gstreamer/gst/playback/gstqueue2.c

/* GStreamer
 * Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
 *                    2003 Colin Walters <cwalters@gnome.org>
 *                    2000,2005,2007 Wim Taymans <wim.taymans@gmail.com>
 *                    2007 Thiago Sousa Santos <thiagoss@lcc.ufcg.edu.br>
 *
 * gstqueue2.c:
 *
 * 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., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

/**
 * SECTION:element-queue2
 * @short_description: Asynchronous data queue.
 *
 * Data is queued until one of the limits specified by the
 * #GstQueue:max-size-buffers, #GstQueue:max-size-bytes and/or
 * #GstQueue:max-size-time properties has been reached. Any attempt to push
 * more buffers into the queue will block the pushing thread until more space
 * becomes available.
 *
 * The queue will create a new thread on the source pad to decouple the
 * processing on sink and source pad.
 *
 * You can query how many buffers are queued by reading the
 * #GstQueue:current-level-buffers property.
 *
 * The default queue size limits are 100 buffers, 2MB of data, or
 * two seconds worth of data, whichever is reached first.
 *
 * If you set temp-location, the element will buffer data on the file
 * specified by it. By using this, it will buffer the entire 
 * stream data on the file independently of the queue size limits, they
 * will only be used for buffering statistics.
 *
 */

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

#include <glib/gstdio.h>

#include <gst/gst.h>
#include <gst/gst-i18n-plugin.h>

static const GstElementDetails gst_queue_details = GST_ELEMENT_DETAILS ("Queue",
    "Generic",
    "Simple data queue",
    "Erik Walthinsen <omega@cse.ogi.edu>, "
    "Wim Taymans <wim.taymans@gmail.com>");

static GstStaticPadTemplate sinktemplate = GST_STATIC_PAD_TEMPLATE ("sink",
    GST_PAD_SINK,
    GST_PAD_ALWAYS,
    GST_STATIC_CAPS_ANY);

static GstStaticPadTemplate srctemplate = GST_STATIC_PAD_TEMPLATE ("src",
    GST_PAD_SRC,
    GST_PAD_ALWAYS,
    GST_STATIC_CAPS_ANY);

GST_DEBUG_CATEGORY_STATIC (queue_debug);
#define GST_CAT_DEFAULT (queue_debug)
GST_DEBUG_CATEGORY_STATIC (queue_dataflow);

enum
{
  LAST_SIGNAL
};

/* default property values */
#define DEFAULT_MAX_SIZE_BUFFERS   100  /* 100 buffers */
#define DEFAULT_MAX_SIZE_BYTES     (2 * 1024 * 1024)    /* 2 MB */
#define DEFAULT_MAX_SIZE_TIME      2 * GST_SECOND       /* 2 seconds */
#define DEFAULT_USE_BUFFERING      FALSE
#define DEFAULT_USE_RATE_ESTIMATE  TRUE
#define DEFAULT_LOW_PERCENT        10
#define DEFAULT_HIGH_PERCENT       99

/* other defines */
#define DEFAULT_BUFFER_SIZE 4096
#define QUEUE_IS_USING_TEMP_FILE(queue) (queue->temp_location != NULL)

enum
{
  PROP_0,
  PROP_CUR_LEVEL_BUFFERS,
  PROP_CUR_LEVEL_BYTES,
  PROP_CUR_LEVEL_TIME,
  PROP_MAX_SIZE_BUFFERS,
  PROP_MAX_SIZE_BYTES,
  PROP_MAX_SIZE_TIME,
  PROP_USE_BUFFERING,
  PROP_USE_RATE_ESTIMATE,
  PROP_LOW_PERCENT,
  PROP_HIGH_PERCENT,
  PROP_TEMP_LOCATION
};

#define GST_TYPE_QUEUE \
  (gst_queue_get_type())
#define GST_QUEUE(obj) \
  (G_TYPE_CHECK_INSTANCE_CAST((obj),GST_TYPE_QUEUE,GstQueue))
#define GST_QUEUE_CLASS(klass) \
  (G_TYPE_CHECK_CLASS_CAST((klass),GST_TYPE_QUEUE,GstQueueClass))
#define GST_IS_QUEUE(obj) \
  (G_TYPE_CHECK_INSTANCE_TYPE((obj),GST_TYPE_QUEUE))
#define GST_IS_QUEUE_CLASS(klass) \
  (G_TYPE_CHECK_CLASS_TYPE((klass),GST_TYPE_QUEUE))
#define GST_QUEUE_CAST(obj) \
  ((GstQueue *)(obj))

typedef struct _GstQueue GstQueue;
typedef struct _GstQueueSize GstQueueSize;
typedef struct _GstQueueClass GstQueueClass;

/* used to keep track of sizes (current and max) */
struct _GstQueueSize
{
  guint buffers;
  guint bytes;
  guint64 time;
  guint64 rate_time;
};

#define GST_QUEUE_CLEAR_LEVEL(l) G_STMT_START {         \
  l.buffers = 0;                                        \
  l.bytes = 0;                                          \
  l.time = 0;                                           \
  l.rate_time = 0;                                      \
} G_STMT_END

struct _GstQueue
{
  GstElement element;

  /*< private > */
  GstPad *sinkpad;
  GstPad *srcpad;

  /* segments to keep track of timestamps */
  GstSegment sink_segment;
  GstSegment src_segment;

  /* flowreturn when srcpad is paused */
  GstFlowReturn srcresult;
  gboolean is_eos;
  gboolean unexpected;

  /* the queue of data we're keeping our hands on */
  GQueue *queue;

  GstQueueSize cur_level;       /* currently in the queue */
  GstQueueSize max_level;       /* max. amount of data allowed in the queue */
  gboolean use_buffering;
  gboolean use_rate_estimate;
  GstClockTime buffering_interval;
  gint low_percent;             /* low/high watermarks for buffering */
  gint high_percent;

  /* current buffering state */
  gboolean is_buffering;
  guint buffering_iteration;

  /* for measuring input/output rates */
  GTimer *in_timer;
  gboolean in_timer_started;
  gdouble last_in_elapsed;
  guint64 bytes_in;
  gdouble byte_in_rate;

  GTimer *out_timer;
  gboolean out_timer_started;
  gdouble last_out_elapsed;
  guint64 bytes_out;
  gdouble byte_out_rate;

  GMutex *qlock;                /* lock for queue (vs object lock) */
  gboolean waiting_add;
  GCond *item_add;              /* signals buffers now available for reading */
  gboolean waiting_del;
  GCond *item_del;              /* signals space now available for writing */

  /* temp location stuff */
  gchar *temp_location;
  FILE *temp_file;
  guint64 writing_pos;
  guint64 reading_pos;
  /* we need this to send the first new segment event of the stream
   * because we can't save it on the file */
  gboolean segment_event_received;
  GstEvent *starting_segment;

};

struct _GstQueueClass
{
  GstElementClass parent_class;
};

#define STATUS(queue, pad, msg) \
  GST_CAT_LOG_OBJECT (queue_dataflow, queue, \
                      "(%s:%s) " msg ": %u of %u buffers, %u of %u " \
                      "bytes, %" G_GUINT64_FORMAT " of %" G_GUINT64_FORMAT \
                      " ns, %"G_GUINT64_FORMAT" items", \
                      GST_DEBUG_PAD_NAME (pad), \
                      queue->cur_level.buffers, \
                      queue->max_level.buffers, \
                      queue->cur_level.bytes, \
                      queue->max_level.bytes, \
                      queue->cur_level.time, \
                      queue->max_level.time, \
                      (guint64) (QUEUE_IS_USING_TEMP_FILE(queue) ? \
                        queue->writing_pos - queue->reading_pos : \
                        queue->queue->length))

#define GST_QUEUE_MUTEX_LOCK(q) G_STMT_START {                          \
  g_mutex_lock (q->qlock);                                              \
} G_STMT_END

#define GST_QUEUE_MUTEX_LOCK_CHECK(q,label) G_STMT_START {              \
  GST_QUEUE_MUTEX_LOCK (q);                                             \
  if (q->srcresult != GST_FLOW_OK)                                      \
    goto label;                                                         \
} G_STMT_END

#define GST_QUEUE_MUTEX_UNLOCK(q) G_STMT_START {                        \
  g_mutex_unlock (q->qlock);                                            \
} G_STMT_END

#define GST_QUEUE_WAIT_DEL_CHECK(q, label) G_STMT_START {               \
  STATUS (queue, q->sinkpad, "wait for DEL");                           \
  q->waiting_del = TRUE;                                                \
  g_cond_wait (q->item_del, queue->qlock);                              \
  q->waiting_del = FALSE;                                               \
  if (q->srcresult != GST_FLOW_OK) {                                    \
    STATUS (queue, q->srcpad, "received DEL wakeup");                   \
    goto label;                                                         \
  }                                                                     \
  STATUS (queue, q->sinkpad, "received DEL");                           \
} G_STMT_END

#define GST_QUEUE_WAIT_ADD_CHECK(q, label) G_STMT_START {               \
  STATUS (queue, q->srcpad, "wait for ADD");                            \
  q->waiting_add = TRUE;                                                \
  g_cond_wait (q->item_add, q->qlock);                                  \
  q->waiting_add = FALSE;                                               \
  if (q->srcresult != GST_FLOW_OK) {                                    \
    STATUS (queue, q->srcpad, "received ADD wakeup");                   \
    goto label;                                                         \
  }                                                                     \
  STATUS (queue, q->srcpad, "received ADD");                            \
} G_STMT_END

#define GST_QUEUE_SIGNAL_DEL(q) G_STMT_START {                          \
  if (q->waiting_del) {                                                 \
    STATUS (q, q->srcpad, "signal DEL");                                \
    g_cond_signal (q->item_del);                                        \
  }                                                                     \
} G_STMT_END

#define GST_QUEUE_SIGNAL_ADD(q) G_STMT_START {                          \
  if (q->waiting_add) {                                                 \
    STATUS (q, q->sinkpad, "signal ADD");                               \
    g_cond_signal (q->item_add);                                        \
  }                                                                     \
} G_STMT_END

#define _do_init(bla) \

/* can't use boilerplate as we need to register with Queue2 to avoid conflicts
 * with queue in core elements */
static void gst_queue_class_init (GstQueueClass * klass);
static void gst_queue_init (GstQueue * queue, GstQueueClass * g_class);
static GstElementClass *parent_class;

static GType
gst_queue_get_type (void)
{
  static GType gst_queue_type = 0;

  if (!gst_queue_type) {
    static const GTypeInfo gst_queue_info = {
      sizeof (GstQueueClass),
      NULL,
      NULL,
      (GClassInitFunc) gst_queue_class_init,
      NULL,
      NULL,
      sizeof (GstQueue),
      0,
      (GInstanceInitFunc) gst_queue_init,
      NULL
    };

    gst_queue_type =
        g_type_register_static (GST_TYPE_ELEMENT, "GstQueue2",
        &gst_queue_info, 0);
  }
  return gst_queue_type;
}

static void gst_queue_finalize (GObject * object);

static void gst_queue_set_property (GObject * object,
    guint prop_id, const GValue * value, GParamSpec * pspec);
static void gst_queue_get_property (GObject * object,
    guint prop_id, GValue * value, GParamSpec * pspec);

static GstFlowReturn gst_queue_chain (GstPad * pad, GstBuffer * buffer);
static GstFlowReturn gst_queue_bufferalloc (GstPad * pad, guint64 offset,
    guint size, GstCaps * caps, GstBuffer ** buf);
static GstFlowReturn gst_queue_push_one (GstQueue * queue);
static void gst_queue_loop (GstPad * pad);

static gboolean gst_queue_handle_sink_event (GstPad * pad, GstEvent * event);

static gboolean gst_queue_handle_src_event (GstPad * pad, GstEvent * event);
static gboolean gst_queue_handle_src_query (GstPad * pad, GstQuery * query);

static GstCaps *gst_queue_getcaps (GstPad * pad);

static GstFlowReturn gst_queue_get_range (GstPad * pad, guint64 offset,
    guint length, GstBuffer ** buffer);
static gboolean gst_queue_src_checkgetrange_function (GstPad * pad);

static gboolean gst_queue_src_activate_pull (GstPad * pad, gboolean active);
static gboolean gst_queue_src_activate_push (GstPad * pad, gboolean active);
static gboolean gst_queue_sink_activate_push (GstPad * pad, gboolean active);
static GstStateChangeReturn gst_queue_change_state (GstElement * element,
    GstStateChange transition);

static gboolean gst_queue_is_empty (GstQueue * queue);
static gboolean gst_queue_is_filled (GstQueue * queue);

/* static guint gst_queue_signals[LAST_SIGNAL] = { 0 }; */

static void
gst_queue_class_init (GstQueueClass * klass)
{
  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
  GstElementClass *gstelement_class = GST_ELEMENT_CLASS (klass);

  parent_class = g_type_class_peek_parent (klass);

  gobject_class->set_property = GST_DEBUG_FUNCPTR (gst_queue_set_property);
  gobject_class->get_property = GST_DEBUG_FUNCPTR (gst_queue_get_property);

  /* properties */
  g_object_class_install_property (gobject_class, PROP_CUR_LEVEL_BYTES,
      g_param_spec_uint ("current-level-bytes", "Current level (kB)",
          "Current amount of data in the queue (bytes)",
          0, G_MAXUINT, 0, G_PARAM_READABLE));
  g_object_class_install_property (gobject_class, PROP_CUR_LEVEL_BUFFERS,
      g_param_spec_uint ("current-level-buffers", "Current level (buffers)",
          "Current number of buffers in the queue",
          0, G_MAXUINT, 0, G_PARAM_READABLE));
  g_object_class_install_property (gobject_class, PROP_CUR_LEVEL_TIME,
      g_param_spec_uint64 ("current-level-time", "Current level (ns)",
          "Current amount of data in the queue (in ns)",
          0, G_MAXUINT64, 0, G_PARAM_READABLE));

  g_object_class_install_property (gobject_class, PROP_MAX_SIZE_BYTES,
      g_param_spec_uint ("max-size-bytes", "Max. size (kB)",
          "Max. amount of data in the queue (bytes, 0=disable)",
          0, G_MAXUINT, DEFAULT_MAX_SIZE_BYTES, G_PARAM_READWRITE));
  g_object_class_install_property (gobject_class, PROP_MAX_SIZE_BUFFERS,
      g_param_spec_uint ("max-size-buffers", "Max. size (buffers)",
          "Max. number of buffers in the queue (0=disable)",
          0, G_MAXUINT, DEFAULT_MAX_SIZE_BUFFERS, G_PARAM_READWRITE));
  g_object_class_install_property (gobject_class, PROP_MAX_SIZE_TIME,
      g_param_spec_uint64 ("max-size-time", "Max. size (ns)",
          "Max. amount of data in the queue (in ns, 0=disable)",
          0, G_MAXUINT64, DEFAULT_MAX_SIZE_TIME, G_PARAM_READWRITE));

  g_object_class_install_property (gobject_class, PROP_USE_BUFFERING,
      g_param_spec_boolean ("use-buffering", "Use buffering",
          "Emit GST_MESSAGE_BUFFERING based on low-/high-percent thresholds",
          DEFAULT_USE_BUFFERING, G_PARAM_READWRITE));
  g_object_class_install_property (gobject_class, PROP_USE_RATE_ESTIMATE,
      g_param_spec_boolean ("use-rate-estimate", "Use Rate Estimate",
          "Estimate the bitrate of the stream to calculate time level",
          DEFAULT_USE_RATE_ESTIMATE, G_PARAM_READWRITE));
  g_object_class_install_property (gobject_class, PROP_LOW_PERCENT,
      g_param_spec_int ("low-percent", "Low percent",
          "Low threshold for buffering to start",
          0, 100, DEFAULT_LOW_PERCENT, G_PARAM_READWRITE));
  g_object_class_install_property (gobject_class, PROP_HIGH_PERCENT,
      g_param_spec_int ("high-percent", "High percent",
          "High threshold for buffering to finish",
          0, 100, DEFAULT_HIGH_PERCENT, G_PARAM_READWRITE));

  g_object_class_install_property (gobject_class, PROP_TEMP_LOCATION,
      g_param_spec_string ("temp-location", "Temporary File Location",
          "Location of a temporary file to store data in",
          NULL, G_PARAM_READWRITE));

  gst_element_class_add_pad_template (gstelement_class,
      gst_static_pad_template_get (&srctemplate));
  gst_element_class_add_pad_template (gstelement_class,
      gst_static_pad_template_get (&sinktemplate));

  gst_element_class_set_details (gstelement_class, &gst_queue_details);

  /* set several parent class virtual functions */
  gobject_class->finalize = GST_DEBUG_FUNCPTR (gst_queue_finalize);

  gstelement_class->change_state = GST_DEBUG_FUNCPTR (gst_queue_change_state);
}

static void
gst_queue_init (GstQueue * queue, GstQueueClass * g_class)
{
  queue->sinkpad = gst_pad_new_from_static_template (&sinktemplate, "sink");

  gst_pad_set_chain_function (queue->sinkpad,
      GST_DEBUG_FUNCPTR (gst_queue_chain));
  gst_pad_set_activatepush_function (queue->sinkpad,
      GST_DEBUG_FUNCPTR (gst_queue_sink_activate_push));
  gst_pad_set_event_function (queue->sinkpad,
      GST_DEBUG_FUNCPTR (gst_queue_handle_sink_event));
  gst_pad_set_getcaps_function (queue->sinkpad,
      GST_DEBUG_FUNCPTR (gst_queue_getcaps));
  gst_pad_set_bufferalloc_function (queue->sinkpad,
      GST_DEBUG_FUNCPTR (gst_queue_bufferalloc));
  gst_element_add_pad (GST_ELEMENT (queue), queue->sinkpad);

  queue->srcpad = gst_pad_new_from_static_template (&srctemplate, "src");

  gst_pad_set_activatepull_function (queue->srcpad,
      GST_DEBUG_FUNCPTR (gst_queue_src_activate_pull));
  gst_pad_set_activatepush_function (queue->srcpad,
      GST_DEBUG_FUNCPTR (gst_queue_src_activate_push));
  gst_pad_set_getrange_function (queue->srcpad,
      GST_DEBUG_FUNCPTR (gst_queue_get_range));
  gst_pad_set_checkgetrange_function (queue->srcpad,
      GST_DEBUG_FUNCPTR (gst_queue_src_checkgetrange_function));
  gst_pad_set_getcaps_function (queue->srcpad,
      GST_DEBUG_FUNCPTR (gst_queue_getcaps));
  gst_pad_set_event_function (queue->srcpad,
      GST_DEBUG_FUNCPTR (gst_queue_handle_src_event));
  gst_pad_set_query_function (queue->srcpad,
      GST_DEBUG_FUNCPTR (gst_queue_handle_src_query));
  gst_element_add_pad (GST_ELEMENT (queue), queue->srcpad);

  /* levels */
  GST_QUEUE_CLEAR_LEVEL (queue->cur_level);
  queue->max_level.buffers = DEFAULT_MAX_SIZE_BUFFERS;
  queue->max_level.bytes = DEFAULT_MAX_SIZE_BYTES;
  queue->max_level.time = DEFAULT_MAX_SIZE_TIME;
  queue->max_level.rate_time = DEFAULT_MAX_SIZE_TIME;
  queue->use_buffering = DEFAULT_USE_BUFFERING;
  queue->use_rate_estimate = DEFAULT_USE_RATE_ESTIMATE;
  queue->low_percent = DEFAULT_LOW_PERCENT;
  queue->high_percent = DEFAULT_HIGH_PERCENT;

  gst_segment_init (&queue->sink_segment, GST_FORMAT_TIME);
  gst_segment_init (&queue->src_segment, GST_FORMAT_TIME);

  queue->srcresult = GST_FLOW_WRONG_STATE;
  queue->is_eos = FALSE;
  queue->in_timer = g_timer_new ();
  queue->out_timer = g_timer_new ();

  queue->qlock = g_mutex_new ();
  queue->waiting_add = FALSE;
  queue->item_add = g_cond_new ();
  queue->waiting_del = FALSE;
  queue->item_del = g_cond_new ();
  queue->queue = g_queue_new ();

  /* tempfile related */
  queue->temp_location = NULL;
  queue->temp_file = NULL;

  GST_DEBUG_OBJECT (queue,
      "initialized queue's not_empty & not_full conditions");
}

/* called only once, as opposed to dispose */
static void
gst_queue_finalize (GObject * object)
{
  GstQueue *queue = GST_QUEUE (object);

  GST_DEBUG_OBJECT (queue, "finalizing queue");

  while (!g_queue_is_empty (queue->queue)) {
    GstMiniObject *data = g_queue_pop_head (queue->queue);

    gst_mini_object_unref (data);
  }

  g_queue_free (queue->queue);
  g_mutex_free (queue->qlock);
  g_cond_free (queue->item_add);
  g_cond_free (queue->item_del);
  g_timer_destroy (queue->in_timer);
  g_timer_destroy (queue->out_timer);

  /* temp_file path cleanup  */
  if (queue->temp_location != NULL)
    g_free (queue->temp_location);

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

static GstCaps *
gst_queue_getcaps (GstPad * pad)
{
  GstQueue *queue;
  GstPad *otherpad;
  GstCaps *result;

  queue = GST_QUEUE (GST_PAD_PARENT (pad));

  otherpad = (pad == queue->srcpad ? queue->sinkpad : queue->srcpad);
  result = gst_pad_peer_get_caps (otherpad);
  if (result == NULL)
    result = gst_caps_new_any ();

  return result;
}

static GstFlowReturn
gst_queue_bufferalloc (GstPad * pad, guint64 offset, guint size, GstCaps * caps,
    GstBuffer ** buf)
{
  GstQueue *queue;
  GstFlowReturn result;

  queue = GST_QUEUE (GST_PAD_PARENT (pad));

  /* Forward to src pad, without setting caps on the src pad */
  result = gst_pad_alloc_buffer (queue->srcpad, offset, size, caps, buf);

  return result;
}

/* calculate the diff between running time on the sink and src of the queue.
 * This is the total amount of time in the queue. */
static void
update_time_level (GstQueue * queue)
{
  gint64 sink_time, src_time;

  sink_time =
      gst_segment_to_running_time (&queue->sink_segment, GST_FORMAT_TIME,
      queue->sink_segment.last_stop);

  src_time = gst_segment_to_running_time (&queue->src_segment, GST_FORMAT_TIME,
      queue->src_segment.last_stop);

  GST_DEBUG_OBJECT (queue, "sink %" GST_TIME_FORMAT ", src %" GST_TIME_FORMAT,
      GST_TIME_ARGS (sink_time), GST_TIME_ARGS (src_time));

  if (sink_time >= src_time)
    queue->cur_level.time = sink_time - src_time;
  else
    queue->cur_level.time = 0;
}

/* take a NEWSEGMENT event and apply the values to segment, updating the time
 * level of queue. */
static void
apply_segment (GstQueue * queue, GstEvent * event, GstSegment * segment)
{
  gboolean update;
  GstFormat format;
  gdouble rate, arate;
  gint64 start, stop, time;

  gst_event_parse_new_segment_full (event, &update, &rate, &arate,
      &format, &start, &stop, &time);

  GST_DEBUG_OBJECT (queue,
      "received NEWSEGMENT update %d, rate %lf, applied rate %lf, "
      "format %d, "
      "%" G_GINT64_FORMAT " -- %" G_GINT64_FORMAT ", time %"
      G_GINT64_FORMAT, update, rate, arate, format, start, stop, time);

  if (format == GST_FORMAT_BYTES) {
  }

  /* now configure the values, we use these to track timestamps on the
   * sinkpad. */
  if (format != GST_FORMAT_TIME) {
    /* non-time format, pretent the current time segment is closed with a
     * 0 start and unknown stop time. */
    update = FALSE;
    format = GST_FORMAT_TIME;
    start = 0;
    stop = -1;
    time = 0;
  }
  gst_segment_set_newsegment_full (segment, update,
      rate, arate, format, start, stop, time);

  GST_DEBUG_OBJECT (queue,
      "configured NEWSEGMENT %" GST_SEGMENT_FORMAT, segment);

  /* segment can update the time level of the queue */
  update_time_level (queue);
}

/* take a buffer and update segment, updating the time level of the queue. */
static void
apply_buffer (GstQueue * queue, GstBuffer * buffer, GstSegment * segment)
{
  GstClockTime duration, timestamp;

  timestamp = GST_BUFFER_TIMESTAMP (buffer);
  duration = GST_BUFFER_DURATION (buffer);

  /* if no timestamp is set, assume it's continuous with the previous 
   * time */
  if (timestamp == GST_CLOCK_TIME_NONE)
    timestamp = segment->last_stop;

  /* add duration */
  if (duration != GST_CLOCK_TIME_NONE)
    timestamp += duration;

  GST_DEBUG_OBJECT (queue, "last_stop updated to %" GST_TIME_FORMAT,
      GST_TIME_ARGS (timestamp));

  gst_segment_set_last_stop (segment, GST_FORMAT_TIME, timestamp);

  /* calc diff with other end */
  update_time_level (queue);
}

static void
update_buffering (GstQueue * queue)
{
  gint percent;
  gboolean post = FALSE;

  if (!queue->use_buffering || queue->high_percent <= 0)
    return;

#define GET_PERCENT(format) ((queue->max_level.format) > 0 ? \
		(queue->cur_level.format) * 100 / (queue->max_level.format) : 0)

  if (queue->is_eos) {
    /* on EOS we are always 100% full, we set the var here so that it we can
     * resue the logic below to stop buffering */
    percent = 100;
  } else {
    /* figure out the percent we are filled, we take the max of all formats. */
    percent = GET_PERCENT (bytes);
    percent = MAX (percent, GET_PERCENT (time));
    percent = MAX (percent, GET_PERCENT (buffers));

    /* also apply the rate estimate when we need to */
    if (queue->use_rate_estimate)
      percent = MAX (percent, GET_PERCENT (rate_time));
  }

  if (queue->is_buffering) {
    post = TRUE;
    /* if we were buffering see if we reached the high watermark */
    if (percent >= queue->high_percent)
      queue->is_buffering = FALSE;
  } else {
    /* we were not buffering, check if we need to start buffering if we drop
     * below the low threshold */
    if (percent < queue->low_percent) {
      queue->is_buffering = TRUE;
      queue->buffering_iteration++;
      post = TRUE;
    }
  }
  if (post) {
    /* scale to high percent so that it becomes the 100% mark */
    percent = percent * 100 / queue->high_percent;
    /* clip */
    if (percent > 100)
      percent = 100;

    GST_DEBUG_OBJECT (queue, "buffering %d percent", percent);
    gst_element_post_message (GST_ELEMENT_CAST (queue),
        gst_message_new_buffering (GST_OBJECT_CAST (queue), percent));
  } else {
    GST_DEBUG_OBJECT (queue, "filled %d percent", percent);
  }

#undef GET_PERCENT
}

static void
reset_rate_timer (GstQueue * queue)
{
  queue->bytes_in = 0;
  queue->bytes_out = 0;
  queue->byte_in_rate = 0.0;
  queue->byte_out_rate = 0.0;
  queue->last_in_elapsed = 0.0;
  queue->last_out_elapsed = 0.0;
  queue->in_timer_started = FALSE;
  queue->out_timer_started = FALSE;
}

/* the interval in seconds to recalculate the rate */
#define RATE_INTERVAL    0.2
/* Tuning for rate estimation. We use a large window for the input rate because
 * it should be stable when connected to a network. The output rate is less
 * stable (the elements preroll, queues behind a demuxer fill, ...) and should
 * therefore adapt more quickly. */
#define AVG_IN(avg,val)  ((avg) * 15.0 + (val)) / 16.0
#define AVG_OUT(avg,val) ((avg) * 3.0 + (val)) / 4.0

static void
update_in_rates (GstQueue * queue)
{
  gdouble elapsed, period;
  gdouble byte_in_rate;

  if (!queue->in_timer_started) {
    queue->in_timer_started = TRUE;
    g_timer_start (queue->in_timer);
    return;
  }

  elapsed = g_timer_elapsed (queue->in_timer, NULL);

  /* recalc after each interval. */
  if (queue->last_in_elapsed + RATE_INTERVAL < elapsed) {
    period = elapsed - queue->last_in_elapsed;

    GST_DEBUG_OBJECT (queue,
        "rates: period %f, in %" G_GUINT64_FORMAT, period, queue->bytes_in);

    byte_in_rate = queue->bytes_in / period;

    if (queue->byte_in_rate == 0.0)
      queue->byte_in_rate = byte_in_rate;
    else
      queue->byte_in_rate = AVG_IN (queue->byte_in_rate, byte_in_rate);

    /* reset the values to calculate rate over the next interval */
    queue->last_in_elapsed = elapsed;
    queue->bytes_in = 0;
  }

  if (queue->byte_in_rate > 0.0) {
    queue->cur_level.rate_time =
        queue->cur_level.bytes / queue->byte_in_rate * GST_SECOND;
  }
  GST_DEBUG_OBJECT (queue, "rates: in %f, time %" GST_TIME_FORMAT,
      queue->byte_in_rate, GST_TIME_ARGS (queue->cur_level.rate_time));
}

static void
update_out_rates (GstQueue * queue)
{
  gdouble elapsed, period;
  gdouble byte_out_rate;

  if (!queue->out_timer_started) {
    queue->out_timer_started = TRUE;
    g_timer_start (queue->out_timer);
    return;
  }

  elapsed = g_timer_elapsed (queue->out_timer, NULL);

  /* recalc after each interval. */
  if (queue->last_out_elapsed + RATE_INTERVAL < elapsed) {
    period = elapsed - queue->last_out_elapsed;

    GST_DEBUG_OBJECT (queue,
        "rates: period %f, out %" G_GUINT64_FORMAT, period, queue->bytes_out);

    byte_out_rate = queue->bytes_out / period;

    if (queue->byte_out_rate == 0.0)
      queue->byte_out_rate = byte_out_rate;
    else
      queue->byte_out_rate = AVG_OUT (queue->byte_out_rate, byte_out_rate);

    /* reset the values to calculate rate over the next interval */
    queue->last_out_elapsed = elapsed;
    queue->bytes_out = 0;
  }
  GST_DEBUG_OBJECT (queue, "rates: out %f, time %" GST_TIME_FORMAT,
      queue->byte_out_rate, GST_TIME_ARGS (queue->cur_level.rate_time));
}

static void
gst_queue_write_buffer_to_file (GstQueue * queue, GstBuffer * buffer)
{
  guint size;
  guint8 *data;
  int ret;

  fseek (queue->temp_file, queue->writing_pos, SEEK_SET);

  data = GST_BUFFER_DATA (buffer);
  size = GST_BUFFER_SIZE (buffer);

  ret = fwrite (data, 1, size, queue->temp_file);
  if (ret < size) {
    /* FIXME do something useful here */
    GST_ERROR_OBJECT (queue, "fwrite returned error");
  }
  queue->writing_pos += size;
}

/* see if there is enough data in the file to read a full buffer */
static gboolean
gst_queue_have_data (GstQueue * queue, guint64 offset, guint length)
{
  GST_DEBUG_OBJECT (queue,
      "offset %" G_GUINT64_FORMAT ", len %u, write %" G_GUINT64_FORMAT, offset,
      length, queue->writing_pos);
  if (queue->is_eos)
    return TRUE;

  if (offset + length < queue->writing_pos)
    return TRUE;

  return FALSE;
}

static GstFlowReturn
gst_queue_create_read (GstQueue * queue, guint64 offset, guint length,
    GstBuffer ** buffer)
{
  size_t res;
  GstBuffer *buf;

  /* check if we have enough data at @offset. If there is not enough data, we
   * block and wait. */
  while (!gst_queue_have_data (queue, offset, length)) {
    GST_QUEUE_WAIT_ADD_CHECK (queue, out_flushing);
  }

#ifdef HAVE_FSEEKO
  if (fseeko (queue->temp_file, (off_t) offset, SEEK_SET) != 0)
    goto seek_failed;
#elif defined (G_OS_UNIX)
  if (lseek (fileno (queue->temp_file), (off_t) offset,
          SEEK_SET) == (off_t) - 1)
    goto seek_failed;
#else
  if (fseek (queue->temp_file, (long) offset, SEEK_SET) != 0)
    goto seek_failed;
#endif

  buf = gst_buffer_new_and_alloc (length);

  /* this should not block */
  GST_LOG_OBJECT (queue, "Reading %d bytes", length);
  res = fread (GST_BUFFER_DATA (buf), 1, length, queue->temp_file);
  GST_LOG_OBJECT (queue, "read %" G_GSIZE_FORMAT " bytes", res);

  if (G_UNLIKELY (res == 0)) {
    /* check for errors or EOF */
    if (ferror (queue->temp_file))
      goto could_not_read;
    if (feof (queue->temp_file) && length > 0)
      goto eos;
  }

  length = res;

  GST_BUFFER_SIZE (buf) = length;
  GST_BUFFER_OFFSET (buf) = offset;
  GST_BUFFER_OFFSET_END (buf) = offset + length;

  *buffer = buf;

  queue->reading_pos = offset + length;

  return GST_FLOW_OK;

  /* ERRORS */
out_flushing:
  {
    GST_DEBUG_OBJECT (queue, "we are flushing");
    return GST_FLOW_WRONG_STATE;
  }
seek_failed:
  {
    GST_ELEMENT_ERROR (queue, RESOURCE, READ, (NULL), GST_ERROR_SYSTEM);
    return GST_FLOW_ERROR;
  }
could_not_read:
  {
    GST_ELEMENT_ERROR (queue, RESOURCE, READ, (NULL), GST_ERROR_SYSTEM);
    gst_buffer_unref (buf);
    return GST_FLOW_ERROR;
  }
eos:
  {
    GST_DEBUG ("non-regular file hits EOS");
    gst_buffer_unref (buf);
    return GST_FLOW_UNEXPECTED;
  }
}

/* should be called with QUEUE_LOCK */
static GstMiniObject *
gst_queue_read_item_from_file (GstQueue * queue)
{
  GstMiniObject *item;

  if (queue->starting_segment != NULL) {
    item = GST_MINI_OBJECT_CAST (queue->starting_segment);
    queue->starting_segment = NULL;
  } else {
    GstFlowReturn ret;
    GstBuffer *buffer;

    ret =
        gst_queue_create_read (queue, queue->reading_pos, DEFAULT_BUFFER_SIZE,
        &buffer);
    switch (ret) {
      case GST_FLOW_OK:
        item = GST_MINI_OBJECT_CAST (buffer);
        break;
      case GST_FLOW_UNEXPECTED:
        item = GST_MINI_OBJECT_CAST (gst_event_new_eos ());
        break;
      default:
        item = NULL;
        break;
    }
  }
  return item;
}

static gboolean
gst_queue_open_temp_location_file (GstQueue * queue)
{
  /* nothing to do */
  if (queue->temp_location == NULL)
    goto no_filename;

  /* open the file for update/writing */
  queue->temp_file = g_fopen (queue->temp_location, "wb+");
  /* error creating file */
  if (queue->temp_file == NULL)
    goto open_failed;

  queue->writing_pos = 0;
  queue->reading_pos = 0;

  return TRUE;

  /* ERRORS */
no_filename:
  {
    GST_ELEMENT_ERROR (queue, RESOURCE, NOT_FOUND,
        (_("No file name specified.")), (NULL));
    return FALSE;
  }
open_failed:
  {
    GST_ELEMENT_ERROR (queue, RESOURCE, OPEN_READ,
        (_("Could not open file \"%s\" for reading."), queue->temp_location),
        GST_ERROR_SYSTEM);
    return FALSE;
  }
}

static void
gst_queue_close_temp_location_file (GstQueue * queue)
{
  /* nothing to do */
  if (queue->temp_file == NULL)
    return;

  /* we don't remove the file so that the application can use it as a cache
   * later on */
  fflush (queue->temp_file);
  fclose (queue->temp_file);
  remove (queue->temp_location);
  queue->temp_file = NULL;
}

static void
gst_queue_locked_flush (GstQueue * queue)
{
  if (QUEUE_IS_USING_TEMP_FILE (queue)) {
    gst_queue_close_temp_location_file (queue);
    gst_queue_open_temp_location_file (queue);
  } else {
    while (!g_queue_is_empty (queue->queue)) {
      GstMiniObject *data = g_queue_pop_head (queue->queue);

      /* Then lose another reference because we are supposed to destroy that
         data when flushing */
      gst_mini_object_unref (data);
    }
  }
  GST_QUEUE_CLEAR_LEVEL (queue->cur_level);
  gst_segment_init (&queue->sink_segment, GST_FORMAT_TIME);
  gst_segment_init (&queue->src_segment, GST_FORMAT_TIME);
  if (queue->starting_segment != NULL)
    gst_event_unref (queue->starting_segment);
  queue->starting_segment = NULL;
  queue->segment_event_received = FALSE;

  /* we deleted a lot of something */
  GST_QUEUE_SIGNAL_DEL (queue);
}

/* enqueue an item an update the level stats */
static void
gst_queue_locked_enqueue (GstQueue * queue, gpointer item)
{
  if (GST_IS_BUFFER (item)) {
    GstBuffer *buffer;
    guint size;

    buffer = GST_BUFFER_CAST (item);
    size = GST_BUFFER_SIZE (buffer);

    /* add buffer to the statistics */
    queue->cur_level.buffers++;
    queue->cur_level.bytes += size;
    queue->bytes_in += size;
    /* apply new buffer to segment stats */
    apply_buffer (queue, buffer, &queue->sink_segment);
    /* update the byterate stats */
    update_in_rates (queue);

    if (QUEUE_IS_USING_TEMP_FILE (queue)) {
      gst_queue_write_buffer_to_file (queue, buffer);
    }

  } else if (GST_IS_EVENT (item)) {
    GstEvent *event;

    event = GST_EVENT_CAST (item);

    switch (GST_EVENT_TYPE (event)) {
      case GST_EVENT_EOS:
        /* Zero the thresholds, this makes sure the queue is completely
         * filled and we can read all data from the queue. */
        queue->is_eos = TRUE;
        break;
      case GST_EVENT_NEWSEGMENT:
        apply_segment (queue, event, &queue->sink_segment);
        /* This is our first new segment, we hold it
         * as we can't save it on the temp file */
        if (QUEUE_IS_USING_TEMP_FILE (queue)) {
          if (queue->segment_event_received)
            goto unexpected_event;

          queue->segment_event_received = TRUE;
          queue->starting_segment = event;
        }
        /* a new segment allows us to accept more buffers if we got UNEXPECTED
         * from downstream */
        queue->unexpected = FALSE;
        break;
      default:
        if (QUEUE_IS_USING_TEMP_FILE (queue))
          goto unexpected_event;
        break;
    }
  } else {
    g_warning ("Unexpected item %p added in queue %s (refcounting problem?)",
        item, GST_OBJECT_NAME (queue));
    /* we can't really unref since we don't know what it is */
    item = NULL;
  }

  if (item) {
    /* update the buffering status */
    update_buffering (queue);

    if (!QUEUE_IS_USING_TEMP_FILE (queue))
      g_queue_push_tail (queue->queue, item);
    GST_QUEUE_SIGNAL_ADD (queue);
  }

  return;

  /* ERRORS */
unexpected_event:
  {
    g_warning
        ("Unexpected event of kind %s can't be added in temp file of queue %s ",
        gst_event_type_get_name (GST_EVENT_TYPE (item)),
        GST_OBJECT_NAME (queue));
    gst_event_unref (GST_EVENT_CAST (item));
    return;
  }
}

/* dequeue an item from the queue and update level stats */
static GstMiniObject *
gst_queue_locked_dequeue (GstQueue * queue)
{
  GstMiniObject *item;

  if (QUEUE_IS_USING_TEMP_FILE (queue))
    item = gst_queue_read_item_from_file (queue);
  else
    item = g_queue_pop_head (queue->queue);

  if (item == NULL)
    goto no_item;

  if (GST_IS_BUFFER (item)) {
    GstBuffer *buffer;
    guint size;

    buffer = GST_BUFFER_CAST (item);
    size = GST_BUFFER_SIZE (buffer);

    GST_CAT_LOG_OBJECT (queue_dataflow, queue,
        "retrieved buffer %p from queue", buffer);

    queue->cur_level.buffers--;
    queue->cur_level.bytes -= size;
    queue->bytes_out += size;
    apply_buffer (queue, buffer, &queue->src_segment);
    /* update the byterate stats */
    update_out_rates (queue);
    /* update the buffering */
    update_buffering (queue);

  } else if (GST_IS_EVENT (item)) {
    GstEvent *event = GST_EVENT_CAST (item);

    GST_CAT_LOG_OBJECT (queue_dataflow, queue,
        "retrieved event %p from queue", event);

    switch (GST_EVENT_TYPE (event)) {
      case GST_EVENT_EOS:
        /* queue is empty now that we dequeued the EOS */
        GST_QUEUE_CLEAR_LEVEL (queue->cur_level);
        break;
      case GST_EVENT_NEWSEGMENT:
        apply_segment (queue, event, &queue->src_segment);
        break;
      default:
        break;
    }
  } else {
    g_warning
        ("Unexpected item %p dequeued from queue %s (refcounting problem?)",
        item, GST_OBJECT_NAME (queue));
    item = NULL;
  }
  GST_QUEUE_SIGNAL_DEL (queue);

  return item;

  /* ERRORS */
no_item:
  {
    GST_CAT_LOG_OBJECT (queue_dataflow, queue, "the queue is empty");
    return NULL;
  }
}

static gboolean
gst_queue_handle_sink_event (GstPad * pad, GstEvent * event)
{
  GstQueue *queue;

  queue = GST_QUEUE (GST_OBJECT_PARENT (pad));

  switch (GST_EVENT_TYPE (event)) {
    case GST_EVENT_FLUSH_START:
    {
      GST_CAT_LOG_OBJECT (queue_dataflow, queue, "received flush start event");
      /* forward event */
      gst_pad_push_event (queue->srcpad, event);

      /* now unblock the chain function */
      GST_QUEUE_MUTEX_LOCK (queue);
      queue->srcresult = GST_FLOW_WRONG_STATE;
      /* unblock the loop and chain functions */
      g_cond_signal (queue->item_add);
      g_cond_signal (queue->item_del);
      GST_QUEUE_MUTEX_UNLOCK (queue);

      /* make sure it pauses, this should happen since we sent
       * flush_start downstream. */
      gst_pad_pause_task (queue->srcpad);
      GST_CAT_LOG_OBJECT (queue_dataflow, queue, "loop stopped");
      goto done;
    }
    case GST_EVENT_FLUSH_STOP:
    {
      GST_CAT_LOG_OBJECT (queue_dataflow, queue, "received flush stop event");
      /* forward event */
      gst_pad_push_event (queue->srcpad, event);

      GST_QUEUE_MUTEX_LOCK (queue);
      gst_queue_locked_flush (queue);
      queue->srcresult = GST_FLOW_OK;
      queue->is_eos = FALSE;
      queue->unexpected = FALSE;
      /* reset rate counters */
      reset_rate_timer (queue);
      gst_pad_start_task (queue->srcpad, (GstTaskFunction) gst_queue_loop,
          queue->srcpad);
      GST_QUEUE_MUTEX_UNLOCK (queue);
      goto done;
    }
    default:
      if (GST_EVENT_IS_SERIALIZED (event)) {
        /* serialized events go in the queue */
        GST_QUEUE_MUTEX_LOCK_CHECK (queue, out_flushing);
        /* refuse more events on EOS */
        if (queue->is_eos)
          goto out_eos;
        gst_queue_locked_enqueue (queue, event);
        GST_QUEUE_MUTEX_UNLOCK (queue);
      } else {
        /* non-serialized events are passed upstream. */
        gst_pad_push_event (queue->srcpad, event);
      }
      break;
  }
done:
  return TRUE;

  /* ERRORS */
out_flushing:
  {
    GST_DEBUG_OBJECT (queue, "refusing event, we are flushing");
    GST_QUEUE_MUTEX_UNLOCK (queue);
    gst_event_unref (event);
    return FALSE;
  }
out_eos:
  {
    GST_DEBUG_OBJECT (queue, "refusing event, we are EOS");
    GST_QUEUE_MUTEX_UNLOCK (queue);
    gst_event_unref (event);
    return FALSE;
  }
}

static gboolean
gst_queue_is_empty (GstQueue * queue)
{
  /* never empty on EOS */
  if (queue->is_eos)
    return FALSE;

  if (QUEUE_IS_USING_TEMP_FILE (queue)) {
    return queue->writing_pos == queue->reading_pos;
  } else {
    if (queue->queue->length == 0)
      return TRUE;
  }

  return FALSE;
}

static gboolean
gst_queue_is_filled (GstQueue * queue)
{
  gboolean res;

  /* always filled on EOS */
  if (queue->is_eos)
    return TRUE;

  /* if using file, we're never filled if we don't have EOS */
  if (QUEUE_IS_USING_TEMP_FILE (queue))
    return FALSE;

#define CHECK_FILLED(format) ((queue->max_level.format) > 0 && \
		(queue->cur_level.format) >= (queue->max_level.format))

  /* we are filled if one of the current levels exceeds the max */
  res = CHECK_FILLED (buffers) || CHECK_FILLED (bytes) || CHECK_FILLED (time);

  /* if we need to, use the rate estimate to check against the max time we are
   * allowed to queue */
  if (queue->use_rate_estimate)
    res |= CHECK_FILLED (rate_time);

#undef CHECK_FILLED
  return res;
}

static GstFlowReturn
gst_queue_chain (GstPad * pad, GstBuffer * buffer)
{
  GstQueue *queue;

  queue = GST_QUEUE (GST_OBJECT_PARENT (pad));

  GST_CAT_LOG_OBJECT (queue_dataflow, queue,
      "received buffer %p of size %d, time %" GST_TIME_FORMAT ", duration %"
      GST_TIME_FORMAT, buffer, GST_BUFFER_SIZE (buffer),
      GST_TIME_ARGS (GST_BUFFER_TIMESTAMP (buffer)),
      GST_TIME_ARGS (GST_BUFFER_DURATION (buffer)));

  /* we have to lock the queue since we span threads */
  GST_QUEUE_MUTEX_LOCK_CHECK (queue, out_flushing);
  /* when we received EOS, we refuse more data */
  if (queue->is_eos)
    goto out_eos;
  /* when we received unexpected from downstream, refuse more buffers */
  if (queue->unexpected)
    goto out_unexpected;

  /* We make space available if we're "full" according to whatever
   * the user defined as "full". */
  if (gst_queue_is_filled (queue)) {
    gboolean started;

    /* pause the timer while we wait. The fact that we are waiting does not mean
     * the byterate on the input pad is lower */
    if ((started = queue->in_timer_started))
      g_timer_stop (queue->in_timer);

    GST_CAT_DEBUG_OBJECT (queue_dataflow, queue,
        "queue is full, waiting for free space");
    do {
      /* Wait for space to be available, we could be unlocked because of a flush. */
      GST_QUEUE_WAIT_DEL_CHECK (queue, out_flushing);
    }
    while (gst_queue_is_filled (queue));

    /* and continue if we were running before */
    if (started)
      g_timer_continue (queue->in_timer);
  }

  /* put buffer in queue now */
  gst_queue_locked_enqueue (queue, buffer);
  GST_QUEUE_MUTEX_UNLOCK (queue);

  return GST_FLOW_OK;

  /* special conditions */
out_flushing:
  {
    GstFlowReturn ret = queue->srcresult;

    GST_CAT_LOG_OBJECT (queue_dataflow, queue,
        "exit because task paused, reason: %s", gst_flow_get_name (ret));
    GST_QUEUE_MUTEX_UNLOCK (queue);
    gst_buffer_unref (buffer);

    return ret;
  }
out_eos:
  {
    GST_CAT_LOG_OBJECT (queue_dataflow, queue, "exit because we received EOS");
    GST_QUEUE_MUTEX_UNLOCK (queue);
    gst_buffer_unref (buffer);

    return GST_FLOW_UNEXPECTED;
  }
out_unexpected:
  {
    GST_CAT_LOG_OBJECT (queue_dataflow, queue,
        "exit because we received UNEXPECTED");
    GST_QUEUE_MUTEX_UNLOCK (queue);
    gst_buffer_unref (buffer);

    return GST_FLOW_UNEXPECTED;
  }
}

/* dequeue an item from the queue an push it downstream. This functions returns
 * the result of the push. */
static GstFlowReturn
gst_queue_push_one (GstQueue * queue)
{
  GstFlowReturn result = GST_FLOW_OK;
  GstMiniObject *data;

  data = gst_queue_locked_dequeue (queue);
  if (data == NULL)
    goto no_item;

next:
  if (GST_IS_BUFFER (data)) {
    GstBuffer *buffer;
    GstCaps *caps;

    buffer = GST_BUFFER_CAST (data);
    caps = GST_BUFFER_CAPS (buffer);

    GST_QUEUE_MUTEX_UNLOCK (queue);

    /* set caps before pushing the buffer so that core does not try to do
     * something fancy to check if this is possible. */
    if (caps && caps != GST_PAD_CAPS (queue->srcpad))
      gst_pad_set_caps (queue->srcpad, caps);

    result = gst_pad_push (queue->srcpad, buffer);

    /* need to check for srcresult here as well */
    GST_QUEUE_MUTEX_LOCK_CHECK (queue, out_flushing);
    if (result == GST_FLOW_UNEXPECTED) {
      GST_CAT_LOG_OBJECT (queue_dataflow, queue,
          "got UNEXPECTED from downstream");
      /* stop pushing buffers, we dequeue all items until we see an item that we
       * can push again, which is EOS or NEWSEGMENT. If there is nothing in the
       * queue we can push, we set a flag to make the sinkpad refuse more
       * buffers with an UNEXPECTED return value until we receive something
       * pushable again or we get flushed. */
      while ((data = gst_queue_locked_dequeue (queue))) {
        if (GST_IS_BUFFER (data)) {
          GST_CAT_LOG_OBJECT (queue_dataflow, queue,
              "dropping UNEXPECTED buffer %p", data);
          gst_buffer_unref (GST_BUFFER_CAST (data));
        } else if (GST_IS_EVENT (data)) {
          GstEvent *event = GST_EVENT_CAST (data);
          GstEventType type = GST_EVENT_TYPE (event);

          if (type == GST_EVENT_EOS || type == GST_EVENT_NEWSEGMENT) {
            /* we found a pushable item in the queue, push it out */
            GST_CAT_LOG_OBJECT (queue_dataflow, queue,
                "pushing pushable event %s after UNEXPECTED",
                GST_EVENT_TYPE_NAME (event));
            goto next;
          }
          GST_CAT_LOG_OBJECT (queue_dataflow, queue,
              "dropping UNEXPECTED event %p", event);
          gst_event_unref (event);
        }
      }
      /* no more items in the queue. Set the unexpected flag so that upstream
       * make us refuse any more buffers on the sinkpad. Since we will still
       * accept EOS and NEWSEGMENT we return _FLOW_OK to the caller so that the
       * task function does not shut down. */
      queue->unexpected = TRUE;
      result = GST_FLOW_OK;
    }
  } else if (GST_IS_EVENT (data)) {
    GstEvent *event = GST_EVENT_CAST (data);
    GstEventType type = GST_EVENT_TYPE (event);

    GST_QUEUE_MUTEX_UNLOCK (queue);

    gst_pad_push_event (queue->srcpad, event);

    GST_QUEUE_MUTEX_LOCK_CHECK (queue, out_flushing);
    /* if we're EOS, return UNEXPECTED so that the task pauses. */
    if (type == GST_EVENT_EOS) {
      GST_CAT_LOG_OBJECT (queue_dataflow, queue,
          "pushed EOS event %p, return UNEXPECTED", event);
      result = GST_FLOW_UNEXPECTED;
    }
  }
  return result;

  /* ERRORS */
no_item:
  {
    GST_CAT_LOG_OBJECT (queue_dataflow, queue,
        "exit because we have no item in the queue");
    return GST_FLOW_ERROR;
  }
out_flushing:
  {
    GST_CAT_LOG_OBJECT (queue_dataflow, queue, "exit because we are flushing");
    return GST_FLOW_WRONG_STATE;
  }
}

/* called repeadedly with @pad as the source pad. This function should push out
 * data to the peer element. */
static void
gst_queue_loop (GstPad * pad)
{
  GstQueue *queue;
  GstFlowReturn ret;

  queue = GST_QUEUE (GST_PAD_PARENT (pad));

  /* have to lock for thread-safety */
  GST_QUEUE_MUTEX_LOCK_CHECK (queue, out_flushing);

  if (gst_queue_is_empty (queue)) {
    gboolean started;

    /* pause the timer while we wait. The fact that we are waiting does not mean
     * the byterate on the output pad is lower */
    if ((started = queue->out_timer_started))
      g_timer_stop (queue->out_timer);

    GST_CAT_DEBUG_OBJECT (queue_dataflow, queue,
        "queue is empty, waiting for new data");
    do {
      /* Wait for data to be available, we could be unlocked because of a flush. */
      GST_QUEUE_WAIT_ADD_CHECK (queue, out_flushing);
    }
    while (gst_queue_is_empty (queue));

    /* and continue if we were running before */
    if (started)
      g_timer_continue (queue->out_timer);
  }
  ret = gst_queue_push_one (queue);
  queue->srcresult = ret;
  if (ret != GST_FLOW_OK)
    goto out_flushing;

  GST_QUEUE_MUTEX_UNLOCK (queue);

  return;

  /* ERRORS */
out_flushing:
  {
    gst_pad_pause_task (queue->srcpad);
    GST_CAT_LOG_OBJECT (queue_dataflow, queue,
        "pause task, reason:  %s", gst_flow_get_name (queue->srcresult));
    GST_QUEUE_MUTEX_UNLOCK (queue);
    return;
  }
}

static gboolean
gst_queue_handle_src_event (GstPad * pad, GstEvent * event)
{
  gboolean res = TRUE;
  GstQueue *queue = GST_QUEUE (GST_PAD_PARENT (pad));

#ifndef GST_DISABLE_GST_DEBUG
  GST_CAT_DEBUG_OBJECT (queue_dataflow, queue, "got event %p (%s)",
      event, GST_EVENT_TYPE_NAME (event));
#endif

  /* just forward upstream */
  res = gst_pad_push_event (queue->sinkpad, event);

  return res;
}

static gboolean
gst_queue_peer_query (GstQueue * queue, GstPad * pad, GstQuery * query)
{
  gboolean ret = FALSE;
  GstPad *peer;

  if ((peer = gst_pad_get_peer (pad))) {
    ret = gst_pad_query (peer, query);
    gst_object_unref (peer);
  }
  return ret;
}

static gboolean
gst_queue_handle_src_query (GstPad * pad, GstQuery * query)
{
  GstQueue *queue;

  queue = GST_QUEUE (GST_PAD_PARENT (pad));

  switch (GST_QUERY_TYPE (query)) {
    case GST_QUERY_POSITION:
    {
      gint64 peer_pos;
      GstFormat format;

      if (!gst_queue_peer_query (queue, queue->sinkpad, query))
        goto peer_failed;

      /* get peer position */
      gst_query_parse_position (query, &format, &peer_pos);

      /* FIXME: this code assumes that there's no discont in the queue */
      switch (format) {
        case GST_FORMAT_BYTES:
          peer_pos -= queue->cur_level.bytes;
          break;
        case GST_FORMAT_TIME:
          peer_pos -= queue->cur_level.time;
          break;
        default:
          GST_WARNING_OBJECT (queue, "dropping query in %s format, don't "
              "know how to adjust value", gst_format_get_name (format));
          return FALSE;
      }
      /* set updated position */
      gst_query_set_position (query, format, peer_pos);
      break;
    }
    case GST_QUERY_DURATION:
    {
      GST_DEBUG_OBJECT (queue, "waiting for preroll in duration query");

      GST_QUEUE_MUTEX_LOCK (queue);
      /* we have to wait until the upstream element is at least paused, which
       * happened when we received a first item. */
      while (gst_queue_is_empty (queue)) {
        GST_QUEUE_WAIT_ADD_CHECK (queue, flushing);
      }
      GST_QUEUE_MUTEX_UNLOCK (queue);

      if (!gst_queue_peer_query (queue, queue->sinkpad, query))
        goto peer_failed;

      GST_DEBUG_OBJECT (queue, "peer query success");
      break;
    }
    default:
      /* peer handled other queries */
      if (!gst_queue_peer_query (queue, queue->sinkpad, query))
        goto peer_failed;
      break;
  }

  return TRUE;

  /* ERRORS */
peer_failed:
  {
    GST_DEBUG_OBJECT (queue, "failed peer query");
    return FALSE;
  }
flushing:
  {
    GST_DEBUG_OBJECT (queue, "flushing while waiting for query");
    GST_QUEUE_MUTEX_UNLOCK (queue);
    return FALSE;
  }
}

static GstFlowReturn
gst_queue_get_range (GstPad * pad, guint64 offset, guint length,
    GstBuffer ** buffer)
{
  GstQueue *queue;
  GstFlowReturn ret;

  queue = GST_QUEUE_CAST (gst_pad_get_parent (pad));

  GST_QUEUE_MUTEX_LOCK_CHECK (queue, out_flushing);
  length = (length == -1) ? DEFAULT_BUFFER_SIZE : length;
  offset = (offset == -1) ? queue->reading_pos : offset;

  /* function will block when the range is not yet available */
  ret = gst_queue_create_read (queue, offset, length, buffer);
  GST_QUEUE_MUTEX_UNLOCK (queue);

  gst_object_unref (queue);

  return ret;

  /* ERRORS */
out_flushing:
  {
    GST_DEBUG_OBJECT (queue, "we are flushing");
    GST_QUEUE_MUTEX_UNLOCK (queue);
    return GST_FLOW_WRONG_STATE;
  }
}

static gboolean
gst_queue_src_checkgetrange_function (GstPad * pad)
{
  GstQueue *queue;
  gboolean ret;

  queue = GST_QUEUE (gst_pad_get_parent (pad));
  /* we can operate in pull mode when we are using a tempfile */
  ret = QUEUE_IS_USING_TEMP_FILE (queue);
  gst_object_unref (GST_OBJECT (queue));

  return ret;
}

/* sink currently only operates in push mode */
static gboolean
gst_queue_sink_activate_push (GstPad * pad, gboolean active)
{
  gboolean result = TRUE;
  GstQueue *queue;

  queue = GST_QUEUE (gst_pad_get_parent (pad));

  if (active) {
    GST_QUEUE_MUTEX_LOCK (queue);
    GST_DEBUG_OBJECT (queue, "activating push mode");
    queue->srcresult = GST_FLOW_OK;
    queue->is_eos = FALSE;
    queue->unexpected = FALSE;
    reset_rate_timer (queue);
    GST_QUEUE_MUTEX_UNLOCK (queue);
  } else {
    /* unblock chain function */
    GST_QUEUE_MUTEX_LOCK (queue);
    GST_DEBUG_OBJECT (queue, "deactivating push mode");
    queue->srcresult = GST_FLOW_WRONG_STATE;
    gst_queue_locked_flush (queue);
    GST_QUEUE_MUTEX_UNLOCK (queue);
  }

  gst_object_unref (queue);

  return result;
}

/* src operating in push mode, we start a task on the source pad that pushes out
 * buffers from the queue */
static gboolean
gst_queue_src_activate_push (GstPad * pad, gboolean active)
{
  gboolean result = FALSE;
  GstQueue *queue;

  queue = GST_QUEUE (gst_pad_get_parent (pad));

  if (active) {
    GST_QUEUE_MUTEX_LOCK (queue);
    GST_DEBUG_OBJECT (queue, "activating push mode");
    queue->srcresult = GST_FLOW_OK;
    queue->is_eos = FALSE;
    queue->unexpected = FALSE;
    result = gst_pad_start_task (pad, (GstTaskFunction) gst_queue_loop, pad);
    GST_QUEUE_MUTEX_UNLOCK (queue);
  } else {
    /* unblock loop function */
    GST_QUEUE_MUTEX_LOCK (queue);
    GST_DEBUG_OBJECT (queue, "deactivating push mode");
    queue->srcresult = GST_FLOW_WRONG_STATE;
    /* the item add signal will unblock */
    g_cond_signal (queue->item_add);
    GST_QUEUE_MUTEX_UNLOCK (queue);

    /* step 2, make sure streaming finishes */
    result = gst_pad_stop_task (pad);
  }

  gst_object_unref (queue);

  return result;
}

/* pull mode, downstream will call our getrange function */
static gboolean
gst_queue_src_activate_pull (GstPad * pad, gboolean active)
{
  gboolean result;
  GstQueue *queue;

  queue = GST_QUEUE (gst_pad_get_parent (pad));

  if (active) {
    if (QUEUE_IS_USING_TEMP_FILE (queue)) {
      GST_QUEUE_MUTEX_LOCK (queue);
      GST_DEBUG_OBJECT (queue, "activating pull mode");
      queue->srcresult = GST_FLOW_OK;
      queue->is_eos = FALSE;
      queue->unexpected = FALSE;
      result = TRUE;
      GST_QUEUE_MUTEX_UNLOCK (queue);
    } else {
      GST_QUEUE_MUTEX_LOCK (queue);
      GST_DEBUG_OBJECT (queue, "no temp file, cannot activate pull mode");
      /* this is not allowed, we cannot operate in pull mode without a temp
       * file. */
      queue->srcresult = GST_FLOW_WRONG_STATE;
      result = FALSE;
      GST_QUEUE_MUTEX_UNLOCK (queue);
    }
  } else {
    GST_QUEUE_MUTEX_LOCK (queue);
    GST_DEBUG_OBJECT (queue, "deactivating pull mode");
    queue->srcresult = GST_FLOW_WRONG_STATE;
    /* this will unlock getrange */
    g_cond_signal (queue->item_add);
    result = TRUE;
    GST_QUEUE_MUTEX_UNLOCK (queue);
  }
  gst_object_unref (queue);

  return result;
}

static GstStateChangeReturn
gst_queue_change_state (GstElement * element, GstStateChange transition)
{
  GstQueue *queue;
  GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;

  queue = GST_QUEUE (element);

  switch (transition) {
    case GST_STATE_CHANGE_NULL_TO_READY:
      break;
    case GST_STATE_CHANGE_READY_TO_PAUSED:
      if (QUEUE_IS_USING_TEMP_FILE (queue)) {
        if (!gst_queue_open_temp_location_file (queue))
          ret = GST_STATE_CHANGE_FAILURE;
      }
      queue->segment_event_received = FALSE;
      queue->starting_segment = NULL;
      break;
    case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
      break;
    default:
      break;
  }

  ret = GST_ELEMENT_CLASS (parent_class)->change_state (element, transition);

  switch (transition) {
    case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
      break;
    case GST_STATE_CHANGE_PAUSED_TO_READY:
      if (QUEUE_IS_USING_TEMP_FILE (queue))
        gst_queue_close_temp_location_file (queue);
      if (queue->starting_segment != NULL) {
        gst_event_unref (queue->starting_segment);
        queue->starting_segment = NULL;
      }
      break;
    case GST_STATE_CHANGE_READY_TO_NULL:
      break;
    default:
      break;
  }

  return ret;
}

/* changing the capacity of the queue must wake up
 * the _chain function, it might have more room now
 * to store the buffer/event in the queue */
#define QUEUE_CAPACITY_CHANGE(q)\
  g_cond_signal (queue->item_del);

/* Changing the minimum required fill level must
 * wake up the _loop function as it might now
 * be able to preceed.
 */
#define QUEUE_THRESHOLD_CHANGE(q)\
  g_cond_signal (queue->item_add);

static gboolean
gst_queue_set_temp_location (GstQueue * queue, const gchar * location)
{
  GstState state;

  /* the element must be stopped in order to do this */
  GST_OBJECT_LOCK (queue);
  state = GST_STATE (queue);
  if (state != GST_STATE_READY && state != GST_STATE_NULL)
    goto wrong_state;
  GST_OBJECT_UNLOCK (queue);

  /* set new location */
  g_free (queue->temp_location);
  queue->temp_location = g_strdup (location);

  g_object_notify (G_OBJECT (queue), "temp-location");

  return TRUE;

/* ERROR */
wrong_state:
  {
    GST_DEBUG_OBJECT (queue, "setting temp-location in wrong state");
    GST_OBJECT_UNLOCK (queue);
    return FALSE;
  }
}

static void
gst_queue_set_property (GObject * object,
    guint prop_id, const GValue * value, GParamSpec * pspec)
{
  GstQueue *queue = GST_QUEUE (object);

  /* someone could change levels here, and since this
   * affects the get/put funcs, we need to lock for safety. */
  GST_QUEUE_MUTEX_LOCK (queue);

  switch (prop_id) {
    case PROP_MAX_SIZE_BYTES:
      queue->max_level.bytes = g_value_get_uint (value);
      QUEUE_CAPACITY_CHANGE (queue);
      break;
    case PROP_MAX_SIZE_BUFFERS:
      queue->max_level.buffers = g_value_get_uint (value);
      QUEUE_CAPACITY_CHANGE (queue);
      break;
    case PROP_MAX_SIZE_TIME:
      queue->max_level.time = g_value_get_uint64 (value);
      /* set rate_time to the same value. We use an extra field in the level
       * structure so that we can easily access and compare it */
      queue->max_level.rate_time = queue->max_level.time;
      QUEUE_CAPACITY_CHANGE (queue);
      break;
    case PROP_USE_BUFFERING:
      queue->use_buffering = g_value_get_boolean (value);
      break;
    case PROP_USE_RATE_ESTIMATE:
      queue->use_rate_estimate = g_value_get_boolean (value);
      break;
    case PROP_LOW_PERCENT:
      queue->low_percent = g_value_get_int (value);
      break;
    case PROP_HIGH_PERCENT:
      queue->high_percent = g_value_get_int (value);
      break;
    case PROP_TEMP_LOCATION:
      gst_queue_set_temp_location (queue, g_value_dup_string (value));
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
  }

  GST_QUEUE_MUTEX_UNLOCK (queue);
}

static void
gst_queue_get_property (GObject * object,
    guint prop_id, GValue * value, GParamSpec * pspec)
{
  GstQueue *queue = GST_QUEUE (object);

  GST_QUEUE_MUTEX_LOCK (queue);

  switch (prop_id) {
    case PROP_CUR_LEVEL_BYTES:
      g_value_set_uint (value, queue->cur_level.bytes);
      break;
    case PROP_CUR_LEVEL_BUFFERS:
      g_value_set_uint (value, queue->cur_level.buffers);
      break;
    case PROP_CUR_LEVEL_TIME:
      g_value_set_uint64 (value, queue->cur_level.time);
      break;
    case PROP_MAX_SIZE_BYTES:
      g_value_set_uint (value, queue->max_level.bytes);
      break;
    case PROP_MAX_SIZE_BUFFERS:
      g_value_set_uint (value, queue->max_level.buffers);
      break;
    case PROP_MAX_SIZE_TIME:
      g_value_set_uint64 (value, queue->max_level.time);
      break;
    case PROP_USE_BUFFERING:
      g_value_set_boolean (value, queue->use_buffering);
      break;
    case PROP_USE_RATE_ESTIMATE:
      g_value_set_boolean (value, queue->use_rate_estimate);
      break;
    case PROP_LOW_PERCENT:
      g_value_set_int (value, queue->low_percent);
      break;
    case PROP_HIGH_PERCENT:
      g_value_set_int (value, queue->high_percent);
      break;
    case PROP_TEMP_LOCATION:
      g_value_set_string (value, queue->temp_location);
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
  }

  GST_QUEUE_MUTEX_UNLOCK (queue);
}

static gboolean
plugin_init (GstPlugin * plugin)
{
  GST_DEBUG_CATEGORY_INIT (queue_debug, "queue2", 0, "queue element");
  GST_DEBUG_CATEGORY_INIT (queue_dataflow, "queue2_dataflow", 0,
      "dataflow inside the queue element");

#ifdef ENABLE_NLS
  GST_DEBUG ("binding text domain %s to locale dir %s", GETTEXT_PACKAGE,
      LOCALEDIR);
  bindtextdomain (GETTEXT_PACKAGE, LOCALEDIR);
#endif /* ENABLE_NLS */

  return gst_element_register (plugin, "queue2", GST_RANK_NONE, GST_TYPE_QUEUE);
}

GST_PLUGIN_DEFINE (GST_VERSION_MAJOR,
    GST_VERSION_MINOR,
    "queue2",
    "Queue newer version", plugin_init, VERSION, GST_LICENSE,
    GST_PACKAGE_NAME, GST_PACKAGE_ORIGIN)