, GST_ALSA_CAPS_NEGO);

    /* sync the params */
    if (GST_FLAG_IS_SET (this, GST_ALSA_RUNNING)) gst_alsa_stop_audio (this);
    g_free (this->format);
    this->format = format;
    if (! gst_alsa_start_audio (this)) {
      gst_element_error (GST_ELEMENT (this), "Probed format doesn't work");
      return GST_PAD_LINK_REFUSED;
    }

    return GST_PAD_LINK_OK;
  }

  return GST_PAD_LINK_DELAYED;

out:
  g_free (format);
  GST_FLAG_UNSET (this, GST_ALSA_CAPS_NEGO);
  return ret;
}

static GstElementStateReturn
gst_alsa_change_state (GstElement *element)
{
  int err;
  GstAlsa *this;

  g_return_val_if_fail (element != NULL, FALSE);
  this = GST_ALSA (element);

  switch (GST_STATE_TRANSITION (element)) {
  case GST_STATE_NULL_TO_READY:
    if (! (GST_FLAG_IS_SET (element, GST_ALSA_OPEN) ||
           gst_alsa_open_audio (this))) return GST_STATE_FAILURE;
    break;
  case GST_STATE_READY_TO_PAUSED:
    if (! (GST_FLAG_IS_SET (element, GST_ALSA_RUNNING) ||
           gst_alsa_start_audio (this))) return GST_STATE_FAILURE;
    this->transmitted = 0;
    break;
  case GST_STATE_PAUSED_TO_PLAYING:
    if (snd_pcm_state (this->handle) == SND_PCM_STATE_PAUSED) {
      if ((err = snd_pcm_pause (this->handle, 0)) < 0) {
        GST_ERROR_OBJECT (this, "Error unpausing sound: %s", snd_strerror (err));
        return GST_STATE_FAILURE;
      }
      gst_alsa_clock_start (this->clock);
    }
    break;
  case GST_STATE_PLAYING_TO_PAUSED:
    if (GST_ALSA_CAPS_IS_SET (this, GST_ALSA_CAPS_PAUSE)) {
      if (snd_pcm_state (this->handle) == SND_PCM_STATE_RUNNING) {
        if ((err = snd_pcm_pause (this->handle, 1)) < 0) {
          GST_ERROR_OBJECT (this, "Error pausing sound: %s", snd_strerror (err));
          return GST_STATE_FAILURE;
        }
        gst_alsa_clock_stop (this->clock);
      }
      break;
    }
    /* if device doesn't know how to pause, we just stop */
  case GST_STATE_PAUSED_TO_READY:
    if (GST_FLAG_IS_SET (element, GST_ALSA_RUNNING)) gst_alsa_stop_audio (this);
    g_free (this->format);
    this->format = NULL;
    break;
  case GST_STATE_READY_TO_NULL:
    if (GST_FLAG_IS_SET (element, GST_ALSA_OPEN)) gst_alsa_close_audio (this);
    break;

  default:
    g_assert_not_reached();
  }

  if (GST_ELEMENT_CLASS (parent_class)->change_state)
    return GST_ELEMENT_CLASS (parent_class)->change_state (element);

  return GST_STATE_SUCCESS;
}

static GstClock *
gst_alsa_get_clock (GstElement *element)
{ return GST_CLOCK (GST_ALSA (element)->clock); }

static void
gst_alsa_set_clock (GstElement *element, GstClock *clock)
{ /* we need this function just so everybody knows we use a clock */ }

/*** AUDIO PROCESSING *********************************************************/

inline snd_pcm_sframes_t
gst_alsa_update_avail (GstAlsa *this)
{
  snd_pcm_sframes_t avail = snd_pcm_avail_update (this->handle);
  if (avail < 0) {
    if (avail == -EPIPE) {
      gst_alsa_xrun_recovery (this);
    } else {
      GST_WARNING_OBJECT (this, "unknown ALSA avail_update return value (%d)", (int) avail);
    }
  }
  return avail;
}

/* returns TRUE, if the loop should go on */
inline gboolean
gst_alsa_pcm_wait (GstAlsa *this)
{
  int err;

  if (snd_pcm_state (this->handle) == SND_PCM_STATE_RUNNING) {
    if ((err = snd_pcm_wait (this->handle, 1000)) < 0) {
      if (err == EINTR) {
        /* happens mostly when run under gdb, or when exiting due to a signal */
        GST_DEBUG ("got interrupted while waiting");
        if (gst_element_interrupt (GST_ELEMENT (this))) {
          return TRUE;
        } else {
          return FALSE;
        }
      }
      GST_ERROR_OBJECT (this, "error waiting for alsa pcm: (%d: %s)", err, snd_strerror (err));
      return FALSE;
    }
  }
  return TRUE;
}

/**
 * error out or make sure we're in SND_PCM_STATE_RUNNING afterwards 
 * return FALSE if we're not
 */
inline gboolean
gst_alsa_start (GstAlsa *this)
{
  GST_DEBUG ("Setting state to RUNNING");

  switch (snd_pcm_state(this->handle)) {
    case SND_PCM_STATE_XRUN:
      gst_alsa_xrun_recovery (this);
      return gst_alsa_start (this);
    case SND_PCM_STATE_SETUP:
      ERROR_CHECK (snd_pcm_prepare (this->handle), "error preparing: %s");
    case SND_PCM_STATE_SUSPENDED:
    case SND_PCM_STATE_PREPARED:
      ERROR_CHECK (snd_pcm_start(this->handle), "error starting playback: %s");
      break;
    case SND_PCM_STATE_PAUSED:
      ERROR_CHECK (snd_pcm_pause (this->handle, 0), "error unpausing: %s");
      break;
    case SND_PCM_STATE_RUNNING:
      break;
    case SND_PCM_STATE_DRAINING:
    case SND_PCM_STATE_OPEN:
      /* this probably happens when someone replugged a pipeline and we're in a
         really weird state because our cothread wasn't busted */
      return FALSE;
    default:
      /* it's a bug when we get here */
      g_assert_not_reached ();
      break;
  }
  gst_alsa_clock_start (this->clock);
  return TRUE;
}
void
gst_alsa_xrun_recovery (GstAlsa *this)
{
  snd_pcm_status_t *status;
  gint err;

  snd_pcm_status_alloca (&status);

  if ((err = snd_pcm_status (this->handle, status)) < 0)
    GST_ERROR_OBJECT (this, "status error: %s", snd_strerror (err));

  if (snd_pcm_status_get_state (status) == SND_PCM_STATE_XRUN) {
    struct timeval now, diff, tstamp;

    gettimeofday (&now, 0);
    snd_pcm_status_get_trigger_tstamp (status, &tstamp);
    timersub (&now, &tstamp, &diff);
    GST_INFO_OBJECT (this, "alsa: xrun of at least %.3f msecs", diff.tv_sec * 1000 + diff.tv_usec / 1000.0);

    /* if we're allowed to recover, ... */
    if (this->autorecover) {
      /* ... then increase the period size or buffer size / period count to
         prevent further xruns (at the cost of increased latency and memory
         usage). */
      if (this->period_count >= 4) {
        this->period_size *= 2;
        this->period_count /= 2;
      } else {
        this->period_count *= 2;
      }
    }
  }

  if (!(gst_alsa_stop_audio (this) && gst_alsa_start_audio (this))) {
    gst_element_error (GST_ELEMENT (this), "alsasink: Error restarting audio after xrun");
  }
}

/*** AUDIO SETUP / START / STOP ***********************************************/

void
gst_alsa_set_eos (GstAlsa *this)
{
  gst_alsa_drain_audio (this);
  gst_element_set_eos (GST_ELEMENT (this));
}
static gboolean
gst_alsa_open_audio (GstAlsa *this)
{
  g_assert (this != NULL);
  g_assert (this->handle == NULL);

  GST_INFO ( "Opening alsa device \"%s\"...\n", this->device);

#if 0
  /* enable this to get better debugging */
  ERROR_CHECK (snd_output_stdio_attach (&this->out, stderr, 0),
               "error opening log output: %s");
#endif
  /* we use non-blocking i/o */
  ERROR_CHECK (snd_pcm_open (&this->handle, this->device, 
                             GST_ALSA_GET_CLASS (this)->stream, SND_PCM_NONBLOCK),
               "error opening pcm device %s: %s\n", this->device);

  GST_FLAG_SET (this, GST_ALSA_OPEN);
  return TRUE;
}
/* if someone finds an easy way to merge this with _set_hw_params, go ahead */
static gboolean
gst_alsa_probe_hw_params (GstAlsa *this, GstAlsaFormat *format)
{
  snd_pcm_hw_params_t *hw_params;
  snd_pcm_access_mask_t *mask;
  snd_pcm_uframes_t period_size;
  unsigned int period_count;

  g_return_val_if_fail (this != NULL, FALSE);
  g_return_val_if_fail (format != NULL, FALSE);
  
  GST_INFO ( "Probing format: %s %dHz, %d channels\n",
            snd_pcm_format_name (format->format), format->rate, format->channels);

  snd_pcm_hw_params_alloca (&hw_params);
  SIMPLE_ERROR_CHECK (snd_pcm_hw_params_any (this->handle, hw_params));
  SIMPLE_ERROR_CHECK (snd_pcm_hw_params_set_periods_integer (this->handle, hw_params));

  /* enable this for soundcard specific debugging */
  /* snd_pcm_hw_params_dump (hw_params, this->out); */
  
  mask = alloca (snd_pcm_access_mask_sizeof ());
  snd_pcm_access_mask_none (mask);
  if (GST_ELEMENT (this)->numpads == 1) {
    snd_pcm_access_mask_set (mask, this->mmap ? SND_PCM_ACCESS_MMAP_INTERLEAVED : SND_PCM_ACCESS_RW_INTERLEAVED);
  } else {
    snd_pcm_access_mask_set (mask, this->mmap ? SND_PCM_ACCESS_MMAP_NONINTERLEAVED : SND_PCM_ACCESS_RW_NONINTERLEAVED);
  }
  SIMPLE_ERROR_CHECK (snd_pcm_hw_params_set_access_mask (this->handle, hw_params, mask));
  
  SIMPLE_ERROR_CHECK (snd_pcm_hw_params_set_format (this->handle, hw_params, format->format));
  SIMPLE_ERROR_CHECK (snd_pcm_hw_params_set_channels (this->handle, hw_params, format->channels));
  SIMPLE_ERROR_CHECK (snd_pcm_hw_params_set_rate (this->handle, hw_params, format->rate, 0));

  period_count = this->period_count;
  SIMPLE_ERROR_CHECK (snd_pcm_hw_params_set_periods_near (this->handle, hw_params, &period_count, 0));
  period_size = this->period_size;
  SIMPLE_ERROR_CHECK (snd_pcm_hw_params_set_period_size_near (this->handle, hw_params, &period_size, 0));

  return TRUE;
}
/**
 * You must set all hw parameters at once and can't use already set params and
 * change them.
 * Thx ALSA for not documenting this
 */
static gboolean
gst_alsa_set_hw_params (GstAlsa *this)
{
  snd_pcm_hw_params_t *hw_params;
  snd_pcm_access_mask_t *mask;

  g_return_val_if_fail (this != NULL, FALSE);
  g_return_val_if_fail (this->handle != NULL, FALSE);

  if (this->format) {
    GST_INFO ( "Preparing format: %s %dHz, %d channels",
              snd_pcm_format_name (this->format->format), this->format->rate, this->format->channels);
  } else {
    GST_INFO ( "Preparing format: (none)");
  }

  snd_pcm_hw_params_alloca (&hw_params);
  ERROR_CHECK (snd_pcm_hw_params_any (this->handle, hw_params),
               "Broken configuration for this PCM: %s");
  ERROR_CHECK (snd_pcm_hw_params_set_periods_integer (this->handle, hw_params), 
               "cannot restrict period size to integral value: %s");

  /* enable this for soundcard specific debugging */
  /* snd_pcm_hw_params_dump (hw_params, this->out); */
  
  mask = alloca (snd_pcm_access_mask_sizeof ());
  snd_pcm_access_mask_none (mask);
  if (GST_ELEMENT (this)->numpads == 1) {
    snd_pcm_access_mask_set (mask, this->mmap ? SND_PCM_ACCESS_MMAP_INTERLEAVED : SND_PCM_ACCESS_RW_INTERLEAVED);
  } else {
    snd_pcm_access_mask_set (mask, this->mmap ? SND_PCM_ACCESS_MMAP_NONINTERLEAVED : SND_PCM_ACCESS_RW_NONINTERLEAVED);
  }
  ERROR_CHECK (snd_pcm_hw_params_set_access_mask (this->handle, hw_params, mask),
               "The Gstreamer ALSA plugin does not support your hardware. Error: %s");
  
  if (this->format) {
    ERROR_CHECK (snd_pcm_hw_params_set_format (this->handle, hw_params, this->format->format),
                 "Sample format (%s) not available: %s", snd_pcm_format_name (this->format->format));
    ERROR_CHECK (snd_pcm_hw_params_set_channels (this->handle, hw_params, this->format->channels),
                 "Channels count (%d) not available: %s", this->format->channels);
    ERROR_CHECK (snd_pcm_hw_params_set_rate (this->handle, hw_params, this->format->rate, 0),
                 "error setting rate (%d): %s", this->format->rate);
  }

  ERROR_CHECK (snd_pcm_hw_params_set_periods_near (this->handle, hw_params, &this->period_count, 0), 
               "error setting buffer size to %u: %s", (guint) this->period_count);
  ERROR_CHECK (snd_pcm_hw_params_set_period_size_near (this->handle, hw_params, &this->period_size, 0), 
               "error setting period size to %u frames: %s", (guint) this->period_size);

  ERROR_CHECK (snd_pcm_hw_params (this->handle, hw_params),
               "Could not set hardware parameters: %s");

  /* now get the pcm caps */
  GST_ALSA_CAPS_SET (this, GST_ALSA_CAPS_PAUSE, snd_pcm_hw_params_can_pause (hw_params));
  GST_ALSA_CAPS_SET (this, GST_ALSA_CAPS_RESUME, snd_pcm_hw_params_can_resume (hw_params));
  GST_ALSA_CAPS_SET (this, GST_ALSA_CAPS_SYNC_START, snd_pcm_hw_params_can_sync_start (hw_params));
  
  if (this->mmap) {
    this->transmit = GST_ALSA_GET_CLASS (this)->transmit_mmap;
  } else {
    this->transmit = GST_ALSA_GET_CLASS (this)->transmit_rw;
  }

  return TRUE;
}
static gboolean
gst_alsa_set_sw_params (GstAlsa *this)
{
  snd_pcm_sw_params_t *sw_params;

  snd_pcm_sw_params_alloca (&sw_params);
  ERROR_CHECK (snd_pcm_sw_params_current (this->handle, sw_params),
               "Could not get current software parameters: %s");
  
  ERROR_CHECK (snd_pcm_sw_params_set_silence_size (this->handle, sw_params, 0),
               "could not set silence size: %s");
  ERROR_CHECK (snd_pcm_sw_params_set_silence_threshold (this->handle, sw_params, 0),
               "could not set silence threshold: %s");
  ERROR_CHECK (snd_pcm_sw_params_set_avail_min (this->handle, sw_params, this->period_size),
               "could not set avail min: %s");
  /* we start explicitly */
  ERROR_CHECK (snd_pcm_sw_params_set_start_threshold (this->handle, sw_params, this->period_size * this->period_count + 1),
               "could not set start mode: %s");
  ERROR_CHECK (snd_pcm_sw_params_set_stop_threshold (this->handle, sw_params, this->period_size * this->period_count),
               "could not set stop mode: %s");
  ERROR_CHECK (snd_pcm_sw_params_set_xfer_align(this->handle, sw_params, 1),
               "Unable to set transfer align for playback: %s");
  ERROR_CHECK (snd_pcm_sw_params (this->handle, sw_params),
               "could not set sw_params: %s");
  
  return TRUE;
}

static gboolean
gst_alsa_start_audio (GstAlsa *this)
{
  g_assert (GST_FLAG_IS_SET (this, GST_ALSA_OPEN));
  
  if (!gst_alsa_set_hw_params (this))
    return FALSE;
  if (!gst_alsa_set_sw_params (this))
    return FALSE;
  
  GST_FLAG_SET (this, GST_ALSA_RUNNING);
  return TRUE;
}
static gboolean
gst_alsa_drain_audio (GstAlsa *this)
{
  g_assert (this != NULL);
  g_return_val_if_fail (this->handle != NULL, FALSE);

  GST_DEBUG ("stopping alsa");
  
  switch (snd_pcm_state (this->handle)) {
    case SND_PCM_STATE_XRUN:
    case SND_PCM_STATE_RUNNING:
      gst_alsa_clock_stop (this->clock);
      /* fall through - clock is already stopped when paused */
    case SND_PCM_STATE_PAUSED:
      /* snd_pcm_drain only works in blocking mode */
      ERROR_CHECK (snd_pcm_nonblock(this->handle, 0), "couldn't set blocking mode: %s");
      ERROR_CHECK (snd_pcm_drain (this->handle), "couldn't stop and drain buffer: %s");
      ERROR_CHECK (snd_pcm_nonblock(this->handle, 1), "couldn't set non-blocking mode: %s");
      break;
    default:
      break;
  }

  GST_FLAG_UNSET (this, GST_ALSA_RUNNING);  
  return TRUE;
}

static gboolean
gst_alsa_stop_audio (GstAlsa *this)
{
  g_assert (this != NULL);
  g_return_val_if_fail (this->handle != NULL, FALSE);

  GST_DEBUG ("stopping alsa, skipping pending frames");
  
  switch (snd_pcm_state (this->handle)) {
    case SND_PCM_STATE_XRUN:
    case SND_PCM_STATE_RUNNING:
      gst_alsa_clock_stop (this->clock);
      /* fall through - clock is already stopped when paused */
    case SND_PCM_STATE_PAUSED:
      ERROR_CHECK (snd_pcm_drop (this->handle),
                   "couldn't stop (dropping frames): %s");
      break;
    default:
      break;
  }

  GST_FLAG_UNSET (this, GST_ALSA_RUNNING);  
  return TRUE;
}

static gboolean
gst_alsa_close_audio (GstAlsa *this)
{
  g_return_val_if_fail (this != NULL, FALSE);
  g_return_val_if_fail (this->handle != NULL, FALSE);

  ERROR_CHECK (snd_pcm_close (this->handle), "Error closing device: %s");

  this->handle = NULL;
  GST_FLAG_UNSET (this, GST_ALSA_OPEN);

  return TRUE;
}

/*** QUERYING/FORMAT/CONVERSION FUNCTIONS *************************************/

static const GstFormat *
gst_alsa_get_formats (GstPad *pad)
{
  static const GstFormat formats[] = {
    GST_FORMAT_TIME,
    GST_FORMAT_DEFAULT,
    GST_FORMAT_BYTES,
    0
  };
  return formats;
}

static gboolean
gst_alsa_pad_convert (GstPad *pad, GstFormat src_format, gint64 src_value,
		      GstFormat *dest_format, gint64 *dest_value)
{
  return gst_alsa_convert (GST_ALSA (GST_PAD_PARENT (pad)), src_format, src_value, dest_format, dest_value);
}

static gboolean
gst_alsa_convert (GstAlsa *this, GstFormat src_format, gint64 src_value,
	          GstFormat *dest_format, gint64 *dest_value)
{
  gboolean res = TRUE;

  if (src_format == *dest_format) {
    *dest_value = src_value;
    return TRUE;
  }
  if (this->format == NULL)
    return FALSE;

  switch (src_format) {
    case GST_FORMAT_BYTES:
      switch (*dest_format) {
        case GST_FORMAT_DEFAULT:
	  *dest_value = gst_alsa_bytes_to_samples (this, (guint) src_value);
          break;
        case GST_FORMAT_TIME:
	  *dest_value = gst_alsa_bytes_to_timestamp (this, (guint) src_value);
          break;
        default:
          res = FALSE;
	  break;
      }
      break;
    case GST_FORMAT_TIME:
      switch (*dest_format) {
        case GST_FORMAT_DEFAULT:
	  *dest_value = gst_alsa_timestamp_to_samples (this, (GstClockTime) src_value);
          break;
        case GST_FORMAT_BYTES:
	  *dest_value = gst_alsa_timestamp_to_bytes (this, (GstClockTime) src_value);
          break;
        default:
          res = FALSE;
	  break;
      }
      break;
    case GST_FORMAT_DEFAULT:
      switch (*dest_format) {
        case GST_FORMAT_TIME:
	  *dest_value = gst_alsa_samples_to_timestamp (this, (guint) src_value);
          break;
        case GST_FORMAT_BYTES:
	  *dest_value = gst_alsa_samples_to_bytes (this, (guint) src_value);
          break;
        case GST_FORMAT_DEFAULT:
          g_assert_not_reached ();
	  /* fall through */
        default:
          res = FALSE;
	  break;
      }
      break;
    default:
      res = FALSE;
  }

  return res;
}

static const GstQueryType *
gst_alsa_get_query_types (GstPad *pad)
{
  static const GstQueryType query_types[] = {
    GST_QUERY_LATENCY,
    GST_QUERY_POSITION,
    0,
  };
  return query_types;
}

static gboolean
gst_alsa_query_func (GstElement *element, GstQueryType type, GstFormat *format, gint64 *value)
{
  gboolean res = FALSE;
  GstAlsa *this = GST_ALSA (element);

  switch (type) {
    case GST_QUERY_LATENCY: {
      snd_pcm_sframes_t delay;
      ERROR_CHECK (snd_pcm_delay (this->handle, &delay), "Error getting delay: %s");
      res = gst_alsa_convert (this, GST_FORMAT_DEFAULT, (gint64) delay, format, value); 
      break;
    }
    case GST_QUERY_POSITION:
      res = gst_alsa_convert (this, GST_FORMAT_DEFAULT, this->transmitted, format, value);
      break;
    default:
      break;
  }

  return res;
}

static gboolean
gst_alsa_query (GstElement *element, GstQueryType type, GstFormat *format, gint64 *value)
{
  return gst_alsa_pad_query (GST_ALSA (element)->pad[0], type, format, value);
}

static gboolean
gst_alsa_pad_query (GstPad *pad, GstQueryType type, GstFormat *format, gint64 *value)
{
  if (gst_alsa_query_func (GST_PAD_PARENT (pad), type, format, value))
    return TRUE;

  if (GST_PAD_DIRECTION (pad) == GST_PAD_SINK && gst_pad_query (gst_pad_get_peer (pad), type, format, value))
    return TRUE;

  return FALSE;
}

inline snd_pcm_uframes_t
gst_alsa_timestamp_to_samples (GstAlsa *this, GstClockTime time)
{
  return (snd_pcm_uframes_t) ((time * this->format->rate + this->format->rate / 2) / GST_SECOND);
}

inline GstClockTime
gst_alsa_samples_to_timestamp (GstAlsa *this, snd_pcm_uframes_t samples)
{
  return (GstClockTime) (samples * GST_SECOND / this->format->rate);
}

inline snd_pcm_uframes_t
gst_alsa_bytes_to_samples (GstAlsa *this, guint bytes)
{
  return bytes / (snd_pcm_format_physical_width (this->format->format) / 8) / (GST_ELEMENT (this)->numpads == 1 ? this->format->channels : 1);
}

inline guint
gst_alsa_samples_to_bytes (GstAlsa *this, snd_pcm_uframes_t samples)
{
  return samples * snd_pcm_format_physical_width (this->format->format) / 8 * (GST_ELEMENT (this)->numpads == 1 ? this->format->channels : 1);
}

inline GstClockTime
gst_alsa_bytes_to_timestamp (GstAlsa *this, guint bytes)
{
  return gst_alsa_samples_to_timestamp (this, gst_alsa_bytes_to_samples (this, bytes));
}

inline guint
gst_alsa_timestamp_to_bytes (GstAlsa *this, GstClockTime time)
{
  return gst_alsa_samples_to_bytes (this, gst_alsa_timestamp_to_samples (this, time));
}