/* GStreamer
 * Copyright (C) 2008 Nokia Corporation. All rights reserved.
 *   Contact: Stefan Kost <stefan.kost@nokia.com>
 * Copyright (C) 2008 Sebastian Dröge <sebastian.droege@collabora.co.uk>.
 *
 * 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:gstbaseparse
 * @short_description: Base class for stream parsers
 * @see_also: #GstBaseTransform
 *
 * This base class is for parser elements that process data and splits it 
 * into separate audio/video/whatever frames.
 *
 * It provides for:
 * <itemizedlist>
 *   <listitem><para>One sinkpad and one srcpad</para></listitem>
 *   <listitem><para>Handles state changes</para></listitem>
 *   <listitem><para>Does flushing</para></listitem>
 *   <listitem><para>Push mode</para></listitem>
 *   <listitem><para>Pull mode</para></listitem>
 *   <listitem><para>Handles events (NEWSEGMENT/EOS/FLUSH)</para></listitem>
 *   <listitem><para>Handles seeking in both modes</para></listitem>
 *   <listitem><para>
 *        Handles POSITION/DURATION/SEEKING/FORMAT/CONVERT queries
 *   </para></listitem>
 * </itemizedlist>
 *
 * The purpose of this base class is to provide a basic functionality of
 * a parser and share a lot of rather complex code.
 *
 * Description of the parsing mechanism:
 * <orderedlist>
 * <listitem>
 *   <itemizedlist><title>Set-up phase</title>
 *   <listitem><para>
 *     GstBaseParse class calls @set_sink_caps to inform the subclass about
 *     incoming sinkpad caps. Subclass should set the srcpad caps accordingly.
 *   </para></listitem>
 *   <listitem><para>
 *     GstBaseParse calls @start to inform subclass that data processing is
 *     about to start now.
 *   </para></listitem>
 *   <listitem><para>
 *      At least in this point subclass needs to tell the GstBaseParse class
 *      how big data chunks it wants to receive (min_frame_size). It can do 
 *      this with @gst_base_parse_set_min_frame_size.
 *   </para></listitem>
 *   <listitem><para>
 *      GstBaseParse class sets up appropriate data passing mode (pull/push)
 *      and starts to process the data.
 *   </para></listitem>
 *   </itemizedlist>
 * </listitem>
 * <listitem>
 *   <itemizedlist>
 *   <title>Parsing phase</title>
 *     <listitem><para>
 *       GstBaseParse gathers at least min_frame_size bytes of data either 
 *       by pulling it from upstream or collecting buffers into internal
 *       #GstAdapter.
 *     </para></listitem>
 *     <listitem><para>
 *       A buffer of min_frame_size bytes is passed to subclass with
 *       @check_valid_frame. Subclass checks the contents and returns TRUE
 *       if the buffer contains a valid frame. It also needs to set the
 *       @framesize according to the detected frame size. If buffer didn't
 *       contain a valid frame, this call must return FALSE and optionally
 *       set the @skipsize value to inform base class that how many bytes
 *       it needs to skip in order to find a valid frame. The passed buffer
 *       is read-only.
 *     </para></listitem>
 *     <listitem><para>
 *       After valid frame is found, it will be passed again to subclass with
 *       @parse_frame call. Now subclass is responsible for parsing the
 *       frame contents and setting the buffer timestamp, duration and caps.
 *     </para></listitem>
 *     <listitem><para>
 *       Finally the buffer can be pushed downstream and parsing loop starts
 *       over again.
 *     </para></listitem>
 *     <listitem><para>
 *       During the parsing process GstBaseClass will handle both srcpad and
 *       sinkpad events. They will be passed to subclass if @event or
 *       @src_event callbacks have been provided.
 *     </para></listitem>
 *   </itemizedlist>
 * </listitem>
 * <listitem>
 *   <itemizedlist><title>Shutdown phase</title>
 *   <listitem><para>
 *     GstBaseParse class calls @stop to inform the subclass that data
 *     parsing will be stopped.
 *   </para></listitem>
 *   </itemizedlist>
 * </listitem>
 * </orderedlist>
 *
 * Subclass is responsible for providing pad template caps for
 * source and sink pads. The pads need to be named "sink" and "src". It also 
 * needs to set the fixed caps on srcpad, when the format is ensured (e.g. 
 * when base class calls subclass' @set_sink_caps function).
 *
 * This base class uses GST_FORMAT_DEFAULT as a meaning of frames. So,
 * subclass conversion routine needs to know that conversion from
 * GST_FORMAT_TIME to GST_FORMAT_DEFAULT must return the
 * frame number that can be found from the given byte position.
 *
 * GstBaseParse uses subclasses conversion methods also for seeking. If
 * subclass doesn't provide @convert function, seeking will get disabled.
 *
 * Subclass @start and @stop functions will be called to inform the beginning
 * and end of data processing.
 *
 * Things that subclass need to take care of:
 * <itemizedlist>
 *   <listitem><para>Provide pad templates</para></listitem>
 *   <listitem><para>
 *      Fixate the source pad caps when appropriate
 *   </para></listitem>
 *   <listitem><para>
 *      Inform base class how big data chunks should be retrieved. This is
 *      done with @gst_base_parse_set_min_frame_size function.
 *   </para></listitem>
 *   <listitem><para>
 *      Examine data chunks passed to subclass with @check_valid_frame
 *      and tell if they contain a valid frame
 *   </para></listitem>
 *   <listitem><para>
 *      Set the caps and timestamp to frame that is passed to subclass with
 *      @parse_frame function.
 *   </para></listitem>
 *   <listitem><para>Provide conversion functions</para></listitem>
 *   <listitem><para>
 *      Update the duration information with @gst_base_parse_set_duration
 *   </para></listitem>
 * </itemizedlist>
 *
 */

/* TODO:
 *  - Allow sending NEWSEGMENT event after handling the next frame
 *  - Timestamp tracking and setting
 *  - Allow dropping of frames outside the segment
 *  - Send queries upstream
 */

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

#include <stdlib.h>
#include <string.h>

#include "gstbaseparse.h"

GST_DEBUG_CATEGORY_STATIC (gst_base_parse_debug);
#define GST_CAT_DEFAULT gst_base_parse_debug

/* Supported formats */
static GstFormat fmtlist[] = {
  GST_FORMAT_DEFAULT,
  GST_FORMAT_BYTES,
  GST_FORMAT_TIME,
  0
};

#define GST_BASE_PARSE_GET_PRIVATE(obj)  \
    (G_TYPE_INSTANCE_GET_PRIVATE ((obj), GST_TYPE_BASE_PARSE, GstBaseParsePrivate))

struct _GstBaseParsePrivate
{
  GstActivateMode pad_mode;

  gint64 duration;
  GstFormat duration_fmt;

  guint min_frame_size;

  gboolean discont;
  gboolean flushing;

  gint64 offset;
  gint64 pending_offset;

  GList *pending_events;

  GstBuffer *cache;
};

struct _GstBaseParseClassPrivate
{
  gpointer _padding;
};

static GstElementClass *parent_class = NULL;

static void gst_base_parse_base_init (gpointer g_class);
static void gst_base_parse_base_finalize (gpointer g_class);
static void gst_base_parse_class_init (GstBaseParseClass * klass);
static void gst_base_parse_init (GstBaseParse * parse,
    GstBaseParseClass * klass);

GType
gst_base_parse_get_type (void)
{
  static GType base_parse_type = 0;

  if (!base_parse_type) {
    static const GTypeInfo base_parse_info = {
      sizeof (GstBaseParseClass),
      (GBaseInitFunc) gst_base_parse_base_init,
      (GBaseFinalizeFunc) gst_base_parse_base_finalize,
      (GClassInitFunc) gst_base_parse_class_init,
      NULL,
      NULL,
      sizeof (GstBaseParse),
      0,
      (GInstanceInitFunc) gst_base_parse_init,
    };

    base_parse_type = g_type_register_static (GST_TYPE_ELEMENT,
        "GstFlacBaseParse", &base_parse_info, G_TYPE_FLAG_ABSTRACT);
  }
  return base_parse_type;
}

static void gst_base_parse_finalize (GObject * object);

static gboolean gst_base_parse_sink_activate (GstPad * sinkpad);
static gboolean gst_base_parse_sink_activate_push (GstPad * pad,
    gboolean active);
static gboolean gst_base_parse_sink_activate_pull (GstPad * pad,
    gboolean active);
static gboolean gst_base_parse_handle_seek (GstBaseParse * parse,
    GstEvent * event);

static gboolean gst_base_parse_src_event (GstPad * pad, GstEvent * event);
static gboolean gst_base_parse_sink_event (GstPad * pad, GstEvent * event);
static gboolean gst_base_parse_query (GstPad * pad, GstQuery * query);
static gboolean gst_base_parse_sink_setcaps (GstPad * pad, GstCaps * caps);
static const GstQueryType * gst_base_parse_get_querytypes (GstPad * pad);

static GstFlowReturn gst_base_parse_chain (GstPad * pad, GstBuffer * buffer);
static void gst_base_parse_loop (GstPad * pad);

static gboolean gst_base_parse_check_frame (GstBaseParse *parse,
    GstBuffer *buffer, guint *framesize, gint *skipsize);

static gboolean gst_base_parse_parse_frame (GstBaseParse *parse,
    GstBuffer *buffer);

static gboolean gst_base_parse_sink_eventfunc (GstBaseParse * parse,
    GstEvent * event);

static gboolean gst_base_parse_src_eventfunc (GstBaseParse * parse,
    GstEvent * event);

static gboolean gst_base_parse_is_seekable (GstBaseParse * parse);

static void gst_base_parse_drain (GstBaseParse *parse);

static void
gst_base_parse_base_init (gpointer g_class)
{
  GstBaseParseClass *klass = GST_BASE_PARSE_CLASS (g_class);
  GstBaseParseClassPrivate *priv;

  GST_DEBUG_CATEGORY_INIT (gst_base_parse_debug, "flacbaseparse", 0,
      "baseparse element");

  /* TODO: Remove this once GObject supports class private data */
  priv = g_slice_new0 (GstBaseParseClassPrivate);
  if (klass->priv)
    memcpy (priv, klass->priv, sizeof (GstBaseParseClassPrivate));
  klass->priv = priv;
}

static void
gst_base_parse_base_finalize (gpointer g_class)
{
  GstBaseParseClass *klass = GST_BASE_PARSE_CLASS (g_class);
  
  g_slice_free (GstBaseParseClassPrivate, klass->priv);
  klass->priv = NULL;
}

static void
gst_base_parse_finalize (GObject * object)
{
  GstBaseParse *parse  = GST_BASE_PARSE (object);

  g_mutex_free (parse->parse_lock);
  g_object_unref (parse->adapter);

  if (parse->pending_segment) {
    gst_event_replace (&parse->pending_segment, NULL);
  }
  if (parse->close_segment) {
    gst_event_replace (&parse->close_segment, NULL);
  }

  if (parse->priv->cache) {
    gst_buffer_unref (parse->priv->cache);
    parse->priv->cache = NULL;
  }

  g_list_foreach (parse->priv->pending_events, (GFunc) gst_mini_object_unref, NULL);
  g_list_free (parse->priv->pending_events);
  parse->priv->pending_events = NULL;

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

static void
gst_base_parse_class_init (GstBaseParseClass * klass)
{
  GObjectClass *gobject_class;

  gobject_class = G_OBJECT_CLASS (klass);
  g_type_class_add_private (klass, sizeof (GstBaseParsePrivate));
  parent_class = g_type_class_peek_parent (klass);
  gobject_class->finalize = GST_DEBUG_FUNCPTR (gst_base_parse_finalize);

  /* Default handlers */
  klass->check_valid_frame = gst_base_parse_check_frame;
  klass->parse_frame = gst_base_parse_parse_frame;
  klass->event = gst_base_parse_sink_eventfunc;
  klass->src_event = gst_base_parse_src_eventfunc;
  klass->is_seekable = gst_base_parse_is_seekable;
}

static void
gst_base_parse_init (GstBaseParse * parse,
    GstBaseParseClass * bclass)
{
  GstPadTemplate *pad_template;

  GST_DEBUG_OBJECT (parse, "gst_base_parse_init");

  parse->priv = GST_BASE_PARSE_GET_PRIVATE (parse);

  pad_template =
      gst_element_class_get_pad_template (GST_ELEMENT_CLASS (bclass), "sink");
  g_return_if_fail (pad_template != NULL);
  parse->sinkpad = gst_pad_new_from_template (pad_template, "sink");
  gst_pad_set_event_function (parse->sinkpad,
      GST_DEBUG_FUNCPTR (gst_base_parse_sink_event));
  gst_pad_set_setcaps_function (parse->sinkpad,
      GST_DEBUG_FUNCPTR (gst_base_parse_sink_setcaps));
  gst_pad_set_chain_function (parse->sinkpad,
      GST_DEBUG_FUNCPTR (gst_base_parse_chain));
  gst_pad_set_activate_function (parse->sinkpad,
      GST_DEBUG_FUNCPTR (gst_base_parse_sink_activate));
  gst_pad_set_activatepush_function (parse->sinkpad,
      GST_DEBUG_FUNCPTR (gst_base_parse_sink_activate_push));
  gst_pad_set_activatepull_function (parse->sinkpad,
      GST_DEBUG_FUNCPTR (gst_base_parse_sink_activate_pull));
  gst_element_add_pad (GST_ELEMENT (parse), parse->sinkpad);

  GST_DEBUG_OBJECT (parse, "sinkpad created");

  pad_template =
      gst_element_class_get_pad_template (GST_ELEMENT_CLASS (bclass), "src");
  g_return_if_fail (pad_template != NULL);
  parse->srcpad = gst_pad_new_from_template (pad_template, "src");
  gst_pad_set_event_function (parse->srcpad,
      GST_DEBUG_FUNCPTR (gst_base_parse_src_event));
  gst_pad_set_query_type_function (parse->srcpad,
      GST_DEBUG_FUNCPTR (gst_base_parse_get_querytypes));
  gst_pad_set_query_function (parse->srcpad,
      GST_DEBUG_FUNCPTR (gst_base_parse_query));
  gst_element_add_pad (GST_ELEMENT (parse), parse->srcpad);
  GST_DEBUG_OBJECT (parse, "src created");

  parse->parse_lock = g_mutex_new ();
  parse->adapter = gst_adapter_new ();
  parse->pending_segment = NULL;
  parse->close_segment = NULL;

  parse->priv->pad_mode = GST_ACTIVATE_NONE;
  parse->priv->duration = -1;
  parse->priv->min_frame_size = 1;
  parse->priv->discont = FALSE;
  parse->priv->flushing = FALSE;
  parse->priv->offset = 0;
  GST_DEBUG_OBJECT (parse, "init ok");
}



/**
 * gst_base_parse_check_frame:
 * @parse: #GstBaseParse.
 * @buffer: GstBuffer.
 * @framesize: This will be set to tell the found frame size in bytes.
 * @skipsize: Output parameter that tells how much data needs to be skipped
 *            in order to find the following frame header.
 *
 * Default callback for check_valid_frame.
 * 
 * Returns: Always TRUE.
 */
static gboolean
gst_base_parse_check_frame (GstBaseParse *parse,
                            GstBuffer *buffer,
                            guint *framesize,
                            gint *skipsize)
{
  *framesize = GST_BUFFER_SIZE (buffer);
  *skipsize = 0;
  return TRUE;
}


/**
 * gst_base_parse_parse_frame:
 * @parse: #GstBaseParse.
 * @buffer: #GstBuffer.
 *
 * Default callback for parse_frame.
 */
static gboolean
gst_base_parse_parse_frame (GstBaseParse *parse, GstBuffer *buffer)
{
  /* FIXME: Could we even _try_ to do something clever here? */
  GST_BUFFER_TIMESTAMP (buffer) = GST_CLOCK_TIME_NONE;
  GST_BUFFER_DURATION (buffer) = GST_CLOCK_TIME_NONE;
  return TRUE;
}


/**
 * gst_base_parse_bytepos_to_time:
 * @parse: #GstBaseParse.
 * @bytepos: Position (in bytes) to be converted.
 * @pos_in_time: #GstClockTime pointer where the result is set.
 *
 * Convert given byte position into #GstClockTime format.
 * 
 * Returns: TRUE if conversion succeeded.
 */
static gboolean
gst_base_parse_bytepos_to_time (GstBaseParse *parse, gint64 bytepos,
                                GstClockTime *pos_in_time)
{
  GstBaseParseClass *klass;
  gboolean res = FALSE;

  klass = GST_BASE_PARSE_GET_CLASS (parse);

  if (klass->convert) {
    res = klass->convert (parse, GST_FORMAT_BYTES, bytepos,
                          GST_FORMAT_TIME, (gint64 *) pos_in_time);
  }
  return res;
}


/**
 * gst_base_parse_sink_event:
 * @pad: #GstPad that received the event.
 * @event: #GstEvent to be handled.
 *
 * Handler for sink pad events.
 *
 * Returns: TRUE if the event was handled.
 */
static gboolean
gst_base_parse_sink_event (GstPad * pad, GstEvent * event)
{
  GstBaseParse *parse;
  GstBaseParseClass *bclass;
  gboolean handled = FALSE;
  gboolean ret = TRUE;


  parse = GST_BASE_PARSE (gst_pad_get_parent (pad));
  bclass = GST_BASE_PARSE_GET_CLASS (parse);

  GST_DEBUG_OBJECT (parse, "handling event %d", GST_EVENT_TYPE (event));

  /* Cache all events except EOS, NEWSEGMENT and FLUSH_STOP if we have a
   * pending segment */
  if (parse->pending_segment && GST_EVENT_TYPE (event) != GST_EVENT_EOS
      && GST_EVENT_TYPE (event) != GST_EVENT_NEWSEGMENT
      && GST_EVENT_TYPE (event) != GST_EVENT_FLUSH_START
      && GST_EVENT_TYPE (event) != GST_EVENT_FLUSH_STOP) {
    parse->priv->pending_events = g_list_append (parse->priv->pending_events, event);
    ret = TRUE;
  } else {

    if (bclass->event)
      handled = bclass->event (parse, event);

    if (!handled)
      ret = gst_pad_event_default (pad, event);
  }

  gst_object_unref (parse);
  GST_DEBUG_OBJECT (parse, "event handled");
  return ret;
}


/**
 * gst_base_parse_sink_eventfunc:
 * @parse: #GstBaseParse.
 * @event: #GstEvent to be handled.
 *
 * Element-level event handler function.
 *
 * Returns: TRUE if the event was handled and not need forwarding.
 */
static gboolean
gst_base_parse_sink_eventfunc (GstBaseParse * parse, GstEvent * event)
{
  gboolean handled = FALSE;
  GstEvent **eventp;

  switch (GST_EVENT_TYPE (event))
  {
    case GST_EVENT_NEWSEGMENT:
    {
      gdouble rate, applied_rate;
      GstFormat format;
      gint64 start, stop, pos;
      gboolean update;

      gst_event_parse_new_segment_full (event, &update, &rate, &applied_rate,
                                        &format, &start, &stop, &pos);


      if (format == GST_FORMAT_BYTES) {
        GstClockTime seg_start, seg_stop, seg_pos;

        /* stop time is allowed to be open-ended, but not start & pos */
        seg_stop = GST_CLOCK_TIME_NONE;
        parse->priv->pending_offset = pos;

        if (gst_base_parse_bytepos_to_time (parse, start, &seg_start) &&
            gst_base_parse_bytepos_to_time (parse, pos, &seg_pos))
        {
          gst_event_unref (event);
          event = gst_event_new_new_segment_full (update, rate, applied_rate,
              GST_FORMAT_TIME, seg_start, seg_stop, seg_pos);
          format = GST_FORMAT_TIME;
          GST_DEBUG_OBJECT (parse, "Converted incoming segment to TIME. "
              "start = %" GST_TIME_FORMAT ", stop = %" GST_TIME_FORMAT
                  ", pos = %" GST_TIME_FORMAT, GST_TIME_ARGS (seg_start),
                  GST_TIME_ARGS (seg_stop), GST_TIME_ARGS (seg_pos));
        }
      }

      if (format != GST_FORMAT_TIME) {
        /* Unknown incoming segment format. Output a default open-ended 
        * TIME segment */
        gst_event_unref (event);
        event = gst_event_new_new_segment_full (update, rate, applied_rate,
            GST_FORMAT_TIME, 0, GST_CLOCK_TIME_NONE, 0);
      }

      gst_event_parse_new_segment_full (event, &update, &rate, &applied_rate,
                                        &format, &start, &stop, &pos);

      gst_segment_set_newsegment_full (&parse->segment, update, rate,
                                       applied_rate, format, start, stop, pos);

      GST_DEBUG_OBJECT (parse, "Created newseg rate %g, applied rate %g, "
          "format %d, start = %" GST_TIME_FORMAT ", stop = %" GST_TIME_FORMAT
          ", pos = %" GST_TIME_FORMAT, rate, applied_rate, format,
          GST_TIME_ARGS (start), GST_TIME_ARGS (stop), GST_TIME_ARGS (pos));

      /* save the segment for later, right before we push a new buffer so that
       * the caps are fixed and the next linked element can receive
       * the segment. */
      eventp = &parse->pending_segment;
      gst_event_replace (eventp, event);
      gst_event_unref (event);
      handled = TRUE;
      break;
    }

    case GST_EVENT_FLUSH_START:
      parse->priv->flushing = TRUE;
      /* Wait for _chain() to exit by taking the srcpad STREAM_LOCK */
      GST_PAD_STREAM_LOCK (parse->srcpad);
      handled = gst_pad_push_event (parse->srcpad, event);
      GST_PAD_STREAM_UNLOCK (parse->srcpad);
      break;

    case GST_EVENT_FLUSH_STOP:
      gst_adapter_clear (parse->adapter);
      parse->priv->flushing = FALSE;
      parse->priv->discont = TRUE;
      break;

    case GST_EVENT_EOS:
      gst_base_parse_drain (parse);
      break;

    default:
      break;
  }

  return handled;
}


/**
 * gst_base_parse_src_event:
 * @pad: #GstPad that received the event.
 * @event: #GstEvent that was received.
 *
 * Handler for source pad events.
 *
 * Returns: TRUE if the event was handled.
 */
static gboolean
gst_base_parse_src_event (GstPad * pad, GstEvent * event)
{
  GstBaseParse *parse;
  GstBaseParseClass *bclass;
  gboolean handled = FALSE;
  gboolean ret = TRUE;

  parse = GST_BASE_PARSE (gst_pad_get_parent (pad));
  bclass = GST_BASE_PARSE_GET_CLASS (parse);

  GST_DEBUG_OBJECT (parse, "event %d, %s", GST_EVENT_TYPE (event),
             GST_EVENT_TYPE_NAME (event));

  if (bclass->src_event)
    handled = bclass->src_event (parse, event);

  if (!handled)
    ret = gst_pad_event_default (pad, event);

  gst_object_unref (parse);
  return ret;
}


/**
 * gst_base_parse_src_eventfunc:
 * @parse: #GstBaseParse.
 * @event: #GstEvent that was received.
 *
 * Default srcpad event handler.
 *
 * Returns: TRUE if the event was handled and can be dropped.
 */
static gboolean
gst_base_parse_src_eventfunc (GstBaseParse * parse, GstEvent * event)
{
  gboolean handled = FALSE;
  GstBaseParseClass *bclass;

  bclass = GST_BASE_PARSE_GET_CLASS (parse);

  switch (GST_EVENT_TYPE (event)) {
    case GST_EVENT_SEEK:
    {
      if (bclass->is_seekable (parse)) {
        handled = gst_base_parse_handle_seek (parse, event);
        gst_event_unref (event);
      }
      break;
    }
    default:
      break;
  }
  return handled;
}


/**
 * gst_base_parse_is_seekable:
 * @parse: #GstBaseParse.
 *
 * Default handler for is_seekable.
 *
 * Returns: Always TRUE.
 */
static gboolean
gst_base_parse_is_seekable (GstBaseParse * parse)
{
  return TRUE;
}


/**
 * gst_base_parse_handle_and_push_buffer:
 * @parse: #GstBaseParse.
 * @klass: #GstBaseParseClass.
 * @buffer: #GstBuffer.
 *
 * Parses the frame from given buffer and pushes it forward. Also performs
 * timestamp handling and checks the segment limits.
 *
 * This is called with srcpad STREAM_LOCK held.
 *
 * Returns: #GstFlowReturn
 */
static GstFlowReturn
gst_base_parse_handle_and_push_buffer (GstBaseParse *parse,
                                       GstBaseParseClass *klass,
                                       GstBuffer *buffer)
{
  GstFlowReturn ret;
  GstClockTime last_stop = GST_CLOCK_TIME_NONE;

  if (parse->priv->discont) {
    GST_DEBUG_OBJECT (parse, "marking DISCONT");
    GST_BUFFER_FLAG_SET (buffer, GST_BUFFER_FLAG_DISCONT);
    parse->priv->discont = FALSE;
  }

  ret = klass->parse_frame (parse, buffer);

  /* FIXME: Check the output buffer for any missing metadata,
   *        keep track of timestamp and calculate everything possible
   *        if not set already */

  if (GST_BUFFER_TIMESTAMP_IS_VALID (buffer))
    last_stop = GST_BUFFER_TIMESTAMP (buffer);
  if (last_stop != GST_CLOCK_TIME_NONE && GST_BUFFER_DURATION_IS_VALID (buffer))
    last_stop += GST_BUFFER_DURATION (buffer);

  gst_buffer_set_caps (buffer, GST_PAD_CAPS (parse->srcpad));

  /* TODO: Add to seek table */

  if (ret == GST_FLOW_OK) {
    if (GST_BUFFER_TIMESTAMP_IS_VALID (buffer) && 
        GST_CLOCK_TIME_IS_VALID (parse->segment.stop) &&
        GST_BUFFER_TIMESTAMP (buffer) > parse->segment.stop) {
      GST_LOG_OBJECT (parse, "Dropped frame, after segment");
      gst_buffer_unref (buffer);
    } else if (GST_BUFFER_TIMESTAMP_IS_VALID (buffer) && 
        GST_BUFFER_DURATION_IS_VALID (buffer) &&
        GST_CLOCK_TIME_IS_VALID (parse->segment.start) &&
        GST_BUFFER_TIMESTAMP (buffer) + GST_BUFFER_DURATION_IS_VALID (buffer)
            < parse->segment.start) {
      /* FIXME: subclass needs way to override the start as downstream might
       * need frames before for proper decoding */
      GST_LOG_OBJECT (parse, "Dropped frame, before segment");
      gst_buffer_unref (buffer);
    } else {
      ret = gst_pad_push (parse->srcpad, buffer);
      GST_LOG_OBJECT (parse, "frame (%d bytes) pushed: %d", GST_BUFFER_SIZE (buffer), ret);
    }
  }
  else {
    gst_buffer_unref (buffer);
  }

  /* Update current running segment position */
  if (ret == GST_FLOW_OK && last_stop != GST_CLOCK_TIME_NONE)
    gst_segment_set_last_stop (&parse->segment, GST_FORMAT_TIME,
                             last_stop);

  /* convert internal flow to OK and mark discont for the next buffer. */
  if (ret == GST_BASE_PARSE_FLOW_DROPPED) {
    parse->priv->discont = TRUE;
    ret = GST_FLOW_OK;
  }
  return ret;
}


/**
 * gst_base_parse_drain:
 * @parse: #GstBaseParse.
 *
 * Drains the adapter until it is empty. It decreases the min_frame_size to
 * match the current adapter size and calls chain method until the adapter
 * is emptied or chain returns with error.
 */
static void
gst_base_parse_drain (GstBaseParse *parse)
{
  guint avail;

  for (;;) {
    avail = gst_adapter_available (parse->adapter);
    if (!avail) break;

    gst_base_parse_set_min_frame_size (parse, avail);
    if (gst_base_parse_chain (parse->sinkpad, NULL) != GST_FLOW_OK) {
      break;
    }
  }
}


/**
 * gst_base_parse_chain:
 * @pad: #GstPad.
 * @buffer: #GstBuffer.
 *
 * Returns: #GstFlowReturn.
 */
static GstFlowReturn
gst_base_parse_chain (GstPad * pad, GstBuffer * buffer)
{
  GstBaseParseClass *bclass;
  GstBaseParse *parse;
  GstFlowReturn ret = GST_FLOW_OK;
  GstBuffer *outbuf = NULL;
  GstBuffer *tmpbuf = NULL;
  guint fsize = 0;
  gint skip = -1;
  const guint8 *data;
  guint min_size;

  parse = GST_BASE_PARSE (GST_OBJECT_PARENT (pad));
  bclass = GST_BASE_PARSE_GET_CLASS (parse);

  if (parse->pending_segment) {
    GST_DEBUG_OBJECT (parse, "chain pushing a pending segment");
    gst_pad_push_event (parse->srcpad, parse->pending_segment);
    parse->pending_segment = NULL;
    parse->priv->offset = parse->priv->pending_offset;

    /* Make sure that adapter doesn't have any old data after
       newsegment has been pushed */

    /* FIXME: when non-flushing seek occurs, chain is still processing the
       data from old segment. If this processing loop is then interrupted
       (e.g. paused), chain function exists and next time it gets called
       all this old data gets lost and playback continues from new segment */
    gst_adapter_clear (parse->adapter);
  }

  if (parse->priv->pending_events) {
    GList *l;

    for (l = parse->priv->pending_events; l != NULL; l = l->next) {
      gst_pad_push_event (parse->srcpad, GST_EVENT (l->data));
    }
    g_list_free (parse->priv->pending_events);
    parse->priv->pending_events = NULL;
  }

  if (buffer) {
    GST_LOG_OBJECT (parse, "buffer size: %d, offset = %lld",
            GST_BUFFER_SIZE(buffer), GST_BUFFER_OFFSET (buffer));


    gst_adapter_push (parse->adapter, buffer);
  }

  /* Parse and push as many frames as possible */
  /* Stop either when adapter is empty or we are flushing */
  while (!parse->priv->flushing) {
    tmpbuf = gst_buffer_new ();

    GST_BASE_PARSE_LOCK (parse);
    min_size = parse->priv->min_frame_size;
    GST_BASE_PARSE_UNLOCK (parse);

    /* Synchronization loop */
    for (;;) {
      /* Collect at least min_frame_size bytes */
      if (gst_adapter_available (parse->adapter) < min_size)
      {
        GST_DEBUG_OBJECT (parse, "not enough data available (only %d bytes)",
                   gst_adapter_available (parse->adapter));
        gst_buffer_unref (tmpbuf);
        goto done;
      }

      data = gst_adapter_peek (parse->adapter, min_size);
      GST_BUFFER_DATA (tmpbuf) = (guint8 *) data;
      GST_BUFFER_SIZE (tmpbuf) = min_size;
      GST_BUFFER_OFFSET (tmpbuf) = parse->priv->offset;
      GST_BUFFER_FLAG_SET (tmpbuf, GST_MINI_OBJECT_FLAG_READONLY);

      if (parse->priv->discont) {
        GST_DEBUG_OBJECT (parse, "marking DISCONT");
        GST_BUFFER_FLAG_SET (buffer, GST_BUFFER_FLAG_DISCONT);
      }

      skip = -1;
      if (bclass->check_valid_frame (parse, tmpbuf, &fsize, &skip)) {
        break;
      }
      if (skip > 0) {
        GST_LOG_OBJECT (parse, "finding sync, skipping %d bytes", skip);
        gst_adapter_flush (parse->adapter, skip);
        parse->priv->offset += skip;
      }
      else if (skip == -1) {
        /* subclass didn't touch this value. By default we skip 1 byte */
        GST_LOG_OBJECT (parse, "finding sync, skipping 1 byte");
        gst_adapter_flush (parse->adapter, 1);
        parse->priv->offset++;
      }
      /* There is a possibility that subclass set the skip value to zero.
         This means that it has probably found a frame but wants to ask
         more data (by increasing the min_size) to be sure of this. */
    }
    gst_buffer_unref (tmpbuf);
    tmpbuf = NULL;

    if (skip > 0) {
      /* Subclass found the sync, but still wants to skip some data */
      GST_LOG_OBJECT (parse, "skipping %d bytes", skip);
      gst_adapter_flush (parse->adapter, skip);
      parse->priv->offset += skip;
    }

    /* Grab lock to prevent a race with FLUSH_START handler */
    GST_PAD_STREAM_LOCK (parse->srcpad);

    /* FLUSH_START event causes the "flushing" flag to be set. In this
     * case we can leave the frame pushing loop */
    if (parse->priv->flushing) {
      GST_PAD_STREAM_UNLOCK (parse->srcpad);
      break;
    }

    /* FIXME: Would it be more efficient to make a subbuffer instead? */
    outbuf = gst_adapter_take_buffer (parse->adapter, fsize);

    /* Subclass may want to know the data offset */
    GST_BUFFER_OFFSET (outbuf) = parse->priv->offset;
    parse->priv->offset += fsize;

    ret = gst_base_parse_handle_and_push_buffer (parse, bclass, outbuf);
    GST_PAD_STREAM_UNLOCK (parse->srcpad);

    if (ret != GST_FLOW_OK) {
      GST_LOG_OBJECT (parse, "push returned %d", ret);
      break;
    }
  }

done:
  GST_LOG_OBJECT (parse, "chain leaving");
  return ret;
}

static GstFlowReturn
gst_base_parse_pull_range (GstBaseParse *parse, guint size, GstBuffer **buffer)
{
  GstFlowReturn ret = GST_FLOW_OK;

  g_return_val_if_fail (buffer != NULL, GST_FLOW_ERROR);

  /* Caching here actually makes much less difference than one would expect.
   * We do it mainly to avoid pulling buffers of 1 byte all the time */
  if (parse->priv->cache) {
    guint64 cache_offset = GST_BUFFER_OFFSET (parse->priv->cache);
    guint cache_size = GST_BUFFER_SIZE (parse->priv->cache);

    if (cache_offset <= parse->priv->offset &&
        (parse->priv->offset + size) < (cache_offset + cache_size)) {
      *buffer = gst_buffer_create_sub (parse->priv->cache,
            parse->priv->offset - cache_offset, size);
      return GST_FLOW_OK;
    }
    /* not enough data in the cache, free cache and get a new one */
    gst_buffer_unref (parse->priv->cache);
    parse->priv->cache = NULL;
  }

  /* refill the cache */
  ret = gst_pad_pull_range (parse->sinkpad, parse->priv->offset, MAX (size, 64 * 1024),
      &parse->priv->cache);
  if (ret != GST_FLOW_OK) {
    parse->priv->cache = NULL;
    return ret;
  }

  if (GST_BUFFER_SIZE (parse->priv->cache) >= size) {
    *buffer = gst_buffer_create_sub (parse->priv->cache, 0, size);
    return GST_FLOW_OK;
  }

  /* Not possible to get enough data, try a last time with
   * requesting exactly the size we need */
  gst_buffer_unref (parse->priv->cache);
  parse->priv->cache = NULL;

  ret = gst_pad_pull_range (parse->sinkpad, parse->priv->offset, size,
      &parse->priv->cache);

  if (ret != GST_FLOW_OK) {
    GST_DEBUG_OBJECT (parse, "pull_range returned %d", ret);
    *buffer = NULL;
    return ret;
  }

  if (GST_BUFFER_SIZE (parse->priv->cache) < size) {
    GST_WARNING_OBJECT (parse, "Dropping short buffer at offset %"
        G_GUINT64_FORMAT ": wanted %u bytes, got %u bytes", parse->priv->offset,
        size, GST_BUFFER_SIZE (parse->priv->cache));

    gst_buffer_unref (parse->priv->cache);
    parse->priv->cache = NULL;

    *buffer = NULL;
    return GST_FLOW_UNEXPECTED;
  }

  *buffer = gst_buffer_create_sub (parse->priv->cache, 0, size);

  return GST_FLOW_OK;
}

/**
 * gst_base_parse_loop:
 * @pad: GstPad
 *
 * Loop that is used in pull mode to retrieve data from upstream.
 */
static void
gst_base_parse_loop (GstPad * pad)
{
  GstBaseParse *parse;
  GstBaseParseClass *klass;
  GstBuffer *buffer, *outbuf;
  gboolean ret = FALSE;
  guint fsize = 0, min_size;
  gint skip = 0;

  parse = GST_BASE_PARSE (gst_pad_get_parent (pad));
  klass = GST_BASE_PARSE_GET_CLASS (parse);

  if (parse->close_segment) {
    GST_DEBUG_OBJECT (parse, "loop sending close segment");
    gst_pad_push_event (parse->srcpad, parse->close_segment);
    parse->close_segment = NULL;
  }

  if (parse->pending_segment) {
    GST_DEBUG_OBJECT (parse, "loop push pending segment");
    gst_pad_push_event (parse->srcpad, parse->pending_segment);
    parse->pending_segment = NULL;
  }

  /* TODO: Check if we reach segment stop limit */

  while (TRUE) {

    GST_BASE_PARSE_LOCK (parse);
    min_size = parse->priv->min_frame_size;
    GST_BASE_PARSE_UNLOCK (parse);

    ret = gst_base_parse_pull_range (parse, min_size, &buffer);

    if (ret == GST_FLOW_UNEXPECTED)
      goto eos;
    else if (ret != GST_FLOW_OK)
      goto need_pause;

    if (parse->priv->discont) {
      GST_DEBUG_OBJECT (parse, "marking DISCONT");
      GST_BUFFER_FLAG_SET (buffer, GST_BUFFER_FLAG_DISCONT);
    }

    skip = -1;
    if (klass->check_valid_frame (parse, buffer, &fsize, &skip)) {
      break;
    }
    if (skip > 0) {
      GST_LOG_OBJECT (parse, "finding sync, skipping %d bytes", skip);
      parse->priv->offset += skip;
    }
    else if (skip == -1) {
      GST_LOG_OBJECT (parse, "finding sync, skipping 1 byte");
      parse->priv->offset++;
    }
    GST_DEBUG_OBJECT (parse, "finding sync...");
    gst_buffer_unref (buffer);
  }

  if (fsize <= GST_BUFFER_SIZE (buffer)) {
    outbuf = gst_buffer_create_sub (buffer, 0, fsize);
    gst_buffer_unref (buffer);
  } else {
    gst_buffer_unref (buffer);
    ret = gst_base_parse_pull_range (parse, fsize, &outbuf);
    
    if (ret == GST_FLOW_UNEXPECTED)
      goto eos;
    else if (ret != GST_FLOW_OK)
      goto need_pause;
  }

  parse->priv->offset += fsize;

  /* Does the subclass want to skip too? */
  if (skip > 0)
    parse->priv->offset += skip;

  /* This always unrefs the outbuf, even if error occurs */
  ret = gst_base_parse_handle_and_push_buffer (parse, klass, outbuf);

  if (ret != GST_FLOW_OK) {
    GST_DEBUG_OBJECT (parse, "flow: %s", gst_flow_get_name (ret));
    if (GST_FLOW_IS_FATAL (ret)) {
      GST_ELEMENT_ERROR (parse, STREAM, FAILED, (NULL),
                         ("streaming task paused, reason: %s",
                          gst_flow_get_name (ret)));
      gst_pad_push_event (pad, gst_event_new_eos ());
    }
    goto need_pause;
  }

  gst_object_unref (parse);
  return;

need_pause:
  {
    GST_LOG_OBJECT (parse, "pausing task");
    gst_pad_pause_task (pad);
    gst_object_unref (parse);
    return;
  }
eos:
  {
    GST_LOG_OBJECT (parse, "pausing task %d", ret);
    gst_pad_push_event (parse->srcpad, gst_event_new_eos ());
    gst_pad_pause_task (pad);
    gst_object_unref (parse);
    return;
  }
}


/**
 * gst_base_parse_sink_activate:
 * @sinkpad: #GstPad to be activated.
 *
 * Returns: TRUE if activation succeeded.
 */
static gboolean
gst_base_parse_sink_activate (GstPad * sinkpad)
{
  GstBaseParse *parse;
  gboolean result = TRUE;

  parse = GST_BASE_PARSE (gst_pad_get_parent (sinkpad));
  
  GST_DEBUG_OBJECT (parse, "sink activate");

  if (gst_pad_check_pull_range (sinkpad)) {
    GST_DEBUG_OBJECT (parse, "trying to activate in pull mode");
    result = gst_pad_activate_pull (sinkpad, TRUE);
  } else {
    GST_DEBUG_OBJECT (parse, "trying to activate in push mode");
    result = gst_pad_activate_push (sinkpad, TRUE);
  }

  GST_DEBUG_OBJECT (parse, "sink activate return %d", result);
  gst_object_unref (parse);
  return result;
}


/**
 * gst_base_parse_activate:
 * @parse: #GstBaseParse.
 * @active: TRUE if element will be activated, FALSE if disactivated.
 *
 * Returns: TRUE if the operation succeeded.
 */
static gboolean
gst_base_parse_activate (GstBaseParse *parse, gboolean active)
{
  GstBaseParseClass *klass;
  gboolean result = FALSE;

  GST_DEBUG_OBJECT (parse, "activate");

  klass = GST_BASE_PARSE_GET_CLASS (parse);

  if (active) {
    if (parse->priv->pad_mode == GST_ACTIVATE_NONE && klass->start)
      result = klass->start (parse);

    GST_OBJECT_LOCK (parse);
    gst_segment_init (&parse->segment, GST_FORMAT_TIME);
    parse->priv->duration = -1;
    parse->priv->discont = FALSE;
    parse->priv->flushing = FALSE;
    parse->priv->offset = 0;

    if (parse->pending_segment)
      gst_event_unref (parse->pending_segment);

    parse->pending_segment =
        gst_event_new_new_segment (FALSE, parse->segment.rate,
                                   parse->segment.format,
                                   parse->segment.start,
				   parse->segment.stop,
                                   parse->segment.last_stop);

    GST_OBJECT_UNLOCK (parse);
  }
  else {
    /* We must make sure streaming has finished before resetting things
    * and calling the ::stop vfunc */
    GST_PAD_STREAM_LOCK (parse->sinkpad);
    GST_PAD_STREAM_UNLOCK (parse->sinkpad);

    if (parse->priv->pad_mode != GST_ACTIVATE_NONE && klass->stop)
      result = klass->stop (parse);

    g_list_foreach (parse->priv->pending_events, (GFunc) gst_mini_object_unref, NULL);
    g_list_free (parse->priv->pending_events);
    parse->priv->pending_events = NULL;

    if (parse->priv->cache) {
      gst_buffer_unref (parse->priv->cache);
      parse->priv->cache = NULL;
    }

    parse->priv->pad_mode = GST_ACTIVATE_NONE;
  }
  GST_DEBUG_OBJECT (parse, "activate: %d", result);
  return result;
}


/**
 * gst_base_parse_sink_activate_push:
 * @pad: #GstPad to be (de)activated.
 * @active: TRUE when activating, FALSE when deactivating.
 *
 * Returns: TRUE if (de)activation succeeded.
 */
static gboolean
gst_base_parse_sink_activate_push (GstPad * pad, gboolean active)
{
  gboolean result = TRUE;
  GstBaseParse *parse;

  parse = GST_BASE_PARSE (gst_pad_get_parent (pad));
  
  GST_DEBUG_OBJECT (parse, "sink activate push");

  result = gst_base_parse_activate (parse, active);

  if (result)
    parse->priv->pad_mode = active ? GST_ACTIVATE_PUSH : GST_ACTIVATE_NONE;

  GST_DEBUG_OBJECT (parse, "sink activate push: %d", result);
  
  gst_object_unref (parse);
  return result;
}


/**
 * gst_base_parse_sink_activate_pull:
 * @sinkpad: #GstPad to be (de)activated.
 * @active: TRUE when activating, FALSE when deactivating.
 *
 * Returns: TRUE if (de)activation succeeded.
 */
static gboolean
gst_base_parse_sink_activate_pull (GstPad * sinkpad, gboolean active)
{
  gboolean result = FALSE;
  GstBaseParse *parse;

  parse = GST_BASE_PARSE (gst_pad_get_parent (sinkpad));

  GST_DEBUG_OBJECT (parse, "activate pull");

  result = gst_base_parse_activate (parse, active);

  if (result) {
    if (active) {
      result &= gst_pad_start_task (sinkpad,
                                    (GstTaskFunction) gst_base_parse_loop,
                                    sinkpad);
    } else {
      result &= gst_pad_stop_task (sinkpad);
    }
  }

  if (result)
    parse->priv->pad_mode = active ? GST_ACTIVATE_PULL : GST_ACTIVATE_NONE;

  GST_DEBUG_OBJECT (parse, "sink activate pull: %d", result);

  gst_object_unref (parse);
  return result;
}


/**
 * gst_base_parse_set_duration:
 * @parse: #GstBaseParse.
 * @fmt: #GstFormat.
 * @duration: duration value.
 *
 * Sets the duration of the currently playing media. Subclass can use this
 * when it notices a change in the media duration.
 */
void gst_base_parse_set_duration (GstBaseParse *parse,
                                  GstFormat fmt,
                                  gint64 duration)
{
  g_return_if_fail (parse != NULL);

  GST_BASE_PARSE_LOCK (parse);
  if (duration != parse->priv->duration) {
    GstMessage *m;

    m = gst_message_new_duration (GST_OBJECT (parse), fmt, duration);
    gst_element_post_message (GST_ELEMENT (parse), m);

    /* TODO: what about duration tag? */
  }
  parse->priv->duration = duration;
  parse->priv->duration_fmt = fmt;
  GST_DEBUG_OBJECT (parse, "set duration: %lld", duration);
  GST_BASE_PARSE_UNLOCK (parse);
}


/**
 * gst_base_parse_set_min_frame_size:
 * @parse: #GstBaseParse.
 * @min_size: Minimum size of the data that this base class should give to
 *            subclass.
 *
 * Subclass can use this function to tell the base class that it needs to
 * give at least #min_size buffers.
 */
void gst_base_parse_set_min_frame_size (GstBaseParse *parse, guint min_size)
{
  g_return_if_fail (parse != NULL);

  GST_BASE_PARSE_LOCK (parse);
  parse->priv->min_frame_size = min_size;
  GST_LOG_OBJECT (parse, "set frame_min_size: %d", min_size);
  GST_BASE_PARSE_UNLOCK (parse);
}


/**
 * gst_base_parse_get_querytypes:
 * @pad: GstPad
 *
 * Returns: A table of #GstQueryType items describing supported query types.
 */
static const GstQueryType *
gst_base_parse_get_querytypes (GstPad * pad)
{
  static const GstQueryType list[] = {
    GST_QUERY_POSITION,
    GST_QUERY_DURATION,
    GST_QUERY_FORMATS,
    GST_QUERY_SEEKING,
    GST_QUERY_CONVERT,
    0
  };

  return list;
}


/**
 * gst_base_parse_query:
 * @pad: #GstPad.
 * @query: #GstQuery.
 *
 * Returns: TRUE on success.
 */
static gboolean
gst_base_parse_query (GstPad * pad, GstQuery * query)
{
  GstBaseParse *parse;
  GstBaseParseClass *klass;
  gboolean res = FALSE;

  parse = GST_BASE_PARSE (GST_PAD_PARENT (pad));
  klass = GST_BASE_PARSE_GET_CLASS (parse);

  /* If subclass doesn't provide conversion function we can't reply
     to the query either */
  if (!klass->convert) {
    return FALSE;
  }

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

      GST_DEBUG_OBJECT (parse, "position query");

      gst_query_parse_position (query, &format, NULL);

      g_mutex_lock (parse->parse_lock);

      if (format == GST_FORMAT_BYTES) {
        dest_value = parse->priv->offset;
        res = TRUE;
      }
      else if (format == parse->segment.format &&
          GST_CLOCK_TIME_IS_VALID (parse->segment.last_stop))
      {
        dest_value = parse->segment.last_stop;
        res = TRUE;
      } else {
        /* priv->offset is updated in both PUSH/PULL modes */
        res = klass->convert (parse, GST_FORMAT_BYTES, parse->priv->offset,
                              format, &dest_value);
      }
      g_mutex_unlock (parse->parse_lock);

      if (res)
        gst_query_set_position (query, format, dest_value);
      else
        res = gst_pad_query_default (pad, query);

      break;
    }
    case GST_QUERY_DURATION:
    {
      GstFormat format;
      gint64 dest_value;

      GST_DEBUG_OBJECT (parse, "duration query");

      gst_query_parse_duration (query, &format, NULL);

      g_mutex_lock (parse->parse_lock);

      if (format == GST_FORMAT_BYTES) {
        res = gst_pad_query_peer_duration (parse->sinkpad, &format,
                                           &dest_value);
      }
      else if (parse->priv->duration != -1 &&
          format == parse->priv->duration_fmt)
      {
        dest_value = parse->priv->duration;
        res = TRUE;
      } else if (parse->priv->duration != -1) {
        res = klass->convert (parse, parse->priv->duration_fmt,
                              parse->priv->duration,
                              format, &dest_value);
      }

      g_mutex_unlock (parse->parse_lock);

      if (res)
        gst_query_set_duration (query, format, dest_value);
      else
        res = gst_pad_query_default (pad, query);
      break;
    }
    case GST_QUERY_SEEKING:
    {
      GstFormat fmt;
      gboolean seekable = FALSE;

      GST_DEBUG_OBJECT (parse, "seeking query");

      gst_query_parse_seeking (query, &fmt, NULL, NULL, NULL);

      if (fmt != GST_FORMAT_TIME)
      {
        return gst_pad_query_default (pad, query);
      }

      seekable = klass->is_seekable (parse);

      /* TODO: could this duration be calculated/converted if subclass
               hasn't given it? */
      gst_query_set_seeking (query, GST_FORMAT_TIME, seekable, 0,
                             (parse->priv->duration == -1) ?
                                 GST_CLOCK_TIME_NONE : parse->priv->duration);

      GST_DEBUG_OBJECT (parse, "seekable: %d", seekable);
      res = TRUE;
      break;
    }
    case GST_QUERY_FORMATS:
      gst_query_set_formatsv (query, 3, fmtlist);
      res = TRUE;
      break;

    case GST_QUERY_CONVERT:
    {
      GstFormat src_format, dest_format;
      gint64 src_value, dest_value;

      gst_query_parse_convert (query, &src_format, &src_value,
                               &dest_format, &dest_value);

      /* FIXME: hm? doesn't make sense 
       * We require all those values to be given
      if (src_format && src_value && dest_format && dest_value ) { */
        res = klass->convert (parse, src_format, src_value,
                              dest_format, &dest_value);
        if (res) {
          gst_query_set_convert (query, src_format, src_value,
                                 dest_format, dest_value);
        }
      /*}*/
      break;
    }
    default:
      res = gst_pad_query_default (pad, query);
      break;
  }
  return res;
}


/**
 * gst_base_parse_handle_seek:
 * @parse: #GstBaseParse.
 * @event: #GstEvent.
 *
 * Returns: TRUE if seek succeeded.
 */
static gboolean
gst_base_parse_handle_seek (GstBaseParse * parse, GstEvent * event)
{
  GstBaseParseClass *klass;
  gdouble rate;
  GstFormat format;
  GstSeekFlags flags;
  GstSeekType cur_type = GST_SEEK_TYPE_NONE, stop_type;
  gboolean flush, update, res = TRUE;
  gint64 cur, stop, seekpos;
  GstSegment seeksegment = { 0, };
  GstFormat dstformat;

  klass = GST_BASE_PARSE_GET_CLASS (parse);

  gst_event_parse_seek (event, &rate, &format, &flags,
                        &cur_type, &cur, &stop_type, &stop);

  /* no negative rates yet */
  if (rate < 0.0)
    goto negative_rate;

  if (cur_type != GST_SEEK_TYPE_SET)
    goto wrong_type;

  /* For any format other than TIME, see if upstream handles
   * it directly or fail. For TIME, try upstream, but do it ourselves if
   * it fails upstream */
  if (format != GST_FORMAT_TIME) {
    gst_event_ref (event);
    return gst_pad_push_event (parse->sinkpad, event);
  }
  else {
    gst_event_ref (event);
    if (gst_pad_push_event (parse->sinkpad, event))
      return TRUE;
  }

  /* get flush flag */
  flush = flags & GST_SEEK_FLAG_FLUSH;

  dstformat = GST_FORMAT_BYTES;
  if (!gst_pad_query_convert (parse->srcpad, format, cur,
                              &dstformat, &seekpos))
  {
    GST_DEBUG_OBJECT (parse, "conversion failed");
    return FALSE;
  }

  GST_DEBUG_OBJECT (parse, "seek position %lld in bytes: %lld", cur, seekpos);

  if (parse->priv->pad_mode == GST_ACTIVATE_PULL) {
    gint64 last_stop;

    GST_DEBUG_OBJECT (parse, "seek in PULL mode");

    if (flush) {
      if (parse->srcpad) {
        GST_DEBUG_OBJECT (parse, "sending flush start");
        gst_pad_push_event (parse->srcpad, gst_event_new_flush_start ());
      }
    }
    else {
      gst_pad_pause_task (parse->sinkpad);
    }

    /* we should now be able to grab the streaming thread because we stopped it
     * with the above flush/pause code */
    GST_PAD_STREAM_LOCK (parse->sinkpad);

    /* save current position */
    last_stop = parse->segment.last_stop;
    GST_DEBUG_OBJECT (parse, "stopped streaming at %" G_GINT64_FORMAT, last_stop);

    /* copy segment, we need this because we still need the old
     * segment when we close the current segment. */
    memcpy (&seeksegment, &parse->segment, sizeof (GstSegment));

    GST_DEBUG_OBJECT (parse, "configuring seek");
    gst_segment_set_seek (&seeksegment, rate, format, flags,
                          cur_type, cur, stop_type, stop, &update);

    /* figure out the last position we need to play. If it's configured (stop !=
     * -1), use that, else we play until the total duration of the file */
    if ((stop = seeksegment.stop) == -1)
      stop = seeksegment.duration;

    parse->priv->offset = seekpos;

    /* prepare for streaming again */
    if (flush) {
      GST_DEBUG_OBJECT (parse, "sending flush stop");
      gst_pad_push_event (parse->srcpad, gst_event_new_flush_stop ());
    }
    else {
      if (parse->close_segment)
        gst_event_unref (parse->close_segment);

      parse->close_segment = gst_event_new_new_segment (TRUE,
          parse->segment.rate, parse->segment.format,
          parse->segment.accum, parse->segment.last_stop,
          parse->segment.accum);

      /* keep track of our last_stop */
      seeksegment.accum = parse->segment.last_stop;

      GST_DEBUG_OBJECT (parse, "Created close seg format %d, "
          "start = %" GST_TIME_FORMAT ", stop = %" GST_TIME_FORMAT
          ", pos = %" GST_TIME_FORMAT, format,
          GST_TIME_ARGS (parse->segment.accum),
          GST_TIME_ARGS (parse->segment.last_stop),
          GST_TIME_ARGS (parse->segment.accum));
    }

    memcpy (&parse->segment, &seeksegment, sizeof (GstSegment));

    /* store the newsegment event so it can be sent from the streaming thread.*/
    if (parse->pending_segment)
      gst_event_unref (parse->pending_segment);

    /* This will be sent later in _loop() */
    parse->pending_segment =
        gst_event_new_new_segment (FALSE, parse->segment.rate,
                                   parse->segment.format,
                                   parse->segment.last_stop, stop,
                                   parse->segment.last_stop);

    GST_DEBUG_OBJECT (parse, "Created newseg format %d, "
        "start = %" GST_TIME_FORMAT ", stop = %" GST_TIME_FORMAT
        ", pos = %" GST_TIME_FORMAT, format,
        GST_TIME_ARGS (parse->segment.last_stop),
        GST_TIME_ARGS (stop),
        GST_TIME_ARGS (parse->segment.last_stop));

    /* mark discont if we are going to stream from another position. */
    if (last_stop != parse->segment.last_stop) {
      GST_DEBUG_OBJECT (parse, "mark DISCONT, we did a seek to another position");
      parse->priv->discont = TRUE;
    }

    /* Start streaming thread if paused */
    gst_pad_start_task (parse->sinkpad,
                        (GstTaskFunction) gst_base_parse_loop,
                         parse->sinkpad);

    GST_PAD_STREAM_UNLOCK (parse->sinkpad);
  }
  else {
    GstEvent *new_event;
    /* The only thing we need to do in PUSH-mode is to send the
       seek event (in bytes) to upstream. Segment / flush handling happens
       in corresponding src event handlers */
    GST_DEBUG_OBJECT (parse, "seek in PUSH mode");
    new_event = gst_event_new_seek(rate, GST_FORMAT_BYTES, flush,
                                             GST_SEEK_TYPE_SET, seekpos,
                                             stop_type, stop);

    res = gst_pad_push_event (parse->sinkpad, new_event);
  }

done:
  return res;

  /* ERRORS */
negative_rate:
  {
    GST_DEBUG_OBJECT (parse, "negative playback rates are not supported yet.");
    res = FALSE;
    goto done;
  }
wrong_type:
  {
    GST_DEBUG_OBJECT (parse, "unsupported seek type.");
    res = FALSE;
    goto done;
  }
}


/**
 * gst_base_parse_sink_setcaps:
 * @pad: #GstPad.
 * @caps: #GstCaps.
 *
 * Returns: TRUE if caps were accepted.
 */
static gboolean
gst_base_parse_sink_setcaps (GstPad * pad, GstCaps * caps)
{
  GstBaseParse *parse;
  GstBaseParseClass *klass;
  gboolean res = TRUE;

  gchar *caps_str = gst_caps_to_string (caps);
  g_free (caps_str);

  parse = GST_BASE_PARSE (gst_pad_get_parent (pad));
  klass = GST_BASE_PARSE_GET_CLASS (parse);
  
  GST_DEBUG_OBJECT (parse, "setcaps: %s", caps_str);

  if (klass->set_sink_caps)
    res = klass->set_sink_caps (parse, caps);

  parse->negotiated = res;
  gst_object_unref (parse);
  return gst_pad_set_caps (pad, caps);
}

