gstreamer/gst/mpegdemux/gstsectionfilter.c

 /*
  * This library is licensed under 2 different licenses and you
  * can choose to use it under the terms of either one of them. The
  * two licenses are the MPL 1.1 and the LGPL.
  *
  * MPL:
  *
  * The contents of this file are subject to the Mozilla Public License
  * Version 1.1 (the "License"); you may not use this file except in
  * compliance with the License. You may obtain a copy of the License at
  * http://www.mozilla.org/MPL/.
  *
  * Software distributed under the License is distributed on an "AS IS"
  * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
  * License for the specific language governing rights and limitations
  * under the License.
  *
  * LGPL:
  *
  * 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.
  *
  * The Original Code is Fluendo MPEG Demuxer plugin.
  *
  * The Initial Developer of the Original Code is Fluendo, S.L.
  * Portions created by Fluendo, S.L. are Copyright (C) 2005
  * Fluendo, S.L. All Rights Reserved.
  *
  * Contributor(s): Wim Taymans <wim@fluendo.com>
  */

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

#include "gstsectionfilter.h"

#ifndef __always_inline
#if (__GNUC__ > 3) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 1)
#define __always_inline inline __attribute__((always_inline))
#else
#define __always_inline inline
#endif
#endif

#ifndef DISABLE_INLINE
#define FORCE_INLINE __always_inline
#else
#define FORCE_INLINE
#endif

GST_DEBUG_CATEGORY (gstflusectionfilter_debug);
#define GST_CAT_DEFAULT (gstflusectionfilter_debug)

void
gst_section_filter_init (GstSectionFilter * filter)
{
  g_return_if_fail (filter != NULL);
  filter->adapter = gst_adapter_new ();
  /* continuity counter can at max be 15
   * we make 255 as an indication that
   * there is no last continuity counter */
  filter->last_continuity_counter = 255;
  filter->section_length = G_MAXUINT16;
}

void
gst_section_filter_uninit (GstSectionFilter * filter)
{
  g_return_if_fail (filter != NULL);
  if (filter->adapter)
    g_object_unref (filter->adapter);
  filter->adapter = NULL;
}

void
gst_section_filter_clear (GstSectionFilter * filter)
{
  g_return_if_fail (filter != NULL);
  if (filter->adapter) {
    gst_adapter_clear (filter->adapter);
    filter->last_continuity_counter = 255;
    filter->section_length = G_MAXUINT16;
  }
}

static FORCE_INLINE gboolean
gst_section_is_complete (GstSectionFilter * filter)
{
  /* section length measures size of section from 3 bytes into section
   * (ie after section length field finished) until end of section)
   */
  guint avail_bytes = gst_adapter_available (filter->adapter);
  if (filter->section_length == avail_bytes - 3) {
    return TRUE;
  } else if (filter->section_length < (int) (avail_bytes - 3)) {
    GST_DEBUG ("section length seems to be less than available bytes for "
        "rest of section.");
    return TRUE;
  }
  return FALSE;
}

/* returns True when section finished and ready to parse */
/* FIXME: especially for multi-section tables, we need to handle pusi correctly
 * and handle cases where a new section starts in the same transport packet.
 */
gboolean
gst_section_filter_push (GstSectionFilter * filter, gboolean pusi,      /* determines whether start or not */
    guint8 continuity_counter, GstBuffer * buf)
{
  g_return_val_if_fail (filter != NULL, FALSE);

  /* check if it's the first packet of a section or
   * if it continues the section */
  if (pusi) {
    const guint8 *data = GST_BUFFER_DATA (buf);
    if (filter->last_continuity_counter != 255) {
      GST_WARNING ("section lost, last continuity counter: %d, "
          "we now have a pusi at continuity counter: %d",
          filter->last_continuity_counter, continuity_counter);
      gst_section_filter_clear (filter);
    }
    filter->section_length = GST_READ_UINT16_BE (data + 1);
    filter->section_length &= 0x0fff;
    if (filter->section_length > 4093) {
      GST_DEBUG ("section length too big");
      goto failure;
    }
    gst_adapter_push (filter->adapter, buf);
    filter->last_continuity_counter = continuity_counter;
    return gst_section_is_complete (filter);
  } else if (filter->last_continuity_counter == continuity_counter - 1 ||
      (filter->last_continuity_counter == 15 && continuity_counter == 0)) {
    GST_DEBUG ("section still going, no pusi");
    gst_adapter_push (filter->adapter, buf);
    filter->last_continuity_counter = continuity_counter;
    return gst_section_is_complete (filter);
  }
  /* we have lost the section and we are not a start
   * section, so clear what was in it */
  else {
    GST_WARNING ("section lost, last continuity counter: %d, "
        "new continuity counter but not pusi: %d",
        filter->last_continuity_counter, continuity_counter);
    gst_section_filter_clear (filter);
    goto failure;
  }
failure:
  gst_buffer_unref (buf);
  return FALSE;
}